Battery with fixing member

Abstract

To provide a battery in which damage to an electrode tab group is suitably prevented. [Solution] The battery 100 disclosed herein includes electrode bodies 20a (first electrode body), 20b, 20c (second electrode bodies) in the shape of a flattened hexahedron, each having a pair of rectangular flat outer surfaces 27, each including a positive electrode 22 and a negative electrode 24, and a battery case 10 that houses these. Here, a fixing member 1 is arranged from at least one of the pair of flat outer surfaces 27 of the electrode bodies 20a, 20c to a positive electrode current collector 50 or a negative electrode current collector 60.

Description

[Technical Field]

[0001] The present invention relates to a battery provided with a fixing member. [Background technology]

[0002] Batteries such as lithium-ion secondary batteries generally include a flattened hexahedron-shaped electrode assembly having a positive electrode and a negative electrode (hereinafter simply referred to as "electrodes"); an exterior housing having an opening and housing the electrode assembly; a sealing plate sealing the opening of the exterior housing; and terminals electrically connected to the electrodes inside the exterior housing and extending from the sealing plate to the exterior housing. This type of battery typically includes an electrode tab group including multiple tabs for collecting current on the electrodes, and the electrode tab group is connected to the terminals via an electrode current collector. For example, Patent Document 1 listed below discloses a battery in which a positive electrode tab group is provided at one longitudinal end of the electrode assembly and a negative electrode tab group is provided at the other longitudinal end. The patent document also discloses a technology in which the electrode tab group is connected to the electrode current collector in a folded state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-50069 Summary of the Invention [Problem to be solved by the invention]

[0004] During use, the battery may be subjected to external vibrations, shocks, and the like. The tabs, for example, are part of the current collector and are soft and susceptible to external forces. Therefore, if an external force (specifically, an external force applied in the longitudinal direction of the electrode body) displaces the electrode body from its predetermined position, placing a load on the electrode tab group, the electrode tab group may be damaged. This is undesirable because it may result in unstable or defective electrical connections between the electrodes and terminals. Furthermore, the inventors' investigations have found that, particularly when the electrode tab group is connected to the electrode current collector in a bent state, the electrode tab group is susceptible to damage due to the concentration of external forces at the bent portions.

[0005] The present invention has been made in view of the above circumstances, and its main object is to provide a battery in which damage to the electrode tab group is suitably prevented. [Means for solving the problem]

[0006] The present invention provides a battery comprising: a first electrode assembly having a flattened hexahedron shape including a positive electrode and a negative electrode and a pair of rectangular flat outer surfaces; and a battery case housing the first electrode assembly. The battery case comprises an exterior body having a bottom wall, a pair of first side walls extending from the bottom wall and facing each other, a pair of second side walls extending from the bottom wall and facing each other, and an opening facing the bottom wall; and a sealing plate sealing the opening. A positive electrode terminal and a negative electrode terminal are attached to the sealing plate, and a positive electrode tab group including multiple positive electrode tabs is arranged on the side of one of the pair of second side walls, and a negative electrode tab group including multiple negative electrode tabs is arranged on the side of the other of the pair of second side walls. The positive electrode tab group and the positive electrode terminal are electrically connected via a positive electrode current collector, and the positive electrode tab group is joined to the positive electrode current collector in a state where it is curved so as to extend along the second side wall, and the negative electrode tab group and the negative electrode terminal are electrically connected via a negative electrode current collector, and the negative electrode tab group is joined to the negative electrode current collector in a state where it is curved so as to extend along the second side wall. Here, a fixing member is arranged from at least one of the pair of flat outer surfaces to the positive electrode current collector or the negative electrode current collector.

[0007] By disposing the fixing member as described above, the electrode assembly is fixed to the rigid electrode current collecting portion fixed to the sealing plate, which makes it possible to suitably suppress longitudinal movement of the electrode assembly within the battery case, thereby suppressing the load on the electrode tab group and suitably preventing damage to the electrode tab group.

[0008] In one aspect of the battery disclosed herein, the positive electrode tab group is joined to the surface of the positive electrode current collector facing the first electrode body, and the negative electrode tab group is joined to the surface of the negative electrode current collector facing the first electrode body.

[0009] In one aspect of the battery disclosed herein, the positive electrode tab group is joined to the positive electrode current collector in a state where it is gathered on one of the pair of flat outer surfaces, and the negative electrode tab group is joined to the negative electrode current collector in a state where it is gathered on one of the pair of flat outer surfaces.

[0010] In a preferred aspect of the battery disclosed herein, the fixing member does not cover either the joint between the positive electrode tab group and the positive electrode current collector or the joint between the negative electrode tab group and the negative electrode current collector. This configuration is preferable because it can reliably prevent damage to the electrode tab group due to load applied thereto caused by interference between the fixing member and the electrode tab group.

[0011] In one embodiment of the battery disclosed herein, the positive electrode tab is made of aluminum or aluminum alloy foil, and the negative electrode tab is made of copper or copper alloy foil, and the fixing member is disposed from at least one of the pair of flat outer surfaces to the negative electrode current collector, but is not disposed from either of the pair of flat outer surfaces to the positive electrode current collector.

[0012] In a preferred embodiment of the battery disclosed herein, the positive electrode current collector includes a positive electrode first current collector disposed between the sealing plate and the first electrode body and a positive electrode second current collector to which the positive electrode tab group is joined, and the negative electrode current collector includes a negative electrode first current collector disposed between the sealing plate and the first electrode body and a negative electrode second current collector to which the negative electrode tab group is joined. Here, the fixing member covers at least the joint between the positive electrode first current collector and the positive electrode second current collector or the joint between the negative electrode first current collector and the negative electrode second current collector. In this way, by fixing the electrode body to a position on the electrode current collector close to the sealing plate, longitudinal movement of the electrode body within the battery case can be more effectively suppressed.

[0013] In one embodiment of the battery disclosed herein, the pair of flat outer surfaces are made of separators, and a layer containing polyvinylidene fluoride is formed on the outermost surface of the separator.

[0014] In one aspect of the battery disclosed herein, a second electrode body having the same configuration as the first electrode body is further disposed within the battery case.

[0015] In one aspect of the battery of this aspect, one or more electrode bodies having the same configuration as the first electrode body are further disposed between the first electrode body and the second electrode body.

[0016] In a preferred embodiment of the battery of this type, the first electrode body, an electrode body disposed between the first electrode body and the second electrode body, and the second electrode body are fixed together, and this configuration makes it possible to suitably suppress longitudinal movement of the electrode body disposed between the first electrode body and the second electrode body.

[0017] In a preferred embodiment of the battery of this type, the fixing member for the first electrode body and the fixing member for the second electrode body are not disposed between the first electrode body, the electrode body disposed between the first electrode body and the second electrode body, or the second electrode body. This configuration reduces the cumulative thickness of the electrode body group, thereby mitigating the pressure distribution experienced by each electrode body. This effectively suppresses uneven reactions in each electrode body.

[0018] In a preferred embodiment of the battery of this aspect, an auxiliary fixing member is further arranged from one of the pair of flat outer surfaces of the first electrode body that faces the first side wall to the other of the pair of flat outer surfaces of the second electrode body that faces the first side wall. Here, the auxiliary fixing member is arranged on the first electrode body, an electrode body arranged between the first electrode body and the second electrode body, and a portion other than the positive electrode current collector and the negative electrode current collector of the second electrode body. With this configuration, longitudinal movement of the electrode body arranged between the first electrode body and the second electrode body can be suitably suppressed.

[0019] In a preferred embodiment of the battery of this type, insulating members are disposed within the battery case between the flat outer surface of the first electrode body and a first side wall of the pair of first side walls that faces the flat outer surface of the first electrode body, and between the other first side wall of the pair of first side walls and the flat outer surface of the second electrode body. Here, the coefficient of friction between the first electrode body, an electrode body disposed between the first electrode body and the second electrode body, and the second electrode body is greater than the coefficient of friction between the insulating member and the flat outer surface of the first electrode body and the coefficient of friction between the insulating member and the flat outer surface of the second electrode body. This configuration can effectively suppress longitudinal movement of each electrode body.

[0020] In a preferred embodiment of the battery of this type, the insulating member is made of a resin film, and the coefficient of friction between the first electrode body, the electrode body disposed between the first electrode body and the second electrode body, and the second electrode body is greater than the coefficient of friction between the insulating member and the first side wall. This configuration makes it possible to effectively suppress movement of each electrode body in the longitudinal direction. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view schematically illustrating a battery according to an embodiment. [Figure 2] FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a schematic vertical cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2 is a schematic diagram showing an electrode assembly attached to a sealing plate according to one embodiment. [Figure 6] FIG. 2 is a perspective view schematically showing an electrode assembly to which a positive electrode second current collecting portion and a negative electrode second current collecting portion are attached according to one embodiment. [Figure 7] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body according to one embodiment. [Figure 8] 3 is a partially enlarged cross-sectional view schematically showing the vicinity of the positive electrode terminal in FIG. 2. FIG. [Figure 9] 1 is a perspective view schematically showing a sealing plate to which a positive electrode terminal, a negative electrode terminal, a positive electrode first connection part, a negative electrode first connection part, a positive electrode insulating member, and a negative electrode insulating member are attached according to one embodiment. FIG. [Figure 10] FIG. 10 is a perspective view of the sealing plate of FIG. 9 turned upside down. [Figure 11] 5A to 5C are schematic cross-sectional views illustrating a battery insertion step according to one embodiment. [Figure 12] FIG. 10 is a schematic diagram showing an electrode assembly attached to a sealing plate according to another embodiment. [Figure 13] FIG. 10 is a schematic diagram showing an electrode assembly attached to a sealing plate according to another embodiment. [Figure 14] FIG. 10 is a schematic diagram showing an electrode assembly attached to a sealing plate according to another embodiment. [Figure 15] FIG. 10 is a schematic diagram showing an electrode assembly attached to a sealing plate according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, some preferred embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters necessary for carrying out the present invention other than those specifically mentioned in this specification (for example, the general configuration and manufacturing process of a battery that do not characterize the present invention) can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be carried out based on the contents disclosed in this specification and the technical common sense in the relevant field. Furthermore, in this specification, the expression "A to B" indicating a numerical range means not less than A and not more than B, and also includes the meanings "preferably greater than A" and "preferably smaller than B."

[0023] In this specification, the term "battery" refers to any power storage device capable of extracting electrical energy, and is a concept that encompasses primary batteries and secondary batteries. In addition, in this specification, the term "secondary battery" refers to any power storage device that can be repeatedly charged and discharged, and is a concept that encompasses so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as electric double layer capacitors.

[0024] <Battery 100> FIG. 1 is a perspective view of a battery 100. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic longitudinal cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a schematic transverse cross-sectional view taken along line IV-IV in FIG. 1. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the symbols X, Y, and Z in the drawings represent the short side direction of the battery 100, the long side direction perpendicular to the short side direction (which can also be referred to as the longitudinal direction of the electrode body), and the up-down direction, respectively. However, these directions are merely used for convenience of description and do not limit the installation form of the battery 100 in any way.

[0025] As shown in FIG. 2, the battery 100 includes a battery case 10, an electrode assembly 20, a positive terminal 30, a negative terminal 40, a positive current collector 50, a negative current collector 60, a positive insulating member 70, and a negative insulating member 80. Although not shown, the battery 100 further includes an electrolyte. The battery 100 is a lithium-ion secondary battery. The battery 100 is characterized by including a fixing member 1, which will be described later, but the rest of the configuration may be the same as a conventional battery. The fixing member 1 is an example of a fixing member disclosed herein.

[0026] The battery case 10 is a housing that houses the electrode assembly 20. Here, the battery case 10 has a flat, bottomed, rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like. As shown in FIG. 2, the battery case 10 includes an exterior body 12 having an opening 12h, and a sealing plate (lid) 14 that closes the opening 12h.

[0027] As shown in FIG. 1 , the exterior body 12 includes a bottom wall 12a, a pair of long side walls 12b extending from the bottom wall 12a and facing each other, and a pair of short side walls 12c extending from the bottom wall 12a and facing each other. The bottom wall 12a is generally rectangular. The bottom wall 12a faces the opening 12h. The area of ​​the short side wall 12c is smaller than the area of ​​the long side wall 12b. The long side wall 12b and the short side wall 12c are examples of the first side wall and second side wall disclosed herein. The sealing plate 14 is attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The sealing plate 14 faces the bottom wall 12a of the exterior body 12. The sealing plate 14 is generally rectangular in plan view. The battery case 10 is integrated by joining (for example, welding) a sealing plate 14 to the periphery of the opening 12h of the exterior body 12. The battery case 10 is hermetically sealed (sealed).

[0028] As shown in FIG. 2 , the sealing plate 14 is provided with a liquid inlet 15, a gas release valve 17, and two terminal outlet holes 18 and 19. The liquid inlet 15 is for injecting an electrolyte after the sealing plate 14 is assembled to the exterior body 12. The liquid inlet 15 is sealed with a sealing member 16. The gas release valve 17 is configured to break when the pressure inside the battery case 10 reaches or exceeds a predetermined value, thereby releasing gas inside the battery case 10 to the outside. The terminal outlet holes 18 and 19 are formed at both ends of the sealing plate 14 in the long side direction Y. The terminal outlet holes 18 and 19 penetrate the sealing plate 14 in the up-down direction Z. The terminal outlet holes 18 and 19 each have an inner diameter large enough to insert the positive electrode terminal 30 and the negative electrode terminal 40 before they are attached to the sealing plate 14 (before crimping).

[0029] The positive electrode terminal 30 and the negative electrode terminal 40 are each fixed to the sealing plate 14. The positive electrode terminal 30 is disposed on one side of the sealing plate 14 in the long side direction Y (the left side in FIGS. 1 and 2). The negative electrode terminal 40 is disposed on the other side of the sealing plate 14 in the long side direction Y (the right side in FIGS. 1 and 2). As shown in FIG. 1, the positive electrode terminal 30 and the negative electrode terminal 40 are exposed on the outer surface of the sealing plate 14. As shown in FIG. 2, the positive electrode terminal 30 and the negative electrode terminal 40 extend from the inside to the outside of the sealing plate 14 through the terminal lead-out holes 18, 19. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are crimped to the peripheral portions of the sealing plate 14 surrounding the terminal lead-out holes 18, 19 by crimping. The positive electrode terminal 30 and the negative electrode terminal 40 have crimped portions 30c, 40c formed at their ends on the exterior body 12 side (lower ends in FIG. 2).

[0030] As shown in Fig. 2, the positive electrode terminal 30 is electrically connected to the positive electrode 22 of the electrode assembly 20 via a positive electrode current collector 50 inside the exterior housing 12. The negative electrode terminal 40 is electrically connected to the negative electrode 24 of the electrode assembly 20 via a negative electrode current collector 60 inside the exterior housing 12. The positive electrode terminal 30 is insulated from the sealing plate 14 by a positive electrode insulating member 70 and a gasket 90. The negative electrode terminal 40 is insulated from the sealing plate 14 by a negative electrode insulating member 80 and a gasket 90. The positive electrode terminal 30 and the negative electrode terminal 40 are examples of terminals disclosed herein.

[0031] The positive electrode terminal 30 is preferably made of a metal, more preferably made of aluminum or an aluminum alloy, for example. The negative electrode terminal 40 is preferably made of a metal, more preferably made of copper or a copper alloy, for example. The negative electrode terminal 40 may be formed by joining two conductive members together. For example, the portion connected to the negative electrode current collecting part 60 may be made of copper or a copper alloy, and the portion exposed on the outer surface of the sealing plate 14 may be made of aluminum or an aluminum alloy.

[0032] As shown in FIG. 1 , a plate-shaped positive electrode external conductive member 32 and a plate-shaped negative electrode external conductive member 42 are attached to the outer surface of the sealing plate 14. The positive electrode external conductive member 32 is electrically connected to the positive electrode terminal 30. The negative electrode external conductive member 42 is electrically connected to the negative electrode terminal 40. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are members to which bus bars are attached when electrically connecting multiple batteries 100 to each other. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are preferably made of metal, more preferably aluminum or an aluminum alloy. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by an external insulating member 92. However, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are not essential and may be omitted in other embodiments.

[0033] FIG. 5 is a perspective view schematically showing the electrode assembly 20 attached to the sealing plate 14. The electrode assembly 20 here has three electrode assemblies 20a, 20b, and 20c. The electrode assemblies 20a, 20b, and 20c each have a pair of rectangular flat outer surfaces 27 and are formed in a flat hexahedral shape. The electrode assemblies 20a and 20c are examples of the first electrode assembly and the second electrode assembly disclosed herein. However, the number of electrode assemblies arranged inside one exterior housing 12 is not particularly limited and may be two or more (plural), or may be one. The electrode assembly 20 here is arranged inside the exterior housing 12 while covered with an insulating member 29 (see FIG. 3) made of a resin film.

[0034] FIG. 6 is a perspective view schematically showing the electrode assembly 20a. FIG. 7 is a schematic diagram showing the configuration of the electrode assembly 20a. Note that the electrode assembly 20a will be described in detail below as an example, but the electrode assemblies 20b and 20c can also have a similar configuration. As shown in FIG. 7, the electrode assembly 20a has a positive electrode 22 and a negative electrode 24. In this example, the electrode assembly 20a is a flat-shaped wound electrode assembly formed by stacking a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 with a strip-shaped separator 26 interposed therebetween and winding them around a winding axis WL.

[0035] The electrode body 20a is disposed inside the exterior body 12 with the winding axis WL oriented parallel to the long side direction Y. In other words, the electrode body 20a is disposed inside the exterior body 12 with the winding axis WL oriented parallel to the bottom wall 12a and perpendicular to the short side wall 12c. An end face of the electrode body 20a (in other words, the stacking surface where the positive electrode 22 and the negative electrode 24 are stacked, the end face in the long side direction Y in FIG. 7) faces the short side wall 12c.

[0036] 3, the electrode body 20a has a pair of curved portions 20r that face the bottom wall 12a and the sealing plate 14 of the exterior body 12, and a flat portion 20f that connects the pair of curved portions 20r and faces the long side wall 12b of the exterior body 12. However, the electrode body 20a may also be a laminated electrode body formed by stacking a plurality of square-shaped (typically rectangular) positive electrodes and a plurality of square-shaped (typically rectangular) negative electrodes in an insulated state.

[0037] As shown in FIG. 7, the positive electrode 22 includes a positive electrode current collector 22c, a positive electrode active material layer 22a, and a positive electrode protective layer 22p bonded to at least one surface of the positive electrode current collector 22c. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments. The positive electrode current collector 22c is strip-shaped. The positive electrode current collector 22c is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. Here, the positive electrode current collector 22c is a metal foil, specifically, an aluminum foil. The width of the positive electrode current collector 22c perpendicular to the long side direction Y (see FIG. 7) is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but is preferably 0.5 mm or greater.

[0038] A plurality of positive electrode tabs 22t are provided at one end of the positive electrode current collector 22c in the long side direction Y (the left end in FIG. 7). The plurality of positive electrode tabs 22t each protrude toward one side in the long side direction Y (the left side in FIG. 7). The plurality of positive electrode tabs 22t protrude further in the long side direction Y than the separator 26. The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction of the positive electrode 22. Each of the plurality of positive electrode tabs 22t is trapezoidal. Here, the positive electrode tab 22t is part of the positive electrode current collector 22c and is made of metal foil (aluminum foil, aluminum alloy foil, etc.). The positive electrode tab 22t is a portion of the positive electrode current collector 22c where the positive electrode active material layer 22a and the positive electrode protective layer 22p are not formed (current collector exposed portion). However, the positive electrode tab 22t may be a member separate from the positive electrode current collector 22c. The positive electrode tab 22t may be provided at the other end in the long side direction Y (the right end in FIG. 7), or at both ends in the long side direction Y.

[0039] As shown in FIG. 4, the positive electrode tabs 22t are stacked at one end in the long side direction Y (the left end in FIG. 4, i.e., on the side of one of the pair of short side walls 12c (second side walls)) to form a positive electrode tab group 23. The positive electrode tabs 22t are bent and curved so that their outer ends extend along the short side wall 12c. The positive electrode tab group 23 is electrically connected to the positive electrode terminal 30 via the positive electrode current collector 50. The positive electrode tabs 22t are preferably bent and joined to a surface of a positive electrode second current collector 52 (described later) on the electrode body side, and electrically connected to the positive electrode terminal 30. Furthermore, as shown in FIG. 4, the positive electrode tab group 23 is preferably joined in a state where they are gathered together on one of the pair of flat outer surfaces 27. The size of the multiple positive electrode tabs 22t (the length in the long side direction Y and the width perpendicular to the long side direction Y, see FIG. 7 ) can be appropriately adjusted, for example, by their formation position, taking into consideration the state of connection to the positive electrode current collecting part 50. The width perpendicular to the long side direction Y of the positive electrode tab 22t is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but is preferably 3 μm to 50 μm, more preferably 5 μm to 30 μm, and particularly preferably 10 μm to 20 μm. Here, the multiple positive electrode tabs 22t have different sizes so that their outer edges are aligned when bent. The positive electrode tab group 23 is an example of an electrode tab group disclosed herein.

[0040] As shown in FIG. 7, the positive electrode active material layer 22a is provided in a strip-like shape along the longitudinal direction of the strip-shaped positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (e.g., a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide) capable of reversibly absorbing and releasing charge carriers. When the total solid content of the positive electrode active material layer 22a is taken as 100 mass%, the positive electrode active material may account for approximately 80 mass% or more, typically 90 mass% or more, for example, 95 mass% or more. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a conductive material, a binder, various additives, etc. Examples of the conductive material include a carbon material such as acetylene black (AB). Examples of the binder include polyvinylidene fluoride (PVdF).

[0041] As shown in FIG. 7, the positive electrode protective layer 22p is provided at the boundary between the positive electrode current collector 22c and the positive electrode active material layer 22a in the long side direction Y. Here, the positive electrode protective layer 22p is provided at one end of the positive electrode current collector 22c in the long side direction Y (the left end in FIG. 7). However, the positive electrode protective layer 22p may be provided at both end portions in the long side direction Y. The positive electrode protective layer 22p is provided in a strip shape along the positive electrode active material layer 22a. The positive electrode protective layer 22p contains an inorganic filler (e.g., alumina). When the entire solid content of the positive electrode protective layer 22p is taken as 100% by mass, the inorganic filler may account for approximately 50% by mass or more, typically 70% by mass or more, for example, 80% by mass or more. The positive electrode protective layer 22p may contain optional components other than the inorganic filler, such as a conductive material, a binder, and various additive components. The conductive material and binder may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a.

[0042] As shown in FIG. 7, the negative electrode 24 includes a negative electrode current collector 24c and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector 24c. The negative electrode current collector 24c is strip-shaped. The negative electrode current collector 24c is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. Here, the negative electrode current collector 24c is a metal foil, specifically, a copper foil. The width (see FIG. 7) of the negative electrode current collector 24c perpendicular to the long side direction Y is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but is preferably 0.5 mm or greater.

[0043] A plurality of negative electrode tabs 24t are provided at one end of the negative electrode current collector 24c in the long side direction Y (the right end in FIG. 7). The plurality of negative electrode tabs 24t protrude toward one side in the long side direction Y (the right side in FIG. 7). The plurality of negative electrode tabs 24t protrude further in the long side direction Y than the separator 26. The plurality of negative electrode tabs 24t are provided at intervals (intermittently) along the longitudinal direction of the negative electrode 24. Each of the plurality of negative electrode tabs 24t is trapezoidal. Here, the negative electrode tab 24t is part of the negative electrode current collector 24c and is made of metal foil (copper foil, copper alloy, etc.). Here, the negative electrode tab 24t is a portion of the negative electrode current collector 24c on which the negative electrode active material layer 24a is not formed (current collector exposed portion). However, the negative electrode tab 24t may be a member separate from the negative electrode current collector 24c. The negative electrode tab 24t may be provided at the other end in the long side direction Y (the left end in FIG. 7), or at both ends in the long side direction Y.

[0044] As shown in FIG. 4, the negative electrode tabs 24t are stacked at one end in the long side direction Y (the right end in FIG. 4, i.e., the other of the pair of short side walls 12c (second side walls)) to form a negative electrode tab group 25. The negative electrode tabs 24t are bent and curved so that their outer ends extend along the short side wall 12c. The negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 60. The negative electrode tabs 24t are preferably bent and joined to a surface of a negative electrode second current collector 62 (described later) on the electrode body side, and electrically connected to the negative electrode terminal 40. Furthermore, as shown in FIG. 4, the negative electrode tab group 25 is preferably joined in a state where they are gathered together on one of the pair of flat outer surfaces 27. The size of the multiple negative electrode tabs 24t (the length in the long side direction Y and the width perpendicular to the long side direction Y; see FIG. 7 ) can be adjusted appropriately, for example, by their formation position, taking into consideration the state of connection to the negative electrode current collecting part 60. The width perpendicular to the long side direction Y of the negative electrode tab 24t is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but is preferably 3 μm to 50 μm, more preferably 5 μm to 30 μm, and particularly preferably 5 μm to 20 μm. Here, the multiple negative electrode tabs 24t have different sizes so that their outer edges are aligned when bent. The negative electrode tab group 25 is an example of an electrode tab group disclosed herein.

[0045] The negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of the strip-shaped negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (e.g., a carbon material such as graphite) that can reversibly store and release charge carriers. When the total solid content of the negative electrode active material layer 24a is taken as 100 mass%, the negative electrode active material may account for approximately 80 mass% or more, typically 90 mass% or more, for example 95 mass% or more. The negative electrode active material layer 24a may contain optional components other than the negative electrode active material, such as a binder, a dispersant, and various additives. Examples of the binder that can be used include rubbers such as styrene butadiene rubber (SBR). Examples of the dispersant that can be used include celluloses such as carboxymethyl cellulose (CMC).

[0046] The separator 26 is a member that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. A porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable as the separator 26. A heat resistance layer (HRL) containing an inorganic filler may be provided on the surface of the separator 26. Examples of inorganic fillers that can be used include alumina, boehmite, aluminum hydroxide, and titania.

[0047] The electrolyte may be the same as conventional ones and is not particularly limited. The electrolyte is, for example, a non-aqueous electrolyte containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may be in a solid state (solid electrolyte) and integrated with the electrode assembly 20.

[0048] The positive electrode current collecting part 50 forms a conductive path that electrically connects the positive electrode tab group 23 consisting of multiple positive electrode tabs 22t to the positive electrode terminal 30. As shown in FIG. 2, the positive electrode current collecting part 50 includes a positive electrode first current collecting part 51 disposed between the sealing plate 14 and the electrode body 20a, and a positive electrode second current collecting part 52 to which the positive electrode tab group 23 is joined. The positive electrode first current collecting part 51 and the positive electrode second current collecting part 52 may be made of the same metal type as the positive electrode current collector 22c, for example, a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel.

[0049] FIG. 8 is a partially enlarged cross-sectional view schematically illustrating the vicinity of the positive electrode terminal 30 in FIG. 2. FIG. 9 is a perspective view schematically illustrating the sealing plate 14. FIG. 10 is a perspective view of the sealing plate of FIG. 9 turned upside down. FIG. 10 shows the surface of the sealing plate 14 on the side of the exterior body 12 (inner surface). As shown in FIGS. 8 to 10, the positive electrode first current collecting part 51 is attached to the inner surface of the sealing plate 14. The positive electrode first current collecting part 51 is an example of a current collecting part disclosed herein. The positive electrode first current collecting part 51 has a first region 51a and a second region 51b. The positive electrode first current collecting part 51 may be formed by bending a single member by, for example, press processing, or may be formed by integrating multiple members by welding or the like. Here, the positive electrode first current collecting part 51 is fixed to the sealing plate 14 by crimping.

[0050] The first region 51a is a portion disposed between the sealing plate 14 and the electrode assembly group 20. The first region 51a extends along the long side direction Y. The first region 51a extends horizontally along the inner surface of the sealing plate 14. A positive electrode insulating member 70 is disposed between the sealing plate 14 and the first region 51a. The first region 51a is insulated from the sealing plate 14 by the positive electrode insulating member 70. The first region 51a is electrically connected to the positive electrode terminal 30 by crimping. A through-hole 51h penetrating the first region 51a in the up-down direction Z is formed in a position corresponding to the terminal lead-out hole 18 of the sealing plate 14. The second region 51b is a portion disposed between the short side wall 12c of the exterior body 12 and the electrode assembly group 20. The second region 51b extends from one end of the first region 51a in the long side direction Y (the left end in FIG. 8) toward the short side wall 12c of the exterior body 12. The second region 51b extends in the up-down direction Z.

[0051] The positive electrode second current collecting portion 52 extends along the short side wall 12c of the exterior body 12. As shown in FIG. 6 , the positive electrode second current collecting portion 52 has a current collecting plate connection portion 52a, an inclined portion 52b, and a tab joint portion 52c. The current collecting plate connection portion 52a is electrically connected to the positive electrode first current collecting portion 51. The current collecting plate connection portion 52a extends along the up-down direction Z. The current collecting plate connection portion 52a is disposed substantially perpendicular to the winding axis WL of the electrode bodies 20a, 20b, and 20c. The current collecting plate connection portion 52a has a recess 52d that is thinner than its surroundings. The recess 52d has a through-hole 52e that penetrates in the short side direction X. A joint with the positive electrode first current collecting portion 51 is formed in the through-hole 52e. The joint is a welded joint formed by welding, such as ultrasonic welding, resistance welding, or laser welding. The positive electrode second current collecting portion 52 may be provided with a fuse.

[0052] The tab joint 52c is attached to the positive electrode tab group 23 and is electrically connected to the multiple positive electrode tabs 22t. As shown in FIG. 5, the tab joint 52c extends along the up-down direction Z. The tab joint 52c is disposed substantially perpendicular to the winding axis WL of the electrode assemblies 20a, 20b, and 20c. The surface of the tab joint 52c that is connected to the multiple positive electrode tabs 22t is disposed substantially parallel to the short side wall 12c of the outer casing 12. As shown in FIG. 4, a joint J with the positive electrode tab group 23 is formed in the tab joint 52c. The joint J is a welded joint formed by welding, such as ultrasonic welding, resistance welding, or laser welding, with the multiple positive electrode tabs 22t stacked on top of each other. The welded joint positions the multiple positive electrode tabs 22t toward one side of the short side direction X of the electrode assemblies 20a, 20b, and 20c. This allows the plurality of positive electrode tabs 22t to be bent more suitably, and the curved positive electrode tab group 23 as shown in FIG. 4 can be stably formed.

[0053] The inclined portion 52b connects the lower end of the current collector plate connection portion 52a to the upper end of the tab joint portion 52c. The inclined portion 52b is inclined relative to the current collector plate connection portion 52a and the tab joint portion 52c. The inclined portion 52b connects the current collector plate connection portion 52a to the tab joint portion 52c so that the current collector plate connection portion 52a is located closer to the center than the tab joint portion 52c in the long side direction Y. This increases the accommodation space for the electrode assembly group 20, thereby achieving a high energy density of the battery 100. The lower end of the inclined portion 52b (in other words, the end portion on the bottom wall 12a side of the exterior body 12) is preferably located below the lower end of the positive electrode tab group 23. This allows the multiple positive electrode tabs 22t to be bent more suitably, stably forming a curved positive electrode tab group 23 as shown in FIG. 4.

[0054] The negative electrode current collector 60 forms a conductive path electrically connecting the negative electrode tab group 25, which is composed of multiple negative electrode tabs 24t, to the negative electrode terminal 40. As shown in FIG. 2 , the negative electrode current collector 60 includes a negative electrode first current collector 61 disposed between the sealing plate 14 and the electrode body 20a, and a negative electrode second current collector 62 to which the negative electrode tab group 25 is joined. The negative electrode first current collector 61 is an example of a current collector disclosed herein. The negative electrode first current collector 61 and the negative electrode second current collector 62 may be made of the same metal as the negative electrode current collector 24c, such as a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The configurations of the negative electrode first current collector 61 and the negative electrode second current collector 62 may be the same as those of the positive electrode first current collector 51 and the positive electrode second current collector 52 of the positive electrode current collector 50.

[0055] As shown in FIG. 10 , the negative electrode first current collecting portion 61 has a first region 61a and a second region 61b. A negative electrode insulating member 80 is disposed between the sealing plate 14 and the first region 61a. The first region 61a is insulated from the sealing plate 14 by the negative electrode insulating member 80. A through-hole 61h penetrating in the up-down direction Z is formed in the first region 61a at a position corresponding to the terminal lead-out hole 19 of the sealing plate 14. As shown in FIG. 6 , the negative electrode second current collecting portion 62 has a current collecting plate connection portion 62a electrically connected to the negative electrode first current collecting portion 61, an inclined portion 62b, and a tab joint portion 62c attached to the negative electrode tab group 25 and electrically connected to the multiple negative electrode tabs 24t. The current collecting plate connection portion 62a has a recess 62d connected to the tab joint portion 62c. A through-hole 62e penetrating in the short-side direction X is provided in the recess 62d.

[0056] The positive electrode insulating member 70 is a member that insulates the sealing plate 14 and the positive electrode first current collecting portion 51 inside the battery case 10. The positive electrode insulating member 70 is made of, for example, a resin material that is resistant to the electrolyte solution used, has electrical insulating properties, and is elastically deformable. The positive electrode insulating member 70 is preferably made of, for example, a polyolefin resin such as polypropylene (PP), a fluorinated resin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), or polyphenylene sulfide (PPS). As shown in FIG. 2, the positive electrode insulating member 70 has a base portion 70a and a protruding portion 70b. Here, the base portion 70a and the protruding portion 70b are integrally molded.

[0057] The base portion 70a is a portion that is disposed between the sealing plate 14 and the first region 51a of the positive electrode first current collecting portion 51 in the vertical direction Z. The base portion 70a extends horizontally along the first region 51a of the positive electrode first current collecting portion 51. The base portion 70a has a through-hole (not shown) that penetrates in the vertical direction Z. The through-hole is formed at a position corresponding to the terminal lead-out hole 18 of the sealing plate 14.

[0058] The protrusions 70b each protrude further toward the electrode body group 20 than the base portion 70a. As shown in Fig. 10, the protrusions 70b are provided closer to the center of the sealing plate 14 (to the right in Fig. 10) than the base portion 70a in the long side direction Y. As shown in Fig. 3, the protrusions 70b face the curved portions 20r of the electrode bodies 20a, 20b, and 20c that constitute the electrode body group 20.

[0059] 2, the negative electrode insulating member 80 is disposed symmetrically to the positive electrode insulating member 70 with respect to the long side direction Y of the electrode body group 20. The specific configuration of the negative electrode insulating member 80 may be similar to that of the positive electrode insulating member 70. Here, like the positive electrode insulating member 70, the negative electrode insulating member 80 has a base portion 80a disposed between the sealing plate 14 and the negative electrode first current collecting portion 61, and a protrusion portion 80b.

[0060] As shown in FIG. 5, in the battery 100 according to this embodiment, the fixing member 1 is arranged in a U-shape from the flat outer surface 27a to the flat outer surface 27f to cover the positive electrode second current collecting portion 52 of the three electrode bodies 20a, 20b, and 20c. By fixing the electrode bodies 20a, 20b, and 20c using the fixing member 1 in this manner, movement of the electrode body 20b in the longitudinal direction can be more suitably suppressed. Furthermore, the fixing member 1 according to this embodiment is arranged to cover three joints between the positive electrode first current collecting portion 51 and the positive electrode second current collecting portion 52. By fixing the electrode body group 20 to a position on the positive electrode current collecting portion 50 close to the sealing plate 14 in this manner, movement of the electrode body group 20 in the longitudinal direction can be more suitably suppressed.

[0061] The fixing member 1 preferably includes, for example, a substrate and an adhesive layer formed on the substrate. Examples of the substrate include polyethylene (PE), polypropylene (PP), polyester, nylon, vinyl chloride, Teflon (registered trademark), polyimide, Kapton (registered trademark), polyphenylene sulfide, and polyethylene naphthalate. The thickness of the substrate is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but it can be approximately 5 μm to 100 μm, preferably 10 μm to 50 μm. Examples of materials constituting the adhesive layer include acrylic adhesives, silicone adhesives, and rubber adhesives. The adhesive layer preferably has adhesiveness at room temperature (typically, about 20°C). The thickness of the adhesive layer is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but it can be approximately 5 μm to 100 μm, preferably 5 μm to 20 μm.

[0062] 3, in the battery 100 according to this embodiment, an insulating member 29 is disposed within the battery case 10 between the flat outer surface 27a and one of the pair of long side walls 12b (first side walls) that faces the flat outer surface 27a, and between the other of the pair of long side walls 12b and the flat outer surface 27f. The coefficient of friction between the electrode assemblies 20a, 20b, and 20c (i.e., the coefficient of friction between the flat outer surfaces 27b and 27c, and between the flat outer surfaces 27d and 27e; hereinafter also referred to as friction coefficient A) is greater than the coefficient of friction between the insulating member 29a and the flat outer surface 27a and the coefficient of friction between the insulating member 29b and the flat outer surface 27f (hereinafter also referred to as friction coefficient B). This configuration is preferable because it suppresses movement of the electrode assembly group 20 in the longitudinal direction. Here, the friction coefficients A and B can be, for example, those measured in accordance with the provisions of JIS K7125. The difference between the friction coefficients A and B can be approximately 0.1 to 0.9, preferably approximately 0.5 to 0.8, but is not limited to this. One method for achieving the difference between the friction coefficients A and B described above is to appropriately select materials for the insulating member 29 and the flat outer surface 27. Those skilled in the art can easily select such materials by conducting preliminary tests, etc.

[0063] Furthermore, in the battery 100 according to this embodiment, the coefficient of friction between the electrode assembly 20a and the electrode assembly 20b (i.e., the coefficient of friction between the flat outer surface 27b and the flat outer surface 27c) and the coefficient of friction between the electrode assembly 20b and the electrode assembly 20c (i.e., the coefficient of friction between the flat outer surface 27d and the flat outer surface 27e) (hereinafter also referred to as friction coefficient C) are greater than the coefficient of friction between the insulating member 29 and the long side wall 12b (i.e., the coefficient of friction between the insulating member 29a and the long side wall 12b, and the coefficient of friction between the insulating member 29b and the long side wall 12b; hereinafter also referred to as friction coefficient D). This configuration is preferable because it suppresses movement of the electrode assembly group 20 in the longitudinal direction. Here, the coefficients of friction C and D can be, for example, coefficients of friction measured in accordance with the provisions of JIS K7125. The difference between the coefficients of friction C and D can be approximately 0.1 to 0.9, preferably approximately 0.5 to 0.8, but is not limited to this. One method for achieving the difference between the coefficients of friction C and D is to appropriately select materials for the insulating member 29, the long side wall 12b, and the flat outer surface 27. Those skilled in the art can easily select such materials by conducting preliminary tests or the like.

[0064] 5, in the battery 100 according to this embodiment, no fixing member 1 is disposed between the electrode body 20a and the electrode body 20b, and between the electrode body 20b and the electrode body 20c. With this configuration, the cumulative thickness of the electrode body group 20 can be reduced, thereby mitigating the pressure distribution experienced by each electrode body constituting the electrode body group 20. This is preferable because it makes it possible to suitably suppress uneven reactions in each electrode body constituting the electrode body group 20.

[0065] <Method of manufacturing the battery 100> The manufacturing method of the battery 100 is characterized by the inclusion of the fixing member 1 described above. The remaining manufacturing process may be the same as conventional methods. In addition to the fixing member 1, the battery 100 can be manufactured by preparing the battery case 10 (exterior body 12 and sealing plate 14), the electrode assembly 20 (electrode assemblies 20a, 20b, 20c), the electrolyte, the positive electrode terminal 30, the negative electrode terminal 40, the positive electrode current collector 50 (first positive electrode current collector 51 and second positive electrode current collector 52), the negative electrode current collector 60 (first negative electrode current collector 61 and second negative electrode current collector 62), the positive electrode insulating member 70, and the negative electrode insulating member 80, for example, by a manufacturing method including a first mounting step, a second mounting step, an insertion step, and a sealing step. The manufacturing method disclosed herein may further include other steps at any stage.

[0066] 9 and 10 is produced. Specifically, first, the positive electrode terminal 30, the positive electrode first current collecting portion 51, the positive electrode insulating member 70, the negative electrode terminal 40, the negative electrode first current collecting portion 61, and the negative electrode insulating member 80 are attached to the sealing plate 14.

[0067] The positive electrode terminal 30, the positive electrode first current collecting portion 51, and the positive electrode insulating member 70 are fixed to the sealing plate 14 by, for example, crimping (riveting). As shown in FIG. 8 , crimping is performed by sandwiching a gasket 90 between the outer surface of the sealing plate 14 and the positive electrode terminal 30, and then sandwiching the positive electrode insulating member 70 between the inner surface of the sealing plate 14 and the positive electrode first current collecting portion 51. The material of the gasket 90 may be the same as that of the positive electrode insulating member 70. More specifically, the positive electrode terminal 30 before crimping is inserted from above the sealing plate 14 into the through-hole 90h of the gasket 90, the terminal lead-out hole 18 of the sealing plate 14, the through-hole 70h of the positive electrode insulating member 70, and the through-hole 51h of the positive electrode first current collecting portion 51, in that order, so that the positive electrode terminal 30 protrudes below the sealing plate 14. Then, the portion of the positive electrode terminal 30 that protrudes downward from the sealing plate 14 is crimped so that a compressive force is applied in the vertical direction Z. As a result, a crimped portion 30c is formed at the tip end portion of the positive electrode terminal 30 (the lower end portion in FIG. 2).

[0068] By such crimping, the gasket 90, the sealing plate 14, the positive electrode insulating member 70, and the positive electrode first current collecting portion 51 are integrally fixed to the sealing plate 14, and the terminal pull-out hole 18 is sealed. Note that the crimped portion 30c may be welded to the positive electrode first current collecting portion 51. This can further improve the reliability of electrical continuity.

[0069] The negative electrode terminal 40, the negative electrode first current collecting portion 61, and the negative electrode insulating member 80 can be fixed together in the same manner as for the positive electrode side described above. That is, the negative electrode terminal 40 before crimping is inserted from above the sealing plate 14, sequentially through the through hole of the gasket, the terminal lead-out hole 19 of the sealing plate 14, the through hole of the negative electrode insulating member 80, and the through hole of the negative electrode first current collecting portion 61, so that it protrudes below the sealing plate 14. Then, the portion of the negative electrode terminal 40 that protrudes below the sealing plate 14 is crimped so that a compressive force is applied in the up-down direction Z. This forms a crimped portion 40c at the tip end (the lower end in FIG. 2 ) of the negative electrode terminal 40.

[0070] Next, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are attached to the outer surface of the sealing plate 14 via the external insulating member 92. The material of the external insulating member 92 may be the same as that of the positive electrode insulating member 70. The timing of attaching the positive electrode external conductive member 32 and the negative electrode external conductive member 42 may be after the insertion step (for example, after the liquid injection hole 15 is sealed).

[0071] In the second mounting step, a second combined body as shown in FIG. 5 is produced using the first combined body produced in the first mounting step. That is, an electrode body group 20 integrated with a sealing plate 14 is produced. Specifically, as shown in FIG. 6, three electrode bodies 20a each having a positive electrode second current collecting portion 52 and a negative electrode second current collecting portion 62 attached thereto are first prepared and arranged side by side in the short side direction X as electrode bodies 20a, 20b, and 20c. At this time, the electrode bodies 20a, 20b, and 20c may all be arranged in parallel such that the positive electrode second current collecting portion 52 is arranged on one side in the long side direction Y (the left side in FIG. 5) and the negative electrode second current collecting portion 62 is arranged on the other side in the long side direction Y (the right side in FIG. 5).

[0072] Next, as shown in FIG. 4, with the multiple positive electrode tabs 22t bent, the positive electrode first current collecting portion 51 (specifically, the second region 51b) fixed to the sealing plate 14 is joined to the positive electrode second current collecting portion 52 (specifically, the current collecting plate connection portion 52a) of each of the electrode bodies 20a, 20b, and 20c. Also, with the multiple negative electrode tabs 24t bent, the negative electrode first current collecting portion 61 fixed to the sealing plate 14 is joined to the negative electrode second current collecting portion 62 of each of the electrode bodies 20a, 20b, and 20c. Examples of joining methods that can be used include ultrasonic welding, resistance welding, and laser welding. In particular, welding using high-energy rays such as lasers is preferably used. By this welding process, joints are formed in the recesses 52d of the positive electrode second current collecting portion 52 and the recesses 62d of the negative electrode second current collecting portion 62.

[0073] Next, as shown in FIG. 5, the fixing member 1 is arranged in a U-shape from the flat outer surface 27a to the flat outer surface 27f to cover the positive electrode second current collecting portions 52 of the three electrode bodies 20a, 20b, and 20c. The timing for arranging the fixing member 1 may be before joining the positive electrode first current collecting portion 51 (specifically, the second region 51b) fixed to the sealing plate 14 to the positive electrode second current collecting portions 52 (specifically, the current collecting plate connection portions 52a) of the electrode bodies 20a, 20b, and 20c. That is, in the embodiment shown in FIG. 6, the fixing member 1 may be arranged after bending the positive electrode tab group 23. From the viewpoint of improving work efficiency, it is more preferable to arrange the fixing member 1 at the aforementioned timing.

[0074] In the insertion step, the second combined product prepared in the second attachment step is housed in the internal space of the exterior body 12. FIG. 11 is a schematic cross-sectional view illustrating the insertion step. Specifically, first, an insulating resin sheet (resin film) made of a resin material such as polyethylene (PE) is folded into a bag or box shape to prepare an insulating member 29. Next, the electrode assembly 20 is housed in the insulating member 29. Then, the electrode assembly 20 covered with the insulating member 29 is inserted into the exterior body 12. If the weight of the electrode assembly 20 is heavy, approximately 1 kg or more, for example 1.5 kg or more, or even 2 to 3 kg, it is advisable to insert the electrode assembly 20 into the exterior body 12 with the long side wall 12b of the exterior body 12 positioned so as to intersect with the direction of gravity (with the exterior body 12 facing sideways).

[0075] In the sealing step, a sealing plate 14 is joined to the edge of the opening 12h of the exterior body 12 to seal the opening 12h. The sealing step can be performed simultaneously with or after the insertion step. In the sealing step, the exterior body 12 and the sealing plate 14 are preferably welded together. The welding of the exterior body 12 and the sealing plate 14 can be performed by, for example, laser welding. Thereafter, an electrolyte is injected through the liquid inlet 15, and the liquid inlet 15 is closed with a sealing member 16 to hermetically seal the battery 100. In this manner, the battery 100 can be manufactured.

[0076] Battery 100 can be used for a variety of purposes, but is preferably used in applications where external forces such as vibrations and shocks may be applied during use, such as a power source (driving power source) for a motor mounted on a moving body (typically a vehicle such as a passenger car or truck). The type of vehicle is not particularly limited, but examples include plug-in hybrid vehicles (PHVs), hybrid vehicles (HVs), and electric vehicles (EVs). Battery 100 can also be preferably used as a battery pack in which multiple batteries 100 are arranged in a predetermined arrangement direction and a load is applied from the arrangement direction using a restraining mechanism.

[0077] Although several embodiments of the present invention have been described above, the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiments. For example, it is possible to replace part of the above-described embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0078] In the above embodiment, in the electrode assembly 20a, the positive electrode tab group 23 and the negative electrode tab group 25 are joined together in a state where they are gathered on the flat outer surface 27a side (see FIG. 4 ), but this is not limited to this. For example, in the electrode assembly 20a, the positive electrode tab group 23 may be joined together in a state where they are gathered on the flat outer surface 27a side, and the negative electrode tab group 25 may be joined together in a state where they are gathered on the flat outer surface 27b side. Alternatively, the positive electrode tab group 23 (negative electrode tab group 25) may be joined together in a state where they are gathered separately on the flat outer surface 27a side and the flat outer surface 27b side. The same applies to the electrode assemblies 20b and 20c.

[0079] In the above embodiment, the positive electrode tab group 23 and the negative electrode tab group 25 in the electrode body 20a are bent once (see FIG. 4), but this is not limited to this. For example, they may be bent multiple times. The same applies to the electrode bodies 20b and 20c.

[0080] In the above embodiment, the fixing members 1 are arranged on the flat outer surface 27a of the electrode body 20a so that their length in the Y direction is approximately 1 / 20 of the length La of the flat outer surface 27a in the Y direction (see FIG. 5 ), but this is not limited thereto. For example, the length of the fixing members in the Y direction can be approximately (1 / 30) La or more, and from the viewpoint of improving the fixing strength, it can be preferably (1 / 20) La or more, more preferably (1 / 10) La or more, and even more preferably (1 / 5) La or more. Furthermore, the length of the fixing members in the Y direction may be La, or can be (3 / 4) La or less, (1 / 2) La or less, or (1 / 3) La or less. The same applies to the length in the Y direction of the fixing members 1 arranged on the flat outer surface 27f.

[0081] In the above embodiment, the fixing member 1 is arranged in a U-shape so as to cover the positive electrode second current collecting portion 52 of the three electrode bodies 20a, 20b, and 20c from the flat outer surface 27a to the flat outer surface 27f, but this is not limiting. For example, the fixing member may be arranged in a U-shape so as to cover the negative electrode second current collecting portion 62 of the three electrode bodies 20a, 20b, and 20c from the flat outer surface 27a to the flat outer surface 27f. Note that, compared to when the fixing member is arranged in a U-shape on the positive electrode side (i.e., the arrangement described above), when the fixing member is arranged in a U-shape on the negative electrode side (i.e., the arrangement described below), fixing the electrode body to the negative electrode side is preferable because buckling of the positive electrode tab group, which is thought to be prone to buckling and stretching, can be suitably prevented. Furthermore, for example, the fixing member may be arranged from the flat outer surface 27a of the electrode body 20a to the positive electrode second current collecting portion 52 and from the positive electrode second current collecting portion 52 of the electrode body 20b, and from the flat outer surface 27f of the electrode body 20c to the negative electrode second current collecting portion 62 and from the negative electrode current collecting portion 62 of the electrode body 20b. Note that these are merely examples, and various other configurations are possible.

[0082] In the above embodiment, the fixing member 1 is disposed so as to cover three joints between the positive electrode first current collector 51 and the positive electrode second current collector 52. However, the present invention is not limited to this. For example, as shown in FIG. 12, the fixing member 1a may be disposed in a U-shape so as to cover the vicinity of the center of the positive electrode second current collector 52 of the three electrode bodies 20a, 20b, and 20c. Furthermore, as shown in FIG. 13, the fixing member 1b may be disposed in a U-shape so as to cover the lower part of the positive electrode second current collector 52 of the three electrode bodies 20a, 20b, and 20c. Furthermore, the embodiments of FIGS. 5, 12, and 13 can be appropriately combined. Note that, when the fixing member is disposed as shown in FIGS. 12 and 13, it is preferable that the tab joint 52c is not covered. Furthermore, while the above description focuses on the positive electrode second current collector 52, the same applies to the negative electrode second current collector 62. Note that these are merely examples, and various other configurations are possible.

[0083] In the above embodiment, a mode has been described in which the fixing member 1 is also disposed on the positive electrode second current collecting portion 52 of the electrode body 20b, but this is not limiting. For example, as shown in Fig. 14, the fixing member 1c may be disposed from the flat outer surface 27a of the electrode body 20a to the positive electrode second current collecting portion 52, and from the flat outer surface 27f of the electrode body 20c to the positive electrode second current collecting portion 52. In this case, it is preferable that movement of the electrode body 20b in the longitudinal direction be suppressed by friction generated between the flat outer surface 27b and the flat outer surface 27c, and between the flat outer surface 27d and the flat outer surface 27e.

[0084] Alternatively, when the flat outer surface is formed by the separator 26, as in the electrode assemblies 20a, 20b, and 20c according to this embodiment (see FIG. 7), an adhesive layer may be provided on the flat outer surface of the electrode assemblies 20a, 20b, and 20c (i.e., the outermost surface of the separator) to suppress longitudinal movement of the electrode assembly 20b. An example of the adhesive layer is a layer containing PVdF. The adhesive layer may also contain other components such as an inorganic filler. Examples of the inorganic filler include alumina, boehmite, aluminum hydroxide, and titania. Here, when the total components constituting the adhesive layer are taken as 100% by mass, the PVdF content can be approximately 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The PVdF content may be 100% by mass or, for example, 90% by mass or less, and preferably 80% by mass or less.

[0085] Another preferred embodiment is a fixing member arrangement method as shown in FIG. 15. In FIG. 15, fixing members 1d and 1e are arranged from the flat outer surface 27a to the flat outer surface 27f, respectively, so as to cover the lower portions of the positive electrode second current collectors 52 provided on the three electrode bodies 20a, 20b, and 20c near the centers thereof. Fixing members 1f and 1g are arranged from the flat outer surface 27a to the flat outer surface 27f, respectively, so as to cover the lower portions of the negative electrode second current collectors 62 provided on the three electrode bodies 20a, 20b, and 20c near the centers thereof. Furthermore, auxiliary fixing members 1h, 1i, and 1j are arranged in a U-shape from the flat outer surface 27a to the flat outer surface 27f in the areas other than the positive electrode second current collectors 52 and the negative electrode second current collectors 62. This can suitably suppress movement of the electrode body 20b in the longitudinal direction. In FIG. 15, fixing members 1d, 1e, and 1h and fixing members 1f, 1g, and 1i are arranged symmetrically with respect to center line CL passing through the center of battery case 10 in the Y direction. However, this is not limited thereto and they may be arranged asymmetrically with respect to CL. In addition, in FIG. 15, auxiliary fixing member 1j is arranged at the center of La. However, this is not limited thereto and they may be arranged offset in the left-right direction (left-right in FIG. 15) as appropriate. As shown in FIG. 15, from the viewpoint of effectively suppressing longitudinal movement of electrode body 20b, it is preferable that all auxiliary fixing members 1h, 1i, and 1j are arranged, but they may be reduced as appropriate. Furthermore, although not shown in FIG. 15, fixing members may be arranged in a U-shape from flat outer surface 27a to flat outer surface 27f to cover sealing plate 14.

[0086] In the above embodiment, the battery 100 is described as having three electrode bodies, but is not limited thereto. For example, multiple (i.e., two or more) electrode bodies may be disposed between the electrode body 20a and the electrode body 20c. In this case, it is preferable that the electrode body 20a, the multiple electrode bodies disposed between the electrode body 20a and the electrode body 20c, and the electrode body 20c are fixed to each other. One example of a method for fixing the electrode bodies to each other is to arrange a fixing member in a U-shape so as to cover the positive electrode second current collector and / or the negative electrode second current collector of each electrode body from the flat outer surface 27a to the flat outer surface 27f. Alternatively, the flat outer surface of each electrode body may be provided with an adhesive layer as described above. This can suitably suppress longitudinal movement of each electrode body.

[0087] In the above embodiment, the battery 100 is described as having three electrode bodies, but this is not limiting. For example, the battery may have only one electrode body. For example, if the battery has the electrode body 20a, the fixing member can be arranged in an L-shape from the flat outer surface 27a to the positive electrode second current collector 52. Alternatively, the fixing member can be arranged in a U-shape from the flat outer surface 27a to the flat outer surface 27b. Here, it is preferable that the fixing member is arranged in a U-shape or other tensioned state, because this firmly fixes the electrode body 20a to the positive electrode second current collector 52. Furthermore, although the positive electrode second current collector 52 has been described above, the same applies to the negative electrode second current collector 62. Note that these are merely examples, and various other configurations are possible. [Explanation of symbols]

[0088] 1, 1a to 1g fixing members 1h~1j Auxiliary fixing members 10 Battery case 12 Exterior body 14 Sealing plate 20 Electrode group 20a (first electrode body), 20b, 20c (second electrode body) Electrode body 27 Flat outer surface 23 Positive electrode tab group (electrode tab group) 25 Negative electrode tab group (electrode tab group) 30 Positive terminal (terminal) 40 Negative terminal (terminal) 50 Positive electrode current collector 51 Positive electrode first current collecting part (current collecting part) 52 Positive electrode second current collecting part 60 Negative electrode current collector 61 Negative electrode first current collecting part 62 Negative electrode second current collecting part 70 Positive electrode insulating material (insulating material) 70a base 70b Protrusion 80 Negative electrode insulating material (insulating material) 80a base 80b Protrusion 100 batteries

Claims

1. A battery comprising: a first electrode body including a positive electrode and a negative electrode and having a pair of flat outer surfaces; and a battery case accommodating the first electrode body, the battery case includes an exterior body having a bottom wall, a pair of first side walls extending from the bottom wall and facing each other, a pair of second side walls extending from the bottom wall and facing each other, and an opening facing the bottom wall; and a sealing plate that seals the opening, a positive electrode terminal and a negative electrode terminal are attached to the sealing plate; a positive electrode tab group including a plurality of positive electrode tabs is disposed on one of the pair of second side walls, a negative electrode tab group including a plurality of negative electrode tabs is disposed on the other second side wall side of the pair of second side walls, the positive electrode tab group and the positive electrode terminal are electrically connected via a positive electrode current collecting portion, the positive electrode tab group is joined to the positive electrode current collecting portion in a curved state so as to extend along one of the pair of second side walls, In the positive electrode current collector, a region facing one of the pair of second side walls includes a first region and a second region, the first region is disposed at a position farther from one of the pair of second side walls than the second region in a direction perpendicular to the one of the pair of second side walls, the negative electrode tab group and the negative electrode terminal are electrically connected via a negative electrode current collecting portion, and the negative electrode tab group is joined to the negative electrode current collecting portion in a curved state so as to extend along the other second side wall of the pair of second side walls, In the negative electrode current collecting portion, a region facing the other of the pair of second side walls includes a third region and a fourth region, the third region is disposed at a position farther from the other second side wall of the pair of second side walls than the fourth region is in a direction perpendicular to the other second side wall of the pair of second side walls, a first fixing member that is disposed from one of the pair of flat outer surfaces, passing through a second side wall side of one of the pair of second side walls of the first region of the positive electrode current collector, and extending to the other flat outer surface of the pair of flat outer surfaces, and that fixes the first region of the positive electrode current collector and the electrode body; a second fixing member that is disposed from one of the pair of flat outer surfaces, passing through the second side wall side of the other of the pair of second side walls of the third region of the negative electrode current collector, and extending to the other of the pair of flat outer surfaces, and that fixes the third region of the negative electrode current collector and the electrode body; A battery equipped with

2. The battery according to claim 1 , wherein the fixing member includes a substrate and an adhesive layer formed on the substrate.

3. the positive electrode tab group is joined to the positive electrode current collecting portion in a state where the positive electrode tab group is gathered on one of the pair of flat outer surfaces, The battery according to claim 1 , wherein the negative electrode tab group is joined to the negative electrode current collector in a state where the negative electrode tab group is gathered on one of the pair of flat outer surfaces.

4. 3. The battery according to claim 1, wherein the electrode assembly is a laminated electrode assembly.

5. the first fixing member has a portion disposed on one of the pair of flat outer surfaces, a portion passing through one of the pair of second side walls of the first region of the positive electrode current collector on a second side wall side of the one of the pair of second side walls, and a portion disposed on the other of the pair of flat outer surfaces, the first fixing member has a U-shape when viewed from a direction perpendicular to the sealing plate, The battery according to claim 1 or 2, wherein the first fixing member is disposed in a tensioned state.

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