Abstract:
In a laminate-cased battery, tab resins are adhered to positive and negative tabs, except outer ends of the tabs, and inserted (i) between a casing and the positive tab and (ii) between the casing and the negative tab in areas where the positive and negative tabs cross a heat-sealed edge of the casing. 
     Each of the tab resins has (i) a crossing area in which the tab resin crosses the heat-sealed edge and (ii) an extension area in which the tab resin extends outward from the casing, in a direction in which the positive and negative tabs extend. Each crossing area includes a high melting point resin layer whose melting point is relatively higher than a melting point of each element that constitutes the extension areas.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (1) Field of the Invention 
         [0002]    The present invention relates to a laminate-cased battery, and in particular to the construction of tab resins adhered to tabs. 
         [0003]    (2) Description of the Related Art 
         [0004]    Laminate-cased batteries have been prevalent with the widespread use of mobile apparatuses, such as mobile phones. The following describes the construction of a laminate-cased battery, with reference to  FIGS. 1A and 1B . 
         [0005]    As shown in  FIG. 1A , a laminate-cased battery has the construction in which an electrode assembly  110  is housed in a laminate casing  75  that is formed with a metal laminate sheet. The electrode assembly  110  is composed of a positive plate  111 , a negative plate  112 , and a separator  113 . The laminate casing  75  is formed by pressing and bending one metal laminate sheet into a bag-shape, and heat-sealing three outer edges  75   b ,  75   c , and  75   d  that are open. The bent portion of the metal laminate sheet is a bottom portion  75   a  of the laminate casing  75 . 
         [0006]    The positive plate  111  and negative plate  112  of the electrode assembly  110  are connected to a positive tab  86  and a negative tab  87 , respectively. The positive and negative tabs  86  and  87  cross the outer edge  75   c  positioned at an upper end of the laminate casing  75  in the z axial direction, and extend outward. Also, tab resins  96  and  97  are adhered to the positive and negative tabs  86  and  87 , to increase the adhesive strength with an inner resin layer of the laminate casing  75 . Also, provided in the outer edge  75   c  are blister portions  75   c   1  and  75   c   2  that have blisters so as to release the positive and negative tabs  86  and  87  in their thickness directions. 
         [0007]    As shown in the enlarged part of  FIG. 1A , the laminate casing  75  has a three-layer structure including a polypropylene layer  751  (hereinafter referred to as “PP layer”), an aluminum layer  752  (hereinafter referred to as “Al layer”), and a nylon layer  753  (hereinafter referred to as “Ny layer”) that are laminated in the stated order from the inside. The tab resin  96  also has a three-layer structure including a modified PP layer  961 , a polyethylene naphthalate layer  962  (hereinafter referred to as “PEN layer”), and a modified PP layer  963 , in the stated order from the side of the positive tab  86 . Note that the reason for adopting the construction in which the tab resin  96  includes the PEN layer  962  is to prevent contact between (i) the positive and negative tabs  86  and  87  and (ii) the Al layer  752  of the laminate casing  75 , by the PEN layer  962  functioning as a heat-resistant layer during the heat-sealing (see, for example, Japanese laid-open patent application No. 2000-268789, and Japanese laid-open patent application No. 2001-035477). 
         [0008]    Generally, as shown in  FIG. 1B , a circuit board  115  is attached to the laminate-cased battery, and the positive and negative tabs  86  and  87  are bent into a U shape. This improves space efficiency and substantial energy efficiency. Here, the tab resins  96  and  97  are also adhered to the portions where the positive and negative tabs  86  and  87  are bent into a U shape. Therefore, an exposed edge of the Al layer  962  of the laminate casing  75  is not in contact with the positive and negative tabs  86  and  87 . 
         [0009]    Note that the outer edges  75   b  and  75   d , which are on both sides of the laminate casing  75  in the x axial direction of  FIG. 1 , are bent approximately 90[°] to improve space efficiency. 
         [0010]    However, it is difficult for the conventional laminate-cased battery to further improve the energy efficiency by reducing a size of each of the bent portions of the positive and negative tabs  86  and  87 . This is because the tab resins  96  and  97 , which are adhered to the bent portions of tabs  86  and  87 , are obstructions in terms of reducing the curvature radius of the bent portions of the tabs  86  and  87 . Specifically, as shown in the enlarged part of  FIG. 1A , the tab resins  96  and  97  each include the PEN layer  962  that has a higher heat resistance than the modified PP layers  961  and  963 . The PEN layer  962  has a high bending rigidity, which makes it difficult to further reduce the curvature radius of each of the bent portions of the tabs  86  and  87 . 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the above-described problem, the object of the present invention is to provide a laminate-cased battery having a high quality and high energy efficiency, the tabs of which have been bent with a small curvature radius, while securely maintaining insulation between the metal layer of a laminate casing and the tabs when heat-sealing the outer edges of the laminate-cased battery. 
         [0012]    The above object is fulfilled by a laminate-cased battery comprising: an electrode assembly including a positive plate and a negative plate; a casing that is made of a metal laminate sheet composed of a metal layer and resin layers laminated on both main surfaces of the metal layer, the metal laminate sheet being formed into a bag, so as to enclose a space substantially in a shape of a rectangular parallelepiped, an opening edge of the bag being heat-sealed with the electrode assembly housed in the bag; a positive tab that is made of a conductive material, is connected to the positive plate, and extends outward by crossing the heat-sealed edge; a negative tab that is made of a conductive material, is connected to the negative plate, and extends outward by crossing the heat-sealed edge; and a first tab resin that is adhered to the positive tab and has (i) a first crossing area in which the positive tab crosses the heat-sealed edge and (ii) a first extension area that extends more outward from the casing than the first crossing area, and, a second tab resin that is adhered to the negative tab and has (i) a second crossing area in which the negative tab crosses the heat-sealed edge and (ii) a second extension area that extends more outward from the casing than the second crossing area, wherein each of the first and second tab resins in the respective crossing areas includes a high melting point resin layer whose melting point is relatively higher than a melting point of each element constituting the first and second extension areas. In other words, the crossing area includes a high melting point resin layer, whereas the extension area includes a resin layer whose melting point is lower than the high melting point resin layer (hereinafter referred to as “low melting point resin layer”) and does not include the high melting point resin layer. 
         [0013]    As described above, the construction of a tab resin is different for each area in the laminate-cased battery according to the present invention. In other words, in the laminate-cased battery according to the present invention, a tab resin in the crossing area includes a high melting point resin layer. Therefore, the high melting point resin layer remains without fail even when heated during the heat sealing of the opening edge of the casing. This makes it possible to prevent a metal layer (aluminum (Al) layer or such) in a metal laminate sheet from being directly in contact with the positive and negative tabs. 
         [0014]    Also, in the laminate-cased battery according to the present invention, a tab resin in the extension area does not include a high melting point resin layer, but includes a low melting point resin layer. It is easier to bend low melting point resin layers than high melting point resin layers, which results in the positive and negative tabs in the extension area having high bending performance. Therefore, it is possible to reduce the curvature radius of the positive and negative tabs when the positive and negative tabs are bent after a circuit board is mounted, thereby improving space efficiency. 
         [0015]    The extension area is hardly heated during the heat sealing of the opening edge of the casing. Therefore, the tab resin in the extension area remains without fail, thereby maintaining insulation between (i) the metal layer exposed at the opening edge of the casing and (i) the positive and negative tabs. 
         [0016]    The above-described effect of the laminate-cased battery according to the present invention is achieved by focusing attention on the point that each resin layer used for the tab resin generally has different bending rigidity depending on the melting point, specifically on the point that the bending rigidity of the low melting point resin layers is smaller than that of the high melting point resin layers. 
         [0017]    Note that it is possible to adopt the construction that does not include any tab resin in the portions extended from the casing, when only considering the improvement of the bending performance of the positive and negative tabs. However, in a case where the portions do not have any tab resin in practice, the metal layer of the metal laminate sheet, which is exposed at the edge of the casing, makes contact with the positive and negative tabs. Therefore, it is not preferable to remove the tab resin from the extension area. 
         [0018]    Furthermore, it is not preferable to adopt the construction in which the tab resin in the crossing area includes only a low melting point resin layer, since this construction increases the risk of the metal layer of the metal laminate sheet making contact with the positive and negative tabs during the heat sealing. 
         [0019]    As described above, the laminate-cased battery according to the present invention has a high quality and high energy efficiency, the tabs of which have been bent with a small curvature radius, while securely maintaining insulation between the metal layer of a laminate casing and the tabs when heat-sealing the opening edge of the laminate-cased battery. 
         [0020]    The laminate-cased battery according to the present invention can adopt the following variations. 
         [0021]    Each of the first and second tab resins in the respective crossing areas has a lamination structure in which the high melting point resin layer is sandwiched on both sides in a thickness direction, by low melting point resin layers whose melting points are lower than the melting point of the high melting point resin layer. Note that, in the crossing area, the low melting point resin layers sandwiching the high melting point resin layer are not necessarily made of the same resin material as the low melting point resin layers of the tab resin in the extension area. 
         [0022]    Also, in the laminate-cased battery according to the present invention, a whole thickness of each of the tab resins in the respective extension areas may be thinner than a whole thickness of the tab resin in the crossing area. In this way, the bending rigidity of the tab resin in the extension area is improved by the difference in thickness as well as the different kinds of resin. In other words, the positive and negative tabs have been bent with a smaller curvature, thereby further improving energy efficiency. 
         [0023]    Furthermore, in the laminate-cased battery according to the present invention, each of the first and second tab resins in the respective crossing areas may include a polyester layer that is made of polyester as the high melting point resin layer, and each of the first and second tab resins in the respective extension areas may include a layer made of one of modified polypropylene and modified polyethylene as the low melting point resin layer, and may not include the polyester layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    These and the other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings which illustrate a specific embodiment of the invention. 
           [0000]    In the drawings: 
           [0025]      FIG. 1A  is a perspective view (partial cutaway view) showing a laminate-cased battery according to the conventional technique; 
           [0026]      FIG. 1B  is a side view showing a tab  86  of the laminate-cased battery according to the conventional technique; 
           [0027]      FIG. 2  is a perspective view (partial cutaway view) showing a laminate-cased battery  1  according to the present embodiment; 
           [0028]      FIG. 3  is a sectional view showing the construction of an outer edge  20   c  from which a tab  32  is extended and an inner tab resin  42 , in the laminate-cased battery  1  according to the present embodiment; 
           [0029]      FIG. 4A  is a schematic process chart showing a part of a manufacturing process of the laminate-cased battery  1 ; 
           [0030]      FIG. 4B  is a schematic process chart showing a part of the manufacturing process of the laminate-cased battery  1 ; 
           [0031]      FIG. 4C  is a schematic process chart showing a part of the manufacturing process of the laminate-cased battery  1 ; 
           [0032]      FIG. 5A  is a process chart showing a mounting process of a circuit board  60  on the laminate-cased battery  1 ; 
           [0033]      FIG. 5B  is a process chart showing a process of bending the tab  32 , after the circuit board  60  is mounted on the laminate-cased battery  1 ; 
           [0034]      FIG. 6A  is a sectional view showing the construction of an outer edge and tab resin of a laminate-cased battery, according to a comparison 1; and 
           [0035]      FIG. 6B  is a sectional view showing the construction of an outer edge and tab resin of a laminate-cased battery, according to a comparison 2. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    The following describes the preferred embodiment of the present invention with one example. It should be noted that the embodiment used for the descriptions below is merely one example for the clear and detailed descriptions of the construction of the present invention and the acts/effects achieved from the construction. Therefore the present invention shall not be limited to the embodiment described below, except the essential characteristic parts. 
         [0037]    1. Overall Construction 
         [0038]    The following describes the construction of a laminate-cased battery  1  according to the present embodiment, with reference to  FIG. 2 . 
         [0039]    As shown in  FIG. 2 , the laminate-cased battery  1  includes an electrode assembly  10  that is composed of a positive plate  11 , a negative plate  12 , and a separator  13 . The electrode assembly  10  is housed in a housing space of a laminate casing  20 . The positive plate  11  is made of aluminum foil to which lithium cobaltate (LiCoO 2 ) is applied. The negative plate  12  is made of copper foil to which graphite powder is applied. The separator  13  is made of, for example, porous polyethylene having a thickness of 0.02 [mm]. 
         [0040]    Although not shown in  FIG. 2 , the electrode assembly  10  is impregnated with polymer electrolyte. The impregnated polymer electrolyte may be a substance made in the following manner. First, Polyethylene Glycol Diacrylate is mixed with EC/DEC mixture (Mass Ratio 30:70) at 1:10 ratio. Then, 1 [mol/L] of LiPF 6  is added to the mixture, and gelatinized through thermal polymerization. 
         [0041]    The laminate casing  20  is formed with one metal laminate sheet that has been pressed and bent into a bag-shape. Three outer edges  20   b ,  20   c , and  20   d  are heat-sealed while a bottom portion  20   a  positioned at a lower end of the laminate casing  20  in the z axial direction is left unsealed. Here, the outer edge  20   c  corresponds to an “opening edge of the bag”, and is referred to as “heat-sealed edge” after being heat-sealed. 
         [0042]    In the electrode assembly  10 , the positive plate  11  and the negative plate  12  are both connected to tabs  31  and  32 . The tabs  31  and  32  are extended outward by crossing the outer edge  20   c  of the laminate casing  20 , which is positioned at an upper end of the laminate casing  20  in the z axial direction. The tabs  31  and  32  are adhered to inner tab resins  41  and  42  and sealed part tab resins  51  and  52 , in order to increase the adhesive strength with an inner resin layer of the laminate casing  20 , and to insulate the tabs  31  and  32  from a metal layer exposed at an edge of the laminate casing  20 . 
         [0043]    Note that the outer edge  20   c  of the laminate casing  20 , which is positioned at the upper end of the laminate casing  20  in the z axial direction, includes blister portions  20   c   1  and  20   c   2  that release the tabs  31  and  32  in their thickness directions. Also, for higher space efficiency, the outer edges  20   b  and  20   d , which are on both sides of the laminate casing  20  in the x axial direction, are bent along an outer surface of a cup portion that houses the electrode assembly  10 . 
         [0044]    2. Inner Tab Resins  41 ,  42  and Sealed Part Tab Resins  51 ,  52   
         [0045]    The following describes adhesion states of the inner tab resins  41 ,  42  and the sealed part tab resins  51 ,  52 , with respect to the tabs  31  and  32 , with reference to  FIG. 3 .  FIG. 3  is a sectional view showing in detail a portion viewed in the direction of the arrow A in  FIG. 2 . 
         [0046]    As shown in  FIG. 3 , the laminate casing  20  of the laminate-cased battery  1  according to the present embodiment has a three-layer structure. Specifically, the laminate casing  20  includes a PP layer  201 , an Al layer  202 , and an Ny layer  203  laminated in the stated order from the inside. The thicknesses of the layers  201 ,  202 , and  203  are as follows.
       PP layer  201 : 45[μm]   Al layer  202 : 40 [μm]   Ny layer  203 : 25[μm]       
 
         [0050]    Although not shown in  FIG. 3 , a dry laminate adhesive layer having, for example, a thickness of 5 [μm], is arranged between each of the layers  201 ,  202 , and  203 . 
         [0051]    The inner tab resin  42  is composed of two sheet-shaped components  42   a  and  42   b  arranged so as to sandwich the tab  32 . The sheet-shaped components  42   a  and  42   b  constituting the inner tab resin  42  are adhered to the tab  32 , from a portion  32   b  toward the housing space of the laminate casing  20  without interruption. The portion  32   b  is part of a region  32   a  that extends from the outer edge  20   c  of the laminate casing  20 . 
         [0052]    The sealed part tab resin  52  is also composed of two sheet-shaped components  52   a  and  52   b . In the outer edge  20   c  of the laminate casing  20 , the sheet-shaped component  52   a  is arranged between the laminate casing  20  and the sheet-shaped component  42   a  of the inner tab resin  42 , and the sheet-shaped component  52   b  is arranged between the laminate casing  20  and the sheet-shaped component  42   b . The sheet-shaped component  52   a  of the sealed part tab resin  52  has a three-layer structure including a modified PP layer  521 , a PEN layer  522 , and a modified PP layer  523 . The sheet-shaped component  52   b  also has a three-layer structure including a modified PP layer  524 , a PEN layer  525 , and a modified PP layer  526 . 
         [0053]    Here, the sheet-shaped components  42   a  and  42   b  of the inner tab resin  42  are made from modified PP. Therefore, each of the sheet-shaped components  42   a  and  42   b  has a lower melting point and smaller bending rigidity than the PEN layers  522  and  525  that are included in the sheet-shaped components  52   a  and  52   b  of the sealed part tab resin  52 . Also, only the sheet-shaped components  42   a  and  42   b  of the inner tab resin  42  are adhered to the region  32   a  of the tab  32 . Therefore, the thickness of the adhesion resin of the tab  32  is smaller than that of the outer edge  20   c , since the adhesion resin of the outer edge  20   c  includes the sheet-shaped components  52   a  and  52   b  in addition to the sheet-shaped components  42   a  and  42   b.    
         [0054]    Here,  FIG. 3  only shows parts related to the tab  32 . However, the tab  31 , and the inner tab resin  41  and the sealed part tab resin  51  that are adhered thereto also have the same structure as the parts shown in  FIG. 3 . 
         [0055]    3. Manufacturing Method of Laminate-Cased Battery  1   
         [0056]    The following describes a manufacturing method of the laminate-cased battery  1 , with reference to  FIGS. 4A to 4C . Note that  FIGS. 4A to 4C  only show processes related to the formation of the laminate casing  20 . 
         [0057]    As shown in  FIG. 4A , a recessed portion  2000   a , whose size is equivalent to the electrode assembly  10 , is formed in a part of a metal laminate sheet  2000  that has a three layer structure including a PP layer  201 , an Al layer  202 , and an Ny layer  203  (see the enlarged part on the right side of  FIG. 4A ). The recessed portion  2000   a  is formed by press work. Then, resin sheets  520   a  and  520   b  are adhered to portions  2000   b  and  2000   c  that correspond to the outer edge  20   c  of the metal laminate sheet  2000 . 
         [0058]    As shown in the enlarged part on the left side of  FIG. 4A , the resin sheet  520   a  has the three-layer structure including the modified PP layer  521 , the PEN layer  522 , and the modified PP layer  523 . The resin sheet  520   b  also has the same three-layer structure. 
         [0059]    As shown in  FIG. 4B , outer portions  2000   f  and  2000   g , which are portions of the outer edges of the metal laminate sheet  2000 , are removed. At this time, portions of the resin sheets  520   a  and  520   b  on the outer portions  2000   f  and  2000   g  are also removed. In this way, the outer portions  2000   f  and  2000   g  are removed to form (i) remaining portions  2000   d ,  2000   e , and (ii) the sheet-shaped components  52   a ,  52   b  whose edges are adjusted. 
         [0060]    As shown in  FIG. 4C , the electrode assembly  10  to which the positive tab  31  (not shown in  FIG. 4C ) and the negative tab  32  are adhered is inserted in the recessed portion  2000   a  formed in the metal laminate sheet  2000 . Here, the inner tab resins  41  and  42  (the tab  31  and the inner tab resin  41  are not shown in  FIG. 4C ) are preliminarily adhered to the positive tab  31  and the negative tab  32 . As shown in the enlarged part of  FIG. 4C , the inner tab resin  42  is composed of two sheet-shaped components  42   a  and  42   b  that are adhered to each other with the tab  32  in between. 
         [0061]    As described above, the inner tab resins  41  and  42  have a single-layer structure with modified PP. 
         [0062]    Then, with B portion in  FIG. 4C  as a fulcrum, part of the metal laminate sheet  2000  is bent, in a manner that the sheet-shaped components  52   a  and  52   b  sandwich (i) the tab  32  and (ii) the inner tab resin  42  (sheet-shaped components  42   a  and  42   b ). Then, appropriate portions of the metal laminate sheet  2000  are heat-sealed. The same applies to the extending portion of the positive tab  31 . The other outer edges  20   b  and  20   d  are also heat-sealed while the metal laminate sheet  2000  is bent. 
         [0063]    In the above-described way, the laminate-cased battery  1  is completed. 
         [0064]    4. Advantages 
         [0065]    The following describes advantages of the laminate-cased battery  1  according to the present embodiment, with reference to  FIG. 3 ,  FIGS. 5A and 5B . 
         [0066]      FIG. 3  shows the outer edge  20   c  of the laminate casing  20  in the laminate-cased battery  1 . As shown in  FIG. 3 , the sheet-shaped components  52   a  and  52   b  are respectively inserted between the tab  32  and the laminate casing  20 . Here, the sheet-shaped components  52   a  and  52   b  constitute the sealed part tab resin  52 , which includes the PEN layers  522  and  525 . Each of the PEN layers  522  and  525  has a higher heat resistance than modified PP, and remains without fail even after the heat sealing process of the outer edge  20   c . As a result, the laminate-cased battery  1  securely maintains insulation between the Al layer  202  of the laminate casing  20  and the tab  32 . 
         [0067]    Also, in the laminate-cased battery  1 , the inner tab resin  42  having a single-layer structure with modified PP is adhered to the tab  32 , in the portion  32   b  that is part of the region  32   a  extending outward from the laminate casing  20 . Here, the inner tab resin  42  is composed of the sheet-shaped components  42   a  and  42   b . The inner tab resin  42  has the single-layer structure with modified PP that has a smaller bending rigidity than the PEN layers  522  and  525  that are included in the sheet-shaped components  52   a  and  52   b  of the sealed part tab resin  52 . This means that the inner tab resin  42  has a high bending performance after the circuit board is mounted, which is advantageous when manufacturing batteries having high energy efficiency. 
         [0068]    Specifically, as shown in  FIG. 5A , the circuit board  60  is mounted on each of the positive and negative tabs  31  and the negative tab  32  (the positive tab  31  is not shown in  FIG. 5A  or  FIG. 5B ), of the laminate-cased battery  1 . The circuit board  60  includes a substrate  61 , electronic components  62  and  63 , and a land  64 . The electronic components  62  and  63  are mounted on one main surface of the substrate  61 . The land  64  corresponds to each of the positive tab  31  and the negative tab  32 , and is formed on the other main surface of the substrate  61 . The circuit board  60  is attached to the laminate-cased battery  1  by soldering the land  64  to each of the tabs  31  and  32 . 
         [0069]    As shown in  FIG. 5B , the circuit board  60  attached to each of the tabs  31  and  32  is arranged in a space located at the upper end of the laminate casing  20  in the y axial direction of the outer edge  20   c . In other words, the tabs  31  and  32  are bent in positions where the inner tab resins  41  and  42  are adhered to, so that the circuit boards  60  are arranged at the upper end of the laminate casing  20  in the y axial direction of the outer edge  20   c.    
         [0070]    In the laminate-cased battery  1  according to the present invention, only the inner tab resins  41  and  42  that have a single-layer structure with modified PP are adhered to the portions extending from the laminate-cased battery  20 . This makes it possible to perform a bending work while the curvature of a portion C is small. 
         [0071]    Therefore, in the laminate-cased battery  1  according to the present invention, it is possible to achieve high space efficiency with respect to the bending of the tabs  31  and  32 , while maintaining insulation between (i) the Al layer  202  of the laminate casing  20  and (ii) the tabs  31  and  32 . Consequently, the laminate-cased battery  1  has a high quality and high energy efficiency. 
         [0072]    5. Confirmatory Experiment 
       Example 
       [0073]    The laminate-cased battery  1  according to the above-described embodiment is provided as an example. The following are the values of the tab resins  41 ,  42 ,  51 , and  52 . 
         [0074]    Thickness of each of the sheet-shaped components  42   a  and  42   b ; 0.06 [mm] 
         [0075]    Extension length of each of the inner tab resins  41  and  42  from the laminate casing  20 ; 2.0 [mm] 
         [0076]    Thickness of each of the PEN layers  522  and  525  in the sheet-shaped components  52   a  and  52   b ; 0.015 [mm] 
         [0077]    (Comparison 1) 
         [0078]    As shown in  FIG. 6A , a laminate-cased battery according to a comparison 1 is different from the laminate-cased battery  1  according to the above-described embodiment, on the point that the sealed part tab resins  51  and  52  are not inserted. That is, in the laminate-cased battery according to the comparison 1, a tab resin  92  (sheet-shaped components  92   a  and  92   b ) having a single-layer structure with modified PP is adhered to a tab  82 , and a PP layer  701  of a laminate casing  70  and a tab resin  92  are inserted between an Al layer  702  of the laminate casing  70  and the tab  82 . Note that the laminate-cased battery according to the comparison 1 has the same construction as the laminate-cased battery  1  according to the above-described embodiment, except the construction of the tab resin  92 . 
         [0079]    Thickness of each of the sheet-shaped components  92   a  and  92   b ; 0.06 [mm] 
         [0080]    Extension length of the tab resin  92  from the laminate casing  70 ; 2.0 [mm] 
         [0081]    (Comparison 2) 
         [0082]    As shown in  FIG. 6B , in a laminate-cased battery according to a comparison 2, a tab resin composed of sheet-shaped components  97   a  and  97   b  that each have a three-layer structure is adhered to a tab  87 , instead of the tab resin  92  of the laminate-cased battery according to the comparison 1. The sheet-shaped component  97   a  has a three-layer structure including a modified PP layer  971 , a PEN layer  972 , and a modified PP layer  973 , and the sheet-shaped component  97   b  has a three-layer structure including a modified PP layer  974 , a PEN layer  975 , and a modified PP layer  976 . A laminate casing  75  has a three-layer structure including a PP layer  751 , an Al layer  752 , and a Ny layer  753 , which is the same structure as the laminate casings in the above-described embodiment and the comparison 1. 
         [0083]    Thickness of each of the modified PP layers  971  and  974 ; 0.03 [mm] 
         [0084]    Thickness of each of the PEN layers  972  and  975 ; 0.015 [mm] 
         [0085]    Thickness of each of the modified PP layers  973  and  976 ; 0.03 [mm] 
         [0086]    Extension length of each of the tab sheet-shaped components  97   a  and  97   b  from the laminate casing  75 ; 2.0 [mm] 
       (Short Circuits During Heat Sealing Observed) 
       [0087]    When manufacturing laminate-cased batteries according to the above-described embodiment, comparisons  1  and  2 , short circuits caused by heat sealing were observed (Contact between an Al layer of a laminate casing and a tab). The following shows a sealing condition after observing 50 samples for each of the laminate-cased batteries. 
         [0088]    Sealing pressure; 1000 [N] 
         [0089]    Heating temperature; 190[° C.] 
         [0090]    Number of pieces experimented; 50 [pieces] each 
         [0000]    
       
         
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Occurrence of Short Circuit[pieces] 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Example 
                 0/50 
               
               
                   
                 Comparison 1 
                 23/50  
               
               
                   
                 Comparison 2 
                 0/50 
               
               
                   
                   
               
             
          
         
       
     
         [0091]    As shown in a table 1, in the laminate-cased battery of the comparison 1, 23 out of 50 tested samples shorted out. In other words, in the laminate-cased battery of the comparison 1, only the tab resin  92  having the single-layer structure with the modified PP is adhered to the tab  82 . Therefore, during a heat sealing process in which the outer edge of the laminate casing  70  is sealed, the Al layer  702  of the laminate casing  70  is likely to be electrically in contact with the tab  82 . 
         [0092]    Short circuits were not observed in the laminate-cased batteries according to the above-described embodiment and the comparison 2. 
       (Easiness in Bending Tabs) 
       [0093]    In the laminate-cased batteries according to the above-described embodiment and the comparison 2, portions to which the tab resins  42  and  97  are adhered were bent in the following condition. Then, the spring back angles of the portions were measured. The condition of the experiment is as follows. 
         [0094]    Condition; 2 [kgf] (19.6 [N]) Additional weight; 2 [sec.] Hold 
         [0095]    Measurement; Measure angle after leaving for 6 [hr.] 
         [0096]    Number of experiments; 50 [pieces] each 
         [0000]    
       
         
               
               
             
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Average Springback Angle [°] 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Example 
                 34 
               
               
                   
                 Comparison 1 
                 — 
               
               
                   
                 Comparison 2 
                 60 
               
               
                   
                   
               
             
          
         
       
     
         [0097]    As shown in  FIG. 2 , in the laminate-cased battery according to the comparison 2, an average springback angle after leaving for 6 [hr.] is 60[°]. In the laminate-cased battery according to the above-described embodiment, however, an average springback angle after leaving for 6 [hr.] is 34[°]. This means that the springback of the laminate-cased battery according to the above-described embodiment is 26[°] smaller than that of the laminate-cased battery according to the comparison 2. 
         [0098]    Therefore, the laminate-cased battery according to the above-described embodiment has an excellent bending performance in the tabs  31  and  32 , compared to the laminate-cased battery according to the comparison 2. As a result, the tabs  31  and  32  have been bent with small curvature, which is advantageous in terms of the energy efficiency. 
         [0099]    6. Others 
         [0100]    In the above-described embodiment, the inner tab resins  41  and  42  have a single-layer structure with modified PP. However, it is possible to adopt other materials and a multilayer structure. In this case, it is necessary to select a material having a lower melting point and a smaller bending rigidity than the PEN layers  522  and  525  included in the sealed part tab resins  51  and  52 . It is also preferable that the thickness of the inner tab resins  41  and  42  is thin, when considering the bending rigidity. The material of the inner tab resins  41  and  42  does not need to be modified PP, and may be, for example, modified PE. 
         [0101]    Also, although the laminate casing  20  of the three-side sealing type is adopted in the above-described embodiment, it is also possible to adopt a laminate casing of a four-side sealing type. In the four-side sealing type, after two metal laminate sheets are put together, four sides of the outer edges are all sealed. Also, in the above-described embodiment, the positive tab  31  and the negative tab  32  are extended from the same outer edge  20   c . However, it is possible to adopt a structure where the tabs  31  and  32  are extended from different edge portions. 
         [0102]    Although the electrode assembly  10  having a winding structure is adopted in the above-described embodiment, it is possible to adopt an electrode assembly having a lamination (stack) structure. 
         [0103]    Note that the values adopted in the above-described embodiment are merely exemplary, and may be changed when necessary. 
         [0104]    Although the present invention has been fully described by way of examples with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the present invention, they should be construed as being included therein.