Secondary battery

Abstract

This invention provides a secondary battery that appropriately accommodates the expansion and contraction of a battery cell. The battery cell of the lithium-ion secondary battery is characterized by having an electrode body formed by stacking and winding a positive electrode plate and a negative electrode plate separated by a separator within a cell housing having a pair of opposing sidewalls. An elastic member is provided between the electrode body and a cover. The elastic member has a contacting portion that fits tightly against the electrode body, and multiple protrusions extending from the contacting portion toward the cover, the protrusions tapering towards the front end. Therefore, even if the electrode body expands or contracts, it is pressed down with appropriate pressure by the elastic member.

Description

Technical Field

[0001] This disclosure relates to secondary batteries, and more specifically, to secondary batteries having battery cells that do not require stacking. Background Technology

[0002] Previously, for secondary batteries used in electric and hybrid vehicles, multiple battery cells were combined to achieve high voltage. Now, to suppress the expansion and contraction of the battery cells, multiple plate-shaped secondary battery cells are stacked. The stacked cells are then constrained using restraints, thus forming a battery module. This battery module is housed in a casing and mounted in the vehicle as a battery pack.

[0003] However, such battery modules require additional components besides the battery cells, such as constraint parts. This results in problems such as reduced energy density, increased weight, and increased manufacturing costs for the battery pack.

[0004] Therefore, the Cell-to-Pack (CTP, module-less power battery pack) approach was proposed, directly using battery cells as battery pack cells. For example, Figure 17 The energy storage device shown in Patent Document 1 includes a cuboid box-shaped housing 110 and an electrode body 150. The housing 110 has a bottom-shaped cylindrical main body member 121, which has a first main wall portion 111 and a second main wall portion 112. The energy storage device in Patent Document 1 is constructed by elastically compressing the electrode stack portion 150e of the electrode body 150 between the first main wall portion 111 and the second main wall portion 112 in the thickness direction FH of the electrode body 150 using an elastic clamping member 140 on a corrugated plate. With such a structure, multiple battery cells can be combined into a battery pack without external constraints. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2024-111475 Summary of the Invention The problem that the invention aims to solve

[0006] However, the invention disclosed in Patent Document 1 has the problem of not being able to adequately address the degree of expansion and contraction of the battery cell. The subject of this disclosure is to appropriately address the degree of expansion and contraction of battery cells. Methods for solving problems

[0007] One aspect of the secondary battery disclosed herein is characterized by comprising: a cell housing having a pair of opposing sidewalls; an electrode body housed within the cell housing and disposed between the pair of opposing sidewalls, the electrode body being formed by stacking and winding a positive electrode plate and a negative electrode plate separated by a separator; and an elastic member disposed between the electrode body and at least one of the pair of opposing sidewalls, the elastic member having a contact portion that closely adheres to the electrode body and a plurality of protrusions protruding from the contact portion toward the sidewall, the plurality of protrusions tapering toward a front end. In the aforementioned secondary battery, the plurality of protrusions may be disposed on the contact portion. In the aforementioned secondary battery, the plurality of protrusions can be arranged in a matrix in a width direction orthogonal to the protrusion direction of the protrusion and in a length direction orthogonal to the protrusion direction and the width direction. In the aforementioned secondary battery, the protrusion can be shaped like a truncated pyramid. In the aforementioned secondary battery, the protrusion may be shaped like a truncated cone. In the aforementioned secondary battery, the protrusion may include a protrusion disposed at the end of the close-fitting portion in the width direction and a protrusion disposed at the center of the close-fitting portion in the width direction, wherein the height of the protrusion disposed at the end of the close-fitting portion in the width direction is higher than the height of the protrusion disposed at the center of the close-fitting portion in the width direction. In the aforementioned secondary battery, the protrusion may include a protrusion disposed at the end of the close-fitting portion in the width direction and a protrusion disposed at the center of the close-fitting portion in the width direction, wherein the cross-sectional area of ​​the protrusion disposed at the end of the close-fitting portion in the width direction is larger than the cross-sectional area of ​​the protrusion disposed at the center of the close-fitting portion in the width direction. In the aforementioned secondary battery, for the elastic member, when the elastic member is compressed along the thickness direction, the rate of change of the spring constant [N / mm] relative to the initial compression rate [%] of the elastic member can be less than the rate of change of the spring constant [N / mm] when the compression rate [%] is greater than a specified value. In the aforementioned secondary battery, the elastic member can be porous. In the aforementioned secondary battery, the contact portion of the porous elastic member may be provided with an extension portion, which extends in such a way as to connect with the position where the electrolyte is stored due to gravity. In the aforementioned secondary battery, the elastic member may include two elastic members respectively disposed on both sides of the electrode body, one of the two elastic members not having the protrusion. In the aforementioned secondary battery, the cell casing can be a plate-shaped cuboid, and the electrode body is shaped into a flat shape. The aforementioned secondary battery can be a non-aqueous electrolyte secondary battery. The aforementioned secondary battery can be a lithium-ion secondary battery. In the aforementioned secondary battery, the elastic member may contain a capsule-shaped fire extinguishing agent. Invention Effects

[0008] The secondary battery according to the present invention has the effect of being able to appropriately respond to the degree of expansion and contraction of the battery cell. Attached Figure Description

[0009] Figure 1 This is a perspective view of the battery cell according to the first embodiment. Figure 2 This is a schematic diagram illustrating the shape of the battery cell of the first embodiment with the cover and elastic member removed. Figure 3 This is an exploded perspective view of the battery cell according to the first embodiment. Figure 4 yes Figure 1 A cross-sectional view of section IV-IV. Figure 5 This shows when the electrode body expands. Figure 1 A cross-sectional view of the VV portion. Figure 5 (a) shows the battery cell in its initial state. Figure 5 (b) shows the battery cell in an expanded state. Figure 6 The graph shows the ratio of the spring constant [N / mm] of the elastic member to the compression ratio [%) of the elastic member for a uniformly thick elastic member as a comparative example and for the elastic member of the structure of the first embodiment. Figure 7 This is a diagram schematically illustrating the pressure transmission of a comparative example of a protrusion with a uniform cross-sectional area and a protrusion of the first embodiment. Figure 8 This is a perspective view of the elastic member according to the first embodiment. Figure 9 This is a top view of the elastic member of the first embodiment. Figure 10 yes Figure 9 A cross-sectional view of part XX. Figure 11 This is a top view of the elastic member in the second embodiment. Figure 12 This is a schematic diagram showing the expansion of the electrode body, which is a wound body. Figure 12(a) is a top view. Figure 12 (b) is the front view viewed from the length direction Y. Figure 13 This is a top view of the elastic member in the third embodiment. Figure 14 This is a front view of the elastic member in the third embodiment. Figure 15 This shows the electrode body from Figure 14 The main view of the state when the state has expanded. Figure 16 yes Figure 1 A cross-sectional view of the elastic member of the fourth embodiment of part IV-IV. Figure 17 This is a cross-sectional view showing an existing battery cell. Detailed Implementation

[0010] (Summary of the first embodiment) Figure 1 This is a perspective view of the battery cell 1 according to the first embodiment. As described in the background art, the first embodiment is a CTP (Cell-to-Pack) technology that can be appropriately used to directly use the battery cell 1 of a secondary battery as a battery pack. In such a CTP, the battery module is constructed without the use of restraints. Therefore, in the battery cell 1 itself, the shrinkage of the electrode bodies 10 and 11 needs to be compressed in a way that no unnecessary gaps are formed between the positive electrode plate, negative electrode plate, and separator constituting the electrode bodies 10 and 11. Similarly, in the battery cell 1, the expansion of the electrode bodies 10 and 11 needs to be such that no unnecessary stress is generated in order not to damage the cell casing 20.

[0011] In addition, one of the purposes of using CTP is to increase the capacity per unit volume [Ah / m³] 3 To increase the strength of the cell casing 20, the volume of the battery cell 1 is increased to a necessary level, which is contrary to the research topic.

[0012] In order to solve the aforementioned problems, in the battery cell 1 of the first embodiment, the characteristic elastic member 70 can appropriately cope with the degree of expansion and contraction of the battery cell 1.

[0013] (Structure of the first embodiment) The following describes an embodiment of a lithium-ion secondary battery cell 1 as an example. Figures 1-17 The secondary battery of the present invention will be described. However, the present invention is not to be understood in a limiting manner through the various embodiments.

[0014] First, the battery cell 1 of the lithium-ion secondary battery of the first embodiment, which is an example of a secondary battery on which the present invention is based, will be described. Furthermore, for the sake of clarity in the description of the invention, the following description and the accompanying drawings are sometimes appropriately omitted, simplified, or illustrated. Additionally, in the accompanying drawings, the same reference numerals are used to denote the same elements, and repeated descriptions are omitted as needed.

[0015] <Battery Cell 1> The following describes battery cell 1. The orientation of battery cell 1 is not limited. Therefore, in the description of the first embodiment, as... Figure 1 As shown, for ease of explanation, the top surface 34 of the cell casing 20 of the battery cell 1, which includes the external positive terminal 50 and the external negative terminal 52, is positioned vertically upwards. The long side direction of the cell casing 20 of the battery cell 1 is defined as the width direction X. The direction of the short side of the cell casing 20 is defined as the length direction (height direction downwards) Y. The direction orthogonal to the width direction X and the length direction Y is defined as the thickness direction Z of the cell casing 20. Furthermore, in the following explanation, the width direction X is defined as the left-right direction.

[0016] Figure 1 The battery cell 1 shown is a secondary battery that uses a non-aqueous electrolyte and can be repeatedly charged and discharged. A lithium-ion secondary battery is a secondary battery that is charged and discharged by the movement of lithium ions, which act as charge carriers, between the positive and negative electrodes.

[0017] like Figure 1 As shown, the battery cell 1 includes electrode bodies 10 and 11 as wound bodies, a cell housing 20, a non-aqueous electrolyte (not shown), and an elastic member 70. The elastic member 70 will be described in detail below. In the first embodiment, the battery cell 1 has two electrode bodies 10 and 11 arranged side by side along the width direction X of the cell housing 20 within a cell housing 20. Furthermore, in the battery cell 1 of the first embodiment, two electrode bodies 10 and 11 connected in series constitute one battery cell 1. However, in this invention, the number of electrode bodies housed within a cell housing 20 is not particularly limited, and may be one or more. In addition, in Figure 1 The diagrams of the components other than the cell housing 20 and the electrode bodies 10 and 11 housed in the cell housing 20 are omitted.

[0018] <Electrode 10, 11> Electrode bodies 10 and 11 are flat electrode bodies formed by winding positive and negative electrode plates separated by separators. In electrode bodies 10 and 11, long strips of positive and negative electrode plates are stacked separated by two long strip-shaped separators. The positive and negative electrode plates are wound around a winding axis that is parallel to the Y-axis direction orthogonal to the long side direction of the positive and negative electrode plates, and are pressed and shaped into a flat shape.

[0019] The positive electrode plate constituting the positive electrode has a positive electrode composite material layer formed on at least one surface of the positive electrode current collector. From the viewpoint of improving battery performance, the positive electrode composite material layer is preferably formed on both sides of the positive electrode current collector. The components constituting the positive electrode plate can be made of materials suitable for lithium-ion secondary batteries without particular limitations.

[0020] As the positive electrode current collector, for example, a metal foil formed from a metal with aluminum as the main component can be used. The positive electrode active material layer contains a positive electrode active material capable of reversibly absorbing and releasing lithium ions as charge carriers. As the positive electrode active material, for example, a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide can be used. The positive electrode active material layer may contain optional components other than the positive electrode active material. Optional components other than the positive electrode active material include, for example, conductive materials, binders, and various additives. As conductive materials, for example, carbon materials such as graphite, acetylene black (AB), carbon nanotubes (CNTs), and carbon nanofibers (CNFs) can be used. As binders, for example, polyvinylidene fluoride (PVdF) can be used.

[0021] The negative electrode plate constituting the negative electrode has a negative electrode composite material layer formed on at least one surface of an elongated negative electrode current collector. From the viewpoint of improving battery performance, the negative electrode composite material layer is preferably formed on both sides of the negative electrode current collector. The components constituting the negative electrode plate can be made of materials suitable for lithium-ion secondary batteries without particular limitation. For example, a metal foil formed from a metal with copper as the main component can be used as the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material capable of reversibly absorbing and releasing charge carriers. For example, a carbon material such as graphite can be used as the negative electrode active material. The negative electrode composite material layer may also contain optional components other than the negative electrode active material. Optional components other than the negative electrode active material include, for example, binders, dispersants, and various additives. For example, a rubber such as styrene-butadiene rubber (SBR) can be used as a binder. For example, a cellulose such as carboxymethyl cellulose (CMC) can be used as a dispersant.

[0022] A separator is placed between the positive and negative electrode plates to insulate them. The separator retains a non-aqueous electrolyte. Any separator suitable for lithium-ion secondary batteries can be used without particular restriction. Porous sheets formed from olefin resins such as polyethylene (PE) and polypropylene (PP), or resins such as cellulose, can be used as the separator. The separator can be a single-layer structure or a multi-layer structure with two or more layers (e.g., a three-layer structure with PP layers stacked on both sides of a PE layer). Additionally, a heat-resistant layer (HRL) can be formed on the surface of the separator.

[0023] <Cell casing 20> like Figures 1-3 As shown, the cell housing 20 is a casing that houses the electrode bodies 10 and 11 together with the non-aqueous electrolyte. The cell housing 20 has a flattened cuboid shape in the thickness direction Z. The cell housing 20 is molded using an insulating resin. By using an insulating resin as the material for the cell housing 20, it is easier to form recesses, for example, compared to using metal. However, the material of the cell housing 20 is not limited to resin.

[0024] Figure 3 This is an exploded perspective view of the battery cell 1 according to the first embodiment. (See attached image.) Figure 3 As shown, in the battery cell 1 of the first embodiment, the cell housing 20 has a housing body 30 and a cover 40. The opposing portions 23 and 24 of the housing body 30 and the second opposing portions 25 and 26 of the cover 40 correspond to the "pair of opposing sidewalls" of the present invention. The housing body 30 is a box-shaped member with a flat rectangular parallelepiped shape in the thickness direction Z. Figure 1 With such a configuration, the faces constituting the cuboid are related as follows: The main body 30 of the housing has a side portion 31, a top portion 34, a bottom portion 35, a first end portion 32, and a second end portion 33. The side portion 31 faces the cover 40 in the thickness direction Z of the cell housing 20. The first end portion 32 and the second end portion 33 face each other in the width direction X of the cell housing 20. The top portion 34 and the bottom portion 35 face each other in the length direction (height direction) Y of the cell housing 20.

[0025] The cover 40 is a generally rectangular plate-shaped member installed on the housing body 30 in a manner that closes the opening of the housing body 30. The cover 40 seals the housing body 30, which houses the electrode bodies 10 and 11. The cover 40 is glued or fused to the opening end of the housing body 30, etc. This airtightly seals the cell housing 20.

[0026] <Non-aqueous electrolyte> Non-aqueous electrolytes not shown can be used without particular limitations for lithium-ion secondary batteries. A non-aqueous electrolyte is a composition containing a supporting salt in a non-aqueous solvent. As a non-aqueous solvent, aprotic solvents such as carbonates, esters, and ethers can be used. Among aprotic solvents, carbonates such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) are suitable non-aqueous solvents. One such non-aqueous solvent can be used alone, or two or more can be used in combination appropriately. As a supporting salt, lithium salts such as LiPF6, LiBF4, and LiClO4 are suitable, for example. Additives can be included in the electrolyte as needed.

[0027] Figure 2 A schematic diagram illustrating the shape of the battery cell 1 in the first embodiment with the cover 40 and elastic member 70 removed is shown. Figure 2 This diagram illustrates the state in which the electrode bodies 10 and 11 are housed in their respective storage portions 21 and 22, and the housing body 30, to which the insulating cover 60 is mounted, is sealed with a cover 40. In the battery cell 1 of the first embodiment, the electrode bodies 10 and 11 are housed in the storage portions 21 and 22, respectively. Then, a non-aqueous electrolyte is injected into each storage portion 21 and 22, so that the non-aqueous electrolyte is impregnated in each electrode body 10 and 11. Finally, the cover 40 is adhered to the housing body 30 in a manner that covers the first storage portion 21 and the second storage portion 22.

[0028] It should be noted that, in Figure 2 The example shown is an example of providing a cover 40 for the two storage sections 21, 22, but the cover 40 can also be prepared as a separate component for each storage section 21, 22. In this way, by providing a cover 40 for each storage section 21, 22, the welding of the cover 40 becomes easier. It is possible to obtain the effect of being able to change the shape of the cover 40 according to the deviation of each electrode body 10, 11 to adjust the pressure applied to each electrode body 10, 11, etc.

[0029] <External positive terminal 50, external negative terminal 52, etc.> like Figure 3 As shown, in the battery cell 1 of the first embodiment, the housing body 30 is embedded with an external positive terminal 50, an intermediate terminal, and an external negative terminal 52. In addition, the housing body 30 has storage portions 21 and 22 for accommodating the electrode bodies 10 and 11.

[0030] The positive electrode of electrode body 10 is connected to an external positive terminal 50. The external positive terminal 50 connected to the positive electrode of electrode body 10 is, for example, formed of a metal with aluminum as the main component. The negative electrode of electrode body 11 is connected to an external negative terminal 52. The external negative terminal 52 connected to the negative electrode of electrode body 11 is, for example, formed of a metal with copper as the main component.

[0031] The insulating cover 60 is configured to cover the intermediate terminal (not shown) of the top surface 34. The housing body 30 has storage portions 21 and 22 arranged at intervals along the width direction X of the cell housing 20. Electrode body 10 is stored in storage portion 21, and electrode body 11 is stored in storage portion 22. In this stored state, the positive electrode tab group 10a of electrode body 10 is engaged with the external positive terminal 50. The negative electrode tab group 10b of electrode body 10 is engaged with an intermediate negative terminal (not shown). Additionally, in this stored state, the positive electrode tab group 10a of electrode body 11 is engaged with an intermediate positive terminal (not shown). The negative electrode tab group 10b of electrode body 11 is engaged with the external negative terminal 52.

[0032] In the battery cell 1 of the first embodiment, electrode bodies 10 and 11 are housed in housing portions 21 and 22. Then, electrolyte is injected into the housing portions 21 and 22 through each opening, so that the electrolyte is immersed in the electrode bodies 10 and 11. Next, a cover 40 is bonded to the housing body 30 to close each opening of the housing portions 21 and 22, thereby enabling the manufacture of the battery cell 1.

[0033] In the battery cell 1 manufactured in this way, the external positive terminal 50 and the external negative terminal 52 are arranged in a straight line on the same surface. Therefore, the current path in the battery cell 1 is formed by a path that passes through the portion of the electrode bodies 10 and 11 near the terminal arrangement surface and has less meandering relative to the terminal arrangement surface. As a result, the battery cell 1 in the first embodiment can reduce the resistance value as a battery.

[0034] The flat electrode bodies 10 and 11 have curved portions 12 and 13 formed by laminated bodies whose outer surfaces are bent at both ends in the width direction X. Additionally, the electrode bodies 10 and 11 have flat portions 14 and 15 formed by laminated bodies with flat outer surfaces that connect the curved portions 12 and 13. The flat portions 14 and 15 are opposite each other in the thickness direction Z of the electrode bodies 10 and 11.

[0035] Such electrode bodies 10 and 11 have a flat surface 17 formed by XY planes at their upper ends in the thickness direction Z. They also have a flat surface 16 formed by XY planes at their lower ends in the thickness direction Z. Flat surfaces 16 and 17 are opposite each other in the thickness direction Z. Flat surfaces 16 and 17 have a generally rectangular shape.

[0036] The electrode bodies 10 and 11 have an end face 18 at their electrode-side ends in the longitudinal direction Y. An end face 19 is located at the end opposite to end face 18 in the longitudinal direction Y. End faces 18 and 19 are stacked surfaces composed of positive plates, negative plates and separators, and are open to the outside of electrode bodies 10 and 11.

[0037] Electrode bodies 10 and 11 are housed in storage portions 21 and 22 with their winding axes parallel to the length direction Y of the cell housing 20. Regarding the electrode bodies 10 and 11 housed in storage portions 21 and 22, curved portions 12 and 13 are disposed on both sides of the cell housing 20 in the width direction X, and flat portions 14 and 15 are disposed on both sides of the cell housing 20 in the thickness direction Z.

[0038] The cell housing 20 has two opposing surfaces 23a and 25a that face the flat surfaces 16 and 17 of the electrode body 10, and two opposing surfaces 24a and 26a that face the flat surfaces 16 and 17 of the electrode body 11. The opposing surfaces 23a and 24a face the opposing surfaces 25a and 26a in the thickness direction Z of the cell housing 20.

[0039] In the battery cell 1 of the first embodiment, the housing body 30 includes an opposing surface 23a, which is one of a pair of opposing sidewalls opposite to the flat surface 16 of the electrode body 10, and an opposing surface 24a, which is one of a pair of opposing sidewalls opposite to the flat surface 16 of the electrode body 11. The cover 40 includes an opposing surface 25a, which is another of a pair of opposing sidewalls opposite to the flat surface 17 of the electrode body 10, and an opposing surface 26a, which is another of a pair of opposing sidewalls opposite to the flat surface 17 of the electrode body 11.

[0040] Opposing surfaces 23a and 24a are the inner surfaces of the first opposing portions 23 and 24 of the side portion 31, which are opposite to the flat portion 14. Opposing surfaces 25a and 26a are the inner surfaces of the second opposing portions 25 and 26 of the side portion 31, which are opposite to the flat portion 15. Opposing surfaces 23a, 24a, 25a, and 26a face the storage portions 21 and 22 or define the storage portions 21 and 22.

[0041] <Pressure Changes in Battery Cell 1> then, Figure 4 It is along Figure 1 A cross-sectional view of line IV-IV. It should be noted that... Figure 4 In the middle, the structure of the electrode body 10 housed inside the cell casing 20 is similar to... Figure 3 The structure shown is the same as that of the electrode body 11 housed within the cell housing 20. Here, using the structure of the electrode body 11 housed within the cell housing 20 as an example, we will explain the problems that may occur during the charging and discharging of the battery cell 1. Figure 4 As shown, the elastic member 70 is disposed between the electrode body 11 and the cover 40.

[0042] Figure 5 This schematically illustrates the state of electrode 11 when it has expanded. Figure 1 A cross-sectional view of the VV portion. Figure 5 (a) shows the battery cell 1 in its initial state. Figure 5 (b) shows battery cell 1 in an expanded state. Figure 5 In the battery cell 1 shown in (a), the electrode body 11, which is sealed within the cell housing 20, expands and contracts during charging and discharging. Additionally, gas is generated from the electrode body 11. When the battery cell 1 is charged and discharged, the electrode body 11 within the cell housing 20 expands and contracts along the thickness direction Z of the electrode body 11 due to the absorption and release of lithium ions. Furthermore, gas is generated through various reactions, and the internal pressure increases with rising temperature.

[0043] like Figure 5 As shown in (b), in battery cell 1, if the electrode body 11 inside the cell housing 20 expands and gas is generated from the electrode body 11, a pressure F[N] will be generated that presses the cell housing 20 from the inside to the outside in the thickness direction Z. Furthermore, a reaction force F′[N] against the pressure F[N] will act on the electrode body 11 containing the non-aqueous electrolyte. As a result, the electrolyte is squeezed out from the end faces 18 and 19 to the outside of the electrode body 11, and thus the non-aqueous electrolyte leaks out from the electrode body 11.

[0044] The non-aqueous electrolyte leaking from the electrode body 11 flows down along the opposing surfaces 24a and 26a and accumulates at the bottom of the cell housing 20. Furthermore, the electrolyte accumulated at the bottom of the cell housing 20 permeates into the electrode body 11 from the end face 19. Thus, the electrolyte leaking from the electrode body 11 is reabsorbed by the electrode body 11 via the end face 19.

[0045] However, since the pressure F[N] generated by the expansion of the electrode body 11 increases with repeated charging and discharging, the reaction force F′[N] against the pressure F[N] also increases. Therefore, if the electrolyte is only allowed to permeate into the electrode body 11 from the end face 19 during charging and discharging, the salt concentration of the electrolyte maintained in the electrode body 11 during repeated charging and discharging is prone to unevenness, or electrolyte depletion may occur. If the salt concentration of the electrolyte maintained in the electrode body 11 is uneven, or electrolyte depletion occurs, there is a possibility that the internal resistance of the battery cell 1 will increase and the battery performance will decrease.

[0046] <Elastic Component 70> Figure 8 This is a perspective view of the elastic member 70 of the first embodiment. Figure 9 This is a top view of the elastic member 70 of the first embodiment. Figure 10 yes Figure 9 A cross-sectional view of the XX portion. The elastic member 70 of the first embodiment is composed of a contact portion 71 and a protrusion 72 disposed on the contact portion 71. In order to solve the problem of pressure variation as described above, the elastic member 70 in the first embodiment has the following structure.

[0047] <Close-fitting section 71> like Figures 8-10 As shown, the elastic member 70 has a generally square, sheet-like, close-fitting portion 71. (As shown...) Figures 1-4 As shown, the contact portion 71 is configured to cover the cover 40 side in the thickness direction Z of the electrode bodies 10 and 11 of the storage portions 21 and 22. For the contact portion 71, the movement in the width direction X and the length direction Y is restricted by the housing body 30.

[0048] Preferably, the elastic member 70 of the first embodiment is made of an elastic material, preferably capable of retaining the non-aqueous electrolyte. It is also required that the elastic member 70 has corrosion resistance to the non-aqueous electrolyte. Furthermore, it is even more preferable if the elastic member 70 has high heat resistance.

[0049] In the elastic member 70 of the first embodiment, the close-fitting part 71 and the protrusion 72 are integrally formed from the same material. <Function of Protrusion 72> Figure 7 This is a diagram schematically showing the transmission of the reaction force F′[N] of the protrusion 72′ with uniform cross-sectional area in a comparative example and the protrusion 72 in the first embodiment.

[0050] When the elastic members 70 are made of the same material, in the conventional elastic members 70, the protrusion 72' is the cross-sectional area [mm] of the base end portion 72b and the front end portion 72a on the side of the close contact portion 71. 2 They have the same columnar shape. In this case, the reaction force F′[N] is applied equally to the whole.

[0051] On the other hand, in the elastic member 70 of the first embodiment, the protrusion 72 is the cross-sectional area [mm] of the base end portion 72b and the front end portion 72a on the side of the close contact portion 71. 2 Different shapes of truncated pyramids. In this case, regarding the reaction force F′ [N], the cross-sectional area [mm²] 2The pressure per unit [N / mm] of the smaller front end 72a increases. Here, the "compression ratio CR (sometimes simply referred to as "compression ratio CR") [%]" as used in this application refers to the value expressed as a ratio [%] of the length under compression when the free length of the elastic member 70 is set to 0 [%]. Therefore, a large "compression ratio CR [%]" indicates a state of further compression. Even with the same material, for a cross-sectional area [mm²]... 2 The compression ratio CR[%] of the elastic member 70 also increases at the smaller front end 72a. That is, the cross-sectional area [mm²] 2 Smaller portions are easily flattened. By flattening the protrusion 72, a portion of the pressure of the reaction force F′ is absorbed. Therefore, the pressure transmitted to the electrode body 11 via the contact portion 71 is mitigated.

[0052] Figure 6 This is a graph showing the ratio of the "elastic member spring constant SC (sometimes simply referred to as "spring constant SC") [N / mm]" to the "elastic member compression ratio [%)" of the elastic member 70, which is a comparative example with uniform thickness, and the elastic member 70 of the first embodiment. Curve G0 represents the conventional elastic member 70 as a comparative example. Curve G1 represents the elastic member 70 of the first embodiment. For example, a sheet-like elastic member 70 with uniform thickness (not shown) has been conventionally used.

[0053] In such Figure 6 As shown by curve G0, in the case of a sheet-like shape with uniform thickness like the existing elastic member 70, the change of the spring constant SC [N / mm] of the elastic member 70 relative to the compression ratio CR [%) shows a roughly constant proportional relationship. However, if the compression ratio CR [%) of the elastic member 70 increases beyond a certain point, the voids are flattened; if the elastic member 70 is further flattened, the spring constant SC [N / mm] of the elastic member increases sharply. Thus, when the pressure F [N] increases and exceeds the specified compression ratio CR [%), the mechanical strength limit of the cover 40 is reached.

[0054] On the other hand, if Figure 6 As shown in the first embodiment of curve G1, the cross-sectional area [mm] 2As the spring constant SC [N / mm] of the elastic member 70 gradually decreases from the base end 72b to the front end 72a, the compressive pressure [N] decreases due to this portion. Consequently, the change in spring constant SC [N / mm] of the elastic member 70 relative to the compression ratio CR [%) generally exhibits a roughly proportional relationship. However, if the compression ratio CR [%) of the elastic member 70 increases by a certain amount, the front end 72a of the protrusion 72 deforms and absorbs the pressure [N], thus the change in spring constant SC [N / mm] of the elastic member 70 relative to the compression ratio CR [%) decreases. Therefore, even if the compression ratio CR [%) of the elastic member increases, the spring constant SC [N / mm] of the elastic member 70 will not reach the limit of the mechanical strength of the cover 40.

[0055] Furthermore, the material of the elastic member 70 shall be selected by those skilled in the art as the optimal material. In addition, the initial Young's modulus [N / mm] and porosity [%] shall also be selected by those skilled in the art based on the composition of the battery cell 1, the composition of the non-aqueous electrolyte, etc.

[0056] <Structural Example of Elastic Member 70> exist Figures 8-10 In the elastic member 70 shown, for illustrative purposes, the protrusions 72 are arranged in a matrix with a vertical × horizontal dimension of 3 rows × 3 columns. Figures 8-10 The elastic member 70 shown is an example; it can also be configured as at least 2 rows × 2 columns. Furthermore, there is no particular upper limit to the number of rows or columns; for example, multiple protrusions 72 can be arranged as in a 30-row × 30-column configuration. Additionally, the number can be varied depending on the shape of the electrode bodies 10 and 11, such as in a 20-row × 25-column configuration.

[0057] In the first embodiment, each protrusion 72 is shaped like a regular square pyramid frustum, but the cross-sections of the front end 72a and the base end 72b are square. Its cross-sectional area [mm²] 2 The optimal values ​​are determined by those skilled in the art based on factors such as the material. Furthermore, the height in the protruding direction (thickness direction Z) is also determined by those skilled in the art, along with the thickness of the contact portion 71, to be optimal values. Additionally, the spacing of the base end portion 72b is also determined by those skilled in the art to be optimal values.

[0058] (Function of the first embodiment) In the first embodiment, electrode bodies 10 and 11, formed by stacking and winding positive and negative electrode plates separated by a separator, are provided within a battery casing 20 having a casing body 30 and a cover 40. An elastic member 70 is provided between the electrode bodies 10 and 11 and the cover 40 forming the sidewall. The elastic member 70 has a contact portion 71 that is in close contact with the electrode bodies 10 and 11, and a plurality of protrusions 72 that protrude from the contact portion 71 toward the cover 40. Regarding these protrusions 72, the cross-sectional area orthogonal to the protrusion direction of the protrusions 72 decreases from the base end portion 72b toward the front end portion 72a.

[0059] The spring constant SC [N / mm] of such a protrusion 72 varies depending on its position in the thickness direction Z. If a pressure F [N] is applied to the elastic member 70 along the thickness direction Z, the spring constant SC [N / mm] increases proportionally to the compression ratio CR [%] in the thickness direction Z. Furthermore, if the compression ratio CR [%] in the thickness direction Z is greater than a predetermined value, the protrusion 72 absorbs stress by deforming from the front end 72a, and the change in the spring constant SC [N / mm] relative to the compression ratio CR [%] in the thickness direction Z decreases. In other words, even if the pressure F [N] is greater than a certain value, the pressure on the cover 40 will not increase. Therefore, even if the electrode bodies 10 and 11 expand significantly or the internal pressure increases due to gas generation, the mechanical strength of the cover 40 can be suppressed. In addition, if the pressure F [N] decreases, the electrode bodies 10 and 11 are fixed within the cell housing 20 by the elasticity of the elastic member 70 in such a way that the pressure F (reaction force F′) [N] relative to the electrode bodies 10 and 11 is not lower than a predetermined value.

[0060] (Effects of the first implementation method) (1-1) The lithium-ion secondary battery according to the first embodiment has the effect of being able to respond appropriately according to the degree of expansion and contraction of the battery cell 1.

[0061] (1-2) An elastic member 70 is provided between the electrode bodies 10 and 11 in the first embodiment and the cover 40 forming the sidewall. The elastic member 70 has a contact portion 71 that is in close contact with the electrode bodies 10 and 11, and a plurality of protrusions 72 that protrude from the contact portion 71 toward the cover 40. The cross-sectional area of ​​these protrusions 72, which is orthogonal to the protrusion direction, decreases from the base end portion 72b toward the front end portion 72a. Therefore, if the elastic member 70 is subjected to a certain pressure F [N], the spring constant SC [N / mm] is prevented from becoming too large by deformation. Therefore, it has the effect of reducing the pressure F [N] applied to the cover 40. In addition, as a result, it has the effect of miniaturizing, lightening, and reducing the cost of the cell housing 20 of the battery cell 1.

[0062] (1-3) Multiple protrusions 72 are arranged on the close-fitting portion 71. Therefore, they have the effect of dispersing the pressure F[N] applied to the cover 40. (1-4) The plurality of protrusions 72 are arranged in a matrix in a width direction X orthogonal to the thickness direction Z, which is the protrusion direction, and in a length direction Y orthogonal to both the protrusion direction and the width direction X. In other words, the plurality of protrusions 72 are arranged in a matrix in a plane orthogonal to the thickness direction Z, which is the protrusion direction (composed of the width direction X and the length direction Y). Therefore, it has the effect of uniformly dispersing the pressure F[N] applied to the cover 40.

[0063] (1-5) The shape of the protrusion 72 is a truncated quadrangular pyramid centered on the protrusion direction. Therefore, it has the effect of making the rate of change of the spring constant SC [N / mm] change sequentially according to the protrusion direction (thickness direction Z).

[0064] (1-6) Regarding the elastic member 70, when the elastic member 70 is compressed along the thickness direction Z, the spring constant SC [N / mm] shows a certain rate of change relative to the initial compression ratio CR [%] of the elastic member 70. On the other hand, the rate of change of the spring constant SC [N / mm] decreases when the compression ratio CR [%] is greater than a specified value. Therefore, it has the effect of suppressing the spring constant SC [N / mm] from becoming too large even when the pressure F [N] increases.

[0065] (1-7) The elastic member 70 is porous. Therefore, it has the effect of absorbing, retaining, and allowing non-aqueous electrolytes to pass through. Therefore, it can effectively utilize non-aqueous electrolytes.

[0066] (1-8) In the lithium-ion secondary battery of the first embodiment, the cell casing 20 is a plate-shaped cuboid, and the electrode bodies 10 and 11 are shaped into a flat shape. Therefore, the cell casing 20 can be stacked into a battery pack in the thickness direction Z without any restraints. In addition, since the thickness variation in the thickness direction Z of the cell casing 20 is suppressed, it has the effect that problems are not easily generated even if multiple layers are stacked.

[0067] (1-9) The secondary battery of the first embodiment is a lithium-ion secondary battery that is a non-aqueous electrolyte secondary battery. It has the effect of being suitable for use in batteries where lithium ions are absorbed by the electrode bodies 10 and 11 and expand.

[0068] (Second Implementation) Figure 11This is a top view of the elastic member 70 according to the second embodiment. In the second embodiment, the shape and arrangement of the protrusions 72 differ from those in the first embodiment. The following description focuses only on the differences from the first embodiment. In the first embodiment, the protrusions 72 are in the shape of a frustum of a square pyramid. In contrast, in the second embodiment, they are in the shape of a frustum of a cone.

[0069] Furthermore, in the arrangement of the protrusions 72, the rows and columns are staggered. Additionally, as another arrangement not shown, the protrusions 72 can also be arranged in an equilateral triangle with all protrusions 72 spaced equally apart.

[0070] Furthermore, the number of elements arranged, the front end 72a, the base end 72b, and the height in the protrusion direction (thickness direction Z) can be appropriately optimized by those skilled in the art, just as in the first embodiment. (Effects of the second implementation method) (2-1) By making the shape of the protrusion 72 a truncated cone, it has the effect of transmitting pressure more evenly.

[0071] (2-2) Alternatively, the protrusions 72 can be arranged such that the rows and columns are staggered, or that the intervals between the protrusions 72 are all the same. This results in a more uniform transmission of pressure.

[0072] (Third Implementation) Figure 12 This is a schematic diagram showing the expansion of the electrode body 11, which is a wound body. Figure 12 (a) is a top view. Figure 12 (b) is the front view viewed from the length direction Y.

[0073] In electrode body 11, positive and negative electrode plates are stacked with a separator between them. The stacked body is rolled into a cylindrical shape and then shaped into a flat shape by shaping and pressing. Therefore, for example, during charging, lithium ions are inserted into the negative electrode active material, causing the negative electrode plate to expand. In this case, such as... Figure 12 As shown in (a), structurally, expansion tends to occur at the center along the length direction Y, which is the winding direction. Regarding this, as... Figure 12 As shown in (b), the thickness of the central part increases when viewed from the length direction Y.

[0074] Figure 13 This is a top view of the elastic member 70 in the third embodiment. Figure 14 This is a front view of the elastic member 70 in the third embodiment. Figure 15 This shows electrode bodies 10 and 11 from... Figure 14 The main view of the state when the state has expanded.

[0075] like Figure 13 As shown, the protrusion 72 at the center of the width direction X of the closely attached portion 71 in The protrusions 72 at both ends of the close-fitting portion 71 are arranged along the length direction Y, which is parallel to the winding axis. out It is arranged along the length direction Y, which is parallel to the winding axis. In the third embodiment, for the reasons described above, the protrusion 72 at the center of the width direction X of the close-fitting portion 71 is... in The height [mm] is set to be lower than the height [mm] of the end portion in the width direction X. Additionally, the protrusion 72 at the center of the close-fitting portion 71 in the width direction X is... in The cross-sectional area of ​​the front end 72a and the base end 72b [mm] 2 The protrusion 72 is set to be larger than the end portion in the width direction X of the close-fitting portion 71. out Cross-sectional area [mm 2 ]broad.

[0076] On the other hand, the protrusion 72 at the end of the close-fitting portion 71 in the width direction X out The height [mm] is set to be greater than that of the protrusion 72 at the center of the width direction X of the close-fitting part 71. in The height [mm] is high. Additionally, the protrusion 72 at the end of the close-fitting portion 71 in the width direction X is... out The cross-sectional area of ​​the front end 72a and the base end 72b [mm] 2 The protrusion 72 is set to be larger than the central part of the width direction X of the close-fitting part 71. in Cross-sectional area [mm 2 ]narrow.

[0077] In the third embodiment, since the protrusion 72 is configured in this way, it performs the following functions. For example... Figure 14 As shown, when the electrode bodies 10 and 11 do not expand, the protrusion 72 at the end of the close-fitting portion 71 in the width direction X is... out The front end portion 72a is connected to the cover 40. On the other hand, the protrusion 72 at the center of the width direction X of the close-fitting portion 71 in The front end 72a is far from the cover 40.

[0078] like Figure 15 As shown, if the electrode bodies 10 and 11 expand, the protrusion 72 at the end of the close-fitting portion 71 in the width direction X will... out The front end 72a is in contact with the cover 40, but the displacement is small. On the other hand, the protrusion 72 at the center of the width direction X of the close-fitting part 71 inThe front end 72a is far from the cover 40, but is pressed by the expanded electrode bodies 10 and 11, and the protrusion 72 at the center of the width direction X of the close-fitting part 71. in The front end 72a is near the cover 40.

[0079] Furthermore, if the electrode bodies 10 and 11 expand (not shown), the protrusion 72 at the center of the width direction X of the closely attached portion 71 will... in The front end 72a of the protrusion 72 is connected to the cover 40. If the front end 72a of the protrusion 72 is connected to the cover 40, the pressure F[N] from the electrode bodies 10 and 11 is transmitted to the cover 40, and the protrusion 72 at the center of the width direction X of the close-fitting part 71 is connected to the cover 40. in The front end 72a receives a reaction force F′[N] from the cover 40. This stress[N] acts on the protrusion 72. in Compression is performed. This is achieved by making protrusion 72... in Compression can alleviate the pressure on the cover 40 [N].

[0080] (Effects of the third implementation method) (3-1) According to the elastic member 70 of the third embodiment, in the initial stage of expansion of the electrode bodies 10 and 11, only the protrusion 72 at the end of the width direction X of the closely attached portion 71 is close to the elastic member 70. out The front end 72a is connected to the cover 40. In this case, because the pressure F[N] is small, the elastic member 70 can fix the electrode bodies 10 and 11 with sufficient force. When the expansion of the electrode bodies 10 and 11 further increases, the protrusion 72 at the end of the close-fitting part 71 in the width direction X... out The front end 72a is in contact with the cover 40. At this time, although the pressure F[N] also increases, the protrusion 72 at the center of the width direction X of the close-fitting part 71 remains in contact with the cover 40. in The compression ratio CR[%] is still relatively small. Additionally, due to the protrusion 72 at the center of the width direction X of the closely fitting portion 71... in Cross-sectional area [mm 2 The central protrusion 72 is wider than the end protrusion 72, therefore the spring constant SC [N / mm] is also larger. This results in the following effect: even if the electrode bodies 10 and 11 expand significantly and generate a large pressure F [N], the central protrusion 72... in It can also mitigate large pressures F[N] by utilizing sufficient margins in spring constant SC[N / mm] and compression ratio CR[%].

[0081] (3-2) In particular, due to the protrusion 72 at the center of the width direction X of the closely attached portion 71 in The arrangement is along the width direction X of the expansion, thus having the effect of properly responding to the displacement caused by the expansion of the electrode bodies 10 and 11.

[0082] (Fourth Implementation) Figure 16 yes Figure 1 The cross-sectional view of the elastic member 70 of the fourth embodiment in section IV-IV is shown. The elastic member 70 of the fourth embodiment basically has the same structure as the elastic members 70 of the first to third embodiments. The difference is that an extension portion 71a is provided. The elastic member 70 of the fourth embodiment is a porous elastomer, just like the elastic member 70 of the first embodiment. Therefore, it has a structure that can absorb and retain non-aqueous electrolytes. Figure 16 Is with Figure 1 , Figure 4 The battery cell 1 shown has a common structure. Here, in Figure 1 , Figure 4 In this configuration, the top surface 34, which has the outer positive terminal 50 and the outer negative terminal 52, is positioned at the top. However, it can also be used in a configuration where the top surface 34 is at the bottom and the bottom surface 35 is at the top, with the top and bottom surfaces reversed. Therefore, in Figure 16 In the fourth embodiment shown, a configuration is envisioned in which the top surface 34 is the bottom and the bottom surface 35 is the top. In this case, for example, a battery pack is constructed by using a housing with a busbar disposed at the bottom of a box-shaped container (not shown) that houses multiple battery cells 1. Figure 16 In this usage method, the non-aqueous electrolyte that has seeped out from the electrode bodies 10 and 11 and is sealed in the battery cell 1 is stored due to gravity. Figure 16 Above. The non-aqueous electrolyte stored in this way is separated from the electrode body 11 and cannot be used as a carrier for lithium ions.

[0083] Therefore, in the elastic member 70 of the fourth embodiment, when the top part 34 is positioned as the bottom, the non-aqueous electrolyte is stored from the close-fitting part 71 due to gravity. Figure 16 The upper part. Therefore, the extension 71a extends from the close-fitting part 71 to the position where the non-aqueous electrolyte is stored due to gravity.

[0084] Furthermore, in the fourth embodiment, an electrolyte holding sheet 73 with the same structure as the contact portion 71 is disposed between the electrode bodies 10, 11 and the receiving portions 21, 22. The electrolyte holding sheet 73 is a porous sheet capable of absorbing and assisting the non-aqueous electrolyte, extending to the position where the non-aqueous electrolyte is stored due to gravity. In addition, the electrolyte holding sheet 73 is configured as a flat sheet without protrusions 72.

[0085] It should be noted that, although the illustration is omitted, the extension 71a can be provided on the side of the bottom surface 35 when the top surface 34 is in an upward orientation. Of course, the extension 71a can also be provided on both sides. The electrolyte holding sheet 73 can also be provided in a manner that extends towards the bottom surface 35, or it can be configured to extend to both sides.

[0086] It should be noted that, in the fourth embodiment, in addition to the above-described configuration, a capsule-shaped fire extinguishing agent 74 is also disposed within the elastic member 70. The fire extinguishing agent can be, for example, ammonium dihydrogen phosphate, ammonium sulfate, sodium bicarbonate, etc. The capsule of the fire extinguishing agent 74 is, for example, made of a resin such as polypropylene. The capsule typically seals the internal fire extinguishing agent airtightly, thus preventing contact with non-aqueous electrolytes. Furthermore, when the temperature inside the battery cell 1 reaches a certain level, for example, 160°C or higher, the capsule melts, causing the internal fire extinguishing agent to diffuse within the battery cell 1 and extinguish the fire.

[0087] (Effects of the fourth implementation method) (4-1) In the fourth embodiment, the extension 71a extends from the close-fitting portion 71, which is made of a porous sheet, to the position where the non-aqueous electrolyte is stored due to gravity. Therefore, the non-aqueous electrolyte not used in the main reaction is directly absorbed. Furthermore, it has the effect of reducing the non-aqueous electrolyte at the electrode bodies 10 and 11 by utilizing the capillary function of the porous sheet.

[0088] (4-2) Furthermore, in the fourth embodiment, the elastic member 70 is arranged to be in close contact with one side of the electrode bodies 10 and 11, and the electrolyte holding sheet 73 is arranged to be in close contact with the other side of the electrode bodies 10 and 11. One end of the electrolyte holding sheet 73 extends to the position where the non-aqueous electrolyte is stored due to gravity. Therefore, the non-aqueous electrolyte not used in the main reaction is directly absorbed using the electrolyte holding sheet 73. It also has the effect of reducing the non-aqueous electrolyte in the electrode bodies 10 and 11 through the capillary function of the electrolyte holding sheet 73.

[0089] (4-3) The electrolyte holding sheet 73 does not have a protrusion 72. Therefore, the thickness of the battery cell 1 is not increased beyond what is necessary. In addition, since the electrolyte holding sheet 73 is also made of an elastomer, it has the effect of cooperating with the elastic member 70 to cope with the expansion of the electrode bodies 10 and 11 between the cell housing 20 and the electrode bodies 10 and 11.

[0090] (4-4) The elastic member 70 and the electrolyte retaining sheet 73 contain a capsule-shaped fire extinguishing agent 74. The capsule uses a heat-melting resin such as polypropylene to airtightly retain the fire extinguishing agent. Therefore, it has the effect of extinguishing fire within the battery cell 1 when the internal temperature exceeds a specified temperature.

[0091] (Other examples) In this embodiment, a secondary battery is shown to have two electrode bodies 10 and 11 housed in two storage sections 21 and 22. However, it may also have a structure that houses a single electrode body or a structure that houses three or more electrode bodies.

[0092] In this embodiment, the two storage sections 21 and 22 are sealed with a cover 40, but each storage section 21 and 22 can also be sealed with two covers 40 respectively. Regarding protrusion 72, such as Figure 2 , Figure 3 As shown, it can also have multiple protrusions 72. Alternatively, it can be... Figures 8-11 A few protrusions 72 as shown in Figures 13 to 15.

[0093] In the battery cell 1 of this embodiment, in order to insulate the two storage portions 21 and 22, a separator is provided and the cell housing 20 is made of resin. However, if the battery cell 1 is only a single cell, the cell housing 20 can also be made of metal.

[0094] The shape of the protrusion 72 of the present invention is not limited to the shape shown in the example. The cross-sectional area ratio of the front end portion 72a to the base end portion 72b, the height / diameter ratio, etc. are not limited, as long as it is a shape that "taperes towards the front end".

[0095] The arrangement of the protrusions 72 in this invention is not limited to the illustrated arrangement, and is not limited to a matrix or equally spaced arrangement. As long as the pressure F[N] is evenly distributed and transmitted to the cover 40 (side wall), the arrangement is not limited and can also be random.

[0096] The number of protrusions 72 in this invention is not limited to the number shown in the examples. Alternatively, a sheet-like component can be provided that connects to the front end portion 72a side of the protrusion 72 of the present invention.

[0097] about Figure 13 The protrusion 72 of the elastic member 70 shown in the example is disposed at the end of the close-fitting portion 71 in the width direction X. out The height ratio of the protrusion 72 located at the center of the width direction X of the closely attached portion 71 in The height is high. Here, the protrusion 72 is located in the central part. inIt is not limited to one column, but can also be multiple columns. Additionally, a protrusion 72 is disposed at the end of the close-fitting portion 71 in the width direction X. out It is not limited to one column, but can have multiple columns. For example... Figure 13 As shown, a protrusion 72 can also be provided. in 72 protrusions out The protrusion 72 at the intermediate height, other than med In addition, protrusions of various heights can also be provided. med .

[0098] In this embodiment, the battery cell 1 is exemplified as a lithium-ion battery cell 1 that constitutes a CTP (Cell-to-Pack, module-less power battery pack) for vehicle driving. However, the structure, composition, shape, etc., of the secondary battery of the present invention are not limited. Furthermore, it can also be implemented in other non-aqueous electrolyte secondary batteries. In addition, it can also be applied to alkaline secondary batteries such as nickel-metal hydride secondary batteries.

[0099] Regarding the accompanying drawings, reference is made to the drawings for understanding the invention, but sometimes the actual secondary battery is not accurately reflected due to omissions, exaggerations, or stylization, which does not limit the invention. The numerical values, ranges, and compositions used in this embodiment are illustrative and do not limit the scope of the invention. Those skilled in the art can make appropriate optimizations to implement it.

[0100] This invention can be implemented by those skilled in the art by adding, deleting, or modifying elements without departing from the claims.

Claims

1. A secondary battery, characterized in that, have: The battery cell casing has a pair of opposing sidewalls; An electrode body, housed within the cell housing and disposed between a pair of opposing sidewalls, is constructed by stacking and winding positive and negative electrode plates separated by a separator; and An elastic member is disposed between the electrode body and at least one of the pair of opposing sidewalls. The elastic member has a contacting portion that is in close contact with the electrode body and a plurality of protrusions that protrude from the contacting portion toward the sidewall. The multiple protruding parts taper towards the front end.

2. The secondary battery according to claim 1, characterized in that, The plurality of protrusions are disposed on the mating portion.

3. The secondary battery according to claim 2, characterized in that, The plurality of protrusions are arranged in a matrix in a width direction orthogonal to the protrusion direction of the protrusion and in a length direction orthogonal to the protrusion direction and the width direction.

4. The secondary battery according to claim 2, characterized in that, The protrusion is shaped like a truncated pyramid.

5. The secondary battery according to claim 2, characterized in that, The protrusion is shaped like a truncated cone.

6. The secondary battery according to claim 3, characterized in that, The protrusion includes a protrusion disposed at an end of the close-fitting portion in the width direction and a protrusion disposed at the center of the close-fitting portion in the width direction. The height of the protrusion disposed at the end of the close-fitting portion in the width direction is higher than the height of the protrusion disposed at the center of the close-fitting portion in the width direction.

7. The secondary battery according to claim 3, characterized in that, The protrusion includes a protrusion disposed at an end of the close-fitting portion in the width direction and a protrusion disposed at the center of the close-fitting portion in the width direction. The cross-sectional area of ​​the protrusion disposed at the end of the close-fitting portion in the width direction is larger than the cross-sectional area of ​​the protrusion disposed at the center of the close-fitting portion in the width direction.

8. The secondary battery according to claim 1, characterized in that, For the elastic member, when the elastic member is compressed along the thickness direction, the rate of change of the spring constant [N / mm] relative to the initial compression ratio [%] of the elastic member is less than the rate of change of the spring constant [N / mm] when the compression ratio [%] is greater than a specified value.

9. The secondary battery according to claim 1, characterized in that, The elastic member is porous.

10. The secondary battery according to claim 9, characterized in that, An extension is provided at the contact portion of the porous elastic member, and the extension extends in such a way that it contacts the position where the electrolyte is stored due to gravity.

11. The secondary battery according to claim 1, characterized in that, The elastic member includes two elastic members respectively disposed on two sides of the electrode body, one of the two elastic members not having the protrusion.

12. The secondary battery according to claim 1, characterized in that, The battery cell housing is a plate-shaped cuboid, and the electrode body is shaped into a flat shape.

13. The secondary battery according to claim 1, characterized in that, The secondary battery is a non-aqueous electrolyte secondary battery.

14. The secondary battery according to claim 13, characterized in that, The secondary battery is a lithium-ion secondary battery.

15. The secondary battery according to claim 1, characterized in that, The elastic member contains a capsule-shaped fire extinguishing agent.

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