Patent Publication Number: US-2022216564-A1

Title: Secondary battery

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of PCT patent application no. PCT/JP2020/033530, filed on Sep. 4, 2020, which claims priority to Japanese patent application no. JP2019-178787 filed on Sep. 30, 2019, the entire contents of which are being incorporated herein by reference. 
    
    
     BACKGROUND 
     The present technology generally relates to a secondary battery. 
     Various kinds of electronic equipment, including mobile phones, have been widely used. Such widespread use has promoted development of a secondary battery as a power source that is smaller in size and lighter in weight and allows for a higher energy density. A configuration of the secondary battery influences a battery characteristic and has therefore been considered in various ways. 
     Specifically, in order to decrease an electric coupling resistance, a plurality of positive electrode leads and a plurality of negative electrode leads are used. In order to improve a charge and discharge cyclability life under a heavy load condition, a negative electrode is provided with a plurality of lead terminals. In order to prevent a short circuit, etc., a positive electrode lead and a negative electrode lead are each provided with an insulating cover. Other than the above, in order to achieve various purposes in a secondary battery including an outer package member such as a laminated film, a configuration such as a shape of a tab, a shape of a lead, or a sealing structure is made appropriate. 
     SUMMARY 
     The present technology generally relates to a secondary battery. 
     Although consideration has been given in various ways to solve problems of a secondary battery, the secondary battery has not yet achieved sufficient reliability related to a wiring structure inside the secondary battery, and there is still room for improvement in terms thereof. 
     The present technology has been made in view of such an issue and it is an object of the technology to provide a secondary battery that makes it possible to secure higher reliability related to a wiring structure inside thereof. 
     A secondary battery according to an embodiment of the present technology includes an outer package member, a battery device, a first wiring member, second wiring members, and a first insulating member. The outer package member has flexibility. The battery device is accommodated inside the outer package member. The first wiring member extends from an inside to an outside of the outer package member and includes an opposed part opposed to the battery device. The opposed part includes an opposed surface, an opposite surface, and a side surface. The opposed surface is opposed to the battery device. The opposite surface is provided on an opposite side to the opposed surface. The side surface is coupled to the opposed surface and the opposite surface. The second wiring members are disposed inside the outer package member. Each of the second wiring members has a first end coupled to the battery device and a second end coupled to the opposed part at the opposite surface. A portion of each of the second wiring members is bent to lie along the opposed surface, the side surface, and the opposite surface in this order. The first insulating member is disposed to lie along the opposed surface between the opposed part and a portion of the second wiring members. 
     According to the secondary battery of an embodiment of the present technology, the battery device is accommodated inside the outer package member having flexibility. The first wiring member extending from the inside to the outside of the outer package member includes the opposed part opposed to the battery device, and the opposed part includes the opposed surface, the side surface, and a non-opposed surface. The second wiring members are disposed inside the outer package member, and each of the second wiring members has the first end coupled to the battery device and the second end coupled to the opposed part at the opposite surface. A portion of each of the second wiring members is bent to lie along the opposed surface, the side surface, and the opposite surface in this order, and the first insulating member is disposed to lie along the opposed surface between the opposed part and a portion of the second wiring members. Accordingly, it is possible to secure higher reliability related to the wiring structure inside the secondary battery. 
     It should be understood that effects of the technology are not necessarily limited to those described above and may include any of a series of effects described below in relation to the technology. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of a configuration of a secondary battery according to an embodiment of the present technology. 
         FIG. 2  is a perspective view of a configuration of a battery device illustrated in  FIG. 1 . 
         FIG. 3  is a sectional view of respective configurations of a positive electrode and a negative electrode according to an embodiment of the present technology. 
         FIG. 4  is a sectional view of the configuration of the secondary battery illustrated in  FIG. 1 . 
         FIG. 5  is another sectional view of the configuration of the secondary battery illustrated in  FIG. 1 . 
         FIG. 6  is a sectional diagram for describing a manufacturing process of the secondary battery according to an embodiment of the present technology. 
         FIG. 7  is another sectional diagram for describing the manufacturing process of the secondary battery according to an embodiment of the present technology. 
         FIG. 8  is a sectional view of a configuration of a secondary battery of a first comparative example. 
         FIG. 9  is a sectional view of a configuration of a secondary battery of a second comparative example. 
         FIG. 10  is a block diagram illustrating a configuration of an application example of the secondary battery according to an embodiment, which is a battery pack including a single battery. 
         FIG. 11  is a block diagram illustrating a configuration of an application example of the secondary battery according to an embodiment, which is a battery pack including an assembled battery. 
         FIG. 12  is a block diagram illustrating a configuration of an application example of the secondary battery according to an embodiment, which is an electric vehicle. 
     
    
    
     DETAILED DESCRIPTION 
     As described herein, the present disclosure will be described based on examples with reference to the drawings, but the present disclosure is not to be considered limited to the examples, and various numerical values and materials in the examples are considered by way of example. 
     A description is given first of a secondary battery according to an embodiment of the present technology. 
     The secondary battery to be described here is a secondary battery that obtains a battery capacity using insertion and extraction of an electrode reactant, and includes a positive electrode, a negative electrode, and an electrolytic solution. In the secondary battery, to prevent precipitation of the electrode reactant on a surface of the negative electrode during charging, a charge capacity of the negative electrode is greater than a discharge capacity of the positive electrode. In other words, an electrochemical capacity per unit area of the negative electrode is greater than an electrochemical capacity per unit area of the positive electrode. 
     Although not particularly limited in kind, the electrode reactant is a light metal such as an alkali metal or an alkaline earth metal. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the alkaline earth metal include beryllium, magnesium, and calcium. 
     Examples are given below of a case where the electrode reactant is lithium. A secondary battery that obtains a battery capacity using insertion and extraction of lithium is a so-called lithium-ion secondary battery. In the lithium-ion secondary battery, lithium is inserted and extracted in an ionic state. 
       FIG. 1  illustrates a perspective configuration of the secondary battery.  FIG. 2  illustrates a perspective configuration of a battery device  20  illustrated in  FIG. 1 .  FIG. 3  illustrates respective sectional configurations of a positive electrode  21  and a negative electrode  22 .  FIGS. 4 and 5  each illustrate a sectional configuration of the secondary battery illustrated in  FIG. 1 . It should be understood that in  FIG. 3 , the positive electrode  21  and the negative electrode  22  are illustrated together because the positive electrode  21  and the negative electrode  22  have a common configuration.  FIG. 4  illustrates a section taken along a line A-A.  FIG. 5  illustrates a section taken along a line B-B. 
     In the following description, a vertical direction in  FIGS. 4 and 5  is regarded as a height direction of the secondary battery, and a horizontal direction in  FIGS. 4 and 5  is regarded as a width direction of the secondary battery. Further, in the height direction of the secondary battery, an up direction in  FIGS. 4 and 5  is regarded as an upper side of the secondary battery, and a down direction in  FIGS. 4 and 5  is regarded as a lower side of the secondary battery. 
     As illustrated in  FIGS. 1 to 5 , the secondary battery includes an outer package film  10 , the battery device  20 , a positive electrode wiring line  200 , a negative electrode wiring line  300 , a positive electrode sealant  70 , a negative electrode sealant  80 , positive electrode insulating tapes  90  and  100 , negative electrode insulating tapes  110  and  120 , and an auxiliary insulating tape  130 . The positive electrode wiring line  200  includes a positive electrode lead  30  and positive electrode tabs  50 . The negative electrode wiring line  300  includes a negative electrode lead  40  and negative electrode tabs  60 . 
     In the secondary battery, the battery device  20  is contained inside the outer package film  10 . The positive electrode wiring line  200  and the negative electrode wiring line  300  are coupled to the battery device  20 . The positive electrode wiring line  200  and the negative electrode wiring line  300  are led out in a common direction from an inside to an outside of the outer package film  10 . 
     In other words, the secondary battery described here is a secondary battery of a laminated-film type in which the outer package film  10  is used as an outer package member to contain the battery device  20 . Here, the secondary battery has a flat three-dimensional shape. 
     The outer package film  10  is an outer package member having flexibility or softness. More specifically, as illustrated in  FIGS. 1, 3, and 4 , the outer package film  10  is a member having a hollow pouch shape. The outer package film  10  includes one or more of materials including, without limitation, a polymer material and a metal material. 
     Specifically, the outer package film  10  is a three-layer laminated film including a fusion-bonding layer, a metal layer, and a surface protective layer that are stacked in this order from an inner side. The fusion-bonding layer is a polymer film including a polymer material such as polypropylene, and is fusion-bondable by a method such as a thermal fusion bonding method. The metal layer is a metal foil including a metal material such as aluminum. The surface protective layer is a polymer film including a polymer material such as nylon. The number of layers of the outer package film  10  as a laminated film is not particularly limited, and may be two, or four or more. It goes without saying that the outer package film  10  is not limited to a multilayer film, and may be a single-layer film. 
     The outer package film  10  has an opening  10 K 1  through which the positive electrode wiring line  200  is to be led out and an opening  10 K 2  through which the negative electrode wiring line  300  is to be led out. The opening  10 K 1  is sealed by means of the positive electrode sealant  70  in a state where the positive electrode wiring line  200  is led out to the outside of the outer package film  10  via the opening  10 K 1 , as will be described later. In addition, the opening  10 K 2  is sealed by means of the negative electrode sealant  80  in a state where the negative electrode wiring line  300  is led out to the outside of the outer package film  10  via the opening  10 K 2 , as will be described later. 
     It should be understood that the outer package film  10  is formed by sealing an opening  10 K, which will be described later with reference to  FIGS. 6 and 7 , in a state where the positive electrode wiring line  200  and the negative electrode wiring line  300  are each led out via the opening  10 K. Specifically, in a manufacturing process of the secondary battery, portions of the outer package film  10  opposed to each other at the opening  10 K are joined to each other with the positive electrode wiring line  200 , the negative electrode wiring line  300 , the positive electrode sealant  70 , and the negative electrode sealant  80  interposed therebetween, to thereby seal the outer package film  10  except for the openings  10 K 1  and  10 K 2 . As a result, the outer package film  10  has a seal part S at which the opening  10 K is sealed. 
     The battery device  20  is a device causing charging and discharging reactions to proceed. As illustrated in  FIGS. 2 to 5 , the battery device  20  is contained inside the outer package film  10 . The battery device  20  includes the positive electrode  21 , the negative electrode  22 , a separator  23 , and an electrolytic solution which is a liquid electrolyte. It should be understood that  FIGS. 2 to 5  each omit the illustration of the electrolytic solution. 
     The positive electrode  21  and the negative electrode  22  are wound with the separator  23  interposed therebetween. More specifically, the positive electrode  21  and the negative electrode  22  are stacked on each other with the separator  23  interposed therebetween, and are wound in the state of the stack with the separator  23  interposed between the positive electrode  21  and the negative electrode  22 . Thus, the battery device  20  is a wound electrode body including the positive electrode  21  and the negative electrode  22  that are wound with the separator  23  interposed therebetween. The respective numbers of winds of the positive electrode  21 , the negative electrode  22 , and the separator  23  are not particularly limited, and may be freely chosen. 
     It should be understood that the positive electrode  21  has a height smaller than that of the separator  23 . A reason for this is that this prevents a short circuit caused by the positive electrode  21 . The negative electrode  22  has a height smaller than that of the separator  23  and larger than that of the positive electrode  21 . A reason for this is that this prevents a short circuit caused by the negative electrode  22  and also prevents a short circuit between the positive electrode  21  and the negative electrode  22  caused by precipitation of lithium upon charging and discharging. 
     The positive electrode  21  is an electrode included in the battery device  20 . The positive electrode  21  includes a positive electrode current collector  21 A (a current collector) and a positive electrode active material layer  21 B (an active material layer). The positive electrode current collector  21 A is a metal foil including a metal material such as aluminum. The positive electrode active material layer  21 B is provided on each of opposite sides of the positive electrode current collector  21 A. It should be understood that the positive electrode active material layer  21 B may be provided only on one side of the positive electrode current collector  21 A. The positive electrode active material layer  21 B includes a positive electrode active material into which lithium is insertable and from which lithium is extractable. The positive electrode active material includes one or more of lithium-containing compounds including, without limitation, a lithium-containing transition metal compound. Examples of the lithium-containing transition metal compound include an oxide, a phosphoric acid compound, a silicic acid compound, and a boric acid compound each including lithium and one or more transition metal elements as constituent elements. It should be understood that the positive electrode active material layer  21 B may further include, for example, a positive electrode binder and a positive electrode conductor. 
     The negative electrode  22  is another electrode included in the battery device  20 . The negative electrode  22  includes a negative electrode current collector  22 A (another current collector) and a negative electrode active material layer  22 B (another active material layer). The negative electrode current collector  22 A is a metal foil including a metal material such as copper. The negative electrode active material layer  22 B is provided on each of opposite sides of the negative electrode current collector  22 A. It should be understood that the negative electrode active material layer  22 B may be provided only on one side of the negative electrode current collector  22 A. The negative electrode active material layer  22 B includes a negative electrode active material into which lithium is insertable and from which lithium is extractable. The negative electrode active material includes one or more of materials including, without limitation, a carbon material and a metal-based material. Examples of the carbon material include graphite. The metal-based material is a material that includes, as a constituent element or constituent elements, one or more elements among metal elements and metalloid elements that are each able to form an alloy with lithium. Specifically, the metal-based material includes one or more of elements including, without limitation, silicon and tin. The metal-based material may be a simple substance, an alloy, a compound, or a mixture of two or more thereof. It should be understood that the negative electrode active material layer  22 B may further include, for example, a negative electrode binder and a negative electrode conductor. 
     The separator  23  is an insulating porous film interposed between the positive electrode  21  and the negative electrode  22 . The separator  23  allows lithium to pass therethrough while preventing a short circuit between the positive electrode  21  and the negative electrode  22 . This separator  23  includes one or more of polymer materials including, without limitation, polyethylene. 
     The positive electrode  21 , the negative electrode  22 , and the separator  23  are each impregnated with the electrolytic solution. The electrolytic solution includes a solvent and an electrolyte salt. The solvent includes one or more of nonaqueous solvents (organic solvents) including, without limitation, a carbonic-acid-ester-based compound, a carboxylic-acid-ester-based compound, and a lactone-based compound. The electrolyte salt includes one or more of light metal salts including, without limitation, a lithium salt. 
     In the battery device  20  which is the wound electrode body, the positive electrode active material layer  21 B is provided on a portion of the positive electrode current collector  21 A, and the negative electrode active material layer  22 B is provided on a portion of the negative electrode current collector  22 A. 
     Specifically, at each of ends of the positive electrode  21  on an inner side and an outer side of winding, the positive electrode active material layer  21 B is not provided on the positive electrode current collector  21 A, and the positive electrode current collector  21 A thus has exposed parts  21 AH at respective opposite ends. Accordingly, the positive electrode  21  has a foil winding structure in which only the positive electrode current collector  21 A is wound at each of the ends on the inner side and the outer side of the winding. 
     Similarly, at each of ends of the negative electrode  22  on the inner side and the outer side of the winding, the negative electrode active material layer  22 B is not provided on the negative electrode current collector  22 A, and the negative electrode current collector  22 A thus has exposed parts  22 AH at respective opposite ends. Accordingly, the negative electrode  22  has a foil winding structure in which only the negative electrode current collector  22 A is wound at each of the ends on the inner side and the outer side of the winding. 
     It should be understood that  FIG. 2  also illustrates a wound body  20 Z to be used to fabricate the battery device  20  in the manufacturing process of the secondary battery to be described later. The wound body  20 Z has a configuration similar to that of the battery device  20  which is the wound electrode body, except that the positive electrode  21 , the negative electrode  22 , and the separator  23  are each yet to be impregnated with the electrolytic solution. 
     The positive electrode wiring line  200  extends from the inside of the outer package film  10  to the outside of the outer package film  10  via the opening  10 K 1 , and is coupled to the positive electrode  21  of the battery device  20 . The negative electrode wiring line  300  extends from the inside of the outer package film  10  to the outside of the outer package film  10  via the opening  10 K 2 , and is coupled to the negative electrode  22  of the battery device  20 . 
     As illustrated in  FIGS. 1 and 4 , the positive electrode lead  30  is a first wiring member that extends from the inside of the outer package film  10  to the outside of the outer package film  10  via the opening  10 K 1 . 
     One end of the positive electrode lead  30  is coupled to another end of each of the positive electrode tabs  50  inside the outer package film  10 . Here, the one end of the positive electrode lead  30  is coupled to a joint part J 1 , which will be described later, to thereby form a coupling part C 1 . The coupling part C 1  is a part at which the positive electrode lead  30  and the joint part J 1  are coupled to each other by a method such as a welding method. Another end of the positive electrode lead  30  is led out to the outside of the outer package film  10 . 
     Here, inside the outer package film  10 , the positive electrode lead  30  is bent in a direction intersecting with a direction in which the positive electrode lead  30  is led out from the outer package film  10 , i.e., is bent in a horizontal direction in  FIG. 4  intersecting with a vertical direction in  FIG. 4 . The positive electrode lead  30  thus includes lead parts  30 A and  30 B. 
     The lead part  30 A is a part that extends from the inside of the outer package film  10  to the outside of the outer package film  10  via the opening  10 K 1 . The lead part  30 B is an opposed part that extends in a direction intersecting with a direction in which the lead part  30 A extends, while being opposed to the battery device  20  inside the outer package film  10 . The lead part  30 B is coupled to the lead part  30 A. 
     The lead part  30 B includes a lower surface M 1 , an upper surface M 2 , and a side surface M 3 . The lower surface M 1  is a surface with which the lead part  30 B is opposed to the battery device  20 , i.e., is an opposed surface. The upper surface M 2  is a surface provided on an opposite side to the lower surface M 1 , i.e., is an opposite surface. The side surface M 3  is a surface positioned between the lower surface M 1  and the upper surface M 2  and coupled to both the lower surface M 1  and the upper surface M 2 . 
     It should be understood that, as long as the lead part  30 B is opposed to the battery device  20 , the lower surface M 1  of the lead part  30 B may be parallel to an upper surface  20 M of the battery device  20 , or may be inclined with respect to the upper surface  20 M. The angle at which the lower surface M 1  is inclined with respect to the upper surface  20 M is not particularly limited as long as the angle secures the opposed relationship between the lead part  30 B and the battery device  20 . 
     The positive electrode lead  30  includes a material similar to a material included in the positive electrode current collector  21 A. It should be understood that the material included in the positive electrode lead  30  may be the same as or different from the material included in the positive electrode current collector  21 A. 
     The negative electrode lead  40  has a configuration similar to the configuration of the positive electrode lead  30  described above. That is, as illustrated in  FIG. 5 , the negative electrode lead  40  is another first wiring member that extends from the inside of the outer package film  10  to the outside of the outer package film  10  via the opening  10 K 2 . 
     One end of the negative electrode lead  40  is coupled to another end of each of the negative electrode tabs  60  inside the outer package film  10 . Here, the one end of the negative electrode lead  40  is coupled to a joint part J 2 , which will be described later, to thereby form a coupling part C 2 . The coupling part C 2  is a part at which the negative electrode lead  40  and the joint part J 2  are coupled to each other by a method such as a welding method. Another end of the negative electrode lead  40  is led out to the outside of the outer package film  10 . 
     Here, inside the outer package film  10 , the negative electrode lead  40  is bent in a direction intersecting with a direction in which the negative electrode lead  40  is led out from the outer package film  10 , i.e., is bent in a horizontal direction in  FIG. 5  intersecting with a vertical direction in  FIG. 5 . The negative electrode lead  40  thus includes lead parts  40 A and  40 B. 
     The lead part  40 A is a part that extends from the inside of the outer package film  10  to the outside of the outer package film  10  via the opening  10 K 2 . The lead part  40 B is another opposed part that extends in a direction intersecting with a direction in which the lead part  40 A extends, while being opposed to the battery device  20  inside the outer package film  10 . The lead part  40 B is coupled to the lead part  40 A. 
     The lead part  40 B includes a lower surface N 1 , an upper surface N 2 , and a side surface N 3 . The lower surface N 1  is a surface with which the lead part  40 B is opposed to the battery device  20 , i.e., is another opposed surface. The upper surface N 2  is a surface provided on an opposite side to the lower surface N 1 , i.e., is another opposite surface. The side surface N 3  is a surface positioned between the lower surface N 1  and the upper surface N 2  and coupled to both the lower surface N 1  and the upper surface N 2 . 
     It should be understood that, as long as the lead part  40 B is opposed to the battery device  20 , the lower surface N 1  of the lead part  40 B may be parallel to the upper surface  20 M of the battery device  20 , or may be inclined with respect to the upper surface  20 M. The angle at which the lower surface N 1  is inclined with respect to the upper surface  20 M is not particularly limited as long as the angle secures the opposed relationship between the lead part  40 B and the battery device  20 . 
     The negative electrode lead  40  includes a material similar to a material included in the negative electrode current collector  22 A. It should be understood that the material included in the negative electrode lead  40  may be the same as or different from the material included in the negative electrode current collector  22 A. 
     As illustrated in  FIG. 4 , the positive electrode tabs  50  are second wiring members disposed inside the outer package film  10 . A reason why the positive electrode tabs  50  are plural in number is that this allows for a decrease in electric resistance (electric coupling resistance) of the battery device  20  (the positive electrode  21 ). 
     The secondary battery described here includes two positive electrode tabs  50 , i.e., positive electrode tabs  51  and  52 , which are the minimum number of positive electrode tabs  50 . 
     A reason for this is that the electric resistance of the battery device  20  decreases as described above, as compared to a case where the number of the positive electrode tabs  50  is one. Another reason is that, in a case where the number of the positive electrode leads  30  is set to two or more, the positive electrode leads  30  have to be led out from the outer package film  10  to the outside separately from each other, or have to be led out from the outer package film  10  to the outside while being stacked on each other, which results in an increase in the number of the seal parts S or complication of a sealing structure of the seal part S. This causes reliability of the seal part S to be lowered easily. 
     The number of the positive electrode tabs  50  is not particularly limited and is therefore freely chosen. However, in order to decrease the electric resistance of the battery device  20  and to reduce volume loss related to an inner space of the outer package film  10 , the number of the positive electrode tabs  50  is preferably three or less, and more preferably two or less. In addition, in order to reduce the above-described volume loss, the thickness of the positive electrode tabs  50  is preferably smaller than the thickness of the positive electrode lead  30 . 
     One end of each of the positive electrode tabs  51  and  52  is coupled to the battery device  20 , more specifically, to the positive electrode  21  (the positive electrode current collector  21 A). Another end of the positive electrode tab  51  and another end of the positive electrode tab  52  are in contact with each other. Here, the positive electrode tabs  51  and  52  are joined to each other, to thereby form the joint part J 1 . The joint part J 1  is a part at which the other end of the positive electrode tab  51  and the other end of the positive electrode tab  52  are joined to each other by a method such as a welding method. 
     The joint part J 1  is coupled to the one end of the positive electrode lead  30  to thereby form the coupling part C 1 , as described above. Here, the positive electrode lead  30  includes the lead part  30 B inside the outer package film  10  as described above, and accordingly, the joint part J 1  is coupled to the lead part  30 B. In this case, the joint part J 1  is coupled to the lead part  30 B at the upper surface M 2 . 
     In order to form the coupling part C 1 , a portion of the positive electrode tabs  51  and  52 , i.e., the positive electrode tab  51 , is bent to lie along a surface of the lead part  30 B. Specifically, the positive electrode tab  51  is bent to lie along the lower surface Ml, the side surface M 3 , and the upper surface M 2  in this order. The joint part J 1  is thus coupled to the lead part  30 B at the upper surface M 2 , as described above. 
     Each of the positive electrode tabs  51  and  52  includes a material similar to the material included in the positive electrode current collector  21 A. It should be understood that the material included in each of the positive electrode tabs  51  and  52  may be the same as or different from the material included in the positive electrode current collector  21 A. 
     A position of coupling between each of the positive electrode tabs  51  and  52  and the positive electrode  21  is not particularly limited. Here, because the positive electrode  21  is wound in the battery device  20  which is the wound electrode body, the positive electrode tab  51  is coupled to the end (the exposed part  21 AH) of the positive electrode  21  on the inner side of the winding, and the positive electrode tab  52  is coupled to the end (the exposed part  21 AH) of the positive electrode  21  on the outer side of the winding. In other words, because the positive electrode  21  has the foil winding structure, as described above, each of the positive electrode tabs  51  and  52  is coupled to the positive electrode current collector  21 A. A reason for this is that this allows an electric coupling characteristic obtained with use of the positive electrode current collector  21 A to be uniform, making it easier for the charging and discharging reactions to proceed uniformly in the positive electrode  21 . 
     In this case, the positive electrode tabs  51  and  52  are preferably coupled to the positive electrode current collector  21 A (the respective exposed parts  21 AH) at respective positions symmetrical with respect to the center of the positive electrode current collector  21 A in the extending direction of the positive electrode current collector  21 A illustrated in  FIG. 3 . In other words, a distance from the center position of the positive electrode current collector  21 A in the extending direction thereof to the position of coupling between the positive electrode tab  51  and the positive electrode current collector  21 A and a distance from the above-described center position of the positive electrode current collector  21 A to the position of coupling between the positive electrode tab  52  and the positive electrode current collector  21 A are preferably substantially equal. A reason for this is that this allows the electric coupling characteristic obtained with use of the positive electrode current collector  21 A to be more uniform. 
     Although the positive electrode tab  52  is coupled to the positive electrode current collector  21 A (the exposed part  21 AH) on the right side in  FIG. 4  here, the position at which the positive electrode tab  52  is coupled to the positive electrode current collector  21 A is not particularly limited. For example, the positive electrode tab  52  may be coupled to the positive electrode current collector  21 A on the left side in  FIG. 4 . However, in order to allow the length of the positive electrode tab  52  to be short, the positive electrode tab  52  is preferably coupled to the positive electrode current collector  21 A on the right side in  FIG. 4 , i.e., on a side closer to a side to which the positive electrode tab  51  is bent. 
     The negative electrode tabs  60  have a configuration similar to the configuration of the positive electrode tabs  50  described above. That is, as illustrated in  FIG. 5 , the negative electrode tabs  60  are other second wiring members disposed inside the outer package film  10 . A reason why the negative electrode tabs  60  are plural in number is that this allows for a decrease in electric resistance (electric coupling resistance) of the battery device  20  (the negative electrode  22 ). 
     The secondary battery described here includes two negative electrode tabs  60 , i.e., negative electrode tabs  61  and  62 , which are the minimum number of negative electrode tabs  60 . A reason for this is that, in a case where the number of the negative electrode lead  40  is set to two or more, reliability of the seal part S is lowered easily for a reason similar to the reason described above in relation to the two positive electrode tabs  50 , i.e., the positive electrode tabs  51  and  52 . 
     The number of the negative electrode tabs  60  is not particularly limited and is therefore freely chosen. However, the number of the negative electrode tabs  60  is preferably three or less, and more preferably two or less, for a reason similar to that described above in relation to the number of the positive electrode tabs  50 . 
     One end of each of the negative electrode tabs  61  and  62  is coupled to the battery device  20 , more specifically, to the negative electrode  22  (the negative electrode current collector  22 A). Another end of the negative electrode tab  61  and another end of the negative electrode tab  62  are in contact with each other. Here, the negative electrode tabs  61  and  62  are joined to each other, to thereby form the joint part J 2 . The joint part J 2  is a part at which the other end of the negative electrode tab  61  and the other end of the negative electrode tab  62  are joined to each other by a method such as a welding method. 
     The joint part J 2  is coupled to the one end of the negative electrode lead  40  to thereby form the coupling part C 2 , as described above. Here, the negative electrode lead  40  includes the lead part  40 B inside the outer package film  10 , as described above, and accordingly, the joint part J 2  is coupled to the lead part  40 B. In this case, the joint part J 2  is coupled to the lead part  40 B at the upper surface N 2 . 
     In order to form the coupling part C 2 , a portion of the negative electrode tabs  61  and  62 , i.e., the negative electrode tab  61 , is bent to lie along a surface of the lead part  40 B. Specifically, the negative electrode tab  61  is bent to lie along the lower surface N 1 , the side surface N 3 , and the upper surface N 2  in this order. The joint part J 2  is thus coupled to the lead part  40 B at the upper surface N 2 , as described above. 
     Each of the negative electrode tabs  61  and  62  includes a material similar to the material included in the negative electrode current collector  22 A. It should be understood that the material included in each of the negative electrode tabs  61  and  62  may be the same as or different from the material included in the negative electrode current collector  22 A. 
     A position of coupling between each of the negative electrode tabs  61  and  62  and the negative electrode  22  is not particularly limited. Here, because the negative electrode  22  is wound in the battery device  20  which is the wound electrode body, the negative electrode tab  61  is coupled to the end (the exposed part  22 AH) of the negative electrode  22  on the inner side of the winding, and the negative electrode tab  62  is coupled to the end (the exposed part  22 AH) of the negative electrode  22  on the outer side of the winding. In other words, because the negative electrode  22  has the foil winding structure, as described above, each of the negative electrode tabs  61  and  62  is coupled to the negative electrode current collector  22 A. A reason for this is that this allows an electric coupling characteristic obtained with use of the negative electrode current collector  22 A to be uniform, making it easier for the charging and discharging reactions to proceed uniformly in the negative electrode  22 . 
     In this case, the negative electrode tabs  61  and  62  are preferably coupled to the negative electrode current collector  22 A (the respective exposed parts  22 AH) at respective positions symmetrical with respect to the center of the negative electrode current collector  22 A in the extending direction of the negative electrode current collector  22 A illustrated in  FIG. 3 , for a reason similar to the reason described above in relation to the position of coupling between each of the positive electrode tabs  51  and  52  and the positive electrode  21 . 
     Although the negative electrode tab  62  is coupled to the negative electrode current collector  22 A (the exposed part  22 AH) on the right side in  FIG. 5  here, the position at which the negative electrode tab  62  is coupled to the negative electrode current collector  22 A is not particularly limited. For example, the negative electrode tab  62  may be coupled to the negative electrode current collector  22 A on the left side in  FIG. 5 , as with the case described above in relation to the positive electrode tab  52 . However, in order to allow the length of the negative electrode tab  62  to be short, the negative electrode tab  62  is preferably coupled to the negative electrode current collector  22 A on the right side in  FIG. 5 , i.e., on a side closer to a side to which the negative electrode tab  61  is bent. 
     As illustrated in  FIG. 4 , the positive electrode sealant  70  seals the opening  10 K 1  to thereby prevent entry of outside air into the outer package film  10 . The positive electrode sealant  70  is disposed, at the opening  10 K 1 , between the outer package film  10  and the positive electrode lead  30 . Here, the positive electrode sealant  70  covers the periphery of the positive electrode lead  30 , and therefore has a so-called tube shape. However, a range to provide the positive electrode sealant  70  may be expanded to the outside of the outer package film  10 . 
     The positive electrode sealant  70  includes one or more of insulating materials including, without limitation, a polymer material. Examples of the polymer material include polyolefin having adherence to the positive electrode lead  30 . Such a polyolefin is not particularly limited in kind, and examples thereof include polyethylene, polypropylene, modified polyethylene, and modified polypropylene. 
     In particular, in a case where the outer package film  10  includes the fusion-bonding layer which is thermal-fusion-bondable as described above, the positive electrode sealant  70  preferably includes a polymer compound that is thermal-fusion-bondable as with the fusion-bonding layer, and the outer package film  10  and the positive electrode sealant  70  are therefore preferably thermal-fusion-bonded to each other at the opening  10 K 1 . A reason for this is that this makes it easier to seal the opening  10 K 1  by utilizing the thermal fusion bonding between the outer package film  10  and the positive electrode sealant  70  even if the positive electrode lead  30  is present at the opening  10 K 1 . 
     The negative electrode sealant  80  has a configuration similar to the configuration of the positive electrode sealant  70  described above. That is, as illustrated in  FIG. 5 , the negative electrode sealant  80  seals the opening  10 K 2  to thereby prevent entry of outside air into the outer package film  10 . The negative electrode sealant  80  is disposed, at the opening  10 K 2 , between the outer package film  10  and the negative electrode lead  40 . Here, the negative electrode sealant  80  covers the periphery of the negative electrode lead  40 , and therefore has a so-called tube shape. However, a range to provide the negative electrode sealant  80  may be expanded to the outside of the outer package film  10 . 
     The negative electrode sealant  80  includes one or more of insulating materials including, without limitation, a polymer material. Examples of the polymer material include polyolefin having adherence to the negative electrode lead  40 . Details of the kind of polyolefin are as described above. 
     In particular, in a case where the outer package film  10  includes the fusion-bonding layer which is thermal-fusion-bondable as described above, the negative electrode sealant  80  preferably includes a polymer compound that is thermal-fusion-bondable as with the fusion-bonding layer, and the outer package film  10  and the negative electrode sealant  80  are therefore preferably thermal-fusion-bonded to each other at the opening  10 K 2 . A reason for this is that this makes it easier to seal the opening  10 K 2  by utilizing the thermal fusion bonding between the outer package film  10  and the negative electrode sealant  80  even if the negative electrode lead  40  is present at the opening  10 K 2 . 
     The positive electrode insulating tape  90  is a first insulating member that is disposed inside the outer package film  10 , more specifically, is disposed outside the battery device  20 . 
     As illustrated in  FIG. 4 , the positive electrode insulating tape  90  is disposed to lie along the lower surface M 1  between the lead part  30 B and a portion of the positive electrode tabs  50 , i.e., the positive electrode tab  51  of the positive electrode tabs  51  and  52 , and is thus interposed between the coupling part C 1  and the battery device  20 . The positive electrode insulating tape  90  therefore insulates the coupling part C 1  from the battery device  20  (the negative electrode  22 ) to thereby prevent a short circuit between the coupling part Cl and the battery device  20 . 
     Here, the positive electrode insulating tape  90  is disposed to further lie between the lead part  30 B and the battery device  20  along the lower surface M 1 . The positive electrode insulating tape  90  is thus interposed throughout between the coupling part C 1  and the battery device  20 , therefore preventing the short circuit between the coupling part C 1  and the battery device  20  over a wide range. 
     Although the positive electrode insulating tape  90  may be disposed to lie along only the lower surface M 1 , the positive electrode insulating tape  90  is preferably disposed not only to lie along the lower surface M 1  but to further lie along the side surface M 3 , in particular. A reason for this is that this allows a corner of the positive electrode lead  30  (the lead part  30 B), i.e., a sharp corner formed by the lower surface M 1  and the side surface M 3 , to be protected by the positive electrode insulating tape  90 , and accordingly prevents the positive electrode tab  51  from being damaged by coming into contact with the corner. Examples of the damage to be caused on the positive electrode tab  51  include occurrence of a crack and a breakage. 
     The positive electrode insulating tape  90  includes one or more of insulating materials including, without limitation, a polymer material. Examples of the polymer material include polyethylene, polyethylene terephthalate, and polyimide. 
     It should be understood that the positive electrode insulating tape  90  is preferably bonded to the positive electrode lead  30  (the lead part  30 B) and also to the positive electrode tab  51 . A reason for this is that, because the positive electrode insulating tape  90  is fixed to both the lead part  30 B and the positive electrode tab  51 , the position of the positive electrode insulating tape  90  is prevented from deviating easily from the original position even if the secondary battery receives an external load due to, for example, vibration or impact. This makes it easier to maintain a state where the positive electrode insulating tape  90  is interposed between the lead part  30 B and the positive electrode tab  51 , thus preventing a short circuit between the coupling part C 1  and the battery device  20  from occurring easily regardless of presence or absence of the external load. 
     In this case, the positive electrode insulating tape  90  may be bonded to both the lead part  30 B and the positive electrode tab  51  by means of a sticking agent. The sticking agent is not limited to a particular kind, and includes one or more of materials including, without limitation, an acrylic-based sticking agent and a rubber-based sticking agent. Alternatively, the positive electrode insulating tape  90  may be a double-sided sticking tape. It should be understood that the positive electrode insulating tape  90  may be thermal-fusion-bonded to both the lead part  30 B and the positive electrode tab  51 . 
     The positive electrode insulating tape  100  is a second insulating member that is disposed inside the outer package film  10 , more specifically, is disposed outside the battery device  20 . 
     As illustrated in  FIG. 4 , the positive electrode insulating tape  100  is disposed between the coupling part C 1  and the outer package film  10 , and is thus interposed between the coupling part C 1  and the outer package film  10 . The positive electrode insulating tape  100  therefore insulates the coupling part C 1  from its surroundings to thereby prevent a short circuit caused by the coupling part C 1 . 
     The positive electrode insulating tape  100  includes a material similar to the material included in the positive electrode insulating tape  90 . It should be understood that the material included in the positive electrode insulating tape  100  may be the same as or different from the material included in the positive electrode insulating tape  90 . 
     The positive electrode insulating tape  100  is preferably bonded to both the coupling part C 1  and the outer package film  10 . A reason for this is that, because the positive electrode insulating tape  100  is fixed to both the coupling part C 1  and the outer package film  10 , the position of the positive electrode insulating tape  100  is prevented from deviating easily from the original position even if the secondary battery receives an external load. This makes it easier to maintain a state where the positive electrode insulating tape  100  is interposed between the coupling part C 1  and the outer package film  10 , thus preventing a short circuit caused by the coupling part C 1  from occurring easily regardless of presence or absence of the external load. 
     In this case, the positive electrode insulating tape  100  may be bonded to both the coupling part C 1  and the outer package film  10  by means of a sticking agent such as a double-sided sticking tape, or may be thermal-fusion-bonded to both the coupling part C 1  and the outer package film  10 . Details of the kind of the sticking agent are as described above. It should be understood that the positive electrode insulating tape  100  may be thermal-fusion-bonded to both the coupling part C 1  and the outer package film  10 . 
     It should be understood that in a case where the positive electrode insulating tape  100  is a double-sided sticking tape, when the wound body  20 Z is placed inside the outer package film  10  in a later-described manufacturing process of the secondary battery, a sticking characteristic of the positive electrode insulating tape  100  can cause difficulty in placing the wound body  20 Z inside the outer package film  10 . 
     The negative electrode insulating tape  110  has a configuration similar to the configuration of the positive electrode insulating tape  90  described above. That is, the negative electrode insulating tape  110  is another first insulating member that is disposed inside the outer package film  10 , more specifically, is disposed outside the battery device  20 . 
     As illustrated in  FIG. 5 , the negative electrode insulating tape  110  is disposed to lie along the lower surface N 1  between the lead part  40 B and a portion of the negative electrode tabs  60 , i.e., the negative electrode tab  61  of the negative electrode tabs  61  and  62 , and is thus interposed between the coupling part C 2  and the battery device  20 . The negative electrode insulating tape  110  therefore insulates the coupling part C 2  from the battery device  20  (the negative electrode  22 ) to thereby prevent a short circuit between the coupling part C 2  and the battery device  20 . 
     Here, the negative electrode insulating tape  110  is disposed to further lie between the lead part  40 B and the battery device  20  along the lower surface N 1 . The negative electrode insulating tape  110  is thus interposed throughout between the coupling part C 2  and the battery device  20 , therefore preventing the short circuit between the coupling part C 2  and the battery device  20  over a wide range. 
     Although the negative electrode insulating tape  110  may be disposed to lie along only the lower surface N 1 , the negative electrode insulating tape  110  is preferably disposed not only to lie along the lower surface N 1  but to further lie along the side surface N 3  in particular. A reason for this is that this allows a corner of the negative electrode lead  40  (the lead part  40 B), i.e., a sharp corner formed by the lower surface N 1  and the side surface N 3 , to be protected by the negative electrode insulating tape  110 , and accordingly prevents the negative electrode tab  61  from being damaged by coming into contact with the corner. 
     The negative electrode insulating tape  110  includes a material similar to the material included in the positive electrode insulating tape  90 . It should be understood that the material included in the negative electrode insulating tape  110  may be the same as or different from the material included in the positive electrode insulating tape  90 . 
     It should be understood that the negative electrode insulating tape  110  is preferably bonded to the negative electrode lead  40  (the lead part  40 B) and also to the negative electrode tab  61 . A reason for this is that, because the negative electrode insulating tape  110  is fixed to both the lead part  40 B and the negative electrode tab  61 , a short circuit between the coupling part C 2  and the battery device  20  is prevented from occurring easily regardless of presence or absence of the external load, for a reason similar to the reason described above in relation to the positive electrode insulating tape  90 . 
     In this case, the negative electrode insulating tape  110  may be bonded to both the lead part  40 B and the negative electrode tab  61  by means of a sticking agent. Details of the kind of the sticking agent are as described above. Alternatively, the negative electrode insulating tape  110  may be a double-sided sticking tape. It should be understood that the negative electrode insulating tape  110  may be thermal-fusion-bonded to both the lead part  40 B and the negative electrode tab  61 . 
     The negative electrode insulating tape  120  has a configuration similar to the configuration of the positive electrode insulating tape  100  described above. That is, the negative electrode insulating tape  120  is another second insulating member that is disposed inside the outer package film  10 , more specifically, is disposed outside the battery device  20 . 
     As illustrated in  FIG. 5 , the negative electrode insulating tape  120  is disposed between the coupling part C 2  and the outer package film  10 , and is thus interposed between the coupling part C 2  and the outer package film  10 . The negative electrode insulating tape  120  therefore insulates the coupling part C 2  from its surroundings to thereby prevent a short circuit caused by the coupling part C 2 . 
     The negative electrode insulating tape  120  includes a material similar to the material included in the negative electrode insulating tape  110 . It should be understood that the material included in the negative electrode insulating tape  120  may be the same as or different from the material included in the negative electrode insulating tape  110 . 
     The negative electrode insulating tape  120  is preferably bonded to both the coupling part C 2  and the outer package film  10 . A reason for this is that, because the negative electrode insulating tape  120  is fixed to both the coupling part C 2  and the outer package film  10 , a short circuit caused by the coupling part C 2  is prevented from occurring easily regardless of presence or absence of the external load, for a reason similar to the reason described above in relation to the positive electrode insulating tape  100 . 
     In this case, the negative electrode insulating tape  120  may be bonded to both the coupling part C 2  and the outer package film  10  by means of a sticking agent such as a double-sided sticking tape, or may be thermal-fusion-bonded to both the coupling part C 2  and the outer package film  10 . Details of the kind of the sticking agent are as described above. 
     It should be understood that in a case where the negative electrode insulating tape  120  is a double-sided sticking tape, a sticking characteristic of the negative electrode insulating tape  120  can cause difficulty in placing the wound body  20 Z inside the outer package film  10 , for a reason similar to the reason described for the case where the positive electrode insulating tape  100  is a double-sided sticking tape. 
     The auxiliary insulating tape  130  is disposed inside the outer package film  10 , more specifically, is disposed inside the battery device  20 . The auxiliary insulating tape  130  is interposed between electrically conductive components of the battery device  20  that are adjacent to each other, and thereby insulates such electrically conductive components from each other. Here, the secondary battery includes six auxiliary insulating tapes  130 , i.e., auxiliary insulating tapes  131  to  136 . 
     As illustrated in  FIG. 4 , the auxiliary insulating tapes  131  to  133  insulate the positive electrode tabs  51  and  52  from their surroundings. Specifically, the auxiliary insulating tape  131  is interposed between the positive electrode tab  51  and the negative electrode current collector  22 A in the vicinity of an end of the battery device  20  on the inner side of the winding, and extends to lie along the positive electrode tab  51 . The auxiliary insulating tape  132  is interposed between the positive electrode current collector  21 A and the separator  23  in the vicinity of the end of the battery device  20  on the inner side of the winding, and extends to lie along the positive electrode tab  51 . The auxiliary insulating tape  133  is interposed between the positive electrode tab  52  and the separator  23  in the vicinity of an end of the battery device  20  on the outer side of the winding. 
     As illustrated in  FIG. 5 , the auxiliary insulating tapes  134  to  136  insulate the negative electrode tabs  61  and  62  from their surroundings. Specifically, the auxiliary insulating tape  134  is interposed between the negative electrode current collector  22 A and the separator  23  in the vicinity of the end of the battery device  20  on the inner side of the winding, and extends to lie along the negative electrode tab  61 . The auxiliary insulating tape  135  is interposed between the negative electrode tab  61  and the positive electrode current collector  21 A in the vicinity of the end of the battery device  20  on the inner side of the winding, and extends to lie along the negative electrode tab  62 . The auxiliary insulating tape  136  is interposed between the positive electrode current collector  21 A and the separator  23  in the vicinity of the end of the battery device  20  on the outer side of the winding. 
     Each of the auxiliary insulating tapes  131  to  136  includes one or more of insulating materials including, without limitation, a polymer material. Examples of the polymer material include polyethylene, polyethylene terephthalate, and polyimide. 
     Upon charging of the secondary battery, in the battery device  20 , lithium is extracted from the positive electrode  21 , and the extracted lithium is inserted into the negative electrode  22  via the electrolytic solution. Upon discharging of the secondary battery, in the battery device  20 , lithium is extracted from the negative electrode  22 , and the extracted lithium is inserted into the positive electrode  21  via the electrolytic solution. Upon the charging and discharging, lithium is inserted and extracted in an ionic state. 
     For describing the process of manufacturing the secondary battery,  FIG. 6  illustrates a sectional configuration of the secondary battery in the course of manufacture, and corresponds to  FIG. 4 .  FIG. 7  illustrates the sectional configuration of the secondary battery in the course of manufacture for describing the process of manufacturing the secondary battery, and corresponds to  FIG. 5 . 
     In a case of manufacturing the secondary battery, the secondary battery is assembled as described below, with use of the outer package film  10  having the opening  10 K illustrated in each of  FIGS. 6 and 7 . Each of  FIGS. 6 and 7  illustrates the outer package film  10  before sealing, i.e., before formation of the seal part S. The opening  10 K of the outer package film  10  before the sealing has an opening area greater than the opening area of each of the openings  10 K 1  and  10 K 2 , to thereby allow the battery device  20  to be put into the outer package film  10 . 
     Here, described is a case where a double-sided sticking tape is used as each of the positive electrode insulating tapes  90  and  100  and the negative electrode insulating tapes  110  and  120 . 
     First, the positive electrode active material is mixed with, on an as-needed basis, a material such as the positive electrode binder or the positive electrode conductor to thereby obtain a positive electrode mixture. Thereafter, the positive electrode mixture is put into a solvent such as an organic solvent to thereby prepare a paste positive electrode mixture slurry. Lastly, the positive electrode mixture slurry is applied on opposite sides of the positive electrode current collector  21 A to thereby form the positive electrode active material layers  21 B. Thereafter, the positive electrode active material layers  21 B may be compression-molded by means of a machine such as a roll pressing machine. In this case, the positive electrode active material layers  21 B may be heated. The positive electrode active material layers  21 B may be compression-molded multiple times. The positive electrode active material layers  21 B are thus formed on the respective opposite sides of the positive electrode current collector  21 A. As a result, the positive electrode  21  is fabricated. 
     The negative electrode active material layers  22 B are formed on respective opposite sides of the negative electrode current collector  22 A by a procedure similar to the fabrication procedure of the positive electrode  21  described above. Specifically, the negative electrode active material is mixed with, on an as-needed basis, a material such as the negative electrode binder or the negative electrode conductor to thereby obtain a negative electrode mixture. Thereafter, the negative electrode mixture is put into a solvent such as an organic solvent to thereby prepare a paste negative electrode mixture slurry. Thereafter, the negative electrode mixture slurry is applied on the opposite sides of the negative electrode current collector  22 A to thereby form the negative electrode active material layers  22 B. Thereafter, the negative electrode active material layers  22 B may be compression-molded. The negative electrode active material layers  22 B are thus formed on the respective opposite sides of the negative electrode current collector  22 A. As a result, the negative electrode  22  is fabricated. 
     The electrolyte salt is put into a solvent. The electrolyte salt is thereby dispersed or dissolved in the solvent. As a result, the electrolytic solution is prepared. 
     First, the positive electrode tabs  51  and  52  are coupled to the positive electrode  21  (the positive electrode current collector  21 A) by a method such as a welding method, and the negative electrode tabs  61  and  62  are coupled to the negative electrode  22  (the negative electrode current collector  22 A) by a method such as a welding method. Thereafter, the positive electrode  21  and the negative electrode  22  are alternately stacked on each other with the separator  23  interposed therebetween, following which the positive electrode  21 , the negative electrode  22 , and the separator  23  are wound to thereby fabricate the wound body  20 Z. In this case, upon fabrication of the wound body  20 Z (upon winding), each of the auxiliary insulating tapes  131  to  136  is inserted at an appropriate position in middle of the winding. 
     It should be understood that the welding method includes one or more of a laser welding method, a resistance welding method, and any other welding method. Details of the welding method described here apply also to the following. 
     Thereafter, the one end of the positive electrode tab  51  and the one end of the positive electrode tab  52  are joined to each other by a method such as a welding method, to thereby form the joint part J 1 . Further, the one end of the negative electrode tab  61  and the one end of the negative electrode tab  62  are joined to each other by a method such as a welding method, to thereby form the joint part J 2 . 
     Thereafter, the one end of the positive electrode lead  30  (the lead part  30 B) is coupled to the joint part J 1  by a method such as a welding method, to thereby form the coupling part C 1 . Further, the one end of the negative electrode lead  40  (the lead part  40 B) is coupled to the joint part J 2  by a method such as a welding method, to thereby form the coupling part C 2 . Thus, the positive electrode wiring line  200  (the positive electrode lead  30  and the positive electrode tabs  51  and  52 ) and the negative electrode wiring line  300  (the negative electrode lead  40  and the negative electrode tabs  61  and  62 ) are each coupled to the wound body  20 Z. 
     Thereafter, the wound body  20 Z to which the positive electrode wiring line  200  and the negative electrode wiring line  300  are each coupled is placed inside the outer package film  10  through the opening  10 K. The wound body  20 Z is thereby placed inside the outer package film  10  in a state where the positive electrode wiring line  200  and the negative electrode wiring line  300  are each already coupled to the wound body  20 Z. This allows the positive electrode wiring line  200 , the negative electrode wiring line  300 , and the wound body  20 Z to be placed inside the outer package film  10  together. 
     In this case, the positive electrode tab  51  is bent to lie along the lower surface M 1 , the side surface M 3 , and the upper surface M 2  of the lead part  30 B in this order, and the negative electrode tab  61  is bent to lie along the lower surface N 1 , the side surface N 3 , and the upper surface N 2  of the lead part  40 B in this order. 
     The positive electrode insulating tape  90  is disposed to lie along the lower surface M 1  of the lead part  30 B, and is thereby bonded to both the lead part  30 B and the positive electrode tab  51 . Further, the negative electrode insulating tape  110  is disposed to lie along the lower surface N 1  of the lead part  40 B, and is thereby bonded to both the lead part  40 B and the negative electrode tab  61 . 
     Lastly, the electrolytic solution is injected into the outer package film  10  through the opening  10 K, following which portions of the outer package film  10  mutually opposed at the opening  10 K are joined to each other by a method such as a thermal fusion bonding method. 
     In this case, the positive electrode insulating tape  100  is disposed between the coupling part C 1  and the outer package film  10 , and is thereby bonded to both the coupling part C 1  and the outer package film  10 . Further, the negative electrode insulating tape  120  is disposed between the coupling part C 2  and the outer package film  10 , and is thereby bonded to both the coupling part C 2  and the outer package film  10 . 
     Further, the positive electrode sealant  70  is interposed between the outer package film  10  and the positive electrode wiring line  200  at the opening  10 K 1 , and the negative electrode sealant  80  is interposed between the outer package film  10  and the negative electrode wiring line  300  at the opening  10 K 2 . 
     Thus, the opening  10 K 1  is sealed by means of the positive electrode sealant  70  in a state where the positive electrode wiring line  200  is present at the opening  10 K 1 . In addition, the opening  10 K 2  is sealed by means of the negative electrode sealant  80  in a state where the negative electrode wiring line  300  is present at the opening  10 K 2 . Further, the wound body  20 Z including the positive electrode  21 , the negative electrode  22 , and the separator  23  is impregnated with the electrolytic solution. As a result, the battery device  20  which is the wound electrode body is fabricated. 
     Thus, the seal part S is formed while the positive electrode wiring line  200  and the negative electrode wiring line  300  are each led out from the outer package film  10  to the outside. Accordingly, the battery device  20  is sealed inside the outer package film  10 . As a result, the secondary battery of the laminated-film type is completed. 
     According to this secondary battery, the battery device  20  is contained inside the outer package film  10  having flexibility. The positive electrode wiring line  200  (the positive electrode lead  30 ) extending from the inside to the outside of the outer package film  10  includes the lead part  30 B opposed to the battery device  20 , and the lead part  30 B includes the lower surface M 1 , the side surface M 3 , and the upper surface M 2 . The positive electrode tabs  51  and  52  are disposed inside the outer package film  10 . The one end of each of the positive electrode tabs  51  and  52  is coupled to the battery device  20  (the positive electrode  21 ), and the other end of each of the positive electrode tabs  51  and  52  is coupled to the lead part  30 B at the upper surface M 2 . A portion of each of the positive electrode tabs  51  and  52  is bent to lie along the lower surface M 1 , the side surface M 3 , and the upper surface M 2  in this order, and the positive electrode insulating tape  90  is disposed to lie along the lower surface M 1  between the lead part  30 B and the positive electrode tab  51 . Accordingly, it is possible to secure higher reliability related to the wiring structure inside the secondary battery for the following reasons. 
       FIG. 8  illustrates a sectional configuration of a secondary battery of a first comparative example, and corresponds to  FIG. 4 .  FIG. 9  illustrates a sectional configuration of a secondary battery of a second comparative example, and corresponds to  FIG. 4 . 
     As illustrated in  FIG. 8 , the secondary battery of the first comparative example has a configuration almost similar to the configuration of the secondary battery of the present embodiment illustrated in  FIG. 4 , except that the secondary battery of the first comparative example includes a positive electrode lead  140  in place of the positive electrode lead  30  and the positive electrode tabs  50  (i.e., the positive electrode tabs  51  and  52 ), and includes auxiliary insulating tapes  130  (i.e., auxiliary insulating tapes  137  and  138 ) in place of the positive electrode insulating tapes  90  and  100 , the negative electrode insulating tapes  110  and  120 , and the auxiliary insulating tapes  130  (i.e., the auxiliary insulating tapes  131  to  136 ). 
     The positive electrode lead  140  extends from the inside of the outer package film  10  to the outside via the seal part S, and is coupled to the positive electrode  21  (the positive electrode current collector  21 A). That is, the positive electrode lead  140  serves as both the positive electrode lead  30  and the positive electrode tabs  50 . In order to be coupled to the positive electrode  21 , the positive electrode lead  140  is bent twice inside the outer package film  10 . The positive electrode lead  140  is insulated from the negative electrode  22  (the negative electrode current collector  22 A) by means of the auxiliary insulating tapes  136  and  137 , and is insulated from its surroundings by means of the positive electrode sealant  70  between the seal part S and the battery device  20 . 
     As illustrated in  FIG. 9 , the secondary battery of the second comparative example has a configuration similar to the configuration of the secondary battery of the present embodiment illustrated in  FIG. 4 , except that a coupling scheme between the positive electrode lead  30  (the lead part  30 B) and the joint part J 1  is different. 
     The positive electrode tab  51  is bent to lie along only the lower surface M 1  in a folded manner. Accordingly, the joint part J 1  is coupled to the lower surface M 1  of the lead part  30 B to thereby form the coupling part C 1 . 
     In the secondary battery of the first comparative example, as illustrated in  FIG. 8 , one positive electrode lead  140  is used as a coupling terminal to be coupled to electronic equipment. In this case, in order to increase the number of external-coupling terminals for the purpose of decreasing an electric resistance (an electric coupling resistance) of the secondary battery (the battery device  20 ), there is no choice but to increase the number of the positive electrode leads  140 . 
     However, the increase in the number of the positive electrode leads  140  causes an increase in volume occupied by the positive electrode leads  140  inside the outer package film  10 . This, in turn, causes an excessive increase in volume loss of the internal space of the outer package film  10 , and also complicates the sealing structure of a seal part S 1  because it is necessary to seal the outer package film  10  in a state where the plurality of positive electrode leads  140  is led out to the outside. The term “volume loss” refers to a decrease in volume (effective volume) of the internal space of the outer package film  10  available for containing the battery device  20 . Accordingly, the energy density per unit volume of the secondary battery markedly decreases due to the excessive increase in volume loss, and stable sealing of the seal part Si becomes difficult due to the complicated sealing structure. This not only results in a decrease in a characteristic such as a battery capacity characteristic but also results in unstable charging and discharging operations of the secondary battery. As a result, it is difficult to secure higher reliability related to the wiring structure inside the secondary battery. 
     In the secondary battery of the second comparative example, as illustrated in  FIG. 9 , the positive electrode lead  30  and the positive electrode tabs  50  (the positive electrode tabs  51  and  52 ) are used as the external-coupling terminals. Thus, the coupling terminal for the electronic equipment, i.e., the positive electrode lead  30 , and the coupling terminal for the battery device  20 , i.e., the positive electrode tabs  50 , are separated from each other and have their respective roles. In this case, in order to increase the number of coupling terminals for the purpose of decreasing an electric coupling resistance, it is not necessary to increase the number of the positive electrode leads  30 , and it is sufficient that only the number of the positive electrode tabs  50  is increased. Accordingly, the energy density per unit volume of the secondary battery increases due to avoidance of the excessive increase in volume loss, and stable sealing of the seal part S is achieved easily due to the simple sealing structure. 
     However, the positive electrode tab  51  is bent to lie along only the lower surface M 1  of the lead part  30 B in a folded manner. In this case, the positive electrode tab  51  is abruptly bent at a bending part P. In other words, the positive electrode tab  51  is bent at a bending angle that causes the radius of curvature to be markedly small. This lowers physical durability of the positive electrode tab  51 . Accordingly, if the secondary battery receives an external load such as vibration or impact, the positive electrode tab  51  is easily damaged at the bending part P due to the external load. The wording “damaged” refers to occurrence of a crack in the positive electrode tab  51  at the bending part P, or even of a breakage of the positive electrode tab  51  at the bending part P in some cases. This causes the charging and discharging operations of the secondary battery to be easily inhibited due to the damage of the positive electrode tab  51 . Accordingly, it is difficult to secure higher reliability related to the wiring structure inside the secondary battery. 
     In contrast, in the secondary battery of the present embodiment, as illustrated in  FIG. 4 , in a case where the positive electrode lead  30  and the positive electrode tabs  50  (i.e., the positive electrode tabs  51  and  52 ) are used as the coupling terminals for the purpose of decreasing the electric coupling resistance, the positive electrode tab  51  is bent to lie along the lower surface M 1 , the side surface M 3 , and the upper surface M 2  of the lead part  30 B in this order. In this case, the positive electrode tab  51  is bent mildly at the bending part P. In other words, the positive electrode tab  51  is bent at a bending angle that allows the radius of curvature to be sufficiently large. The physical durability of the positive electrode tab  51  is therefore not lowered but is maintained. Accordingly, the positive electrode tab  51  is prevented from being damaged easily at the bending part P even if the secondary battery receives an external load. 
     In addition, the positive electrode insulating tape  90  is disposed to lie along the lower surface M 1  between the lead part  30 B and the positive electrode tab  51 . Accordingly, even though the joint part J 1  is coupled to the upper surface M 2  of the lead part  30 B, the lead part  30 B is insulated from the battery device  20  (the negative electrode  22 ) by means of the positive electrode insulating tape  90 . This prevents a short circuit between the lead part  30 B and the negative electrode  22 . 
     Thus, unlike the secondary batteries of the first and second comparative examples, the secondary battery of the present embodiment makes it possible to secure the energy density per unit area, makes it possible to stably seal the seal part S, and also with the use of the positive electrode lead  30  and the positive electrode tab  51 , makes it possible to improve the physical durability of the positive electrode tab  51  and to prevent a short circuit caused by the positive electrode lead  30  (the lead part  30 B). Accordingly, stable charging and discharging operations of the secondary battery are secured while a characteristic such as the battery capacity characteristic is improved. As a result, it is possible to secure higher reliability related to the wiring structure inside the secondary battery. 
     In this case, in the manufacturing process of the secondary battery, the wound body  20 Z is placed inside the outer package film  10  in the state where the positive electrode wiring line  200  and the negative electrode wiring line  300  are each already coupled to the wound body  20 Z, in particular. This allows the positive electrode wiring line  200 , the negative electrode wiring line  300 , and the wound body  20 Z to be placed inside the outer package film  10  together. Accordingly, it is easy to contain the positive electrode wiring line  200 , the negative electrode wiring line  300 , and the wound body  20 Z inside the outer package film  10 . As a result, it is also possible to manufacture the secondary battery easily and stably. 
     Other than the above, in the secondary battery of the present embodiment, the positive electrode insulating tape  90  may be disposed to further lie between the lead part  30 B and the battery device  20 . This prevents a short circuit between the coupling part C 1  and the battery device  20  over a wide range. Accordingly, it is possible to achieve higher effects. 
     Moreover, the positive electrode insulating tape  90  may be bonded to both the lead part  30 B and the positive electrode tab  51 . This allows the positive electrode insulating tape  90  to be fixed to both the lead part  30 B and the positive electrode tab  51 , and therefore helps to prevent the position of the positive electrode insulating tape  90  from deviating easily from the original position even if the secondary battery receives an external load. As a result, a short circuit between the coupling part C 1  and the battery device  20  is prevented regardless of presence or absence of the external load. Accordingly, it is possible to achieve higher effects. 
     It should be understood that in order to fix the positive electrode insulating tape  90 , it is conceivable to bond the positive electrode insulating tape  90  not to the lead part  30 B but to the battery device  20 . In this case also, the lead part  30 B is insulated from the battery device  20  by means of the positive electrode insulating tape  90 . 
     However, bonding the positive electrode insulating tape  90  to the battery device  20  can cause a defect. Specifically, a physical load upon the bonding of the positive electrode insulating tape  90  causes a shift in winding of the battery device  20  to occur easily. This causes the charging and discharging reactions in the battery device  20  to be ununiform easily. In addition, the surface of the battery device  20  on a side opposed to the lead part  30 B has protrusions and recesses due to a difference in height among the positive electrode  21 , the negative electrode  22 , and the separator  23 . The presence of such protrusions and recesses causes unevenness in bonding of the positive electrode insulating tape  90  to occur easily. In addition, in a case where the positive electrode insulating tape  90  is a bonding tape, the charging and discharging operations are inhibited easily due to entry of the bonding agent of the bonding tape into the battery device  20 . 
     Accordingly, in order to stabilize the charging and discharging operations of the secondary battery, the positive electrode insulating tape  90  is preferably bonded not to the battery device  20  but to the lead part  30 B. 
     Moreover, the positive electrode insulating tape  90  may be disposed not only to lie along the lower surface M 1  but to further lie along the side surface M 3 . This helps to prevent the positive electrode tab  51  from being damaged easily. Accordingly, it is possible to achieve higher effects. 
     Moreover, the positive electrode insulating tape  100  may be disposed between the coupling part C 1  and the outer package film  10 . This prevents a short circuit caused by the coupling part C 1  also by means of the positive electrode insulating tape  100 . Accordingly, it is possible to achieve higher effects. In this case, the positive electrode insulating tape  100  may be bonded to both the coupling part C 1  and the outer package film  10 . This further prevents the short circuit caused by the coupling part C 1  regardless of presence or absence of the external load. Accordingly, it is possible to achieve further higher effects. 
     Moreover, the battery device  20  may be a wound electrode body, and the positive electrode  21  and the negative electrode  22  may therefore be wound with the separator  23  interposed therebetween. This makes it easier to decrease the electric coupling resistance of the battery device  20  only by increasing the number of the positive electrode tabs  50  up to a freely chosen number that is two or greater. Accordingly, it is possible to achieve higher effects. In this case, the positive electrode tabs  51  and  52  may be coupled to the respective exposed parts  21 AH of the positive electrode current collector  21 A. This further decreases the electric coupling resistance, as compared with a case where each of the positive electrode tabs  51  and  52  is coupled to the positive electrode active material layer  21 B. Accordingly, it is possible to achieve further higher effects. 
     Moreover, the secondary battery may include a lithium-ion secondary battery. This makes it possible to stably obtain a sufficient battery capacity by utilizing insertion and extraction of lithium. Accordingly, it is possible to achieve higher effects. 
     Here, the description has been given of the action and effects based on the respective configurations of the positive electrode wiring line  200  (the positive electrode lead  30  (the lead part  30 B) and the positive electrode tabs  50  (the positive electrode tabs  51  and  52 )) and the positive electrode insulating tape  90  with reference to  FIGS. 4, 8, and 9 . However, the negative electrode wiring line  300  (the negative electrode lead  40  (the lead part  40 B) and the negative electrode tabs  60  (the negative electrode tabs  61  and  62 )) and the negative electrode insulating tape  110  have configurations similar to those of the positive electrode wiring line  200  and the positive electrode insulating tape  90 , respectively. Accordingly, it is possible to achieve similar action and effects also on the basis of the respective configurations of the negative electrode wiring line  300  and the negative electrode insulating tape  110 . 
     Next, modifications of the foregoing secondary battery will be described. The configuration of the secondary battery is appropriately modifiable, as will be described below. It should be understood that any two or more of the following series of modifications may be combined. 
     Modification 1 
     In  FIGS. 4 and 5 , the secondary battery includes both the positive electrode insulating tape  90  and the negative electrode insulating tape  110 . However, the secondary battery may include only one of the positive electrode insulating tape  90  and the negative electrode insulating tape  110 . Even in such a case, a short circuit caused by the coupling part C 1  or the coupling part C 2  is prevented, as compared with a case where the secondary battery includes neither the positive electrode insulating tape  90  nor the negative electrode insulating tape  110 . Accordingly, it is possible to achieve similar effects. 
     However, in order to sufficiently prevent the short circuit and to thereby achieve more stable charging and discharging operations of the secondary battery, the secondary battery preferably includes both the positive electrode insulating tape  90  and the negative electrode insulating tape  110 . 
     Modification 2 
     In  FIG. 4 , the positive electrode insulating tape  90  is disposed from between the lead part  30 B and the positive electrode tab  51  to between the lead part  30 B and the battery device  20 , lying along the lower surface M 1 . However, as long as the positive electrode insulating tape  90  is disposed to lie along the lower surface M 1 , the range to dispose the positive electrode insulating tape  90  is not particularly limited. Even in such a case, the coupling part C 1  is insulated from its surroundings by means of the positive electrode insulating tape  90 . Accordingly, it is possible to achieve similar effects. However, in order to sufficiently insulate the coupling part C 1  from its surroundings over a wide range, the range to dispose the positive electrode insulating tape  90  is preferably as wide as possible. 
     The description above related to the positive electrode insulating tape  90  is similarly applicable to the negative electrode insulating tape  110  illustrated in  FIG. 5 . That is, the range to dispose the negative electrode insulating tape  110  is not particularly limited as long as the negative electrode insulating tape  110  is disposed to lie along the lower surface N 1 . 
     Modification 3 
     In  FIG. 4 , the positive electrode insulating tape  90  is bonded to both the lead part  30 B and the positive electrode tab  51 . However, the positive electrode insulating tape  90  may be bonded to only one of the lead part  30 B and the positive electrode tab  51 . Even in such a case, the positive electrode insulating tape  90  is fixed to the lead part  30 B or the positive electrode tab  51 . Accordingly, it is possible to achieve similar effects. However, in order to sufficiently fix the positive electrode insulating tape  90 , the positive electrode insulating tape  90  is preferably bonded to both the lead part  30 B and the positive electrode tab  51 . 
     The description above related to the positive electrode insulating tape  90  is similarly applicable to the negative electrode insulating tape  110  illustrated in  FIG. 5 . That is, the negative electrode insulating tape  110  may be bonded to only one of the lead part  40 B and the negative electrode tab  61 . 
     Modification 4 
     In  FIG. 4 , the secondary battery includes both the positive electrode insulating tape  100  and the negative electrode insulating tape  120 . However, the secondary battery may include only one of the positive electrode insulating tape  100  and the negative electrode insulating tape  120 . Even in such a case, a short circuit caused by the coupling part C 1  or the coupling part C 2  is prevented, as compared with a case where the secondary battery includes neither the positive electrode insulating tape  100  nor the negative electrode insulating tape  120 . Accordingly, it is possible to achieve similar effects. 
     However, in order to sufficiently prevent the short circuit and to thereby achieve more stable charging and discharging operations of the secondary battery, the secondary battery preferably includes both the positive electrode insulating tape  100  and the negative electrode insulating tape  120 . 
     It should be understood that the secondary battery may include neither the positive electrode insulating tape  100  nor the negative electrode insulating tape  120 . Even in such a case, as long as the secondary battery includes the positive electrode insulating tape  90 , the negative electrode insulating tape  110 , or both, the short circuit between the coupling part C 1  or the coupling part C 2  and the battery device  20  is prevented as described above. As a result, it is possible to achieve similar effects. 
     However, in order to sufficiently prevent the short circuit, the secondary battery preferably includes the positive electrode insulating tape  100 , the negative electrode insulating tape  120 , or both. 
     Modification 5 
     In  FIG. 4 , the positive electrode insulating tape  100  is bonded to both the coupling part C 1  and the outer package film  10 . However, the positive electrode insulating tape  100  may be bonded to only one of the coupling part C 1  and the outer package film  10 . Even in such a case, the positive electrode insulating tape  100  is fixed to the coupling part C 1  or the outer package film  10 . Accordingly, it is possible to achieve similar effects. However, in order to sufficiently fix the positive electrode insulating tape  100 , the positive electrode insulating tape  100  is preferably bonded to both the coupling part C 1  and the outer package film  10 . 
     The description above related to the positive electrode insulating tape  100  is similarly applicable to the negative electrode insulating tape  120  illustrated in  FIG. 5 . That is, the negative electrode insulating tape  120  may be bonded to only one of the coupling part C 2  and the outer package film  10 . 
     Modification 6 
     In  FIG. 4 , the number of the positive electrode tabs  50  is two, i.e., the positive electrode tabs  51  and  52  are provided; in  FIG. 5 , the number of the negative electrode tabs  60  is two, i.e., the negative electrode tabs  61  and  62  are provided. However, the number of the positive electrode tabs  50  is not particularly limited as long as it is two or more, and may therefore be three or more. In addition, the number of the negative electrode tabs  60  is not particularly limited as long as it is two or more, and may therefore be three or more. In such cases also, it is possible to achieve similar effects. 
     In such a case, in particular, the greater the number of the positive electrode tabs  50  is, the more the electric resistance (the electric coupling resistance) of the secondary battery (the battery device  20 ) decreases. Accordingly, the greater number of the positive electrode tabs  50  makes it possible to achieve further higher effects. The effects derived from the decrease in the electric resistance of the secondary battery (the battery device  20 ) with increasing number of electrode tabs are similarly achievable also in relation to an increase in the number of the negative electrode tabs  60 . 
     Modification 7 
     In  FIG. 4 , the positive electrode wiring line  200  includes the positive electrode lead  30  and the positive electrode tabs  50 , and the positive electrode lead  30  and each of the positive electrode tabs  50  are coupled to each other. In other words, the positive electrode wiring line  200  includes two kinds of members that are physically separated from each other (i.e., the positive electrode lead  30  and the positive electrode tabs  50 ). 
     However, the positive electrode wiring line  200  may include one kind (one piece) of member in which the positive electrode lead  30  and the positive electrode tabs  50  are integrated together. That is, the positive electrode wiring line  200  may include a member having one end which includes only one part, and another end which is branched into two or more parts. In such a case also, a short circuit is prevented by means of the positive electrode insulating tape  90 . Accordingly, it is possible to achieve similar effects. 
     Modification 7 described above is applicable also to the negative electrode wiring line  300  illustrated in  FIG. 5 . That is, the negative electrode wiring line  300  may include one piece of member in which the negative electrode lead  40  and the negative electrode tabs  60  are integrated together. In such a case also, a short circuit is prevented by means of the negative electrode insulating tape  110 . Accordingly, it is possible to achieve similar effects. 
     Modification 8 
     In  FIG. 4 , the other end of the positive electrode tab  51  and the other end of the positive electrode tab  52  are joined to each other by a method such as a welding method to thereby form the joint part J 1 . However, because it suffices that the positive electrode tabs  51  and  52  are in contact with each other, the positive electrode tabs  51  and  52  may be merely stacked on each other rather than being joined to each other by a method such as a welding method. In such a case also, the positive electrode tabs  51  and  52  are coupled to the lead part  30 B. Accordingly, it is possible to achieve similar effects. 
     Modification 8 described above is applicable also to the negative electrode tabs  61  and  62  illustrated in  FIG. 5 . That is, the negative electrode tabs  61  and  62  may be merely stacked on each other rather than forming the joint part J 2 . In such a case also, the negative electrode tabs  61  and  62  are coupled to the lead part  40 B. Accordingly, it is possible to achieve similar effects. 
     Modification 9 
     The separator  23  which is a porous film is used. However, although not specifically illustrated here, a separator of a stacked type including a polymer compound layer may be used instead of the separator  23  which is the porous film. 
     Specifically, the separator of the stacked type includes a base layer which is the above-described porous film, and a polymer compound layer provided on one side or each of opposite sides of the base layer. A reason for this is that adherence of the separator to both the positive electrode  21  and the negative electrode  22  improves to suppress the occurrence of misalignment of the battery device  20 . This helps to prevent the secondary battery from easily swelling even if, for example, a decomposition reaction of the electrolytic solution occurs. The polymer compound layer includes a polymer compound such as polyvinylidene difluoride. A reason for this is that such a polymer compound has superior physical strength and is electrochemically stable. 
     It should be understood that the base layer, the polymer compound layer, or both may include one or more kinds of particles including, for example, inorganic particles and resin particles. A reason for this is that such particles dissipate heat upon heat generation by the secondary battery, and this improves heat resistance and safety of the secondary battery. The inorganic particles are not particularly limited in kind, and examples thereof include particles of the following materials: aluminum oxide (alumina), aluminum nitride, boehmite, silicon oxide (silica), titanium oxide (titania), magnesium oxide (magnesia), and zirconium oxide (zirconia). 
     In a case of fabricating the separator of the stacked type, a precursor solution including, without limitation, the polymer compound and an organic solvent is prepared, following which the precursor solution is applied on one side or each of opposite sides of the base layer. 
     In the case where the separator of the stacked type is used also, lithium is movable between the positive electrode  21  and the negative electrode  22 . Accordingly, it is possible to achieve similar effects. 
     Modification 10 
     The electrolytic solution which is a liquid electrolyte is used. However, although not specifically illustrated here, an electrolyte layer which is a gel electrolyte may be used instead of the electrolytic solution. 
     In the battery device  20  including the electrolyte layer, the positive electrode  21  and the negative electrode  22  are stacked on each other with the separator  23  and the electrolyte layer interposed therebetween, and the stack of the positive electrode  21 , the negative electrode  22 , the separator  23 , and the electrolyte layer is wound. The electrolyte layer is interposed between the positive electrode  21  and the separator  23 , and between the negative electrode  22  and the separator  23 . 
     Specifically, the electrolyte layer includes a polymer compound together with the electrolytic solution. The electrolytic solution is held by the polymer compound in the electrolyte layer. The configuration of the electrolytic solution is as described above. The polymer compound includes, for example, polyvinylidene difluoride. In a case of forming the electrolyte layer, a precursor solution including, without limitation, the electrolytic solution, the polymer compound, and an organic solvent is prepared, following which the precursor solution is applied on one side or opposite sides of each of the positive electrode  21  and the negative electrode  22 . 
     In the case where the electrolyte layer is used also, lithium is movable between the positive electrode  21  and the negative electrode  22  via the electrolyte layer. Accordingly, it is possible to achieve similar effects. 
     Modification 11 
     In  FIG. 4 , the lead part  30 A extends in the direction intersecting with the extending direction of the lead part  30 B, and the positive electrode lead  30  is therefore bent. However, although not specifically illustrated here, the lead part  30 A may extend in a direction similar to the extending direction of the lead part  30 B. The positive electrode lead  30  may therefore extend in one direction (the horizontal direction in  FIG. 4 ) rather than being bent, and the lead part  30 A may therefore be led out from the outer package film  10  to the outside via the opening  10 K 1  provided in the extending direction of the positive electrode lead  30 . In such a case also, the positive electrode tabs  51  and  52  are coupled to the lead part  30 B. Accordingly, it is possible to achieve similar effects. 
     However, in order to allow for easy coupling of the secondary battery to electronic equipment, the lead part  30 A preferably extends in the direction intersecting with the extending direction of the lead part  30 B. 
     Modification 11 described above is applicable also to the negative electrode lead  40  (the lead parts  40 A and  40 B) illustrated in  FIG. 5 . That is, the lead part  40 A may extend in a direction similar to the extending direction of the lead part  40 B, and the negative electrode lead  40  therefore needs not to be bent. In such a case also, the negative electrode tabs  61  and  62  are coupled to the lead part  40 B. Accordingly, it is possible to achieve similar effects. 
     Modification 12 
     In  FIG. 4 , the positive electrode tabs  50  and the positive electrode current collector  21 A are respective members separated from each other. However, the positive electrode tabs  50  and the positive electrode current collector  21 A may be integrated with each other. In this case, in a process of forming the positive electrode current collector  21 A by means of a punching process on a metal foil, the metal foil may be punched into a configuration in which the positive electrode tabs  50  and the positive electrode current collector  21 A are integrated with each other. It is thereby possible to form the positive electrode current collector  21 A integrated with the positive electrode tabs  50 . In such a case also, the positive electrode tabs  50  are coupled to the lead part  30 B. Accordingly, it is possible to achieve similar effects. 
     Modification 12 described above is applicable also to the negative electrode tabs  60  and the negative electrode current collector  22 A illustrated in  FIG. 5 . That is, the negative electrode tabs  60  and the negative electrode current collector  22 A may be integrated with each other. In such a case also, the negative electrode tabs  60  are coupled to the lead part  40 B. Accordingly, it is possible to achieve similar effects. 
     Next, a description is given of applications (application examples) of the above-described secondary battery. 
     The applications of the secondary battery are not particularly limited as long as they are, for example, machines, equipment, instruments, apparatuses, or systems (an assembly of a plurality of pieces of equipment, for example) in which the secondary battery is usable mainly as a driving power source, an electric power storage source for electric power accumulation, or any other source. The secondary battery used as a power source may serve as a main power source or an auxiliary power source. The main power source is preferentially used regardless of the presence of any other power source. The auxiliary power source may be used in place of the main power source, or may be switched from the main power source on an as-needed basis. In a case where the secondary battery is used as the auxiliary power source, the kind of the main power source is not limited to the secondary battery. 
     Specific examples of the applications of the secondary battery include: electronic equipment including portable electronic equipment; portable life appliances; apparatuses for data storage; electric power tools; battery packs to be mounted as detachable power sources on, for example, laptop personal computers; medical electronic equipment; electric vehicles; and electric power storage systems. Examples of the electronic equipment include video cameras, digital still cameras, mobile phones, laptop personal computers, cordless phones, headphone stereos, portable radios, portable televisions, and portable information terminals. Examples of the portable life appliances include electric shavers. Examples of the apparatuses for data storage include backup power sources and memory cards. Examples of the electric power tools include electric drills and electric saws. Examples of the medical electronic equipment include pacemakers and hearing aids. Examples of the electric vehicles include electric automobiles including hybrid automobiles. Examples of the electric power storage systems include home battery systems for accumulation of electric power for a situation such as emergency. It should be understood that the secondary battery may have a battery structure of the above-described laminated-film type, a cylindrical type, or any other type. Further, multiple secondary batteries may be used, for example, as a battery pack or a battery module. 
     In particular, the battery pack and the battery module are each effectively applied to relatively large-sized equipment, etc., including an electric vehicle, an electric power storage system, and an electric power tool. The battery pack, as will be described later, may include a single battery, or may include an assembled battery. The electric vehicle is a vehicle that operates (travels) using the secondary battery as a driving power source, and may be an automobile that is additionally provided with a driving source other than the secondary battery as described above, such as a hybrid automobile. The electric power storage system is a system that uses the secondary battery as an electric power storage source. An electric power storage system for home use accumulates electric power in the secondary battery which is an electric power storage source, and the accumulated electric power may thus be utilized for using, for example, home appliances. 
     Some application examples of the secondary battery will now be described in detail. The configurations of the application examples described below are merely examples, and are appropriately modifiable. The secondary battery to be used in the following application examples is not limited to a particular kind, and may therefore be of a laminated-film type or a cylindrical type. 
       FIG. 10  illustrates a block configuration of a battery pack including a single battery. The battery pack described here is a simple battery pack (a so-called soft pack) including one secondary battery, and is to be mounted on, for example, electronic equipment typified by a smartphone. 
     As illustrated in  FIG. 10 , the battery pack includes an electric power source  161  and a circuit board  162 . The circuit board  162  is coupled to the electric power source  161 , and includes a positive electrode terminal  163 , a negative electrode terminal  164 , and a temperature detection terminal (a so-called T terminal)  165 . 
     The electric power source  161  includes one secondary battery. The secondary battery has a positive electrode lead coupled to the positive electrode terminal  163  and a negative electrode lead coupled to the negative electrode terminal  164 . The electric power source  161  is couplable to outside via the positive electrode terminal  163  and the negative electrode terminal  164 , and is thus chargeable and dischargeable via the positive electrode terminal  163  and the negative electrode terminal  164 . The circuit board  162  includes a controller  166 , a switch  167 , a PTC device  168 , and a temperature detector  169 . However, the PTC device  68  may be omitted. 
     The controller  166  includes, for example, a central processing unit (CPU) and a memory, and controls an overall operation of the battery pack. The controller  166  detects and controls a use state of the electric power source  161  on an as-needed basis. 
     If a battery voltage of the electric power source  161  (the secondary battery) reaches an overcharge detection voltage or an overdischarge detection voltage, the controller  166  turns off the switch  167 . This prevents a charging current from flowing into a current path of the electric power source  161 . In addition, if a large current flows upon charging or discharging, the controller  166  turns off the switch  167  to block the charging current. The overcharge detection voltage and the overdischarge detection voltage are not particularly limited. For example, the overcharge detection voltage is 4.2 V±0.05 V and the overdischarge detection voltage is 2.4 V±0.1 V. 
     The switch  167  includes, for example, a charge control switch, a discharge control switch, a charging diode, and a discharging diode. The switch  167  performs switching between coupling and decoupling between the electric power source  161  and external equipment in accordance with an instruction from the controller  166 . The switch  167  includes, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET) including a metal-oxide semiconductor. The charging and discharging currents are detected on the basis of an ON-resistance of the switch  167 . 
     The temperature detector  169  includes a temperature detection device such as a thermistor. The temperature detector  169  measures a temperature of the electric power source  161  using the temperature detection terminal  165 , and outputs a result of the temperature measurement to the controller  166 . The result of the temperature measurement to be obtained by the temperature detector  169  is used, for example, in a case where the controller  166  performs charge/discharge control upon abnormal heat generation or in a case where the controller  166  performs a correction process upon calculating a remaining capacity. 
       FIG. 11  illustrates a block configuration of a battery pack including an assembled battery. In the following description, reference will be made as necessary to the components of the battery pack including the single battery (see  FIG. 10 ). 
     As illustrated in  FIG. 11 , the battery pack includes a positive electrode terminal  181  and a negative electrode terminal  182 . Specifically, the battery pack includes, inside a housing  170 , the following components: a controller  171 , an electric power source  172 , a switch  173 , a current measurement unit  174 , a temperature detector  175 , a voltage detector  176 , a switch controller  177 , a memory  178 , a temperature detection device  179 , and a current detection resistor  180 . 
     The electric power source  172  includes an assembled battery in which two or more secondary batteries are coupled to each other, and a type of the coupling of the two or more secondary batteries is not particularly limited. Accordingly, the coupling scheme may be in series, in parallel, or of a mixed type of both. For example, the electric power source  172  includes six secondary batteries coupled to each other in two parallel and three series. 
     Configurations of the controller  171 , the switch  173 , the temperature detector  175 , and the temperature detection device  179  are similar to those of the controller  166 , the switch  167 , and the temperature detector  169  (the temperature detection device). The current measurement unit  174  measures a current using the current detection resistor  180 , and outputs a result of the measurement of the current to the controller  171 . The voltage detector  176  measures a battery voltage of the electric power source  172  (the secondary battery) and provides the controller  171  with a result of the measurement of the voltage that has been subjected to analog-to-digital conversion. 
     The switch controller  177  controls an operation of the switch  173  in response to signals supplied by the current measurement unit  174  and the voltage detector  176 . If a battery voltage reaches an overcharge detection voltage or an overdischarge detection voltage, the switch controller  177  turns off the switch  173  (the charge control switch). This prevents a charging current from flowing into a current path of the electric power source  172 . This enables the electric power source  172  to perform only discharging via the discharging diode, or only charging via the charging diode. In addition, if a large current flows upon charging or discharging, the switch controller  177  blocks the charging current or the discharging current. 
     The switch controller  177  may be omitted and the controller  171  may thus also serve as the switch controller  177 . The overcharge detection voltage and the overdischarge detection voltage are not particularly limited, and are similar to those described above in relation to the battery pack including the single battery. 
     The memory  178  includes, for example, an electrically erasable programmable read-only memory (EEPROM) which is a non-volatile memory, and the memory  178  stores, for example, a numeric value calculated by the controller  171  and data (e.g., an initial internal resistance, a full charge capacity, and a remaining capacity) of the secondary battery measured in the manufacturing process. 
     The positive electrode terminal  181  and the negative electrode terminal  182  are terminals coupled to, for example, external equipment that operates using the battery pack, such as a laptop personal computer, or external equipment that is used to charge the battery pack, such as a charger. The electric power source  172  (the secondary battery) is chargeable and dischargeable via the positive electrode terminal  181  and the negative electrode terminal  182 . 
       FIG. 12  illustrates a block configuration of a hybrid automobile which is an example of the electric vehicle. As illustrated in  FIG. 12 , the electric vehicle includes, inside a housing  183 , the following components: a controller  184 , an engine  185 , an electric power source  186 , a motor  187 , a differential  188 , an electric generator  189 , a transmission  190 , a clutch  191 , inverters  192  and  193 , and sensors  194 . The electric vehicle also includes a front wheel drive shaft  195 , a pair of front wheels  196 , a rear wheel drive shaft  197 , and a pair of rear wheels  198 . The front wheel drive shaft  195  and the pair of front wheels  196  are coupled to the differential  188  and the transmission  190 . 
     The electric vehicle is configured to travel by using one of the engine  185  and the motor  187  as a driving source. The engine  185  is a major power source, such as a gasoline engine. In a case where the engine  185  is used as a power source, a driving force (a rotational force) of the engine  185  is transmitted to the front wheels  196  and the rear wheels  198  via the differential  188 , the transmission  190 , and the clutch  191 , which are driving parts. It should be understood that the rotational force of the engine  185  is transmitted to the electric generator  189 , and the electric generator  189  thus generates alternating-current power by utilizing the rotational force. In addition, the alternating-current power is converted into direct-current power via the inverter  193 , and the direct-current power is thus accumulated in the electric power source  186 . In contrast, in a case where the motor  187  which is a converter is used as a power source, electric power (direct-current power) supplied from the electric power source  186  is converted into alternating-current power via the inverter  192 . Thus, the motor  187  is driven by utilizing the alternating-current power. A driving force (a rotational force) converted from the electric power by the motor  187  is transmitted to the front wheels  196  and the rear wheels  198  via the differential  188 , the transmission  190 , and the clutch  191 , which are the driving parts. 
     When the electric vehicle is decelerated by means of a brake mechanism, a resistance force at the time of the deceleration is transmitted as a rotational force to the motor  187 . Thus, the motor  187  may generate alternating-current power by utilizing the rotational force. The alternating-current power is converted into direct-current power via the inverter  192 , and direct-current regenerative power is thus accumulated in the electric power source  186 . 
     The controller  184  includes, for example, a CPU, and controls an overall operation of the electric vehicle. The electric power source  186  includes one or more secondary batteries and is coupled to an external electric power source. In this case, the electric power source  186  may be supplied with electric power from the external electric power source and thereby accumulate the electric power. The sensors  194  are used to control the number of revolutions of the engine  185  and to control an angle of a throttle valve (a throttle angle). The sensors  194  include one or more of sensors including, without limitation, a speed sensor, an acceleration sensor, and an engine speed sensor. 
     The case where the electric vehicle is a hybrid automobile has been described as an example; however, the electric vehicle may be a vehicle that operates using only the electric power source  186  and the motor  187  and not using the engine  185 , such as an electric automobile. 
     Although not specifically illustrated here, other application examples are also conceivable as application examples of the secondary battery. 
     Specifically, the secondary battery is applicable to an electric power storage system. The electric power storage system includes, inside a building such as a residential house or a commercial building, the following components: a controller, an electric power source including one or more secondary batteries, a smart meter, and a power hub. 
     The electric power source is coupled to electric equipment such as a refrigerator installed inside the building, and is couplable to an electric vehicle such as a hybrid automobile stopped outside the building. Further, the electric power source is coupled, via the power hub, to a home power generator such as a solar power generator installed at the building, and is also coupled, via the smart meter and the power hub, to a centralized power system of an external power station such as a thermal power station. 
     Alternatively, the secondary battery is applicable to an electric power tool such as an electric drill or an electric saw. The electric power tool includes, inside a housing to which a movable part such as a drilling part or a saw blade part is attached, the following components: a controller, and an electric power source including one or more secondary batteries. 
     Although the technology has been described above with reference to some embodiments and examples, the configuration of the technology is not limited to those described with reference to the embodiments and examples above, and is therefore modifiable in a variety of ways. 
     Specifically, although the description above relates to a case where the battery device has a wound-type device structure (the wound electrode body), the device structure of the battery device is not particularly limited, and therefore may be any other device structure such as a stacked-type device structure in which the electrodes (the positive electrode and the negative electrode) are stacked (a stacked electrode body), or a zigzag-folded-type device structure in which the electrodes (the positive electrode and the negative electrode) are folded in a zigzag manner. 
     Further, although the description above relates to a case where the electrode reactant is lithium, the electrode reactant is not particularly limited. Specifically, as described above, the electrode reactant may be another alkali metal such as sodium or potassium, or may be an alkaline earth metal such as beryllium, magnesium, or calcium. Other than the above, the electrode reactant may be another light metal such as aluminum. 
     The effects described herein are mere examples, and effects of the present technology are therefore not limited to those described herein. Accordingly, the present technology may achieve any other effect. 
     It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.