Battery

Abstract

To provide a battery whose reliability is improved suitably.SOLUTION: A battery 100 disclosed here includes an electrode body 20 including a positive electrode 22 and a negative electrode 24, and a battery case 10 that accommodates the electrode body 20. The battery case 10 includes an exterior body 12 including a rectangular opening 12h, a bottom wall 12a facing the rectangular opening 12h, a pair of first side walls 12b, and a pair of second side walls 12c, and a rectangular sealing plate 14 having a gas discharge valve 17 and sealing the opening 12h. A movement restriction member 1 that is connected to an inner surface of the battery case 10 and has a movement restriction surface 1c that restricts movement of the electrode body 20 toward the sealing plate 14 is provided. The movement restriction surface 1c is disposed at an end surface of the electrode body 20 on the sealing plate 14 side so as to face at least a part of a region near an end part of the sealing plate 14 in a longitudinal direction Y.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] For example, Japanese Patent Publication No. 7006613 discloses a battery that can prevent high-temperature molten material such as the electrode body and sparks from being ejected outside the battery case from the gas exhaust valve when an abnormality occurs in the battery and the gas exhaust valve is activated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7006613 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the investigations of the present inventors, it has been found that there is still room for improvement in the above-mentioned batteries in terms of improving reliability. [Means for solving the problem]

[0005] The battery disclosed herein includes an electrode assembly including a positive electrode and a negative electrode, and a battery case that houses the electrode assembly. The battery case includes an exterior body that includes a rectangular opening, a bottom wall facing the rectangular opening, a pair of first side walls, and a pair of second side walls. A rectangular sealing plate that has a gas release valve and seals the opening is also provided. A movement restricting member is connected to the inner surface of the battery case and has a movement restricting surface that restricts movement of the electrode assembly toward the sealing plate. The movement restricting surface is positioned on the end face of the electrode assembly facing the sealing plate so as to face at least a portion of an area near the longitudinal end of the sealing plate. As will be described in detail later, a battery with such a configuration can favorably improve reliability. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view schematically showing a battery according to a first embodiment. [Figure 2] FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic vertical cross-sectional view taken along line IV-IV in FIG. 2. [Figure 5] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body according to one embodiment. [Figure 6] FIG. 3 is a schematic enlarged view showing the vicinity of the negative electrode terminal in FIG. 2. [Figure 7] 3 is a schematic diagram showing the electrode body and movement restricting member of FIG. 2. FIG. [Figure 8] FIG. 2 is a schematic diagram for explaining a gas flow. [Figure 9] FIG. 7 is a view corresponding to FIG. 6 according to the second embodiment. [Figure 10] FIG. 10 is a view corresponding to FIG. 6 according to the third embodiment. [Figure 11] FIG. 8 is a view corresponding to FIG. 7 according to the third embodiment. [Figure 12] 10A and 10B are schematic diagrams for explaining a movement restricting member according to a third embodiment. [Figure 13] 13 is a schematic diagram of the through-hole 201d of FIG. 12 viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, several embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (for example, the general configuration and manufacturing process of a battery that do not characterize the present invention) can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In this specification, the expression "A to B" indicating a range means "A or more and B or less." It also encompasses the meanings of "greater than A" and "less than B."

[0008] In this specification, the term "battery" refers to any power storage device capable of extracting electrical energy, and is a concept that encompasses primary batteries and secondary batteries. Furthermore, in this specification, the term "secondary battery" refers to any power storage device that can be repeatedly charged and discharged by the movement of charge carriers between a positive electrode and a negative electrode via an electrolyte. The electrolyte may be any of a liquid electrolyte (electrolytic solution), a gel electrolyte, and a solid electrolyte. Such secondary batteries include 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 electric double layer capacitors. Below, an embodiment focusing on a lithium-ion secondary battery will be described.

[0009] <Battery configuration> FIG. 1 is a perspective view schematically illustrating a battery 100 according to a first embodiment. The battery 100 is preferably a secondary battery, and more preferably a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic transverse cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a schematic longitudinal cross-sectional view taken along line IV-IV in FIG. 2. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom. In the drawings, the symbol X indicates the direction of the short side of the battery 100, the symbol Y indicates the direction of the long side of the battery 100, and the symbol Z indicates the up-down direction of the battery 100. However, these directions are merely used for convenience of explanation and do not limit the installation form of the battery 100 in any way.

[0010] As shown in FIGS. 1 to 3, the battery 100 includes a battery case 10 (see FIG. 1), a plurality of electrode assemblies 20 (see FIGS. 2 and 3), a positive electrode terminal 30 (see FIGS. 1 and 2), a negative electrode terminal 40 (see FIGS. 1 and 2), a positive electrode current collector 50 (see FIG. 2), and a negative electrode current collector 60 (see FIG. 2). Although not shown, the battery 100 further includes an electrolyte. The battery 100 is a nonaqueous electrolyte secondary battery. The specific configuration of the battery 100 will be described below.

[0011] The battery case 10 is a housing that houses the electrode assembly 20. As shown in FIG. 1, the battery case 10 has a flat, bottomed, rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, aluminum alloy, iron, iron alloy, or the like. As shown in FIG. 2, the battery case 10 includes an exterior body 12 having an opening 12h, and a sealing plate (lid) 14 that seals the opening 12h. The exterior body 12 and the sealing plate 14 have sizes according to the number of electrode assemblies 20 housed (one or more; here, multiple), their sizes, etc.

[0012] As can be seen from FIGS. 1 and 2, the exterior body 12 is a bottomed, rectangular container having an opening 12h on its top surface. As shown in FIG. 1, the exterior body 12 includes a bottom wall 12a, a pair of long side walls 12b extending upward from the long sides of the bottom wall 12a and facing each other, and a pair of short side walls 12c extending upward from the short sides of the bottom wall 12a and facing each other. The bottom wall 12a is generally rectangular. The bottom wall 12a faces the opening 12h (see FIG. 2). The long side walls 12b and the short side walls 12c are examples of a "first side wall" and a "second side wall." The sealing plate 14 is a flat, generally rectangular plate-like member attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The sealing plate 14 faces the bottom wall 12a of the exterior body 12. The sealing plate 14 is generally rectangular. The battery case 10 is integrated by joining (for example, welding) a sealing plate 14 to the periphery of the opening 12h of the exterior body 12. This makes the battery case 10 airtightly sealed (sealed).

[0013] As shown in FIG. 2 , the sealing plate 14 is provided with a liquid inlet 15, a gas release valve 17, and terminal holes 18 and 19. The liquid inlet 15 is a through-hole for injecting electrolyte into the battery case 10 after the sealing plate 14 is assembled to the exterior body 12. The liquid inlet 15 is sealed with a sealing member 16 after the electrolyte is injected. The gas release valve 17 is a thin-walled portion configured to rupture when the pressure inside the battery case 10 reaches a predetermined value or higher, thereby releasing gas inside the battery case 10 to the outside. In this embodiment, the gas release valve 17 is integrated with the sealing plate 14, but in other embodiments, it may be a separate member. The gas release valve 17 is preferably located in a central region of the sealing plate 14 in the longitudinal direction (Y direction in FIG. 1 ). Here, the central region may be, for example, the central region obtained by dividing the length L of the sealing plate 14 in the longitudinal direction into five equal parts.

[0014] The electrolyte may be any electrolyte used in conventionally known batteries without any particular limitations. One example is a non-aqueous electrolyte in which a supporting salt is dissolved in a non-aqueous solvent. Examples of non-aqueous solvents include carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as LiPF6. The electrolyte may contain additives as needed.

[0015] The positive electrode terminal 30 is attached to one end of the sealing plate 14 in the long side direction Y (the left end in FIGS. 1 and 2). The negative electrode terminal 40 is attached to the other end of the sealing plate 14 in the long side direction Y (the right end in FIGS. 1 and 2). The positive electrode terminal 30 and the negative electrode terminal 40 are inserted through the terminal lead-out holes 18 and 19 and are exposed on the outer surface of the sealing plate 14. The positive electrode terminal 30 is electrically connected to a plate-shaped positive electrode external conductive member 32 on the outside of the battery case 10. The negative electrode terminal 40 is electrically connected to a plate-shaped negative electrode external conductive member 42 on the outside of the battery case 10. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are connected to other secondary batteries and external devices via external connection members such as bus bars. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are preferably made of a metal with excellent conductivity, such as aluminum, an aluminum alloy, copper, or a copper alloy. However, the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are not essential and may be omitted in other embodiments.

[0016] As shown in FIGS. 3 and 4 , in the battery 100 of this embodiment, a plurality of (specifically, two) electrode assemblies 20 are accommodated in the battery case 10. However, the number of wound electrode assemblies arranged inside one exterior housing 12 is not particularly limited and may be three or more (multiple), or may be one. While the present embodiment describes a case in which the electrode assembly 20 is a wound electrode assembly, this is not limiting. In other embodiments, the electrode assembly 20 may be a stacked electrode assembly in which a plurality of positive electrodes 22 and negative electrodes 24 are stacked with separators 70 interposed therebetween. The detailed structure of the electrode assembly 20 will be described later. As shown in FIG. 2 , a positive electrode tab group 25 and a negative electrode tab group 27 protrude from the upper portion of the electrode assembly 20. The battery 100 has a so-called upper tab structure in which the positive electrode tab group 25 and the negative electrode tab group 27 are located above the electrode assembly 20. As shown in FIG. 4 , the positive electrode tab group 25 is curved while being joined to the positive electrode current collecting portion 50. Although not shown in the figures, the negative electrode tab group 27 is similarly curved while being joined to the negative electrode current collecting portion 60. Note that the technology disclosed herein can also be applied to, for example, an electrode body in which the positive electrode tabs 22t and the negative electrode tabs 24t are not formed, or an electrode body in which the positive electrode tabs 22t protrude from one end in the width direction of the electrode body 20 (the Y direction in FIG. 2 ) and the negative electrode tabs 24t protrude from the other end.

[0017] The positive electrode current collecting part 50 electrically connects the positive electrode tab group 25 of the electrode body 20 and the positive electrode terminal 30. As shown in FIG. 2, the positive electrode current collecting part 50 is a plate-shaped conductive member extending in the long side direction Y along the inner surface of the sealing plate 14. One end of the positive electrode current collecting part 50 (the right side in FIG. 2) is electrically connected to the positive electrode tab group 25. The other end of the positive electrode current collecting part 50 (the left side in FIG. 2) is electrically connected to the lower end part 30c of the positive electrode terminal 30. The positive electrode terminal 30 and the positive electrode current collecting part 50 are preferably made of a metal with excellent conductivity, such as aluminum or an aluminum alloy.

[0018] The negative electrode current collecting part 60 electrically connects the negative electrode tab group 27 of the electrode body 20 and the negative electrode terminal 40. As shown in FIG. 2, the negative electrode current collecting part 60 is a plate-shaped conductive member extending in the long side direction Y along the inner surface of the sealing plate 14. One end of the negative electrode current collecting part 60 (the left side in FIG. 2) is electrically connected to the negative electrode tab group 27. The other end of the negative electrode current collecting part 60 (the right side in FIG. 2) is electrically connected to the lower end part 40c of the negative electrode terminal 40. The negative electrode terminal 40 and the negative electrode current collecting part 60 are preferably made of a metal with excellent conductivity, such as copper or a copper alloy.

[0019] In the battery 100, various insulating members are used to prevent electrical conduction between the electrode assembly 20 and the battery case 10. For example, as shown in FIG. 1 , the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by an external insulating member 92. As shown in FIG. 2 , gaskets 90 are attached to the terminal lead-out holes 18 and 19 of the sealing plate 14, respectively. This prevents electrical conduction between the positive electrode terminal 30 and the negative electrode terminal 40 inserted into the terminal lead-out holes 18 and 19 and the sealing plate 14. An internal insulating member 94 is disposed between the positive electrode current collector 50 and the negative electrode current collector 60 and the inner surface of the sealing plate 14. This prevents electrical conduction between the positive electrode current collector 50 and the negative electrode current collector 60 and the sealing plate 14. The internal insulating member 94 may have a protrusion that protrudes toward the electrode assembly 20.

[0020] Furthermore, the plurality of electrode bodies 20 are placed inside the exterior body 12 while covered with an electrode body holder 29 (see FIG. 3) made of an insulating resin sheet. This prevents the electrode bodies 20 from coming into direct contact with the exterior body 12. The material of each of the insulating members described above is not particularly limited as long as it has a predetermined insulating property. Examples of such materials include synthetic resin materials such as polyolefin resins such as polypropylene (PP) and polyethylene (PE), and fluorine-based resins such as perfluoroalkoxyalkane and polytetrafluoroethylene (PTFE).

[0021] Fig. 5 is a schematic diagram showing the configuration of the electrode assembly 20. As shown in Fig. 5, the electrode assembly 20 is configured by stacking a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 in a state insulated by two strip-shaped separators 70 interposed therebetween, and winding them in the longitudinal direction around a winding axis WL. Note that the symbol LD in Fig. 5 and other figures indicates the longitudinal direction (i.e., the conveying direction) of the electrode assembly 20 and separator 70 manufactured in strip form. The symbol WD is a direction substantially perpendicular to the longitudinal direction LD and indicates the winding axis direction (also the width direction) of the electrode assembly 20 and separator 70. The winding axis direction WD is substantially parallel to the up-down direction Z of the battery 100 described above.

[0022] Here, the electrode body 20 has a flat outer shape. The electrode body 20 is preferably a flat wound electrode body. The flat electrode body 20 can be formed, for example, by press-molding an electrode body (cylindrical body) wound into a cylindrical shape into a flat shape. As shown in FIG. 3, the flat electrode body 20 has a pair of curved portions 20r whose outer surfaces are curved, and a pair of flat portions 20f whose outer surfaces are flat and connect the pair of curved portions 20r.

[0023] In the battery 100, the electrode assembly 20 is housed inside the battery case 10 so that the winding axis direction WD substantially coincides with the up-down direction Z. In other words, the electrode assembly 20 is disposed inside the battery case 10 with the winding axis direction WD substantially parallel to the long side wall 12b and the short side wall 12c and substantially perpendicular to the bottom wall 12a and the sealing plate 14. As shown in FIG. 3, the pair of curved portions 20r face the pair of short side walls 12c of the exterior body 12. The pair of flat portions 20f face the long side walls 12b of the exterior body 12. The end faces of the electrode assembly 20 (i.e., the stacking surfaces where the positive electrode 22 and the negative electrode 24 are stacked, both ends in the winding axis direction WD in FIG. 5) face the bottom wall 12a and the sealing plate 14.

[0024] 5, the positive electrode 22 is a strip-shaped member. The positive electrode 22 includes a strip-shaped positive electrode current collector 22c, and a positive electrode active material layer 22a and a positive electrode protective layer 22p fixed to at least one surface of the positive electrode current collector 22c. From the viewpoint of battery performance, the positive electrode active material layer 22a is preferably formed on both sides of the positive electrode current collector 22c.

[0025] The components constituting the positive electrode 22 may be any conventionally known material that can be used in general batteries (e.g., lithium-ion secondary batteries) without any particular restrictions. For example, the positive electrode current collector 22c is preferably made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel, and is a metal foil, specifically an aluminum foil, in this example. The thickness of the positive electrode current collector 22c is preferably 5 μm to 30 μm, and more preferably 8 μm to 25 μm.

[0026] As shown in FIG. 5, the positive electrode 22 has a plurality of positive electrode tabs 22t protruding outward (toward the upper side in FIG. 5) from one end side in the winding axis direction WD. The plurality of positive electrode tabs 22t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. Here, the positive electrode tabs 22t are part of the positive electrode 22. The positive electrode tab 22t is a region where the positive electrode active material layer 22a is not formed. Here, a positive electrode protective layer 22p is provided on part of the positive electrode tab 22t. However, the positive electrode protective layer 22p does not necessarily have to be provided on the positive electrode tab 22t. The positive electrode current collector 22c is exposed on at least a part of the positive electrode tab 22t. The positive electrode tab 22t may be a member separate from the positive electrode 22.

[0027] Here, each of the multiple positive electrode tabs 22t is trapezoidal. However, the shape of the positive electrode tabs 22t is not limited to this. Furthermore, the size of the multiple positive electrode tabs 22t is not particularly limited. The shape and size of the positive electrode tabs 22t can be appropriately adjusted by, for example, taking into consideration the state of connection to the positive electrode current collecting part 50, depending on the formation position, etc. The multiple positive electrode tabs 22t are stacked at one end of the positive electrode 22 in the winding axis direction WD (the upper end in FIG. 5) to form a positive electrode tab group 25 (see FIG. 2).

[0028] As shown in FIG. 5, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction LD of the positive electrode current collector 22c. The width of the positive electrode active material layer 22a (the length in the winding axis direction WD; the same applies below) is smaller than the width of the negative electrode active material layer 24a. The positive electrode active material layer 22a contains a positive electrode active material capable of reversibly absorbing and releasing charge carriers. The positive electrode active material is preferably a lithium transition metal composite oxide, and more preferably one containing at least one of Ni (nickel) and Co (cobalt). An example of such a lithium transition metal composite oxide is lithium nickel cobalt manganese composite oxide. The molar ratio of Ni contained in the positive electrode active material may be, for example, 50 mol % or more, 60 mol % or more, or 70 mol % or more, when the total amount of transition metal elements contained in the positive electrode active material is taken as 100 mol %. The volumetric energy density of the battery 100 may be, for example, 500 Wh / L or more, 600 Wh / L or more, or 700 Wh / L or more. When the total solid content of the positive electrode active material layer 22a is taken as 100 mass%, the positive electrode active material may account for approximately 80 mass% or more, typically 90 mass% or more, for example 95 mass% or more. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a binder, a conductive material, and various additive components. The positive electrode active material layer 22a preferably contains a binder and a conductive material in addition to the positive electrode active material. The binder is typically made of resin, and in particular, a fluorine-based resin such as polyvinylidene fluoride (PVdF) is preferred. The conductive material is preferably a carbon material such as acetylene black (AB).

[0029] The positive electrode protective layer 22p is a layer configured to have lower electrical conductivity than the positive electrode active material layer 22a. As shown in FIG. 5, the positive electrode protective layer 22p is provided in a strip shape along the longitudinal direction LD of the positive electrode current collector 22c. The positive electrode protective layer 22p is provided at the boundary between the positive electrode current collector 22c and the positive electrode active material layer 22a in the winding axis direction WD. In this example, the positive electrode protective layer 22p is provided at one end of the positive electrode current collector 22c in the winding axis direction WD, specifically, at the end on the side where the positive electrode tab 22t is located (the upper end in FIG. 5). The provision of the positive electrode protective layer 22p can prevent the positive electrode 22 from coming into direct contact with the negative electrode active material layer 24a when the separator 70 is damaged, thereby preventing an internal short circuit in the battery 100.

[0030] The positive electrode protective layer 22p contains an insulating inorganic filler. An example of the inorganic filler is ceramic particles such as alumina. The positive electrode protective layer 22p may contain optional components other than the inorganic filler, such as a binder, a conductive material, and various additive components. The binder and conductive material may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments.

[0031] 5, the negative electrode 24 is a strip-shaped member. The negative electrode 24 includes a strip-shaped negative electrode current collector 24c and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector 24c. From the viewpoint of battery performance, the negative electrode active material layer 24a is preferably formed on both sides of the negative electrode current collector 24c.

[0032] For each component constituting the negative electrode 24, conventionally known materials that can be used in general batteries (e.g., lithium-ion secondary batteries) can be used without particular limitation. For example, the negative electrode current collector 24c is preferably made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel, and here is a metal foil, specifically a copper foil. The thickness of the negative electrode current collector 24c is preferably 5 μm to 30 μm, and more preferably 8 μm to 25 μm.

[0033] As shown in FIG. 5, in the negative electrode 24, a negative electrode tab 24t protrudes outward (toward the upper side in FIG. 5) from one end edge in the winding axis direction WD. The multiple negative electrode tabs 24t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. In the winding axis direction WD, the negative electrode tab 24t is provided at the end on the same side as the positive electrode tab 22t. Here, the negative electrode tab 24t is part of the negative electrode 24. Here, the negative electrode tab 24t is a region where the negative electrode active material layer 24a is not formed and where the negative electrode current collector 24c is exposed. However, part of the negative electrode active material layer 24a may protrude and be attached to the negative electrode tab 24t. Furthermore, the negative electrode tab 24t may be a member separate from the negative electrode 24.

[0034] Here, each of the multiple negative electrode tabs 24t is trapezoidal. However, the shape and size of the multiple negative electrode tabs 24t can be adjusted as appropriate, similar to the positive electrode tabs 22t. The multiple negative electrode tabs 24t are stacked at one end of the negative electrode 24 in the winding axis direction WD (the upper end in FIG. 5) to form a negative electrode tab group 27 (see FIG. 2).

[0035] As shown in FIG. 5, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction LD of the negative electrode current collector 24c. The width of the negative electrode active material layer 24a is greater than the width of the positive electrode active material layer 22a. The width of the negative electrode active material layer 24a refers to the length of a portion of the negative electrode active material layer 24a in the winding axis direction WD where the thickness is substantially constant. For example, even if a portion of the negative electrode active material layer 24a extends onto the negative electrode tab 24t, the width does not include the negative electrode tab 24t. The negative electrode active material layer 24a contains a negative electrode active material capable of reversibly absorbing and releasing charge carriers. Examples of the negative electrode active material include carbon materials such as graphite and silicon materials. When the total solid content of the negative electrode active material layer 24a is taken as 100% by mass, the negative electrode active material may account for 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 may contain any component other than the negative electrode active material, such as a binder, a conductive material, or various additive components. The negative electrode active material layer 24a preferably contains a binder in addition to the negative electrode active material. The binder preferably contains rubbers such as styrene butadiene rubber (SBR) or celluloses such as carboxymethyl cellulose (CMC). The negative electrode active material layer 24a may contain a carbon material as a conductive material as necessary.

[0036] As shown in FIG. 5, the separator 70 is a strip-shaped member. The separator 70 is an insulating sheet having a plurality of fine through-holes formed therein through which charge carriers can pass. The width of the separator 70 is greater than the width of the negative electrode active material layer 24a. By interposing the separator 70 between the positive electrode 22 and the negative electrode 24, contact between the positive electrode 22 and the negative electrode 24 is prevented and charge carriers (e.g., lithium ions) can be transferred between the positive electrode 22 and the negative electrode 24. Although not particularly limited, the thickness of the separator 70 may be, for example, 3 μm or more, or 5 μm or more. The thickness of the separator 70 may also be, for example, 25 μm or less, 18 μm or less, or 14 μm or less.

[0037] Here, two separators 70 are used for one electrode assembly 20. As in this embodiment, it is preferable that two separators 70, i.e., a first separator and a second separator, are used for one electrode assembly 20. Also, here, the two separators have different configurations, but they may also have similar configurations.

[0038] Next, the movement restricting member 1 included in the battery 100 according to this embodiment will be described. First, as described above, the battery 100 includes an electrode assembly 20 including a positive electrode 22 and a negative electrode 24, and a battery case 10 that houses the electrode assembly 20. The battery case 10 includes an exterior body 12 that includes a rectangular opening 12h, a bottom wall 12a facing the rectangular opening 12h, a pair of first side walls (here, long side walls 12b), and a pair of second side walls (here, short side walls 12c), and a rectangular sealing plate 14 that has a gas release valve 17 and seals the opening 12h. As shown in FIG. 2, the battery 100 includes a movement restricting member 1 that is connected to the inner surface of the battery case 10 and has a movement restricting surface 1c that restricts movement of the electrode assembly 20 toward the sealing plate 14. The movement restricting surface 1c is disposed on the end face of the electrode body 20 facing the sealing plate 14 so as to face at least a part of the region near the end in the longitudinal direction (Y direction in FIG. 2) of the sealing plate 14. When the length of the electrode body 20 in the Y direction is W (see FIG. 3), the region near the end in the longitudinal direction of the sealing plate 14 is, for example, a region up to 1 / 6W from the end in the longitudinal direction Y of the electrode body 20, or may be a region up to 1 / 5W or a region up to 1 / 4W. However, it is not intended to be limited to these.

[0039] For example, in conventional batteries, when an abnormality occurs in the battery, some components of the electrode assembly may move along with the generated gas, reducing the restraining force of the electrode assembly and causing the electrode assembly to become unsecured. In such a case, the force of the gas ejection may cause the electrode assembly to block the gas release valve, causing a sudden rise in the battery's internal pressure and potentially damaging the battery, which is undesirable. In contrast, the battery 100 disclosed herein includes a movement-restricting member 1, which effectively restricts movement of the electrode assembly 20 even when gas is ejected. This prevents the electrode assembly 20 from blocking the gas release valve 17 and effectively releases gas to the outside of the battery 100, thereby effectively preventing damage to the battery 100 due to an increase in the internal pressure of the battery 100. In other words, a battery 100 with favorably improved reliability can be provided.

[0040] FIG. 7 is a schematic diagram showing the electrode assembly 20 and the movement restricting member 1. Note that, in FIG. 7, the positive electrode tab group 22t and the negative electrode tab 24t are omitted for clarity. As shown in FIGS. 6 and 7, the movement restricting member 1 according to this embodiment is divided into three regions: a first region 1a, a second region 1b, and a third region 1c. The first region 1a is connected to the sealing plate 14. The second region 1b extends from the first region 1a toward the electrode assembly 20. The third region 1c (corresponding to the movement restricting surface) bends from the second region 1b and extends along the end face of the electrode assembly 20 facing the sealing plate 14. The second region 1b is connected to the end of the first region 1a facing the center of the sealing plate 14 and to the end of the third region 1c facing the end of the sealing plate 14 in the longitudinal direction of the sealing plate 14 (the Y direction in FIG. 6). The movement restricting member 1 having such a configuration can be obtained, for example, by molding. The thickness of the movement restricting member 1 (width in the Z direction in FIG. 6) can be, for example, 1 mm to 10 mm (preferably 2 mm to 8 mm). However, this is not intended to be limiting. Note that while FIG. 6 shows the movement restricting member 1 in the vicinity of the negative electrode terminal, the configuration of the movement restricting member 1 in the vicinity of the positive electrode terminal is similar.

[0041] The material constituting the movement restricting member 1 is not particularly limited as long as the effects of the technology disclosed herein are exhibited. The material constituting the movement restricting member 1 may be, for example, a metal material or a resin material. Alternatively, a combination of a metal material and a resin material may be used. Specifically, the skeleton of the movement restricting member 1 may be made of metal, and an insulating region (e.g., a resin region) may be provided in a location where there is a particular risk of short circuiting and where insulation is desired. Such a resin region may be provided, for example, by applying a resin, attaching a resin tape, or forming a resin member. For example, a metal movement restricting member 1 is preferable from the perspective of strength, while a resin movement restricting member 1 is preferable from the perspective of insulation. Examples of such metal materials include aluminum, copper, nickel, iron, and alloys thereof. The metal material constituting the movement restricting member 1 is preferably a type that can be connected to, for example, the battery case 10, and is preferably the same type of metal as the battery case 10. Examples of such resin materials include synthetic resin materials such as polyolefin resins such as polypropylene (PP) and polyethylene (PE), and fluorine-based resins such as perfluoroalkoxyalkane and polytetrafluoroethylene (PTFE). In this embodiment, the movement restricting member 1 is made of metal.

[0042] As shown in FIG. 2, in this embodiment, a positive electrode tab 22t provided on the positive electrode 22 and a negative electrode tab 24t provided on the negative electrode 24 are arranged on the end face of the electrode assembly 20 on the sealing plate 14 side. In other words, in the battery 100, the winding axis WL of the electrode assembly 20 is arranged perpendicular to the sealing plate 14 (or the bottom wall 12a). The electrode assembly 20 is a wound electrode assembly that is wound perpendicular to the wide surface of the sealing plate 14. In addition, movement restricting surfaces 1c are arranged on the outer sides of the positive electrode tab 22t and the negative electrode tab 24t in the long side direction of the sealing plate 14 (direction Y in FIG. 2). When the winding axis WL is arranged perpendicular to the sealing plate 14, gas is discharged from the central region toward the sealing plate 14. Furthermore, with the configuration shown in FIG. 8, the flow of gas concentrating from the inside of the positive electrode tab 22t and the negative electrode tab 24t toward the gas discharge valve 17 (see the dashed arrows in FIG. 8) is less likely to be obstructed, and the gas can be more effectively discharged from the discharge valve 17.

[0043] As shown in FIG. 6 , in this embodiment, the movement restricting member 1 is connected to the sealing plate 14. This configuration is preferable because it allows the electrode assembly 20 to be stably fixed to the lower part of the battery case 10. Furthermore, the movement restricting member 1 is preferably connected to at least one of the first side wall 12b, the second side wall 12c, and the bottom wall 12a. This configuration makes it difficult for a load to be applied to the sealing plate 14 even if the electrode assembly 20 moves. This makes it possible to preferably prevent damage to the joint (welded joint) between the sealing plate 14 and the exterior body 12. In this embodiment, the movement restricting member 1 is connected to the second side wall 12c. The movement restricting member 1 can be connected (joined) to the sealing plate 14 (or the first side wall 12b, the second side wall 12c, or the bottom wall 12a) by, for example, laser welding, resistance welding, ultrasonic welding, or by inserting a welding jig.

[0044] <Battery manufacturing method> Next, a description will be given of an example of a method for manufacturing the battery 100. Note that the method for manufacturing the battery 100 disclosed herein may further include other steps at any stage.

[0045] First, two electrode assemblies 20 are prepared. The electrode assemblies 20 can be fabricated using a conventional method for this type of wound electrode assembly. Next, terminals (positive electrode terminal 30 and negative electrode terminal 40), current collecting members (positive electrode current collecting portion 50 and negative electrode current collecting portion 60), external conductive members (positive electrode external conductive member 32 and negative electrode external conductive member 42), insulating members (gasket 90, external insulating member 92, and internal insulating member 94), and movement restricting member 1 are assembled to the sealing plate 14. At this time, the first region 1a of the movement restricting member 1 is connected to the sealing plate 14 by, for example, laser welding. Next, the tab groups (positive electrode tab group 25 and negative electrode tab group 27) provided on the electrode assemblies 20 are connected to the current collecting members (positive electrode current collecting portion 50 and negative electrode current collecting portion 60).

[0046] Next, the electrode assembly 20 attached to the sealing plate 14 is inserted into the exterior body 12. As in this embodiment, the electrode assembly 20 may be wrapped in an electrode assembly holder 29. Next, the exterior body 12 is closed with the sealing plate 14, and the sealing plate 14 and the exterior body 12 are joined together. After that, the electrolyte is poured through the liquid inlet 15 provided in the sealing plate 14, and the liquid inlet 15 is sealed with the sealing member 16. Note that, before sealing the liquid inlet 15 with the sealing member 16, it is preferable that the positive electrode tab 22t and the negative electrode tab 24t extend to positions offset from the opening 12h of the exterior body 12, and that the sealing plate 14 be offset from the opening 12h of the exterior body 12. In this manner, the battery 100 can be manufactured.

[0047] <Battery uses> Battery 100 can be used for a variety of purposes, but is preferably used, for example, as a power source (driving power source) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs). Battery 100 has reduced variation in battery reaction, and is therefore preferably used to construct a battery pack.

[0048] Although one embodiment of the present disclosure has been described above, the above embodiment is merely an example. The present disclosure can be implemented in various other forms. The present disclosure can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiment. For example, it is possible to replace part of the above-described embodiment with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiment. Furthermore, if a technical feature is not described as essential, it can be deleted as appropriate.

[0049] 9 is a view corresponding to FIG. 6 according to the second embodiment. As shown in FIG. 9, the movement restricting member 101 according to the second embodiment is divided into two regions, a first region 101a and a second region 101b. The first region 101a is connected to the second side wall 12c of the exterior body 12. The second region 101b (corresponding to the movement restricting surface) bends from the first region 101a and extends along the end face of the electrode body 20 on the sealing plate 14 side. The first region 101a is connected to the end of the second region 101b on the end side of the sealing plate 14 in the longitudinal direction of the sealing plate 14 (the Y direction in FIG. 9).

[0050] Next, an example of a manufacturing method for the battery according to the second embodiment will be described. First, two electrode assemblies 20 are prepared. The electrode assemblies 20 can be manufactured according to a conventionally known method for this type of wound electrode assembly. Next, terminals (positive electrode terminal 30 and negative electrode terminal 40), current collecting members (positive electrode current collecting portion 50 and negative electrode current collecting portion 60), external conductive members (positive electrode external conductive member 32 and negative electrode external conductive member 42), and insulating members (gasket 90, external insulating member 92, and internal insulating member 94) are assembled to the sealing plate 14. Then, the tab groups (positive electrode tab group 25 and negative electrode tab group 27) provided on the electrode assemblies 20 are connected to the current collecting members (positive electrode current collecting portion 50 and negative electrode current collecting portion 60).

[0051] Next, the electrode assembly 20 attached to the sealing plate 14 is inserted into the exterior body 12 together with the movement-restricting member 101. As in the present embodiment, the electrode assembly 20 may be enclosed in an electrode assembly holder 29. Next, the exterior body 12 is closed with the sealing plate 14, and the sealing plate 14 and the exterior body 12 are joined together. At this time, the first region 101a of the movement-restricting member 101 is connected to the second side wall 12c from the outside of the battery 100, for example, by laser welding. Note that, before the exterior body 12 is closed with the sealing plate 14 and the sealing plate 14 and the exterior body 12 are joined together, it is preferable that the positive electrode tab 22t and the negative electrode tab 24t extend to positions offset from the opening 12h of the exterior body 12, and that the sealing plate 14 is offset from the opening 12h of the exterior body 12. Thereafter, the electrolyte is poured through the liquid pouring hole 15 provided in the sealing plate 14, and then the liquid pouring hole 15 is sealed with the sealing member 16. In this manner, the battery 100 can be manufactured.

[0052] 10 is a view corresponding to FIG. 6 according to the third embodiment. As shown in FIG. 10, the movement restricting member 201 according to the third embodiment is divided into three regions: a first region 201a, a second region 201b, and a third region 201c. The first region 201a (corresponding to the movement restricting surface) extends along the end face of the electrode body 20 on the sealing plate 14 side. The second region 201b bends from the first region 201a and extends from the sealing plate 14 toward the bottom wall 12a. The third region 201c bends from the second region 201b and extends along the bottom wall 12a of the electrode body 20. The second region 201b is connected to the second side wall 12c, and the third region 201c is connected to the bottom wall 12a.

[0053] FIG. 11 is a view corresponding to FIG. 7 according to the third embodiment. FIG. 12 is a schematic diagram for explaining a movement restricting member according to the third embodiment. FIG. 13 is a schematic diagram of the through-hole 201d of FIG. 12 as viewed from above. As shown in FIG. 12, in this embodiment, the through-hole 201d is formed in the movement restricting surface 201a of the movement restricting member 201. As shown in FIG. 13, the through-hole 201d is formed between the curved outer surfaces of the two electrode bodies 20. When viewed from a direction perpendicular to the bottom wall 12a (the Z direction in FIG. 11), the movement restricting member 201 and the bottom wall 12a are connected at a portion that overlaps with the through-hole 201d of the bottom wall 12a. Region A in FIG. 13 indicates the region where the bottom wall 12a and the through-hole 201d overlap. This configuration is preferable because it makes it easier to connect the movement restricting member 201 and the bottom wall 12a, for example, even after the electrode body 20 is housed in the battery case 10. From the viewpoint of more efficient connection, it is preferable that insulating members and other members present in the connection path between the movement restricting member 201 and the battery case 10 have openings or notches that allow laser light to pass through.

[0054] As shown in Fig. 13, in this embodiment, the through-hole 201d has a rectangular shape in a plan view. However, in other embodiments, the through-hole 201d may have various shapes, such as a circular shape, an elliptical shape, or a triangular shape. The size of the through-hole 201d is preferably designed appropriately so that the movement restricting member 201 and the bottom wall 12a can be connected. The through-hole 201d can be formed, for example, when the movement restricting member 201 is manufactured by mold molding. In other embodiments, the through-hole 201d may be a notch.

[0055] To summarize the above, a battery is disclosed in which a movement restricting member is connected to a bottom wall, a through hole and / or a notch is formed in the movement restricting surface of the movement restricting member, and when viewed from a direction perpendicular to the bottom wall, the movement restricting member and the bottom wall are connected in an area that overlaps with the through hole and / or the notch.

[0056] Next, an example of a manufacturing method for the battery according to the third embodiment will be described. First, two electrode assemblies 20 are prepared. The electrode assemblies 20 can be manufactured according to a conventionally known method for this type of wound electrode assembly. Next, terminals (positive electrode terminal 30 and negative electrode terminal 40), current collecting members (positive electrode current collecting portion 50 and negative electrode current collecting portion 60), external conductive members (positive electrode external conductive member 32 and negative electrode external conductive member 42), and insulating members (gasket 90, external insulating member 92, and internal insulating member 94) are assembled to the sealing plate 14. Then, the tab groups (positive electrode tab group 25 and negative electrode tab group 27) provided on the electrode assemblies 20 are connected to the current collecting members (positive electrode current collecting portion 50 and negative electrode current collecting portion 60).

[0057] Next, the electrode assembly 20 attached to the sealing plate 14 is inserted into the exterior body 12 together with the movement-restricting member 201. As in the present embodiment, the electrode assembly 20 may be enclosed in an electrode assembly holder 29. Next, the exterior body 12 is closed with the sealing plate 14, and the sealing plate 14 and the exterior body 12 are joined together. At this time, the third region 1c of the movement-restricting member 201 is connected to the bottom wall 12a from the outside of the battery 100 through the through-hole 201d of the movement-restricting member 201, for example, by laser welding. Note that, before the exterior body 12 is closed with the sealing plate 14 and the sealing plate 14 and the exterior body 12 are joined together, it is preferable that the positive electrode tab 22t and the negative electrode tab 24t extend to positions offset from the opening 12h of the exterior body 12, and that the sealing plate 14 be offset from the opening 12h of the exterior body 12. Thereafter, the electrolyte is poured through the liquid pouring hole 15 provided in the sealing plate 14, and then the liquid pouring hole 15 is sealed with the sealing member 16. In this manner, the battery 100 can be manufactured.

[0058] Alternatively, in the method for manufacturing the battery according to the third embodiment, the movement restricting member 201 can be connected to the battery case 10 in advance, and then the electrode body 20 attached to the sealing plate 14 can be inserted into the exterior body 12. In such a case, the movement restricting member 201 is preferably designed so that the first region 201a of the movement restricting member 201 bends in a direction along the end face of the electrode body 20 on the sealing plate 14 side when the electrode body 20 is inserted.

[0059] Furthermore, with respect to the third embodiment, a recess may be provided in place of the through-hole 201d in the movement restricting member 201. That is, a battery is disclosed in which the movement restricting member is connected to the bottom wall, a first wound electrode body and a second wound electrode body are housed in the battery case so that their winding axes extend perpendicular to the bottom wall, and a recess is formed between the curved outer surface of the first wound electrode body and the curved outer surface of the second wound electrode body and extends perpendicular to the bottom wall, and the movement restricting member is connected to the bottom wall in a region overlapping with the recess when viewed from the direction perpendicular to the bottom wall. This configuration is preferable because it makes it easier to connect the movement restricting member to the bottom wall 12a even after the electrode body 20 is housed in the battery case 10.

[0060] It should be noted that for the materials constituting the movement restricting members 101 and 201, the description of the movement restricting member 1 can be referred to as appropriate.

[0061] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A battery comprising an electrode assembly including a positive electrode and a negative electrode, and a battery case that houses the electrode assembly, wherein the battery case has an exterior body that includes a rectangular opening, a bottom wall that faces the rectangular opening, a pair of first side walls, and a pair of second side walls, and a rectangular sealing plate that has a gas release valve and seals the opening, and further comprises a movement restricting member that is connected to the inner surface of the battery case and has a movement restricting surface that restricts movement of the electrode assembly toward the sealing plate, and the movement restricting surface is arranged on the end face of the electrode assembly facing the sealing plate so as to face at least a part of an area near the end of the sealing plate in the longitudinal direction. Item 2: The battery according to item 1, wherein a positive electrode tab provided on the positive electrode and a negative electrode tab provided on the negative electrode are disposed on an end face of the electrode assembly on the sealing plate side, and the movement restricting surfaces are disposed on the outer sides of the positive electrode tab and the negative electrode tab, respectively, in the longitudinal direction of the sealing plate. Item 3: The battery according to item 1 or 2, wherein the movement restricting member is connected to the sealing plate. Item 4: The battery according to any one of items 1 to 3, wherein the movement restricting member is connected to at least one of the first side wall, the second side wall, and the bottom wall. [Explanation of symbols]

[0062] 1,101,201 Movement restriction member 10 Battery case 12 Exterior body 12a Bottom wall 12b Long side wall 12c short side wall 12h opening 14 Sealing plate 15 Liquid injection hole 16 Sealing member 17 Gas exhaust valve 18,19 Terminal extraction hole 20 Electrode body 20f flat area 20r curved section 22 Positive electrode 22a Cathode active material layer 22c Positive electrode current collector 22p positive electrode protective layer 22t Positive electrode tab 24 Negative electrode 24a Negative active material layer 24c Negative electrode current collector 24t negative electrode tab 25 Positive electrode tab group 27 Negative electrode tab group 29 Electrode holder 30 Positive terminal 30c bottom end 32 Positive electrode external conductive member 34 Heat-resistant layer 40 Negative terminal 40c bottom end 42 negative electrode external conductive member 50 Positive electrode current collector 60 Negative electrode current collector 70 Separator 90 Gasket 92 External insulating member 94 Internal insulating member 100 batteries LD Longitudinal direction U upward WL winding shaft Y Longitudinal direction Z vertical direction

Claims

1. an electrode assembly including a positive electrode and a negative electrode; a battery case that houses the electrode assembly; A battery comprising: The battery case is an exterior body including a rectangular opening, a bottom wall facing the rectangular opening, a pair of first side walls, and a pair of second side walls; a rectangular sealing plate having a gas exhaust valve and sealing the opening; It has a positive electrode tab provided on the positive electrode and a negative electrode tab provided on the negative electrode are disposed on an end surface of the electrode body on the sealing plate side, a pair of movement restricting members connected to an inner surface of the battery case, each having a movement restricting surface that restricts movement of the electrode body toward the sealing plate, the movement restricting surfaces of the pair of movement restricting members are arranged on the end surface of the electrode body facing the sealing plate so as to face at least a part of an area near one end and the other end of the sealing plate in the longitudinal direction, Each of the pair of movement restricting members includes a first region, a second region, and a third region, the first region is a region connected to the sealing plate and the first side wall or the second side wall, the second region is a region that bends from the first region and extends toward the electrode body, the third region is a region that is bent from the second region and extends along the end face of the electrode body on the sealing plate side, Here, the third region constitutes the movement restricting surface of each of the pair of movement restricting members.

2. A battery as described in claim 1, wherein the movement control surface is arranged in the area near one and the other longitudinal ends of the sealing plate, on the outside of the positive electrode tab and the outside of the negative electrode tab of the electrode body, respectively.

3. The battery according to claim 1 , wherein the first region of each of the pair of movement restricting members is welded to the sealing plate.

Images