battery

Abstract

A battery is provided that properly prevents damage to the electrode tab group. In a preferred embodiment of the battery (100) disclosed herein, there is a boundary portion (2) between a formation region (Q) on the positive electrode tab (22t) where a protective layer is formed and an exposed tab region (P) on the positive electrode tab (22t). At least a portion of the separators (26) constituting the electrode body (20a) having a laminated structure are joined to each other, and at least a portion of the joining portion 1 is close to the boundary portion (2).

Description

Technical Field

[0001] This disclosure relates to batteries. Background Technology

[0002] Patent Document 1 discloses a battery in which a group of positive electrode tabs is provided at one end along the length of the electrode body, and a group of negative electrode tabs is provided at the other end. Furthermore, it discloses a technique for connecting the aforementioned electrode tabs to the electrode current collector in a bent state.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-050069 Summary of the Invention

[0006] The purpose of this disclosure is to provide a battery that properly prevents damage to the electrode tab group.

[0007] To achieve the above objectives, this disclosure provides a battery comprising: one or more electrode bodies having a first electrode and a second electrode serving as the counter electrode of the first electrode, stacked together with a separator in the form of a laminated structure; and a battery casing housing the electrode bodies. The battery casing comprises: an outer 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 and having a terminal electrically connected to the first electrode. The electrode body comprises: a first electrode tab group, including a plurality of tabs protruding from an end facing one of the second sidewalls of the pair of second sidewalls; and a second electrode tab group, including a plurality of tabs protruding from an end facing the other of the pair of second sidewalls. The first electrode tab group and the terminal are electrically connected via a current collector. The first electrode tab group is engaged with the current collector in a state where at least a portion of the first electrode tab group is bent in a manner arranged along the second sidewall of one of the pair of second sidewalls. In the tabs, there is a boundary portion between a region where an active material layer or a protective layer is formed and an exposed tab region. Here, at least a portion of the separators constituting the electrode body having the above-described laminated structure are joined together, and at least a portion of the joint is close to the boundary portion.

[0008] According to the inventors' research, it is known that in an electrode tab, the electrode tab is easily damaged in the boundary portion between the region where the active material layer or protective layer is formed and the exposed area of ​​the electrode tab. Based on a battery in which at least a portion of the separators constituting the electrode body are joined together, and at least a portion of the joint is close to the aforementioned boundary portion, it is known that the load applied to the electrode tab is easily distributed to the separators, thus effectively preventing damage to the electrode tab group. Furthermore, the mechanical strength of the aforementioned boundary portion is considered to be enhanced due to the presence of the joined separators. Therefore, damage to the electrode tab group can be effectively prevented.

[0009] In a preferred embodiment of the battery disclosed herein, the separator having the aforementioned joint portion is positioned towards the side of the first electrode tab group with a gentler bend. Since the bent portions (in other words, the gently bend portions of the electrode tab group) are particularly susceptible to damage, the presence of the separator having the joint portion in these portions more effectively prevents damage to the electrode tab group.

[0010] In a preferred embodiment of the battery disclosed herein, at least a portion of the aforementioned joint is adjacent to the aforementioned boundary portion. The joint formed in the separator exists at a location adjacent to the boundary portion, thereby enabling the load applied to the boundary portion to be efficiently distributed throughout the separator. This, in turn, allows for more appropriate prevention of damage to the electrode tab group.

[0011] In a preferred embodiment of the battery disclosed herein, the shortest distance from the root portion of the aforementioned tab to the protruding end of the aforementioned tab of the separator is more than twice the shortest distance from the root portion of the aforementioned tab to the aforementioned boundary portion. The battery with the above structure readily ensures the area of ​​the junction, and is therefore preferred.

[0012] In a preferred embodiment of the battery disclosed herein, the ratio (B / A) of the length A in the protruding direction of the aforementioned tab of the aforementioned joint and the length B in the direction orthogonal to the protruding direction of the aforementioned tab is 1.3 or more. According to the battery having the aforementioned joint structure, the bonding strength between the separators is more appropriately improved, and therefore it is preferred.

[0013] In a preferred embodiment of the battery disclosed herein, the number of separators forming the aforementioned joint portion is three or more, and is less than 40% when the total number of separators constituting the electrode body having the aforementioned stacked structure is set to 100%. The battery with the above structure is preferred because it allows for a more suitable load generated when bending the electrode tab group.

[0014] In a preferred embodiment of the battery disclosed herein, at least a portion of the aforementioned joint is also present in the overlapping portion of the aforementioned tab and the aforementioned separator, and at least a portion of the overlapping portion in the aforementioned tab has the aforementioned protective layer. The battery with the aforementioned joint structure is preferred because it can appropriately suppress vibrations that may be applied to the electrode tabs through the joint. Attached Figure Description

[0015] Figure 1 This is a schematic perspective view of a battery according to one embodiment.

[0016] Figure 2 It is along Figure 1 A schematic longitudinal section of line II-II.

[0017] Figure 3 It is along Figure 1 A schematic longitudinal section of line III-III.

[0018] Figure 4 It is along Figure 1 A schematic cross-sectional view of line IV-IV.

[0019] Figure 5 It is a perspective view schematically showing the electrode assembly mounted on the sealing plate.

[0020] Figure 6 It is a perspective view schematically showing an electrode body with a positive second collector and a negative second collector installed.

[0021] Figure 7 This is a schematic diagram showing the structure of the wound electrode.

[0022] Figure 8 It is a perspective view schematically showing the electrode body in front of the positive electrode second collector and the negative electrode second collector.

[0023] Figure 9 It is along Figure 8 A schematic cross-sectional view of the IX-IX line.

[0024] Figure 10 It is shown Figure 8 A schematic diagram of the structure of the separator 26' and the positive electrode 22'.

[0025] Figure 11 It is shown Figure 8 A schematic diagram of the structure of the separator 26' and the positive electrode 22'.

[0026] Figure 12It is a perspective view schematically showing a sealing plate with a positive terminal, a negative terminal, a positive first collector, a negative first collector, a positive insulating component, and a negative insulating component installed.

[0027] Figure 13 It is Figure 12 A 3D view of the sealing plate turned upside down.

[0028] Figure 14 This is a schematic explanatory diagram illustrating a method for forming a joint in a battery according to one embodiment.

[0029] Figure 15 It pertains to the second embodiment. Figure 10 The corresponding diagram.

[0030] Figure 16 It pertains to the third embodiment. Figure 10 The corresponding diagram.

[0031] Figure 17 It pertains to the fourth embodiment. Figure 10 The corresponding diagram.

[0032] Figure 18 It pertains to the fifth embodiment. Figure 10 The corresponding diagram.

[0033] (Symbol Explanation)

[0034] 1, 101, 201, 301, 401: Joint; 2: Boundary portion; 10: Battery casing; 12: Outer casing; 14: Sealing plate; 15: Liquid injection hole; 16: Sealing component; 17: Gas vent valve; 18, 19: Terminal insertion hole; 20: Electrode group; 20a~20c: Electrode body; 22: Positive electrode; 24: Negative electrode; 26: Separator; 30: Positive terminal; 32: Positive external conductive component; 40: Negative terminal; 42: Negative external conductive component; 50: Positive current collector; 60: Negative current collector; 70: Positive internal insulating component; 80: Negative internal insulating component; 90: Gasket; 92: External insulating component; 100: Battery. Detailed Implementation

[0035] Hereinafter, with reference to the accompanying drawings, several preferred embodiments of the technology disclosed herein will be described. Furthermore, matters not specifically mentioned in this specification and necessary for the implementation of this disclosure (e.g., the general structure and manufacturing process of a battery that are not features of this disclosure) can be grasped as design matters based on prior art in the art. This disclosure can be implemented based on the content disclosed in this specification and common technical knowledge in the art. The following description is not intended to limit the technology disclosed herein to the following embodiments. Additionally, the use of "A to B" to indicate numerical ranges in this specification means A or more and B or less. Therefore, it includes cases exceeding A and below B.

[0036] Furthermore, in this specification, "battery" refers to all energy storage devices capable of extracting electrical energy, and includes both primary and secondary batteries. Additionally, in this specification, "secondary battery" refers to all energy storage devices capable of repeated charging and discharging, and includes so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, as well as capacitors (physical batteries) such as double-layer capacitors.

[0037] Furthermore, the following description addresses the case where the first electrode is set as the positive electrode, but is not intended to limit the scope to this. The techniques disclosed herein can also be applied, for example, to the case where the first electrode is set as the negative electrode.

[0038] First, the structure of the battery 100 involved in this embodiment will be explained. Figure 1 It is a 3D image of battery 100. Figure 2 It is along Figure 1 A schematic longitudinal section of line II-II. Figure 3 It is along Figure 1 A schematic longitudinal section of line III-III. Figure 4 It is along Figure 1 A schematic cross-sectional view of line IV-IV. In the following description, the symbols L, R, F, Rr, U, and D in the figures represent left, right, front, back, top, and bottom, respectively, and the symbols X, Y, and Z in the figures represent the short side direction of battery 100, the long side direction orthogonal to the short side direction (also referred to as the length direction of the electrode body), and the up and down direction, respectively. However, they are only used for illustrative purposes and do not limit any arrangement of battery 100.

[0039] like Figure 2As shown, the battery 100 includes a battery casing 10 and electrode bodies (here, electrode body group 20). In addition to the battery casing 10 and electrode body group 20, the battery 100 according to this embodiment also includes a positive terminal 30, a positive external conductive component 32, a negative terminal 40, a negative external conductive component 42, an external insulating component 92, a positive current collector 50, a negative current collector 60, a positive internal insulating component 70, and a negative internal insulating component 80. Furthermore, although not shown in the figure, the secondary battery 100 according to this embodiment also includes an electrolyte. Here, the battery 100 is a lithium-ion secondary battery. The internal resistance of the battery 100 can be, for example, about 0.2 to 2.0 mΩ.

[0040] The battery casing 10 is a frame that houses the electrode assembly 20. Here, the battery casing 10 has a flat, bottomed rectangular (square) shape. The material of the battery casing 10 can be the same as conventionally used materials, without particular limitation. The battery casing 10 is preferably made of metal, for example, more preferably aluminum, aluminum alloy, iron, iron alloy, etc. Furthermore, the battery casing 10 includes an outer body 12, a sealing plate 14, and a gas vent valve 17. The outer body 12 is a flat, square container with one side forming an opening 12h. Specifically, the outer body 12 is as follows... Figure 1 As shown, the outer casing 12 has a generally rectangular bottom wall 12a, a pair of first side walls 12b extending upward U from the short side of the bottom wall 12a and facing each other, and a pair of second side walls 12c extending upward U from the long side of the bottom wall 12a and facing each other. The area of ​​the first side wall 12b is larger than the area of ​​the second side wall 12c. Furthermore, an opening 12h is formed on the upper surface of the outer casing 12 surrounded by the pair of first side walls 12b and the pair of second side walls 12c. A sealing plate 14 is installed on the outer casing 12 to plug the opening 12h of the outer casing 12. The sealing plate 14 is a generally rectangular plate when viewed from above. The sealing plate 14 faces the bottom wall 12a of the outer casing 12. The battery casing 10 is formed by joining (e.g., welding) the sealing plate 14 to the periphery of the opening 12h of the outer casing 12. The joining of the sealing plate 14 can be performed by welding, for example, laser welding.

[0041] like Figure 1 as well as Figure 2As shown, a gas vent valve 17 is formed on the sealing plate 14. The gas vent valve 17 is configured to open when the pressure inside the battery housing 10 reaches a predetermined value, thereby venting gas from the battery housing 10. In addition to the gas vent valve 17, the sealing plate 14 is also provided with an injection hole 15 and two terminal insertion holes 18 and 19. The injection hole 15 communicates with the internal space of the outer casing 12 and is an opening provided for injecting electrolyte during the manufacturing process of the battery 100. The injection hole 15 is sealed by a sealing member 16. For example, a blind rivet is suitable as the sealing member 16. Thus, the sealing member 16 can be firmly fixed inside the battery housing 10.

[0042] Figure 5 This is a perspective view schematically showing the electrode group 20 installed on the sealing plate 14 before fitting. In this embodiment, a plurality of (here, three) electrode bodies 20a, 20b, and 20c are housed inside the battery casing 10. Furthermore, the number of electrode bodies housed inside a single battery casing 10 is not particularly limited; it can be one or more (multiple). Figure 2 As shown, on one side of the long side direction Y of each electrode body ( Figure 2 The positive current collector 50 is arranged on the left side, and on the other side in the long side direction Y ( Figure 2 The negative electrode current collector 60 is arranged on the right side. Furthermore, the electrode bodies 20a, 20b, and 20c are connected in parallel. However, the electrode bodies 20a, 20b, and 20c can also be connected in series. Here, the electrode body 20a is held in an electrode body holder 29 (see reference 20b) made of resin sheet material. Figure 3 It is housed inside the outer casing 12 of the battery housing 10 in a covered state. Additionally, as... Figure 5 As shown, in the battery 100 according to this embodiment, the separator 26 with the joint 1 is arranged so that it is closer to the side of the positive electrode tab group 23 with a gentler bend (in other words, the bend of the positive electrode tab group 23). Further details of the separator 26 with the joint 1 will be described later.

[0043] Figure 6 This is a schematic three-dimensional view of the electrode body 20a. Figure 7 This is a schematic diagram showing the structure of electrode 20a. Furthermore, the following detailed description uses electrode 20a as an example, but electrode bodies 20b and 20c can also have the same structure.

[0044] like Figure 7As shown, the electrode body 20a has a positive electrode 22, a negative electrode 24, and a separator 26. Here, the electrode body 20a is a wound electrode body formed by stacking strip-shaped positive electrodes 22 and strip-shaped negative electrodes 24 with two strip-shaped separators 26 in between, and winding them around a winding shaft WL. The wound electrode body has a positive and negative electrode stacked structure formed by overlapping multiple positive electrodes 22 and negative electrodes 24 with the separators 26 in between. However, the structure of the electrode body is not limited to the technology disclosed herein. For example, the electrode body may also be a stacked electrode body formed by stacking multiple square-shaped (typically rectangular) positive electrodes and multiple square-shaped (typically rectangular) negative electrodes in an insulated state.

[0045] The electrode body 20a has a flat shape. The electrode body 20a is disposed inside the outer casing 12 with its winding axis WL approximately parallel to the long side direction Y. Specifically, as... Figure 3 As shown, the electrode body 20a has a pair of curved portions (R portions) 20r facing the bottom wall 12a of the outer body 12 and the sealing plate 14, and a flat portion 20f connecting the pair of curved portions 20r and facing the second side wall 12c of the outer body 12. The flat portion 20f extends along the second side wall 12c.

[0046] Positive electrode 22 Figure 7 As shown, it has a positive current collector 22c, a positive active material layer 22a adhered to at least one surface of the positive current collector 22c, and a positive protective layer 22p. However, the positive protective layer 22p is not necessary and can be omitted in other embodiments. The positive current collector 22c is strip-shaped. The positive current collector 22c is made of a conductive metal such as aluminum, aluminum alloy, nickel, or stainless steel. Here, the positive current collector 22c is a metal foil, specifically an aluminum foil.

[0047] At the end 21a on one side of the long side direction Y of the positive current collector 22c ( Figure 7 Multiple positive electrode tabs 22t are provided at the left end of the strip. Multiple positive electrode tabs 22t are provided at intervals (intermittently) along the length of the strip-shaped positive electrode 22. The multiple positive electrode tabs 22t face one side of the winding shaft WL in the axial direction. Figure 7 (on the left side), protruding further outward than the separator 26. Furthermore, the positive electrode tab 22t can also be positioned on the opposite side of the axial direction of the winding shaft WL (e.g., on the left side), further outward than the separator 26. Figure 7(As shown on the right), it can also be provided on both sides of the winding shaft WL in the axial direction. The positive electrode tab 22t is part of the positive current collector 22c and is made of metal foil (aluminum foil). However, the positive electrode tab 22t can also be a component independent of the positive current collector 22c. Here, the positive electrode tab 22t is rectangular in shape, but it is not limited to this and can also be various shapes such as trapezoidal shape. In the positive electrode tab 22t, there is a formation region Q where the positive electrode protective layer 22p is formed, and a tab exposure region P where the positive current collector 22c is exposed without the formation of the positive electrode active material layer 22a and the positive electrode protective layer 22p. In addition, Figure 10 The boundary portion 2 represents the boundary between the formation region Q and the exposed tab region P. Furthermore, in this embodiment, only the positive electrode protective layer 22p is formed on the positive electrode tab 22t, but it is not limited to this; a positive electrode active material layer and a positive electrode protective layer may also be formed on the positive electrode tab. In this case, the region where the positive electrode protective layer is formed can be designated as the formation region.

[0048] like Figure 4 As shown, multiple positive electrode tabs 22t are located at one end of the winding shaft WL in the axial direction. Figure 4 The left end of the electrode is stacked to form a positive electrode tab group 23. The positive electrode tab group 23 includes electrodes arranged in the direction along the surface of the first sidewall 12b. Figure 2 Multiple positive electrode tabs 22t protrude from one end 21a in the Y direction. Furthermore, each of the multiple positive electrode tabs 22t is bent in a manner that aligns the outer ends. This improves the containment of the battery into the battery casing 10, thereby miniaturizing the battery 100. Figure 2 As shown, the positive electrode tab group 23 is electrically connected to the positive terminal 30 via the positive electrode current collector 50. Specifically, regarding the positive electrode tab group 23, at least a portion of the front end of the positive electrode tab group is engaged with the positive electrode current collector 50 in a bent state arranged along one of the second sidewalls 12c of a pair of second sidewalls 12c. The positive electrode tab group 23 and the positive second current collector 52 are connected in the connection portion J (see reference). Figure 4 Furthermore, the second positive collector 52 is electrically connected to the positive terminal 30 via the first positive collector 51. Additionally, regarding the dimensions of the plurality of positive electrode tabs 22t (length along the long side direction Y and width orthogonal to the long side direction Y, refer to...), Figure 7 The connection state with the positive current collector 50 can be taken into account, and the arrangement position can be adjusted appropriately. Here, in order to ensure that the outer ends are aligned when bent, the dimensions of the multiple positive electrode tabs 22t are different from each other.

[0049] like Figure 7As shown, the positive electrode active material layer 22a is arranged in a strip-like manner along the length 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 overall solid content of the positive electrode active material layer 22a is set to 100% by mass, the positive electrode active material can also occupy approximately 80% by mass or more, typically 90% by mass or more, for example, 95% by mass or more. The positive electrode active material layer 22a can also contain any components other than the positive electrode active material, such as conductive materials, binders, various additives, etc. As a conductive material, carbon raw materials such as acetylene black (AB) can be used. As a binder, polyvinylidene fluoride (PVdF) can be used.

[0050] Positive electrode protective layer 22p Figure 7 As shown, a boundary portion is provided between the positive current collector 22c and the positive active material layer 22a along the long side direction Y. Additionally, as... Figure 7 As shown, in the battery 100 according to this embodiment, in the positive electrode tab 22t of the positive electrode current collector 22c, there is a boundary portion 2 between the formation region Q where the positive electrode protective layer 22p is formed and the positive electrode tab exposure region P exposed by the positive electrode tab 22t. Here, the positive electrode protective layer 22p is provided at one end of the winding shaft WL of the positive electrode current collector 22c in the axial direction. Figure 7 (The left end). However, the positive electrode protective layer 22p can also be provided at both ends in the axial direction. The positive electrode protective layer 22p is provided in a strip along the positive electrode active material layer 22a. The positive electrode protective layer 22p contains an inorganic filler (e.g., alumina). When the overall solid content of the positive electrode protective layer 22p is set to 100% by mass, the inorganic filler can also occupy 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 can also contain any component other than the inorganic filler, such as conductive materials, binders, various additives, etc. The conductive materials and binders can also be the same as those exemplified as materials that can be included in the positive electrode active material layer 22a.

[0051] Negative electrode 24 Figure 7 As shown, the device includes a negative current collector 24c and a negative active material layer 24a adhered to at least one surface of the negative current collector 24c. Furthermore, a negative protective layer may be formed at the boundary between the negative current collector and the negative active material layer along the long side Y direction. The negative current collector 24c is strip-shaped. The negative current collector 24c is made of a conductive metal such as copper, copper alloy, nickel, or stainless steel. Here, the negative current collector 24c is a metal foil, specifically a copper foil.

[0052] At one end 21b of the winding shaft WL of the negative current collector 24c in the axial direction. Figure 7 At the right end, multiple negative electrode tabs 24t are provided. Multiple negative electrode tabs 24t are provided at intervals (intermittently) along the length of the strip-shaped negative electrode 24. Each of the multiple negative electrode tabs 24t faces one side in the axial direction ( Figure 7 (on the right side), protruding further outward than the separator 26. However, the negative electrode tab 24t can also be located at the other end in the axial direction ( Figure 7 The negative electrode tab 24t can be located at either end of the negative electrode current collector 24c, or at the left end of the negative electrode tab 24c. It is part of the negative electrode current collector 24c and is made of metal foil (copper foil). However, the negative electrode tab 24t can also be a separate component from the negative electrode current collector 24c. Here, the negative electrode tab 24t is rectangular, but not limited to this; it can also be various shapes such as trapezoidal. At least a portion of the negative electrode tab 24t has an area where the negative electrode current collector 24c is exposed, without forming the negative electrode active material layer 24a.

[0053] like Figure 4 As shown, multiple negative electrode tabs 24t are located at one end in the axial direction ( Figure 4 The negative electrode tab group 25 is formed by stacking the right end of the first sidewall 12b. The negative electrode tab group 25 includes tabs that are stacked from the right end of the first sidewall 12b along the surface direction ( Figure 2 Multiple negative electrode tabs 24t protrude from different ends 21b in the Y direction (existing at different ends 21a). The negative electrode tab group 25 is preferably arranged symmetrically with the positive electrode tab group 23 in the axial direction. Furthermore, each of the multiple negative electrode tabs 24t is bent in a manner that aligns the outer ends. This improves the containment capacity into the battery casing 10, thereby miniaturizing the battery 100. Figure 2 As shown, the negative electrode tab group 25 is electrically connected to the negative terminal 40 via the negative electrode current collector 60. Specifically, regarding the negative electrode tab group 25, at least a portion of the front end portion of the negative electrode tab group is engaged with the negative electrode current collector 60 in a bent state arranged along one of the second sidewalls 12c of a pair of second sidewalls 12c. The negative electrode tab group 25 and the negative second current collector 62 are connected in the connection portion J (see reference). Figure 4 Furthermore, the second negative collector 62 is electrically connected to the negative terminal 40 via the first negative collector 61. Here, similar to the plurality of positive electrode tabs 22t, the plurality of negative electrode tabs 24t are each of different sizes in order to align the outer ends when bent.

[0054] like Figure 7As shown, the negative electrode active material layer 24a is arranged in a strip-like manner along the length of the strip-shaped negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (such as carbon raw material like graphite) capable of reversibly absorbing and releasing charge carriers. When the overall solid content of the negative electrode active material layer 24a is set to 100% by mass, the negative electrode active material can also occupy approximately 80% by mass or more, typically 90% by mass or more, for example 95% by mass or more. The negative electrode active material layer 24a can also contain any components other than the negative electrode active material, such as binders, dispersants, and various additives. As a binder, rubbers such as styrene-butadiene rubber (SBR) can be used. As a dispersant, cellulose-based materials such as carboxymethyl cellulose (CMC) can be used.

[0055] Next, the joint 1 of the separator 26 will be described. Here, Figure 8 This is a perspective view schematically showing the electrode body 20a before the installation of the positive electrode second collector 52 and the negative electrode second collector 62. Figure 9 It is along Figure 8 A schematic cross-sectional view of the IX-IX line. (See diagram below.) Figure 9 As shown, in this embodiment, the five (five-layer) separators in the separator 26 constituting the electrode body 20a having a positive and negative electrode stacked structure are joined together. Furthermore, in Figure 9In the separator 26 with the joint 1, the second separator (second layer) from the outermost separator layer is designated as 26', and the positive electrode, positive current collector, positive electrode active material layer, and positive electrode protective layer located directly below the separator 26' are designated as 22', 22c', 22a', and 22p', respectively. In this embodiment, five separators (five layers) of the separator 26 constituting the electrode body 20a with a positive and negative electrode stacked structure are joined together. However, the number of joined separators 26 (in other words, the number of separators 26 with the joint 1) is not particularly limited as long as the effect of the technology disclosed herein is achieved. Regarding the number of joined separators 26 (layers), from the viewpoint of properly distributing the load applied to the positive electrode tab 22t to the separators 26, three or more separators (three layers) are preferred, more preferably ten or more separators (ten layers) are preferred, and even more preferably twenty or more separators (two layers) are preferred. On the other hand, based on the viewpoint of making the bending load that may be generated when bending the positive electrode tab group 23 more suitable, the number of sheets (layers) of the joint separator 26 is, for example, 90% or less, preferably 60% or less, more preferably 40% or less, and even more preferably 30% or less (e.g., 20% or less) when the total number of sheets (layers) of the separator 26 constituting the electrode body 20a is set to 100%. Furthermore, in the battery 100 according to this embodiment, the separator 26 with the joint 1 is structured towards the side of the positive electrode tab group 23 where the bending is gentler, but this is not a limitation. The separator with the joint can exist at any position in the positive and negative electrode stacked structure, as long as the effects of the technology disclosed herein are utilized.

[0056] Figure 10 as well as Figure 11 It is shown Figure 8 A schematic diagram (top view) of the structure of the separator 26' and the positive electrode 22'. Figure 10 As shown, in this embodiment, the joint 1 is formed in the region from the end r corresponding to the root portion of the positive electrode tab 22t to the end s in the protruding direction of the positive electrode tab 22t of the separator 26 (specifically, the separator 26'). Furthermore, in this embodiment, at least a portion of the joint 1 exists at a position adjacent to the boundary portion 2 (in other words, at a position where it contacts the boundary portion 2). Thus, by positioning at least a portion of the joint 1 adjacent to the boundary portion 2, the load applied to the boundary portion 2 can be efficiently distributed to the separator 26, thereby more appropriately preventing damage to the positive electrode tab group 23.

[0057] like Figure 11As shown, when the shortest distance from end r to end s is defined as p, and the shortest distance from end r to boundary portion 2 is defined as q, the magnitudes of the shortest distances p and q are not particularly limited within the range disclosed here. Regarding the ratio (p / q) of the shortest distance p to the shortest distance q, from the viewpoint of properly ensuring the area of ​​the joint 1, it is, for example, 1.5 or more, preferably 2 or more, and more preferably 2.5 or more. On the other hand, from the viewpoint of the cost of the separator, the above ratio (p / q) is, for example, 5 or less, preferably 4 or less, and more preferably 3 or less.

[0058] Additionally, the protruding direction of the positive electrode tab 22t of the joint 1 ( Figure 11 The length A in the Y direction and the direction orthogonal to the protruding direction ( Figure 10 The ratio (B / A) of the length B in the z-direction is not particularly limited as long as the effect of the technology disclosed herein is achieved. Regarding the aforementioned ratio (B / A), based on the viewpoint of appropriately increasing the bonding strength between the separators 26, it is, for example, 1.1 or more, preferably 1.3 or more, and more preferably 1.5 or more. Furthermore, the aforementioned ratio (B / A) is approximately 3 or less, and can be, for example, 2 or less.

[0059] like Figure 7As shown, the separator 26 is a component that insulates the positive electrode active material layer 22a of the positive electrode 22 and the negative electrode active material layer 24a of the negative electrode 24. For example, a porous sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable as the separator 26. Alternatively, the separator 26 may have a substrate portion made of a porous sheet made of resin and a heat-resistant layer (HRL) containing an inorganic filler disposed on at least one surface of the substrate portion. For example, alumina, boehmite, aluminum hydroxide, titanium dioxide, etc., can be used as the inorganic filler. Alternatively, the separator 26 may also have a substrate portion made of a porous sheet made of resin and an adhesive layer disposed on at least one surface of the substrate portion. For example, a layer containing PVdF or SBR can be used as the adhesive layer. Furthermore, the adhesive layer may also contain other components such as inorganic fillers. As an example of the aforementioned inorganic filler, the example described above can be used. Here, when the components constituting the adhesive layer are set to 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. Alternatively, the PVdF content can also be 100% by mass, and can be, for example, 90% by mass or less, preferably 80% by mass or less. However, the PVdF content is not limited to these. Furthermore, as will be described in detail later, in the case of joining the spacers 26 together by hot stamping, a spacer having a substrate portion made of a porous sheet of resin and an adhesive layer disposed on at least one surface of the substrate portion is preferably used as the spacer.

[0060] The electrolyte can be the same as before, without any particular restrictions. For example, the electrolyte may be a non-aqueous electrolyte containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent may include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl carbonate. The supporting salt may be a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may also be integrated with the electrode assembly 20 in a solid form (solid electrolyte).

[0061] Positive extreme 30 such Figure 2 As shown, it is inserted into one end of the sealing plate 14 in the Y direction along its long side. Figure 2 The positive terminal 30 is inserted into the terminal insertion hole 18 at the left end of the sealing plate 14. The positive terminal 30 is preferably made of metal, more preferably of aluminum or an aluminum alloy. On the other hand, the negative terminal 40 is inserted into the end formed on the other side of the long side in the Y direction of the sealing plate 14. Figure 2The terminal insertion holes 19 are located at the right end of the battery casing 10. Furthermore, the negative terminal 40 is preferably made of metal, more preferably of copper or a copper alloy. Here, these electrode terminals (positive terminal 30, negative terminal 40) protrude from the same surface of the battery casing 10 (specifically, the sealing plate 14). However, the positive terminal 30 and the negative terminal 40 may also protrude from different surfaces of the battery casing 10. Additionally, the electrode terminals (positive terminal 30, negative terminal 40) inserted into the terminal insertion holes 18, 19 are preferably fixed to the sealing plate 14 by riveting or the like.

[0062] As mentioned above, positive extreme 30 such Figure 2 As shown, inside the outer casing 12, via the positive current collector 50 (positive first current collector 51, positive second current collector 52), it connects to the positive electrode 22 of each electrode body 20 (see reference). Figure 7 Electrical connection. The positive terminal 30 is insulated from the sealing plate 14 by the positive internal insulating member 70 and the gasket 90. Furthermore, the positive internal insulating member 70 has a base portion 70a and a protrusion 70b located between the first positive current collector 51 and the sealing plate 14. Moreover, the positive terminal 30, which protrudes to the outside of the battery casing 10 via the terminal insertion hole 18, is connected to the positive external conductive member 32 outside the sealing plate 14. On the other hand, the negative terminal 40... Figure 2 As shown, inside the outer casing 12, via the negative electrode current collector 60 (negative electrode first current collector 61, negative electrode second current collector 62), it connects to the negative electrode 24 of each electrode body (see reference). Figure 7 Electrical connection. The negative terminal 40 is insulated from the sealing plate 14 by the negative internal insulating member 80 and the gasket 90. Furthermore, similar to the positive internal insulating member 70, the negative internal insulating member 80 also has a base portion 80a and a protrusion 80b located between the first negative current collector 61 and the sealing plate 14. Moreover, the negative terminal 40, which protrudes to the outside of the battery casing 10 through the terminal insertion hole 19, is connected to the negative external conductive member 42 outside the sealing plate 14. Furthermore, an external insulating member 92 is interposed between the external conductive members (positive external conductive member 32, negative external conductive member 42) and the sealing plate 14. The external insulating member 92 can insulate the external conductive members 32 and 42 from the sealing plate 14.

[0063] <Battery Manufacturing Methods>

[0064] The battery 100 can be manufactured by preparing, for example, the battery casing 10 (outer body 12 and sealing plate 14), electrode group 20 (electrode bodies 20a, 20b, 20c), electrolyte, positive terminal 30, negative terminal 40, positive current collector 50 (positive first current collector 51 and positive second current collector 52), negative current collector 60 (negative first current collector 61 and negative second current collector 62), positive internal insulation component 70, and negative internal insulation component 80. This can be achieved by a manufacturing method including a first mounting step, a second mounting step, an insertion step, and a sealing step. Furthermore, the manufacturing method disclosed herein may also include other steps at any stage.

[0065] In the first installation step, the following is made: Figure 12 , Figure 13 The first assembly shown. Specifically, firstly, a positive terminal 30, a positive first current collector 51, a positive internal insulation component 70, a negative terminal 40, a negative first current collector 61, and a negative internal insulation component 80 are installed on the sealing plate 14.

[0066] The positive terminal 30, the first positive current collector 51, and the internal positive current collector 70 are fixed to the sealing plate 14, for example, by riveting (rivets). A washer 90 is clamped between the outer surface of the sealing plate 14 and the positive terminal 30, and the internal positive current collector 70 is clamped between the inner surface of the sealing plate 14 and the first positive current collector 51, thereby performing the riveting process. Furthermore, the washer 90 can be made of the same material as the internal positive current collector 70. Specifically, before riveting, the positive terminal 30 is inserted sequentially from above the sealing plate 14 into the through hole of the washer 90, the terminal insertion hole 18 of the sealing plate 14, the through hole of the internal positive current collector 70, and the through hole 51h of the first positive current collector 51, protruding downwards from the sealing plate 14. Moreover, the portion protruding downwards from the sealing plate 14 above the positive terminal 30 is riveted by applying compressive force in the vertical direction Z. Therefore, at the front end of the positive terminal 30 ( Figure 2 The lower end of the part forms a riveting part.

[0067] Through this riveting process, the washer 90, the sealing plate 14, the positive electrode internal insulation component 70, and the positive electrode first collector 51 are integrally fixed to the sealing plate 14, and the terminal insertion hole 18 is sealed. Furthermore, the riveted portion can also be welded to the positive electrode first collector 51. This further improves conductivity reliability.

[0068] The fixing of the negative terminal 40, the first negative current collector 61, and the internal insulating member 80 can be performed in the same manner as the positive terminal side. That is, before riveting, the negative terminal 40 is inserted sequentially from above the sealing plate 14 into the through hole of the washer, the terminal insertion hole 19 of the sealing plate 14, the through hole of the internal insulating member 80, and the through hole 61h of the first negative current collector 61, protruding downwards from the sealing plate 14. Moreover, the portion protruding downwards from the sealing plate 14 above the negative terminal 40 is riveted by applying compressive force in the vertical direction Z. As a result, at the front end of the negative terminal 40 ( Figure 2 The lower end of the part forms a riveting part.

[0069] Next, on the outer surface of the sealing plate 14, with the outer insulating component 92 in between, the positive electrode external conductive component 32 and the negative electrode external conductive component 42 are installed. Furthermore, the material of the outer insulating component 92 can be the same as that of the positive electrode internal insulating component 70. Additionally, the timing of installing the positive electrode external conductive component 32 and the negative electrode external conductive component 42 can also be after the insertion process (e.g., after sealing the injection hole 15).

[0070] In the second installation step, the first assembly prepared in the first installation step is used to create a product as follows: Figure 5 The second assembly shown is an electrode group 20 integrated with the sealing plate 14. First, the fabrication of the electrode body 20a, which has a joint 1, included in the electrode group 20, will be explained. Furthermore, the fabrication method of the electrode body 20a will be described in detail below using the fabrication method of the electrode body 20a as an example, but the electrode bodies 20b and 20c can also be fabricated in the same way.

[0071] First, prepare as follows Figure 7 The electrode body 20a is shown. The electrode body 20a can be manufactured using a conventionally known method for manufacturing such a wound electrode body. Next, the separators constituting a portion of the separators 26 of the electrode body 20a are joined together. As described above, here, the separators 26 constituting the electrode body 20a having a positive and negative electrode stacked structure, counting from the side where the bending is gentler when the positive electrode tab group 23 is bent, up to the 5th sheet (5th layer), are joined together.

[0072] Here, Figure 14 This is a schematic diagram illustrating the method of forming the joint 1. Furthermore, in Figure 14 For ease of explanation, the positive electrode tab group 23 is omitted. For example... Figure 14As shown, in this embodiment, the five (five-layer) separators 26 are joined together by hot stamping the electrode body 20a manufactured as described above. More specifically, the five (five-layer) separators 26 are joined together in the joint 1 by placing the electrode body 20a on an anvil S heated to a predetermined temperature and stamping the portion corresponding to the joint 1 using a die T. Furthermore, the number of separators joined can be adjusted by, for example, the heating temperature of the anvil S, the heating time, and the stamping pressure of the die T. The heating temperature, heating time, and stamping pressure of the die are preferably adjusted appropriately according to the material constituting the separator. Moreover, those skilled in the art can appropriately determine these conditions by conducting preliminary tests.

[0073] Next, for the electrode body 20a with the joint 1 manufactured as described above, three electrode bodies 20a with additionally provided positive electrode second current collector 52 and negative electrode second current collector 62 are prepared (see reference). Figure 6 Electrode bodies 20a, 20b, and 20c are arranged in the short-side direction X. In this case, electrode bodies 20a, 20b, and 20c can all be arranged such that the second positive current collector 52 is positioned on one side of the long-side direction Y. Figure 5 (on the left side), so that the second negative collector 62 is positioned on the other side in the long side direction Y ( Figure 5 They are arranged in parallel on the right side.

[0074] Next, in such Figure 4 With the multiple positive electrode tabs 22t bent as shown, the first positive electrode current collector 51 fixed to the sealing plate 14 and the second positive electrode current collector 52 of the electrode bodies 20a, 20b, and 20c are respectively joined. Similarly, with the multiple negative electrode tabs 24t bent, the first negative electrode current collector 61 fixed to the sealing plate 14 and the second negative electrode current collector 62 of the electrode bodies 20a, 20b, and 20c are respectively joined. As joining methods, for example, ultrasonic welding, resistance welding, laser welding, etc., can be used. In particular, welding using high-energy rays such as lasers is preferred. Through this welding process, joint portions are formed in the recesses of the second positive electrode current collector 52 and the second negative electrode current collector 62, respectively.

[0075] In the insertion process, the second assembly, manufactured in the second installation process, is housed within the internal space of the outer casing 12. Specifically, firstly, for example, an insulating resin sheet made of a resin material such as polyethylene (PE) is bent into a bag or box shape to prepare an electrode holder 29. Next, the electrode group 20 is housed in the electrode holder 29. Then, the electrode group 20 covered by the electrode holder 29 is inserted into the outer casing 12. If the electrode group 20 is heavy, approximately 1 kg or more, for example, 1.5 kg or more, or even 2 to 3 kg, the electrode group 20 is inserted into the outer casing 12 in such a way that the long sidewall 12b of the outer casing 12 is perpendicular to the direction of gravity (making the outer casing 12 transverse), and the electrode group 20 is inserted into the outer casing 12.

[0076] In the sealing process, a sealing plate 14 is joined to the edge of the opening 12h of the outer casing 12 to seal the opening 12h. The sealing process can be performed simultaneously with or after the insertion process. In the sealing process, it is preferable to weld the outer casing 12 and the sealing plate 14. The welding of the outer casing 12 and the sealing plate 14 can be performed by, for example, laser welding. Afterward, electrolyte is injected through the injection hole 15, and the injection hole 15 is plugged with a sealing member 16, thereby sealing the battery 100. As described above, the battery 100 can be manufactured.

[0077] The battery 100 can be used for various purposes, and can be appropriately used as a power source (drive power source) for motors mounted on moving bodies (typically passenger cars, trucks, etc.) where external forces such as vibration or impact may be applied during use. The type of vehicle is not particularly limited; examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs). The battery 100 can also be appropriately used as a battery pack formed by arranging multiple batteries 100 in a predetermined arrangement direction and applying a load from the arrangement direction using a constraint mechanism.

[0078] The above describes several embodiments of this disclosure, but these embodiments are merely examples. This disclosure can be implemented in various other ways. This disclosure can be implemented based on the content disclosed in this specification and common technical knowledge in the field. The technology described in the claims includes examples obtained by various modifications and variations of the embodiments illustrated above. For example, a portion of the above embodiments can be replaced with other variations, and other variations can be added to the above embodiments. In addition, any elements not explicitly stated as necessary for the features of the technology may be appropriately omitted.

[0079] For example, in the above embodiment, the separator is attached only on the positive electrode tab group side, but it is not limited to this. The separator may also be attached only on the negative electrode tab group side, or it may be attached on both the positive and negative electrode tab group sides. Furthermore, the number of separators attached can be the same or different on both the positive and negative electrode tab group sides. In addition, since the positive electrode tabs are often made of metal foil with relatively low rigidity, such as aluminum foil, it is preferable to attach the separator at least on the positive electrode tab group side.

[0080] For example, in the above embodiment, the shape of the joint is rectangular, but it is not limited to this. The shape of the joint can be various shapes, such as square, circle, ellipse, etc. In addition, the joint disclosed herein can also be formed intermittently, for example. Furthermore, in the above embodiment, the shapes of the joints of the two parts are the same, but it is not limited to this, and the shapes of the joints of the two parts can also be different.

[0081] For example, in the above embodiment, at least a portion of the joint exists at a position adjacent to the boundary portion (in other words, the portion connected to the boundary portion), but is not limited thereto. In the art disclosed herein, at least a portion of the joint is sufficient to be close to the boundary portion. Furthermore, in this specification and claims, "close to" means to include the concept of adjacency, and within the scope of achieving the effects of the art disclosed herein, it may also include a solution that exists at a predetermined interval from the object portion. That is, "close to the boundary portion" means that it may also include a solution that is adjacent to the boundary portion and a solution that exists at a predetermined interval from the boundary portion within the scope of achieving the effects of the art disclosed herein. Furthermore, although not intended to be limited thereto, in the case of, for example, the above embodiment, when the length of the separator 26 (specifically, separator 26') in the Z direction is set to 100%, the joint 1 can be formed at an interval of approximately 1% to 5% from the boundary portion 2, with 3% or less being appropriate.

[0082] For example, in the above embodiment, the separators are joined together by hot stamping, but this is not a limitation. The separators can also be joined together by ultrasonic bonding accompanied by heating, or by applying an adhesive. Furthermore, if, for example, the surface of the separator has a protective layer, ultrasonic bonding accompanied by heating is preferred. In the above cases, those skilled in the art can appropriately determine the heating temperature, the frequency of the ultrasonic waves, etc., by conducting preliminary tests. Moreover, when using, for example, an adhesive to join the separators together, Cemedine PPX (registered trademark) is an example of such an adhesive. Alternatively, a hot melt adhesive can also be used.

[0083] Figure 15 It pertains to the second embodiment. Figure 10 The corresponding diagram. For example... Figure 15 As shown, in the second embodiment, the joint 101 exists on both sides of the boundary portion 2. Here, the area forming the joint 101 is not particularly limited as long as the effects of the technology disclosed herein are achieved. When the aforementioned shortest distance p is set to 100%, the joint 101 preferably includes an area of ​​approximately 5% to 30% (e.g., 10% to 20%) in the Y direction centered on the boundary portion 2. Furthermore, the shape of the joint 101 can be designed with reference to, for example, the above (B / A).

[0084] Figure 16 It pertains to the third embodiment. Figure 10 The corresponding diagram. For example... Figure 16 As shown, in the third embodiment, the joint 201 exists in the region lateral to the boundary portion 2 from the end s. Furthermore, Figure 17 It pertains to the fourth embodiment. Figure 10 The corresponding diagram. For example... Figure 17 As shown, in the fourth embodiment, the joint 301 exists in a portion from the end s to the R direction and on the side of the boundary portion 2.

[0085] Figure 18 It pertains to the fifth embodiment. Figure 10 The corresponding diagram. For example... Figure 18 As shown, in the fifth embodiment, the joint 401 exists on both sides of the boundary portion 2 and in the overlapping portion W of the positive electrode tab 22t and the separator 26 (specifically, separator 26'). Furthermore, the overlapping portion W in the positive electrode tab 22t includes a positive electrode protective layer 22p. The battery with the joint 401 having the above structure is preferred because the joint 401 can appropriately suppress vibrations that may be applied to the positive electrode tab 22t.

[0086] Furthermore, the formation of the joint in the above-described embodiments 2 to 5 can be implemented by adjusting, for example, the shape of the die.

Claims

1. A battery comprising: One or more electrode bodies, having a stacked structure in which a first electrode and a second electrode, serving as the counter electrode of the first electrode, are overlapped with a separator in between; and The battery casing houses the electrode body. in, The battery casing includes: The outer casing has 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; as well as A sealing plate is used to seal the opening, and a terminal electrically connected to the first electrode is installed thereon. The electrode body comprises: The first electrode tab group includes a plurality of tabs protruding from an end facing one of the second sidewalls of the pair of second sidewalls; and The second electrode tab group includes a plurality of tabs protruding from an end facing the other of the pair of second sidewalls. The first electrode tab group and the terminal are electrically connected via a current collector. The first electrode tab group engages with the current collector in a state in which at least a portion of the first electrode tab group is bent in a manner arranged along the second sidewall of one of the pair of second sidewalls. Within the electrode tab, there exists a boundary portion between the region where an active material layer or protective layer is formed and the exposed region of the electrode tab. The separators constituting at least a portion of the electrode body having the stacked structure are joined together, and at least a portion of the joint is close to the boundary portion.

2. The battery according to claim 1, wherein, The separator with the joint is positioned towards the side of the first electrode tab group with a gentler bend.

3. The battery according to claim 1 or 2, wherein, At least a portion of the joint is adjacent to the boundary portion.

4. The battery according to claim 1 or 2, wherein, The shortest distance from the root portion of the tab to the protruding end of the tab of the separator is more than twice the shortest distance from the root portion of the tab to the boundary portion.

5. The battery according to claim 1 or 2, wherein, The ratio of the length B of the joint in the direction orthogonal to the protruding direction of the tab to the length A of the joint in the protruding direction of the tab, B / A, is 1.3 or more.

6. The battery according to claim 1 or 2, wherein, The number of separators having the joint is 3 or more, and is less than 40% when the total number of separators constituting the electrode body having the stacked structure is set to 100%.

7. The battery according to claim 1 or 2, wherein, At least a portion of the joint is also present in the overlapping portion of the tab and the separator, and at least a portion of the overlapping portion in the tab has the protective layer.

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