Patent Publication Number: US-2022238967-A1

Title: Secondary battery

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the priority based on Japanese Patent Application No. 2021-011567 filed on Jan. 28, 2021, entire contents of which are incorporated by reference in the present specification. 
     BACKGROUND OF THE DISCLOSURE 
     1. Technical Field 
     The present invention relates to a secondary battery. 
     2. Background 
     A secondary battery such as a lithium ion secondary battery generally has a configuration in which an electrode body accommodated in a battery case and a terminal exposed to outside of the battery case are electrically connected with each other. A secondary battery with such a configuration includes, for example, an electrode body having a first electrode sheet, and a second electrode sheet having a different polarity from that of the first electrode sheet, an exterior body having an opening, and for accommodating the electrode body therein, a sealing plate for sealing the opening of the exterior body, a terminal electrically connected with the electrode sheet in the inside of the exterior body, and extending from the sealing plate to the outside of the exterior body, and a collector electrically connected with the terminal and the electrode body. For example, the electrode body of this kind of secondary battery is provided with electrode tab groups each including a plurality of collecting electrode tabs (a positive electrode tab group and a negative electrode tab group), so that the electrode body and the terminal can be connected with each other via the electrode tab groups and the collector. 
     One example of the secondary battery with the foregoing configuration is shown in Japanese Patent Application Publication No. 2015-141847. In such a secondary battery disclosed in this patent document, a positive electrode tab is arranged at one end of the electrode body, and a negative electrode tab is arranged at the other end thereof. Then, this patent document proposes that the positive electrode tab and the negative electrode tab are bent, and are connected with the collector. As a result, it is possible to implement the combination of a larger capacity and a higher output of the secondary battery. 
     SUMMARY 
     With the secondary battery in which the electrode body is provided with an electrode tab group, the junction between the electrode tab group and the collector may sustain damage (such as foil cutting or peeling of the junction). Specifically, the secondary battery may be applied with an external vibration or impact in use or during manufacturing. When the external force such as a vibration moves the electrode body in the inside of the battery case, and shifts the electrode body from the prescribed arrangement position, a large stress acts on the junction between the electrode tab group and the collector. Herein, an electrode tab forming the electrode tab group includes a part of collecting foil, or the like, and is very soft and has a low strength. For this reason, when the stress due to the movement of the electrode body repeatedly acts thereon, damage thereon may be caused with ease. 
     The present invention was completed in view of the foregoing circumstances. It is an object of the present invention to provide a technology of suppressing the movement of the electrode body in the inside of the battery case, and preventing the damage at the junction between the electrode tab group and the collector. 
     A secondary battery herein disclosed includes: an exterior body having a bottom wall, a pair of first sidewalls extending from the bottom wall, and facing each other, a pair of second sidewalls extending from the bottom wall, and facing each other, and an opening facing the bottom wall; a sealing plate for sealing the opening; an electrode body accommodated in an inside of the exterior body, and including a first electrode sheet, and a second electrode sheet having a different polarity from that of the first electrode sheet; a first electrode tab group provided at a first end face on one side of the electrode body facing one of the pair of first sidewalls, and electrically connected with the first electrode sheet; a second electrode tab group provided on a second end face of the electrode body facing the other of the pair of first sidewalls, and electrically connected with the second electrode sheet; a terminal fixed at the sealing plate; and a collector electrically connected with the terminal and the electrode body. The collector has a first collector to be connected with the first electrode tab group, and a second collector to be connected with the second electrode tab group. At least any one of the first collector and the second collector has: a first region part to be joined with the first electrode tab group or the second electrode tab group, a second region part to be connected with the terminal, and a third region part closer to the electrode body than the first region part. 
     The collector of the secondary battery with the foregoing configuration has a third region part closer to the electrode body than the first region part. Such a third region part restricts the movement of the electrode body. As a result, even when the secondary battery is applied with an external force such as a vibration, it is possible to prevent a large stress from acting on the junction between the electrode tab group and the collector. As a result of this, it is possible to prevent the damage on the junction between the electrode tab group and the collector. 
     In accordance with one preferable aspect of the secondary battery herein disclosed, the third region part is arranged closer to the bottom wall of the exterior body than the first region part, and a step is provided between the first region part and the third region part. With such a configuration, the effects of the technology herein disclosed can be properly exhibited. 
     In accordance with another preferable aspect, the second region part is arranged closer to the sealing plate than the first region part, a step is provided between the second region part and the first region part, and the first region part is closer to the first sidewall of the exterior body than the second region part. With such a configuration, the effects of the technology herein disclosed can be properly exhibited. 
     In accordance with a still other preferable aspect, the third region part is in contact with the first end face or the second end face. With such a configuration, the movement of the electrode body can be more properly suppressed. 
     In accordance with a furthermore preferable aspect, the third region part is closer to the electrode body than the second region part. With such a configuration, the movement of the electrode body can be more properly suppressed. 
     In accordance with a still other preferable aspect, the collector includes an insulation layer on a surface on the electrode body side of the third region part. With such a configuration, in addition to the prevention of breakage at the junction, the short circuit preventing effect can be exhibited. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view schematically showing a secondary battery in accordance with one embodiment; 
         FIG. 2  is a schematic cross sectional view along line II-II of  FIG. 1 ; 
         FIG. 3  is a schematic cross sectional view along line of  FIG. 1 ; 
         FIG. 4  is a perspective view schematically showing an electrode body mounted on a sealing plate; 
         FIG. 5  is a perspective view schematically showing an electrode body with a positive electrode collector and a negative electrode collector mounted thereon; 
         FIG. 6  is a schematic view showing a configuration of an electrode body in one embodiment; 
         FIG. 7  is a partially enlarged cross sectional view schematically showing the vicinity of a positive electrode terminal and a positive electrode collector in one embodiment; 
         FIG. 8  is a perspective view schematically showing a positive electrode collector for use in a secondary battery in accordance with one embodiment; 
         FIG. 9  is a perspective view of the positive electrode collector of  FIG. 8  in a reversed form; 
         FIG. 10  is a partially enlarged cross sectional view schematically showing the vicinity of a positive electrode terminal and a positive electrode collector in second embodiment; 
         FIG. 11  is a partially enlarged cross sectional view schematically showing the vicinity of a positive electrode terminal and a positive electrode collector in third embodiment; and 
         FIG. 12  is a partially enlarged cross sectional view schematically showing the vicinity of a positive electrode terminal and a positive electrode collector in fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Below, referring to the accompanying drawings, some preferable embodiments of the technology herein disclosed will be described. Incidentally, matters necessary for executing the present invention, except for matters specifically referred to in the present specification (e.g., a general configuration and manufacturing process of a secondary battery not characterizing the technology herein disclosed) can be grasped as design matters of those skilled in the art based on the related art in the present field. The technology herein disclosed can be executed based on the contents disclosed in the present specification, and the technical common sense in the present field. 
     In the present specification, the term “secondary battery” denotes an electric storage device capable of repeatedly charging and discharging in general, and is a concept including a so-called storage battery (chemical battery) such as a lithium ion secondary battery or a nickel hydrogen battery, and a capacitor (physical battery) such as an electric double layer capacitor. 
     1. First Embodiment 
     Secondary Battery  100   
       FIG. 1  is a perspective view schematically showing a secondary battery in accordance with one embodiment.  FIG. 2  is a schematic cross sectional view along line II-II of  FIG. 1 .  FIG. 3  is a schematic cross sectional view along line of  FIG. 1 . Further, a reference sign X in each figure referred to in the present specification represents “the depth direction”, a reference sign Y represents “the width direction” and a reference sign Z represents “the height direction”. Further, F in the depth direction X represents the “front”, and Rr represents “the rear”. L in the width direction Y represents the “left”, and R represents the “right”. Then, U in the height direction Z represents the “up”, and D represents the “down”. However, these are merely the directions for convenience of description, and do not restrict the arrangement form of a secondary battery  100  at all. 
     As shown in  FIG. 2 , the secondary battery  100  includes a battery case  10 , an electrode body  20 , a positive electrode terminal  30 , a negative electrode terminal  40 , a positive electrode collector  50 , a negative electrode collector  60 , and an insulator  70 . Although not shown, the secondary battery  100  herein further includes an electrolyte. The secondary battery  100  is herein a lithium ion secondary battery. The positive electrode collector  50  and the negative electrode collector  60  are examples of the first collector and second collector of the secondary battery herein disclosed, respectively. 
     The battery case  10  is a housing for accommodating the electrode body  20  therein. The battery case  10  herein has an outward shape in a flat and bottomed rectangular parallelepiped shape (square shape). The material for the battery case  10  may be the same as the material conventionally used, and has no particular restriction. The battery case  10  is preferably made of a metal, and more preferably includes, for example, aluminum, an aluminum alloy, iron, or an iron alloy. Incidentally, other than the electrode body  20 , an electrolyte (not shown) is also accommodated in the inside of the battery case  10 . For such an electrolyte, the one usable in this kind of secondary battery can be used without particular restriction, and the electrolyte does not characterize the technology herein disclosed, and hence a detailed description thereon is omitted. 
     As shown in  FIG. 2 , the battery case  10  includes an exterior body  12  having an opening  12   h , and a sealing plate (sealing sheet, lid body)  14  for closing the opening  12   h . The exterior body  12  includes, as shown in  FIG. 1 , a bottom wall  12   a  in a rectangular shape in a plan view, a pair of long sidewalls  12   b  extending in the height direction Z from respective long sides of the bottom wall  12   a , and opposed to each other, and a pair of short sidewalls  12   c  extending from the short sides of the bottom wall  12   a  in the height direction, and opposed to each other. The short sidewall  12   c  is one example of a first sidewall of the secondary battery herein disclosed. The long sidewall  12   b  is one example of a second sidewall in the secondary battery herein disclosed. The bottom wall  12   a  is opposed to the opening  12   h . The area of the short sidewall  12   c  is smaller than the area of the long sidewall  12   b . The sealing plate  14  is mounted on the exterior body  12  so as to close the opening  12   h  of the exterior body  12 . The sealing plate  14  is opposed to the bottom wall  12   a  of the exterior body  12 . The sealing plate  14  is in a generally rectangular shape in a plan view. The battery case  10  is integrated by joining the sealing plate  14  with the peripheral edge of the opening  12   h  of the exterior body  12 . The battery case  10  is hermetically sealed (closed). 
     As shown in  FIG. 2 , the sealing plate  14  is provided with a solution introduction port  15 , a gas discharge valve  17 , and two terminal lead-out holes  18  and  19 . The solution introduction port  15  is for introducing an electrolyte after mounting the sealing plate  14  on the exterior body  12 . The solution introduction port  15  is sealed by a sealing member  16 . The gas discharge valve  17  is a thin wall part configured so as to rupture when the pressure in the battery case  10  becomes a prescribed value or higher, and to discharge the gas in the battery case  10 . The terminal lead-out holes  18  and  19  are formed at opposite ends in the width direction Y of the sealing plate  14 , respectively. The terminal lead-out holes  18  and  19  penetrate through the sealing plate  14  in the height direction Z. The terminal lead-out holes  18  and  19  each have an inner diameter of a size allowing the positive electrode terminal  30  and the negative electrode terminal  40  respectively before being mounted on the sealing plate  14  (before caulking) to be inserted therethrough. 
     The secondary battery herein disclosed includes a terminal fixed at the sealing plate. Herein, the positive electrode terminal  30  and the negative electrode terminal  40  are fixed at the sealing plate  14 , respectively. The positive electrode terminal  30  is arranged on one side in the width direction Y of the sealing plate  14  (on the left side of  FIG. 1  and  FIG. 2 ). The negative electrode terminal  40  is arranged on the other side in the width direction Y of the sealing plate  14  (on the right side of  FIG. 1  and  FIG. 2 ). For the positive electrode terminal  30 , for example, aluminum is used. 
     The positive electrode terminal  30  has a flat-sheet-shaped base  31  arranged on the outer surface of the sealing plate  14 , a shaft part  32  extending downward (toward the bottom wall  12   a  side) in the height direction Z from the base  31 , and a collector connection part  33  connected to the positive electrode collector  50  and the shaft part  32  (see  FIG. 7 ). As shown in  FIG. 7 , the base  31  of the positive electrode terminal  30  is exposed to the outer surface of the sealing plate  14 . As shown in  FIG. 7 , the shaft part  32  of the positive electrode terminal  30  is inserted through the terminal lead-out hole  18 , and extends from the outside to the inside of the sealing plate  14 . The positive electrode terminal  30  is herein fixed at the peripheral edge portion surrounding the terminal lead-out hole  18  of the sealing plate  14  by caulking. Further, the collector connection part  33  is the portion to be connected with a positive electrode collector  50  described later. The collector connection part  33  is formed in a L-shaped cross section, and has an upper part  33   a  arranged along the inner surface of the sealing plate  14 , and a lower part  33   b  extending from one end in the width direction Y of the upper part  33   a  (each left end of  FIG. 2  and  FIG. 7 ) downward (toward the bottom wall  12   a  side). At the upper part  33   a  of the collector connection part  33 , a through hole  33   h  penetrating in the height direction Z is formed. Such a through hole  33   h  is arranged at the position corresponding to the terminal lead-out hole  18  of the sealing plate  14 , and the shaft part  32  is inserted therethrough. As a result, the positive electrode terminal  30  is constructed. Incidentally, the collector connection part  33  may be configured by bending one sheet-shaped member by, for example, press working, or may be configured by integrating a plurality of members by weld joining, or the like. Further, for the positive electrode terminal  30  in the present embodiment, the base  31  and the shaft part  32  are integrated with each other, and the collector connection part  33  is a different body (see  FIG. 7 ). However, the detailed structure of the positive electrode terminal  30  has no particular restriction, and may be formed so that the base  31 , the shaft part  32 , and the collector connection part  33  are integrated to one another. Further, although not described in details, for the secondary battery  100  in accordance with the present embodiment, the negative electrode terminal  40  also has generally the same structure as that of the positive electrode terminal  30 . Incidentally, for the material for the negative electrode terminal  40 , copper or the like is used. 
     As shown in  FIG. 2 , the positive electrode terminal  30  is electrically connected with the positive electrode sheet  22  of the electrode body  20  (see  FIG. 6 ) via the positive electrode collector  50  in the inside of the exterior body  12 . The negative electrode terminal  40  is electrically connected with the negative electrode sheet  24  of the electrode body  20  (see  FIG. 6 ) via the negative electrode collector  60  in the inside of the exterior body  12 . Incidentally, both of the positive electrode terminal  30  and the negative electrode terminal  40  are insulated from the sealing plate  14  by an insulator  70  and a gasket  90 . 
     The insulator  70  is arranged between the positive electrode terminal  30  (typically, a collector connection part  33 ) and the inner surface of the sealing plate  14 . The insulator  70  has a flat part  71  arranged along the inner surface of the sealing plate  14 , and a wall part  72  formed so as to descend from the peripheral edge of the flat part  71  toward the electrode body  20  (see  FIG. 7 ). The positive electrode terminal  30  is arranged in the concave part surrounded by the wall part  72 . Further, a through hole  71   h  is formed in the flat part  71 . The gasket  90  is arranged between the positive electrode terminal  30  (typically, the base  31 ) and the outer surface of the sealing plate  14 . Further, the gasket  90  has a tubular projection to be inserted into the terminal lead-out hole  18  of the sealing plate  14 . The projection of such a gasket  90  is arranged so as to be along the inner circumference of the through hole  71   h  of the insulator  70 . Provision of the insulator  70  and the gasket  90  with the foregoing configuration can prevent the contact between the positive electrode terminal  30  and the sealing plate  14 . Incidentally, for the insulation structure using the insulator and the gasket, although the same structure is provided on the negative electrode terminal  40  side, a detailed description thereon will be omitted. Incidentally, the constituent materials for the insulator  70  and the gasket  90  have no particular restriction, and can be resin materials including polyolefin resins (e.g., polypropylene (PP) and polyethylene (PE)), fluorine resins (e.g., perfluoroalkoxy alkane (PFA) and polytetrafluoroethylene (PTFE)), and the like. 
       FIG. 4  is a perspective view schematically showing the electrode body mounted at the sealing plate. Further,  FIG. 5  is a perspective view schematically showing the electrode body including the positive electrode collector and the negative electrode collector mounted thereon. As shown in  FIG. 3  and  FIG. 4 , the secondary battery  100  in accordance with the present embodiment includes three electrode bodies  20 . However, the number of the electrode bodies to be arranged in the inside of one exterior body  12  has no particular restriction, and may be two or more (plural), or may be 1. Further, as shown in  FIG. 4  and  FIG. 5 , a positive electrode collector  50  and a negative electrode collector  60  described later are mounted on each electrode body  20 . Then, the electrode body  20  is herein arranged in the inside of the exterior body  12  while being covered with an electrode body holder  29  (see  FIG. 2 ) including a sheet made of a resin. 
       FIG. 6  is a schematic view showing the configuration of the electrode body. As shown in  FIG. 6 , the electrode body  20  has a positive electrode sheet  22  and a negative electrode sheet  24 . The electrode body  20  is herein a flat-shaped wound electrode body configured such that a band-shaped positive electrode sheet  22  and a band-shaped negative electrode sheet  24  are stacked via a band-shaped separator  26 , and are wound with a winding axis WL as the center. The positive electrode sheet  22  is one example of a first electrode sheet in the secondary battery herein disclosed. Then, the negative electrode sheet  24  is one example of a second electrode sheet in the secondary battery herein disclosed. Incidentally, in the following description, the electrode body  20  is appropriately referred to as a “wound electrode body  20 ”. However, such a description is not intended to restrict the structure of the electrode body in the technology herein disclosed to the wound electrode body. 
     As shown in  FIG. 2 , the wound electrode body  20  is arranged in the inside of the exterior body  12  with the winding axis WL oriented in parallel with the width direction Y. In other words, the wound electrode body  20  is arranged in the inside of the exterior body  12  with the winding axis WL oriented in parallel with the bottom wall  12   a , and orthogonal to the short sidewall  12   c . Then, the opposite end faces of the wound electrode body  20  in the direction along the winding axis WL (i.e., the width direction Y in  FIG. 6 ) are opposed to the short sidewalls  12   c  of the exterior body  12 . In the present specification, for convenience of description, the end face of the wound electrode body  20  opposed to the short sidewall  12   c  on the side close to the positive electrode terminal  30  (on the left side in the width direction Y in  FIG. 2 ) is referred to as a “first end face  20   a ”. Then, the end face of the wound electrode body  20  opposed to the short sidewall  12   c  on the side close to the negative electrode terminal  40  (on the right side in the width direction Y in  FIG. 2 ) is referred to as a “second end face  20   b”.    
     The positive electrode sheet  22  is a long band-shaped member as shown in  FIG. 6 . Such a positive electrode sheet  22  has a positive electrode collecting foil  22   c , and a positive electrode active material layer  22   a  fixed on at least one surface of the positive electrode collecting foil  22   c . Although not particularly restricted, one side edge in the width direction Y of the positive electrode sheet  22  may be provided with a positive electrode protective layer  22   p , if required. Incidentally, for the materials forming the positive electrode active material layer  22   a  and the positive electrode protective layer  22   p , those for used in this kind of secondary battery can be used without particular restriction. The materials do not characterize the technology herein disclosed, and hence will not be described in details. 
     One end in the width direction Y of the band-shaped positive electrode collecting foil  22   c  (the left end of  FIG. 6 ) is provided with a plurality of positive electrode tabs  22   t . The plurality of positive electrode tabs  22   t  respectively protrude toward one side in the width direction Y (the left side of  FIG. 6 ). The plurality of positive electrode tabs  22   t  protrude more outwardly in the width direction Y than the separator  26 . The plurality of positive electrode tabs  22   t  are provided at intervals (intermittently) along the longitudinal direction of the positive electrode sheet  22 . The plurality of positive electrode tabs  22   t  are each in a trapezoidal shape. The positive electrode tab  22   t  is herein a part of the positive electrode collecting foil  22   c , and includes metal foil (e.g., aluminum foil). The positive electrode tab  22   t  is a portion (collecting foil exposed part) of the positive electrode collecting foil  22   c  at which the positive electrode active material layer  22   a  and the positive electrode protective layer  22   p  are not formed. However, the positive electrode tab  22   t  may be a different member from the positive electrode collecting foil  22   c . Further, the positive electrode tab  22   t  may be provided at the other end in the width direction Y (the right end of  FIG. 6 ), or may be provided at each opposite end in the width direction Y. 
     As shown in  FIGS. 2 and 3 , the plurality of positive electrode tabs  22   t  are stacked at one end in the width direction Y (the left end of  FIG. 3 ), and form a positive electrode tab group  23 . In other words, the positive electrode tab group  23  is provided at the first end face  20   a  of the wound electrode body  20  opposed to the short sidewall  12   c  on one side (on the positive electrode terminal  30  side) of the exterior body  12 . The plurality of positive electrode tabs  22   t  are bent and curved so that the ends on the outward side are aligned. The positive electrode tab group  23  is electrically connected with the positive electrode terminal  30  via the positive electrode collector  50 . The plurality of positive electrode tabs  22   t  are preferably bent. The sizes (the length in the width direction Y and the length orthogonal to the width direction Y, see  FIG. 6 ) of the plurality of positive electrode tabs  22   t  can be appropriately adjusted according to, for example, the formation position in consideration of how the positive electrode tabs  22   t  are connected with the positive electrode collector  50 . Incidentally, the positive electrode tab group  23  is one example of the first electrode tab group in the secondary battery herein disclosed. 
     As with the positive electrode sheet  22 , the negative electrode sheet  24  is also a long band-shaped member. The negative electrode sheet  24  has, as shown in  FIG. 6 , a negative electrode collecting foil  24   c , and a negative electrode active material layer  24   a  fixed on at least one surface of the negative electrode collecting foil  24   c . Incidentally, for the materials forming the negative electrode active material layer  24   a , those for use in this kind of secondary battery can be used without particular restriction. The materials do not characterize the technology herein disclosed, and hence will not be described in details. 
     One end in the width direction Y of the band-shaped negative electrode collecting foil  24   c  (the right end of  FIG. 6 ) is provided with a plurality of negative electrode tabs  24   t . The plurality of negative electrode tabs  24   t  protrude toward one side in the width direction Y (the right side of  FIG. 6 ). The plurality of negative electrode tabs  24   t  protrude more outwardly in the width direction Y than the separator  26 . The plurality of negative electrode tabs  24   t  are provided at intervals (intermittently) along the longitudinal direction of the negative electrode sheet  24 . The plurality of negative electrode tabs  24   t  are each in a trapezoidal shape. The negative electrode tab  24   t  is herein a part of the negative electrode collecting foil  24   c , and includes metal foil (e.g., copper foil). The negative electrode tab  24   t  is herein a portion (collecting foil exposed part) of the negative electrode collecting foil  24   c  at which the negative electrode active material layer  24   a  is not formed. However, the negative electrode tab  24   t  may be a different member from the negative electrode collecting foil  24   c . Further, the negative electrode tab  24   t  may be provided at the other end in the width direction Y (the left end of  FIG. 6 ), or may be provided at each opposite end in the width direction Y. 
     As shown in  FIGS. 2 and 3 , the plurality of negative electrode tabs  24   t  are stacked at one end in the width direction Y (the right end of  FIG. 6 ), and form a negative electrode tab group  25 . In other words, the negative electrode tab group  25  is provided at the second end face  20   b  of the wound electrode body  20  opposed to the short sidewall  12   c  on the other side (on the negative electrode terminal  40  side) of the exterior body  12 . The plurality of negative electrode tabs  24   t  are bent and curved so that the ends on the outward side are aligned. The negative electrode tab group  25  is electrically connected with the negative electrode terminal  40  via the negative electrode collector  60 . The plurality of negative electrode tabs  24   t  are preferably bent. The sizes (the length in the width direction Y and the length orthogonal to the width direction Y, see  FIG. 6 ) of the plurality of negative electrode tabs  24   t  can be appropriately adjusted according to, for example, the formation position in consideration of how the negative electrode tabs  24   t  are connected with the negative electrode collector  60 . Incidentally, the negative electrode tab group  25  is one example of the second electrode tab group in the secondary battery herein disclosed. 
     A separator  26  is an insulating member interposed between the positive electrode sheet  22  and the negative electrode sheet  24 . As shown in  FIG. 6 , the wound electrode body  20  in the present embodiment includes two long band-shaped separators  26 . Incidentally, the materials forming the separator  26  may be the same as those of the separator for use in this kind of secondary battery. The materials do not characterize the technology herein disclosed, and hence will not be described in details. 
     Herein, the secondary battery  100  in accordance with the present embodiment is characterized by using a collector of a structure capable of suppressing the movement of the wound electrode body  20  with the foregoing configuration. Below, the case using such a collector for the positive electrode collector  50  will be described by reference to  FIG. 7  to  FIG. 9 . Incidentally,  FIG. 7  is a partially enlarged cross sectional view schematically showing the vicinity of the positive electrode terminal and the positive electrode collector in one embodiment. Further,  FIG. 8  is a perspective view schematically showing the positive electrode collector.  FIG. 9  is a perspective view of the positive electrode collector of  FIG. 8  in a reversed form. 
     The positive electrode collector  50  is one example of the first collector in the secondary battery herein disclosed. The positive electrode collector  50  constructs a conduction path for electrically connecting the positive electrode terminal  30  and the wound electrode body  20 . Specifically, the collector connection part  33  of the positive electrode terminal  30  and the positive electrode collector  50  are connected, thereby constructing the conduction path of the positive electrode terminal  30  and the positive electrode collector  50 . Further, the positive electrode tab group  23  of the wound electrode body  20  and the positive electrode collector  50  are connected with each other, thereby constructing the conduction path of the wound electrode body  20  and the positive electrode collector  50 . Incidentally, the positive electrode collector  50  may include the same metal species as that of the positive electrode collecting foil  22   c . Then, the positive electrode collector  50  in the present embodiment has, as shown in  FIGS. 4, 5 , and  FIGS. 7 to 9 , a first region part  51 , a second region part  52 , and a third region part  53 . 
     The first region part  51  is the portion to be joined with the positive electrode tab group  23  (i.e., the plurality of positive electrode tabs  22   t ). The first region part  51  is a sheet-shaped portion arranged so as to be opposed to the short sidewall  12   c  of the exterior body  12 . Further, the surface of the first region part  51  to be joined with the positive electrode tab group  23  is opposed to the first end face  20   a  of the wound electrode body  20 . As shown in  FIG. 3 , at the first region part  51 , a junction J with the positive electrode tab group  23  is formed. The junction J is, for example, a welded junction obtained by welding the plurality of positive electrode tabs  22   t  being stacked on one another on the surface of the first region part  51  using a conventionally known welding means. The junction J is arranged with the plurality of positive electrode tabs  22   t  set closer to one side in the depth direction X of the wound electrode body  20  (the front side in  FIG. 3 ). 
     The second region part  52  is a portion to be connected with the positive electrode terminal  30 . As shown in  FIGS. 4, 5, and 7 , the second region part  52  is a sheet-shaped portion arranged above the first region part  51  (on the sealing plate  14  side), and extending along the height direction Z. The upper end of the second region part  52  is connected with the collector connection part  33  of the positive electrode terminal  30 , thereby constructing the conduction path of the positive electrode terminal  30  and the positive electrode collector  50 . Specifically, the second region part  52  is provided with a concave part  52   d  with a smaller thickness than that of the periphery thereof. The concave part  52   d  is provided with a through hole  52   e  penetrating in the depth direction X. Then, the collector connection part  33  of the positive electrode terminal  30  is inserted through the through hole  52   e  of the second region part  52 , thereby forming the junction. As a result of this, the positive electrode collector  50  and the positive electrode terminal  30  are fixed. The junction at this step may be the welded junction formed using, for example, a conventionally known welding means. Further, the second region part  52  may be provided with a fuse. The fuse is a portion with a smaller thickness than those of other portions of the second region part  52 , and is configured so as to be ruptured by being applied with a heat at the time of short circuit or at the time of overcharging of the secondary battery  100 . 
     Further, a first step part  54  is provided between the first region part  51  and the second region part  52 . The first step part  54  connects the upper end of the first region part  51  and the lower end of the second region part  52 . The first step part  54  is arranged so as to be along the sealing plate  14  of the exterior body  12 . The first step part  54  is formed so that the second region part  52  is arranged on the side of the center in the width direction Y (closer to the wound electrode body  20 ) than the first region part  51 . In other words, the second region part  52  of the positive electrode collector  50  in the present embodiment is closer to the wound electrode body  20  than the first region part  51 , and the first region part  51  is closer to the short sidewall  12   c  of the exterior body  12  than the second region part  52 . In this manner, the first region part  51  is arranged on the short sidewall  12   c  side. This can contribute to the increase in dimensions in the width direction Y of the wound electrode body  20 , and the increase in volume ratio of the wound electrode body  20  with respect to the internal amount of the exterior body  12 . Further, the first region part  51  below the second region part  52  is set at the junction position with the positive electrode tab group  23 . This can ensure the distance between the lower part  33   b  of the collector connection part  33  and the wound electrode body  20 , and can prevent the contact therebetween. Incidentally, the first step part  54  shown in  FIG. 7  is formed generally perpendicular to each of the first region part  51  and the second region part  52 . However, the angle of the first step part  54  with respect to the first region part  51  has no particular restriction. Incidentally, in the present specification, the wording “A and B being generally perpendicular to each other” includes, other than “the angle formed by A and B being 90 degrees”, the case where the angle can be substantially regarded as perpendicular” so long as the effects of the technology herein disclosed can be implemented. For example, the case where the angle formed by A and B is 85 degrees or more and 95 degrees or less can be included. 
     The third region part  53  is a portion closer to the wound electrode body  20  than the first region part  51 . The third region part  53  in the present embodiment is a sheet-shaped portion connected with the first region part  51  as shown in  FIG. 7 . The third region part  53  is arranged on the lower side of the first region part  51  (on the bottom wall  12   a  side), and extends along the height direction Z. Then, the third region part  53  of the positive electrode collector  50  in the present embodiment is in contact with the first end face  20   a  of the wound electrode body  20 . Further, as described above, the positive electrode collector  50  is fixed with the positive electrode terminal  30  at the second region part  52 . Namely, with the secondary battery  100  in accordance with the present embodiment, the third region part  53  of the positive electrode collector  50  fixed at the positive electrode terminal  30  can restrict the movement of the wound electrode body  20 . As a result, even when the secondary battery  100  is applied with an external force such as a vibration, it is possible to prevent a large stress from acting on the junction J between the positive electrode tab group  23  and the positive electrode collector  50  (first region part  51 ). This can prevent the occurrence of damages in the vicinity of the junction J. Further, when the positive electrode collector  50  is imparted with a function of restricting the movement of the wound electrode body  20  as with the foregoing configuration, the positive electrode collector  50  becomes an integral component for implementing both the connection with the positive electrode terminal  30 , and the restriction on the movement of the wound electrode body  20 . This eliminates the necessity of another component for restricting the movement of the wound electrode body  20 , which can simplify the assembly operation. For example, when the secondary battery  100  is mass-produced using equipment, the equipment functions can be reduced. In other words, by using the positive electrode collector  50  with the foregoing configuration, it is possible to reduce the number of components when the secondary battery  100  is assembled. For this reason, it is possible to provide the secondary battery  100  with high assemblability. 
     Further, in the positive electrode collector  50  in the present embodiment, a second step part  55  is provided between the first region part  51  and the third region part  53 . The second step part  55  connects the lower end of the first region part  51  and the upper end of the third region part  53 . The second step part  55  is arranged so as to be along the sealing plate  14 . Provision of such a second step part  55  can readily construct the positive electrode collector  50  in which the third region part  53  is closer to the wound electrode body  20  than the first region part  51 . Further, such a second step part  55  can be formed only by bending the sheet-shaped positive electrode collector  50 , which can also contribute to the improvement of the manufacturing efficiency. 
     Further, the positive electrode collector  50  in the present embodiment is formed such that the third region part  53  is closer to the wound electrode body  20  than the second region part  52 . In other words, in the positive electrode collector  50 , the length L 1  in the width direction Y of the first step part  54  is shorter than the length L 2  of the second step part  55  in the same direction, so that the third region part  53  is arranged closer to the center than the second region part  52 . This facilitates the contact of the third region part  53  with the first end face  20   a  of the wound electrode body  20 . For this reason, the movement of the wound electrode body  20  in the inside of the battery case  10  can be more properly restricted. 
     Further, as shown in  FIGS. 7 to 9 , an insulation layer  56  is provided on the surface on the wound electrode body  20  side of the third region part  53 . As a result of this, the short circuit preventing effect can be exhibited. Although not particularly restricted, during vibration of the secondary battery, when the end face of the electrode body is in contact with the third region part, such a contact part undergoes deformation. Thus, with the collector as the conduction path, a short circuit may be caused between the first electrode sheet (positive electrode sheet) and the second electrode sheet (negative electrode sheet). Provision of the insulation layer as described above can prevent the short circuit even when excessive deformation is caused, the short circuit can be prevented. Incidentally, the insulation layer  56  may be formed by bonding a film made of a resin to the third region part  53  by an adhesive, or the like. Alternatively, the insulation layer  56  may also be formed by applying a resin material on the surface for solidification. The materials forming the insulation layer  56  has no particular restriction so long as the materials can insulate the positive electrode collector  50  and the wound electrode body  20 , and resin materials such as polyethylene (PE) and polypropylene (PP) can be used. Incidentally, in the embodiment shown, the insulation layer  56  is formed entirely on the surface, and is not limited thereto, and may be formed at least a part of the surface. Still alternatively, the formation of the insulation layer  56  may be omitted. 
     Incidentally, the negative electrode collector  60  in the present embodiment is one example of the second collector in the secondary battery herein disclosed. As shown in  FIG. 2 , the negative electrode collector  60  includes a first region part  61 , a second region part  62 , and a third region part  63  as with the positive electrode collector  50 . As a result of this, the movement of the wound electrode body  20  in the inside of the battery case  10  can be more properly restricted. Incidentally, as described above, the negative electrode collector  60  has substantially the same configuration as that of the positive electrode collector  50 . The detailed description thereon becomes an overlapping description, and hence will be herein omitted. Further, the collector including the first region part, the second region part, and the third region part may be used for either one of the positive electrode collector and the negative electrode collector. 
     Further, the structure of the electrode body  20  in the secondary battery  100  in accordance with the present embodiment is not limited to the foregoing wound electrode body. For example, the electrode body  20  may be a lamination electrode body including a plurality of square-shaped (typically, a rectangular-shaped) positive electrode sheets, and a plurality of square-shaped (typically, rectangular-shaped) negative electrode sheets stacked one on another while being insulated from one another. 
     Up to this point, the secondary battery  100  in accordance with one embodiment of the technology herein disclosed has been described. The secondary battery  100  with the foregoing configuration is usable for various uses, and can be preferably used for uses in which an external force such as a vibration or an impact tends to be applied in use, for example, a power source (a driving power supply) for a motor to be mounted on a mobile unit (typically, a car such as an automobile or a truck). The kind of the automobile has no particular restriction. Examples thereof may include a Plug-in Hybrid Electric Vehicle (PHEV), a Hybrid Electric Vehicle (HEV), and a Battery Electric Vehicle (BEV). The secondary battery  100  can also be preferably used as an assembled battery obtained by arraying a plurality of secondary batteries  100  in a prescribed array direction, and applying a load thereon from the array direction by a binding mechanism. 
     2. Other Embodiments 
     The first embodiment is merely one example of the secondary battery herein disclosed. The technology herein disclosed can be additionally carried out in various forms. Below, other embodiments of the technology herein disclosed will be described. 
     Second Embodiment 
     For example, in the first embodiment, the second step part  55  was provided between the first region part  51  and the third region part  53  of the positive electrode collector  50 . However, the shape of the positive electrode collector  50  is not limited thereto.  FIG. 10  is a partially enlarged cross sectional view schematically showing the vicinity of the positive electrode terminal and the positive electrode collector in the second embodiment. The secondary battery  200  in accordance with the second embodiment includes a positive electrode collector  250  having an inclined part  255  between a first region part  251  and a third region part  253 . Specifically, as shown in  FIG. 10 , the inclined part  255  of the positive electrode collector  250  is preferably configured so as to get closer to the end face  20   a  of the wound electrode body  20  with approach toward the lower side in the height direction Z (the bottom wall  12   a  side) (i.e., to get closer to the center in the width direction Y). Even when the positive electrode collector  250  with such a configuration is used, the movement of the wound electrode body  20  can be properly restricted, and the breakage of the positive electrode tab group  23  by an external force such as a vibration can be prevented. Incidentally, the secondary battery  200  in accordance with the second embodiment may be the same as the secondary battery  100  in accordance with the first embodiment except for the foregoing point. Further, in the second embodiment, a first step part  254  is provided between a first region part  251  and a second region part  252 . However, such a first step part  254  is not an essential structure, and can be changed to an inclined part, or the like. 
     Third Embodiment 
     Further, in the first embodiment, the third region part  53  of the positive electrode collector  50  was formed closer to the bottom wall  12   a  (the lower side in the height direction Z) than the first region part  51 . However, the third region part may only be closer to the wound electrode body than the first region part, and the formation position in the height direction Z has no restriction.  FIG. 11  is a partially enlarged cross sectional view schematically showing the vicinity of the positive electrode terminal and the positive electrode collector in the third embodiment. A secondary battery  300  in accordance with the third embodiment includes a positive electrode collector  350  having a projection-shaped third region part  353  projecting from the second region part  352  (typically, the vicinity of a first step part  354 ) toward the wound electrode body  20  as shown in  FIG. 11 . Then, the projection-shaped third region part  353  is closer to the wound electrode body  20  than the first region part  351 . Even when the positive electrode collector  350  with such a configuration is used, the movement of the wound electrode body  20  can be properly restricted, and the breakage of the positive electrode tab group  23  by an external force such as a vibration can be prevented. Incidentally, although not particularly restricted, the third region part  353  may only be in contact with the side surface of the wound electrode body  20 . Further, the third region part  353  may only have an insulation layer (not shown) on the surface on the wound electrode body  20  side. Incidentally, the secondary battery  300  in accordance with the third embodiment may be the same as the secondary battery  100  in accordance with the first embodiment except for the foregoing point. 
     Fourth Embodiment 
     Further, in the positive electrode collector  50  in the first embodiment, the second region part  52  and the third region part  53  were formed of different members. However, there can be adopted such a configuration that the second region part is set closer to the wound electrode body than the first region part, and also serves as a third region part.  FIG. 12  is a partially enlarged cross sectional view schematically showing the vicinity of the positive electrode terminal and the positive electrode collector in a fourth embodiment. A second region part  452  in a positive electrode collector  450  in a secondary battery  400  in accordance with the fourth embodiment is arranged between the lower part  33   b  of the collector connection part  33  of the positive electrode terminal  30  and the first end face  20   a  of the wound electrode body  20  in the width direction Y. Specifically, in this embodiment, the second region part  452  of the positive electrode collector  450  is inserted between the lower part  33   b  of the collector connection part  33  and the first end face  20   a  of the wound electrode body  20 . When such a configuration is adopted, the second region part  452  is closer to the electrode body  20  than the first region part  451 , and also functions as a third region part  453 . For this reason, the movement of the wound electrode body  20  can be restricted. Incidentally, a first step part  454  is provided between the second region part  452  (the third region part  453 ) and the first region part  451 . Further, although not particularly restricted, an insulation layer (not shown) is preferably provided on the surface on the wound electrode body  20  side of the second region part  452  (the third region part  453 ). Incidentally, the secondary battery  400  in accordance with the fourth embodiment may be the same as the secondary battery  100  in accordance with the first embodiment except for the foregoing point. 
     Up to this point, some embodiments of the technology herein disclosed were described. However, the technology can be executed additionally in various aspects. The technology herein disclosed can be executed based on the contents disclosed in the present specification, and the technical common sense in the present field. For example, a part of the embodiments can be replaced with other modified aspects, and other modified aspects can be added to the embodiments. Further, the technical features can be appropriately deleted unless the technical features are described as essential ones.