Electricity storage device

Abstract

The invention provides a power storage device with improved shell strength. A power storage device (1) disclosed herein is provided with: a case (10); and an electrode body (40) housed in the case (10). A housing (10) is provided with: a housing main body (20) having an opening surrounded by side walls including a pair of first walls (22); and a sealing body (30) that seals the opening. The electrode body (40) has a laminated portion laminated toward the sealing body (30) in a state in which the positive electrode and the negative electrode are insulated from each other. The sealing body (30) is provided with: a base part (31); and a pair of first bent portions (33) extending from the base portion (31) along a pair of first walls (22) of the housing main body (20) and facing each other. The first bent portion (33) is joined to a first wall (22) of the housing main body (20) via a first welded joint portion (80).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electricity storage device. BACKGROUND

[0002] A container for an electricity storage device is disclosed in Japanese Patent Application Publication No. 2013-171729. The container for an electricity storage device includes a main member having an opening, and a cover member having an insertion portion inserted into the main member from the opening. A stacked electrode body housed in the container for an electricity storage device is pressed from both the insertion portion and the main member. Thus, the separation distance of each electrode sheet constituting the electrode body can be appropriately uniformized.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-171729 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, the electrode body sometimes expands due to charging and discharging, or the like. Due to the expansion of the electrode body, a force in which the electrode body pushes the inner surface of the case outward from the case can be applied. Thus, stress can be generated in the case, and the case can be damaged. In recent years, in particular, there is a tendency to use a material having a large expansion rate for the electrode body in order to increase the energy density. Thus, it is desirable to increase the strength of the case.

[0008] SOLUTION TO THE PROBLEM

[0009] One embodiment of the technology disclosed herein is an electricity storage device including a case and an electrode body housed in the case. The case includes a case main body having an opening surrounded by a pair of first walls, and a closure body that closes the opening. The electrode body has a stacked portion stacked toward the closure body in a state in which a positive electrode and a negative electrode are insulated. The closure body has a base portion, and a pair of first bent portions that respectively extend from the base portion along the pair of first walls of the case main body and face each other. The first bent portions are joined to the first walls of the case main body via a welded joint.

[0010] According to the electricity storage device described above, the strength of the case can be increased. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 FIG. 1 is an exploded view schematically showing the configuration of an electricity storage device according to one embodiment.

[0012] Figure 2is a schematic view showing an internal structure of a power storage device according to an embodiment.

[0013] Figure 3 is a schematic view showing an internal structure of a power storage device according to an embodiment. Figure 2

[0014] Figure 4 is a perspective view of the sealing body shown in Figure 1

[0015] Figure 5 is a schematic view showing a structure of an electrode body according to an embodiment.

[0016] Figure 6 is a schematic view of a power storage device according to a modification corresponding to Figure 3

[0017] Figure 7 is a schematic view of a power storage device according to a modification corresponding to Figure 2 DETAILED DESCRIPTION

[0018] Hereinafter, some embodiments of the technology disclosed herein will be described in detail with reference to the accompanying drawings. In this specification, matters other than matters specifically mentioned and matters required for implementation (for example, general configurations and manufacturing processes of power storage devices that are not features of the present disclosure) can be understood as matters of design by those skilled in the art based on the technology of the art. The present disclosure can be implemented based on the content disclosed in this specification and the technical common sense of the art.

[0019] In this specification, a "power storage device" refers to a concept including a device that generates charge-discharge reactions by moving charge carriers between a pair of electrodes (a positive electrode and a negative electrode). That is, the power storage device can include a battery such as a lithium-ion secondary battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lithium-ion capacitor, an electric double-layer capacitor, and a physical battery.

[0020] In this specification, "substantially rectangular" includes rectangles other than a perfect rectangle (oblong). For example, shapes in which the corners connecting the long sides and the short sides of the rectangle are R-shaped (round corners), shapes having notches at the corners, and the like are also included.

[0021] ​​​​Generally, known power storage devices include a case having a case main body and a sealing body, and an electrode body housed in the inside of the case. In many cases, a welding portion is provided at a boundary portion of the sealing body and the case main body. The electrode body sometimes expands due to charging and discharging and the like. In particular, the electrode body expands at the time of charging. Due to the expansion of the electrode body, a force in which the electrode body pushes the sealing body outward can be applied. At this time, a stress greater than that of the central portion of the sealing body is generated at the end portion of the sealing body. If a welding portion for engaging with the case main body is formed at the end portion of the sealing body, stress concentration can occur at the welding portion. Since the welding portion is low in strength, breakage and deformation of the case can easily occur. Thus, according to the present disclosure, a technology for improving the strength of the case can be provided. As one mode of the present technology, a power storage device having a case strength in which breakage or deformation of the case is difficult to occur even in a case where the electrode body expands can be provided.

[0022] <POWER STORAGE DEVICE>

[0023] Hereinafter, a power storage device 1 will be described as one embodiment. Figure 1 is an exploded view schematically showing the configuration of the power storage device according to one embodiment. Figure 2 is a view schematically showing the internal structure of the power storage device according to one embodiment. Figure 3 is a view schematically showing the internal structure of the power storage device according to one embodiment from a direction different from Figure 2 Figure 4 is a view schematically showing the internal structure of the power storage device according to one embodiment from a direction different from Figure 1 Figure 5 is a view schematically showing the internal structure of the power storage device according to one embodiment from a direction different from

[0024] As shown in Figures 1-3 , the power storage device 1 includes a case 10 and an electrode body 40. The electrode body 40 is housed in the case 10. The power storage device 1 is a lithium-ion secondary battery. The power storage device 1 includes a positive electrode 50, a negative electrode 60, and a nonaqueous electrolyte solution (not shown). Hereinafter, each component will be described.

[0025] (1) Case

[0026] As shown in Figures 1-3 ​​As shown, the housing 10 includes a housing body 20 and a sealing body 30. The housing body 20 includes an opening 28 surrounded by side walls. The side walls of the housing body 20 include a pair of first walls 22 and a pair of second walls 24. The housing body 20 has a bottom wall 26 on the side opposite to the opening 28.

[0027] like Figure 1 As shown, the opening 28 is formed by a pair of long sides and a pair of short sides. In top view, the opening 28 is approximately rectangular. A pair of first walls 22 constitute the pair of long sides. Additionally, a pair of second walls 24 constitute the pair of short sides. The opening 28 is large enough to allow the electrode body 40 to be inserted into the interior of the housing body 20. Furthermore, in some embodiments, the opening 28 may also be approximately square or approximately polygonal in top view.

[0028] like Figure 1 as well as Figure 3 As shown, a pair of first walls 22 face each other in the short-side direction X. Here, the first wall 22 has a larger area than the second wall 24. The first wall 22 is generally rectangular. The first wall 22 has a pair of long sides in the long-side direction Y and a pair of short sides in the height direction Z. In some embodiments, the first wall 22 can be a generally square or a generally polygonal shape. Alternatively, the first wall 22 can also be a generally rectangular shape with a long side in the height direction Z and a short side in the long-side direction Y.

[0029] like Figure 1 as well as Figure 2 As shown, a pair of second walls 24 face each other in the long side direction Y. The pair of second walls 24 are adjacent to a pair of first walls 22. Here, the second walls 24 have a smaller area than the first walls 22. The second walls 24 are generally rectangular. The second walls 24 have a pair of long sides in the short side direction X and a pair of short sides in the height direction Z. Alternatively, in some embodiments, the second walls 24 can be generally square or generally polygonal. Furthermore, the second walls 24 can also be generally rectangular, having a long side in the height direction Z and a short side in the long side direction Y.

[0030] like Figures 1-3 As shown, the bottom wall 26 is positioned on the side opposite to the opening 28 in the height direction Z. The bottom wall 26 is generally rectangular. A first wall 22 extends from the long side of the bottom wall 26. A second wall 24 extends from the short side of the bottom wall 26. Alternatively, in some embodiments, the bottom wall 26 may be generally square or generally polygonal.

[0031] In some embodiments, the second opening may be formed instead of the bottom wall 26. That is, the shell body 20 may also be formed as a cylinder including two openings. In this case, the second opening may be sealed by a second sealing body. The second sealing body may also have the same configuration as the sealing body 30.

[0032] The material of the housing body 20 can be, for example, metallic materials such as aluminum, aluminum alloy, iron, or iron alloy. From the viewpoint of ease of processing, the housing body 20 is preferably made of aluminum or aluminum alloy. The housing body 20 is manufactured, for example, by pressure processing of a metal sheet. Alternatively, the housing body 20 can also be composed of multiple components.

[0033] like Figure 2 as well as Figure 3 As shown, the sealing body 30 is installed on the opening 28 of the housing body 20 to seal the opening 28. Figures 1-4 As shown, the sealing body 30 has a base portion 31, a first bend portion 32, and a first fold portion 33. The sealing body 30 also has a second bend portion 34 and a second fold portion 35.

[0034] The base portion 31 is the main surface that covers the opening of the shell body 20. For example... Figures 1-4 As shown, the base portion 31 is a plate-like portion. The base portion 31 faces the bottom wall 26 of the shell body 20. When viewed from above, the base portion 31 has a shape corresponding to the opening 28. Here, the base portion 31 is generally rectangular, having a pair of long sides and a pair of short sides.

[0035] like Figure 1 , 3 As shown in Figure 4, the first bend 32 is located at the end of the base portion 31. The first bend 32 is located between the base portion 31 and the first bend 33. Here, the first bend 32 is a pair of long side portions of the base portion 31. The first bend 32 is located here inside the opening 28 of the housing body 20. The first bend 32 can be curved (R-shaped) or angled. From the viewpoint of improving the strength of the first bend 32, it is preferable that the first bend 32 does not contain weld marks (welded portions).

[0036] like Figure 3 As shown, a pair of first bends 33 are located at both ends of the base portion 31 in the short side direction X. The pair of first bends 33 extend from the base portion 31 along a pair of first walls 22 of the housing body 20. The pair of first bends 33 face each other. Here, the first bend 33 extends from the first bend 32 located at the end of the base portion 31 along the first wall 22. The first bend 33 is joined to the first wall 22 of the housing body 20 via a first welded joint 80. Here, the first bend 33 is in contact with the inner surface (the inner side surface of the housing 10) of the first wall 22 of the housing body 20. That is, the first bend 33 is joined to the inner surface of the first wall 22 of the housing body 20 via the first welded joint 80.

[0037] like Figure 3As shown, the first welded joint 80 is formed by welding the first bent portion 33 and the first wall 22. Here, the first welded joint 80 is formed such that no gap is created between the first bent portion 33 and the first wall 22 that would allow communication between the interior and exterior of the housing 10. The first welded joint 80 is formed, for example, by irradiating the overlapping portion of the first bent portion 33 and the first wall 22 with a laser from the outer surface of the first wall 22.

[0038] The length of the first bend 33 in the height direction Z of the energy storage device 1 is preferably less than half the length of the first wall 22 in the height direction Z, and more preferably less than one-third. This reduces the constraints on the arrangement of other components within the internal space of the housing 10. Furthermore, the length of the first bend 33 is preferably more than one-twentieth of the length of the first wall 22 in the height direction Z, and more preferably more than one-tenth. This increases the area of ​​the first welded joint 80 and improves the bonding strength between the sealing body 30 and the housing body 20.

[0039] like Figures 1-3 As shown, the second bend 34 is located at the end of the base portion 31. The second bend 34 is located between the base portion 31 and the second bend 35. Here, the second bend 34 is a pair of short side portions of the base portion 31. The second bend 34 is located here inside the opening 28 of the housing body 20. The second bend 34 can be curved (R-shaped) or angled. From the viewpoint of improving the strength of the second bend 34, it is preferable that the second bend 34 does not contain weld marks (welded portions).

[0040] like Figure 2 As shown, a pair of second bends 35 are located at both ends of the long side direction Y of the base portion 31. The pair of second bends 35 extend from the base portion 31 along a pair of second walls 24 of the housing body 20. The pair of second bends 35 face each other. Here, the second bend 35 extends from the second bend 34 located at the end of the base portion 31 along the second wall 24. The second bend 35 is joined to the second wall 24 of the housing body 20 via a second welded joint 82. Here, the second bend 35 is in contact with the inner surface (the inner side surface of the housing 10) of the second wall 24 of the housing body 20. That is, the second bend 35 is joined to the inner surface of the second wall 24 of the housing body 20 via the second welded joint 82. Here, the second bend 35 and the first bend 33 are formed continuously. Additionally, in some embodiments, a slit may be provided between the second bend 35 and the first bend 33.

[0041] like Figure 2As shown, the second welded joint 82 is formed by welding the second bend 35 and the second wall 24. Here, the second welded joint 82 is joined to the second wall 24 in such a way that no gap is created between the second bend 35 and the second wall 24 that would allow communication between the interior and exterior of the housing 10. The second welded joint 82 is formed, for example, by irradiating the overlapping portion of the second bend 35 and the second wall 24 with a laser from the outer surface of the second wall 24. Here, the sealing body 30 is fixed to the housing body 20 by the first welded joint 80 and the second welded joint 82, sealing the opening 28 of the housing body 20.

[0042] The length of the second bend 35 in the height direction Z of the energy storage device 1 is preferably less than half the length of the second wall 24 in the height direction Z, and more preferably less than one-third. This reduces the restriction on the arrangement of other components within the internal space of the housing 10. Furthermore, the length of the second bend 35 is preferably more than one-twentieth of the length of the second wall 24 in the height direction Z, and more preferably more than one-tenth. This increases the area of ​​the second welded joint 82 and improves the bonding strength between the sealing body 30 and the housing body 20.

[0043] like Figure 4 As shown, the sealing body 30 has a recess 36 surrounded by the base portion 31, the first bend portion 33, and the second bend portion 35. Because the sealing body 30 has a recess 36, the space occupied by the electrode body 40 inside the housing 10 is increased. This allows for a higher capacity energy storage device 1.

[0044] The sealing body 30 can be made of metals such as aluminum, aluminum alloy, iron, or iron alloy. From the viewpoint of ease of processing, the sealing body 30 is preferably made of aluminum or aluminum alloy. The sealing body 30 is manufactured, for example, by pressure processing of a metal sheet. Alternatively, the sealing body 30 can also be manufactured by bending a metal sheet. Therefore, in this specification, "bent portion" is not limited to a portion formed by bending, but can also be a portion formed by pressure processing or other processing.

[0045] However, in the energy storage device 1, when the electrode body 40 expands, a force is generated that pushes the sealing body 30 outwards towards the housing 10. Consequently, significant stress is generated at the first bend 32, which serves as the end of the base portion 31, within the sealing body 30. Therefore, in the energy storage device 1, the sealing body 30 is joined to the first wall 22 of the housing body 20 via the first welded joint 80. This prevents stress concentration at the first welded joint 80. As a result, the strength of the housing 10 is increased.

[0046] Furthermore, in the energy storage device 1, when the electrode body 40 expands, stress is also generated at the second bend 34 located on the short side of the base portion 31. Therefore, it is preferable that the sealing body 30 is also joined to the second wall 24 of the housing body 20 via the second weld joint 82 on the short side of the base portion 31. This prevents stress concentration at the second weld joint 82. As a result, the strength of the housing 10 can be improved.

[0047] Furthermore, when the electrode body 40 expands and generates a force that pushes the sealing body 30 outward, a larger stress is generated on the long side compared to the short side of the sealing body 30. Therefore, it is preferable that the first bending portion 33 is provided along the first wall 22 of the long side of the opening 28 that constitutes the housing body 20.

[0048] like Figure 3 As shown, the first bend 32 of the sealing body 30 can also be positioned on the upper side (the side away from the bottom wall 26 of the housing body 20) relative to the opening 28 of the housing body 20. Additionally, as... Figure 2 As shown, the second bend 34 of the sealing body 30 can also be positioned on the upper side (the side away from the bottom wall 26 of the housing body 20) relative to the opening 28 of the housing body 20. As a result, since the internal space of the housing 10 is increased, the capacity of the energy storage device 1 can be increased.

[0049] like Figure 1 As shown, the housing 10 has a safety valve 12. Here, the safety valve 12 is provided on the first wall 22. The safety valve 12 is a thin-walled portion designed to rupture and release internal pressure when the interior of the housing 10 reaches a predetermined pressure. Alternatively, in some embodiments, the safety valve 12 may also be provided on the second wall 24, the bottom wall 26, or the sealing body 30. Furthermore, two or more safety valves 12 may be provided. Alternatively, the safety valve 12 may not be provided.

[0050] like Figure 1 As shown, the housing 10 has an injection hole 14. The injection hole 14 is a through hole through which a non-aqueous electrolyte can be injected into the interior of the housing 10. The injection hole 14 connects the interior of the housing 10 to the outside. Here, the injection hole 14 is provided on the first wall 22. During the manufacture of the energy storage device 1, electrolyte is injected into the interior of the housing 10 through the injection hole 14. After the electrolyte is injected, the injection hole 14 is sealed by a sealing plug or the like. Thus, the housing 10 is sealed, preventing electrolyte leakage. In some embodiments, the injection hole 14 may also be provided on the second wall 24, the bottom wall 26, or the sealing body 30. Alternatively, the injection hole 14 may not be provided.

[0051] like Figure 1 as well as Figure 2As shown, the housing 10 has a positive terminal insertion hole 16 and a negative terminal insertion hole 18. The positive terminal insertion hole 16 and the negative terminal insertion hole 18 communicate with the interior and exterior of the housing 10. A positive terminal 57 is installed in the positive terminal insertion hole 16. A negative terminal 67 is installed in the negative terminal insertion hole 18. Here, the positive terminal insertion hole 16 is located on a second wall 24. The negative terminal insertion hole 18 is located on another second wall 24 facing the first second wall 24. Alternatively, in some embodiments, the positive terminal insertion hole 16 and the negative terminal insertion hole 18 may also be located on the first wall 22, the bottom wall 26, or the sealing body 30. The positive terminal insertion hole 16 and the negative terminal insertion hole 18 may also be located on the same surface (wall).

[0052] (2) Positive electrode

[0053] The positive electrode 50 includes a positive electrode plate 51, a positive electrode current collector 56, and a positive terminal 57. The positive electrode plate 51 is electrically connected to the positive electrode current collector 56. The positive electrode current collector 56 is electrically connected to the positive terminal 57.

[0054] like Figure 5 As shown, the positive electrode plate 51 includes: a positive current collector 52; and a positive active material layer 53 fixed to at least one surface of the positive current collector 52. The positive electrode plate 51 may be sheet-like. The material of the positive current collector 52 is a conductive metallic material. The positive current collector 52 is, for example, a metal foil. For example, aluminum, aluminum alloy, etc., can be used as the material of the positive current collector 52.

[0055] The positive electrode active material layer 53 includes a positive electrode active material. The positive electrode active material is a material capable of reversibly adsorbing and releasing charge carriers. Preferably, the positive electrode active material is an oxide containing at least one of Ni, Co, and Mn. Examples include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese composite oxide, and lithium nickel cobalt manganese composite oxide, etc., which are lithium transition metal composite oxides. More preferably, the positive electrode active material is a lithium composite oxide containing Ni (in other words, a Ni-containing lithium composite oxide). In the Ni-containing lithium composite oxide, the Ni content can be, for example, 60 mol% or more and 100 mol% or less relative to the total moles of metals other than Li. Furthermore, in the lithium transition metal composite oxide, a portion of Ni, Co, and Mn can be replaced by Al, Ti, Zr, P, B, Si, Nb, C, etc. Additionally, the particle surface of the lithium transition metal composite oxide of the positive electrode active material can be covered by a compound containing Al, Ti, Zr, W, P, B, Si, Nb, C, etc. The total amount of replacement and addition can be approximately 0.1 to 7% by mass. On the other hand, lithium transition metal phosphate compounds such as lithium iron phosphate can also be used as the positive electrode active material. The positive electrode active material layer 53 may also contain conductive materials, binders, etc. In addition, carbon materials such as carbon black or carbon nanotubes are preferred as the conductive material. In addition, resin binders such as polyvinylidene fluoride are preferred as the binder.

[0056] like Figure 2 As shown, a protruding positive electrode tab 54 is provided at the end of the positive current collector 52. The positive electrode tab 54 has a positive current collector exposure portion exposed on at least a portion of the surface of the positive current collector 52. A positive electrode connection portion 55 is formed by overlapping multiple positive electrode tabs 54. The positive electrode connection portion 55 is formed, for example, by joining the positive current collector exposure portions of multiple positive electrode tabs 54 together by means of, for example, ultrasonic bonding, laser welding, etc. Here, the positive electrode connection portion 55 is positioned facing the second wall 24, which has a positive terminal insertion hole 16. Alternatively, the positive electrode tab 54 may not protrude from the end of the positive current collector 52. For example, the positive current collector exposure portion may be provided in a strip shape at the end of the positive current collector 52 as the positive electrode tab 54.

[0057] like Figure 2 As shown, the positive current collector 56 is electrically connected to the positive connection portion 55. The positive current collector 56 can be made of a metallic material. For example, the positive current collector 56 can be made of a conductive metal component. For example, the positive current collector 56 can be made of one or more plate-shaped metal components. The positive current collector 56 is preferably made of the same material as the positive current collector 52. The positive current collector 56 can be, for example, aluminum, aluminum alloy, etc. The positive current collector 56 and the positive connection portion 55 are joined, for example, by ultrasonic bonding, laser welding, resistance welding, etc.

[0058] like Figure 2As shown, the positive terminal 57 is installed in the positive terminal insertion hole 16 and thus mounted on the housing 10. A portion of the positive terminal 57 is exposed on the outside of the housing 10. The positive terminal 57 is preferably made of metal, for example, more preferably aluminum or an aluminum alloy. The positive terminal 57 is electrically connected to the positive current collector 56 inside the housing 10. Thus, the positive terminal 57 is electrically connected to the positive electrode plate 51. The positive terminal 57 and the positive current collector 56 are joined, for example, by riveting, ultrasonic bonding, laser welding, resistance welding, etc. In addition, in some embodiments, the positive current collector 56 and the positive terminal 57 may be constructed as a single component.

[0059] like Figure 2 As shown, an insulating member 90 is disposed between the positive terminal 57 and the housing 10 (specifically the second wall 24). This prevents the positive terminal 57 from conducting with the housing 10. The insulating member 90 may be, for example, a polyolefin resin such as polypropylene (PP) or polyethylene (PE), a fluorinated resin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), or polyphenylene sulfide (PPS).

[0060] (3) Negative electrode

[0061] The negative electrode 60 includes a negative electrode plate 61, a negative electrode current collector 66, and a negative terminal 67. The negative electrode plate 61 is electrically connected to the negative electrode current collector 66. The negative electrode current collector 66 is electrically connected to the negative terminal 67.

[0062] like Figure 5 As shown, the negative electrode plate 61 includes: a negative current collector 62; and a negative active material layer 63 fixed to at least one surface of the negative current collector 62. The negative electrode plate 61 may be sheet-like. The material of the negative current collector 62 is a conductive metallic material. The negative current collector 62 is, for example, a metal foil. For example, copper or copper alloys can be used as the material of the negative current collector 62.

[0063] The negative electrode active material layer 63 contains a negative electrode active material. The negative electrode active material is a material capable of reversibly adsorbing and releasing charge carriers. Examples of negative electrode active materials include carbon-based negative electrode active materials such as graphite, hard carbon, and soft carbon; Si-containing negative electrode active materials such as Si and silicon oxide; silicon-carbon composite negative electrode active materials; and Sn-based negative electrode active materials such as Sn. The negative electrode active material layer 63 may also contain conductive materials, thickeners, and binders. As a binder, styrene-butadiene rubber or carboxymethyl cellulose is preferred.

[0064] In some embodiments, a Si-containing negative electrode active material is used as the negative electrode active material. The theoretical capacity density of the Si-containing negative electrode active material is higher than that of the carbon-based negative electrode active material. On the other hand, the volume change of the Si-containing negative electrode active material due to charging and discharging is greater than that of the carbon-based negative electrode active material. As a result, the expansion rate of the electrode body 40 increases, and the force pushing the shell 10 from the inside to the outside increases, potentially leading to deformation or breakage of the shell. In the technology of this disclosure, due to the high shell strength, even when using a material with a large volume change, such as the Si-containing negative electrode active material, the possibility of shell deformation or breakage can be reduced.

[0065] like Figure 2 As shown, a protruding negative electrode tab 64 is provided at the end of the negative electrode current collector 62. The negative electrode tab 64 has a negative electrode current collector exposure portion exposed on at least a portion of the surface of the negative electrode current collector 62. A negative electrode connection portion 65 is formed by overlapping multiple negative electrode tabs 64. The negative electrode connection portion 65 is formed by joining the negative electrode current collector exposure portions of multiple negative electrode tabs 64 together with each other, for example, by ultrasonic bonding, laser welding, etc. Here, the negative electrode connection portion 65 is positioned facing the second wall 24 where the negative terminal insertion hole 18 is provided. Alternatively, the negative electrode tab 64 may not protrude from the end of the negative electrode current collector 62. For example, the negative electrode current collector exposure portion may be provided in a strip shape at the end of the negative electrode current collector 62 as the negative electrode tab 64.

[0066] like Figure 2 As shown, the negative current collector 66 is electrically connected to the negative connection portion 65. The negative current collector 66 can be made of a metallic material. For example, the negative current collector 66 can be made of a conductive metal component. For example, the negative current collector 66 can be made of one or more plate-shaped metal components. The negative current collector 66 is preferably made of the same material as the negative current collector 62. The negative current collector 66 can be, for example, copper, copper alloy, etc. The negative current collector 66 and the negative connection portion 65 are joined, for example, by ultrasonic bonding, laser welding, resistance welding, etc.

[0067] like Figure 2 As shown, the negative terminal 67 is installed in the negative terminal insertion hole 18 and thus mounted on the housing 10. A portion of the negative terminal 67 is exposed on the outside of the housing 10. The negative terminal 67 is preferably made of metal, for example, more preferably copper or a copper alloy. The negative terminal 67 is electrically connected to the negative current collector 66 inside the housing 10. Thus, the negative terminal 67 is electrically connected to the negative electrode plate 61. The negative terminal 67 and the negative current collector 66 are joined, for example, by riveting, ultrasonic bonding, laser welding, resistance welding, etc. In addition, in some embodiments, the negative current collector 66 and the negative terminal 67 may be constructed as a single component.

[0068] like Figure 2As shown, an insulating member 90 is arranged between the negative terminal 67 and the case 10 (specifically, the second wall 24). Thereby, the negative terminal 67 and the case 10 are prevented from being in conduction.

[0069] (4) Electrode body

[0070] The electrode body 40 is a power generation element in the power storage device 1. The electrode body 40 is stacked in a state where the positive electrode 50 and the negative electrode 60 are insulated. Here, as shown, the electrode body 40 has the positive electrode plate 51, the negative electrode plate 61, and the separator 70. The positive electrode plate 51 and the negative electrode plate 61 have a stacked portion 42 that is alternately stacked with the separator 70 interposed therebetween. Inside the case 10, the electrode body 40 is arranged in a manner that the stacking direction of the stacked portion 42 faces the sealing body 30. The positive electrode plate 51 and the negative electrode plate 61 are formed in a substantially rectangular shape in plan view. Figure 5

[0071] When the electrode body 40 is charged and discharged, the volume change is particularly likely to occur in the stacking direction of the stacked portion 42. Thus, in the power storage device 1 in which the electrode body 40 is arranged in a manner that the stacking direction of the stacked portion 42 faces the sealing body 30, when the electrode body 40 expands, the force that pushes the sealing body 30 outward becomes stronger. In the present technology, since the strength of the case 10 is improved, even with the above-described configuration, the possibility of the case 10 being damaged or deformed can be reduced.

[0072] As shown, in the present embodiment, the separator 70 is in a multi-folded shape (also referred to as a meandering shape) in which it is alternately folded back at regular intervals. The surface of the electrode plate (positive electrode plate 51 and negative electrode plate 61) in the thickness direction (stacking direction) of the electrode plate is sandwiched by the folded-back separator 70. The separator 70 is wound on the outermost circumferential portion of the multi-folded structure, forming the outer circumferential surface of the electrode body 40. At the terminal portion of the separator 70, in order to prevent the winding from loosening, a winding termination tape 44 is attached. Figure 5

[0073] The separator 70 can be the same as in the past and is not particularly limited. The separator 70 can be a single-layer structure or a structure of two or more layers having different properties or characteristics (thickness or porosity, etc.), such as a three-layer structure. The separator 70 is, for example, made of resin, and is preferably composed of a polyolefin resin. As the polyolefin resin, polyethylene, polypropylene, or a mixture thereof is preferable.

[0074] Between the electrode body 40 and the case 10, an electrode body support (not shown) having insulating properties can be arranged in order to prevent the electrode body 40 and the case 10 from being in conduction. The material of the electrode body support can be, for example, a polyamide resin, a polyolefin resin (e.g., polypropylene, polyethylene), or the like.

[0075] ​​It is preferable that the base portion 31 of the sealing body 30 directly or indirectly contacts the electrode body 40 in the stacking direction of the stacked portion 42 of the electrode body 40. It is more preferable that the electrode body 40 directly or indirectly contacts the base portion 31 of the sealing body 30 when the electrode body 40 is in a discharged state (for example, SOC is 20% or less). According to this configuration, the sealing body 30 can apply a restraining pressure to the electrode body 40 from the stacking direction. Thus, when the power storage device 1 is used as a battery that constitutes a battery module, the restraining pressure by an external member can be weakened or omitted. Thus, in one example of a manufacturing method of the power storage device 1, the base portion 31 of the sealing body 30 is welded and joined to the case main body 20 while pressing the electrode body 40 housed in the case main body 20 from the stacking direction by the base portion 31 of the sealing body 30. In addition, "the base portion 31 of the sealing body 30 indirectly contacts the electrode body 40" means that the base portion 31 of the sealing body 30 contacts the electrode body 40 with another member interposed therebetween, and means a state in which the base portion 31 can press the electrode body 40 with the other member interposed therebetween.

[0076] The thickness of the stacked portion 42 of the electrode body 40 in the stacking direction can be greater than the height of the case main body 20 in the height direction Z. The base portion 31 of the sealing body 30 easily presses the electrode body 40 from the stacking direction. Thus, when the power storage device 1 is used as a battery that constitutes a battery module, the restraining pressure by an external member can be weakened or omitted.

[0077] (5) Electrolyte

[0078] The electrolyte is not particularly limited and can be the same as in the past. The electrolyte is, for example, a nonaqueous electrolyte including a nonaqueous solvent (organic solvent) and a supporting salt (electrolyte salt such as a lithium salt or a sodium salt). As one example of the nonaqueous solvent, carbonates such as ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate can be given. As one example of the supporting salt, a fluorine-containing lithium salt such as lithium hexafluorophosphate (LiPF6) can be given.

[0079] The power storage device 1 can be used for various uses. As appropriate uses, vehicle-mounted uses, specifically, a driving power source mounted on a vehicle such as an electric vehicle (BEV), a hybrid vehicle (HEV), and a plug-in hybrid vehicle (PHEV) can be given. In addition, the power storage device 1 can be used as a battery for a small-sized power storage device or the like. The power storage device 1 can typically be used in the form of a battery module in which a plurality of batteries are connected in series and / or in parallel.

[0080] The above describes some embodiments, but the above-described embodiments are merely examples. The present technology can also be implemented in various other ways. In the technology recited in the claims, configurations in which the above-described example embodiments are variously modified and changed are included. For example, part of the above-described embodiments can be replaced with other modifications, and other modifications can be added to the above-described embodiments. In addition, if the technical feature is not described as an essential configuration, it can be appropriately deleted.

[0081] In the above-described embodiments, the first bent portion 33 of the sealing body 30 is joined to the inner surface of the first wall 22 of the case main body 20. However, this is not limiting. Figure 6 Figure 3 A schematic view of the power storage device 100 of a modification corresponding to Figure 7 Figure 2 A schematic view of the power storage device 100 of a modification corresponding to Figure 6 As shown in FIG. 9, in the power storage device 100, the first bent portion 33 of the sealing body 30 is disposed outside the case main body 20. The first bent portion 33 is joined to the outer surface of the first wall 22 of the case main body 20 via the first welded joint 80. According to this configuration, stress concentration at the first welded joint 80 is suppressed, and thus the strength of the case 10 is improved. In addition, as shown in FIG. 10, in the power storage device 100, the second bent portion 35 of the sealing body 30 is disposed outside the case main body 20. The second bent portion 35 is joined to the outer surface of the second wall 24 of the case main body 20 via the second welded joint 82. According to this configuration, stress concentration at the second welded joint 82 is suppressed, and thus the strength of the case 10 is improved. Figure 7

[0082] In addition, in the above-described embodiments, the electrode body 40 is a laminated electrode body using a strip-shaped separator 70 having a multi-fold structure, but this is not limiting. For example, the electrode body can be a laminated electrode body in which a plurality of substantially rectangular separator sheets are prepared and stacked with one or more separator sheets interposed between the positive electrode plate 51 and the negative electrode plate 61. In addition, it can be a flat-shaped wound electrode body in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are overlapped with a strip-shaped separator sheet interposed therebetween and wound. In the case of a flat-shaped wound electrode body, the stacking portion 42 is formed in the thickness direction in which flat surfaces of the wound electrode body face each other, for example.

[0083] In addition, in the above-described embodiments, one electrode body 40 is housed in the case 10, but in some embodiments, the electrode body 40 can be a plurality of electrode bodies.

[0084] As described above, as specific modes of the technology disclosed herein, the following can be cited.

[0085] ​​​Item 1: A power storage device, wherein

[0086] The above-described power storage device includes:

[0087] a housing; and

[0088] an electrode body housed in the above-described housing,

[0089] The above-described housing includes:

[0090] a housing main body having an opening surrounded by side walls including a pair of first walls; and

[0091] a sealing body sealing the above-described opening,

[0092] The above-described electrode body has a layering portion layered toward the above-described sealing body in a state in which a positive electrode and a negative electrode are insulated from each other,

[0093] The above-described sealing body has:

[0094] a base portion; and

[0095] a pair of first bent portions respectively extending from the above-described base portion along the pair of first walls of the above-described housing main body and facing each other,

[0096] The above-described first bent portions are joined to the pair of first walls of the above-described housing main body via welding joints.

[0097] Item 2: The power storage device according to Item 1, wherein

[0098] The above-described opening is surrounded by a pair of long sides and a pair of short sides,

[0099] The above-described pair of first walls constitute the pair of long sides.

[0100] Item 3: The power storage device according to Item 2, wherein

[0101] The above-described side walls further include a pair of second walls,

[0102] The above-described second walls constitute the pair of short sides,

[0103] The above-described sealing body has a pair of second bent portions respectively extending from the above-described base portion along the pair of second walls of the above-described housing main body and facing each other.

[0104] Item 4: The power storage device according to Item 3, wherein

[0105] The above-described second bent portions are joined to the pair of second walls of the above-described housing main body via second welding joints.

[0106] Item 5: The power storage device according to any one of Items 1 to 4, wherein

[0107] The first bent portion is joined to the inner surface of the first wall of the housing main body via the first welding joint.

[0108] Item 6: The power storage device according to any one of items 1 to 5, wherein

[0109] The first bent portion is joined to the outer surface of the first wall of the housing main body via the first welding joint.

[0110] Item 7: The power storage device according to any one of items 1 to 6, wherein

[0111] The base portion of the sealing body directly or indirectly contacts the electrode body in the stacking direction of the stacked portion of the electrode body.

[0112] Explanation of Reference Numerals

[0113] 1 Power storage device

[0114] 10 Housing

[0115] 12 Safety valve

[0116] 14 Liquid injection hole

[0117] 16 Positive electrode terminal insertion hole

[0118] 18 Negative electrode terminal insertion hole

[0119] 20 Housing main body

[0120] 22 First wall

[0121] 24 Second wall

[0122] 26 Bottom wall

[0123] 28 Opening

[0124] 30 Sealing body

[0125] 31 Base portion

[0126] 32 First elbow portion

[0127] 33 First bent portion

[0128] 34 Second elbow portion

[0129] 35 Second bent portion

[0130] 36 Concave portion

[0131] 40 Electrode body

[0132] 42 Stacked portion

[0133] 44 winding termination tape

[0134] 50 positive electrode

[0135] 51 positive electrode plate

[0136] 52 positive electrode current collector

[0137] 53 positive electrode active material layer

[0138] 54 positive electrode tab

[0139] 55 positive electrode connecting portion

[0140] 56 positive electrode current collecting portion

[0141] 57 positive electrode terminal

[0142] 60 negative electrode

[0143] 61 negative electrode plate

[0144] 62 negative electrode current collector

[0145] 63 negative electrode active material layer

[0146] 64 negative electrode tab

[0147] 65 negative electrode connecting portion

[0148] 66 negative electrode current collecting portion

[0149] 67 negative electrode terminal

[0150] 70 separator

[0151] 80 first welding joint

[0152] 82 second welding joint

[0153] 90 insulating member

Claims

1. An energy storage device, wherein, The above-mentioned energy storage device has the following features: case; as well as An electrode body, which is housed within the aforementioned housing. The aforementioned housing includes: The housing body has an opening surrounded by side walls including a pair of first walls; as well as A sealing element that seals the aforementioned opening. The electrode body has a laminated portion, which is laminated onto the sealing body in a state of insulation between the positive and negative electrodes. The above-mentioned sealing body has the following characteristics: The base; and A pair of first bends, which extend from the base portion along the pair of first walls of the shell body and face each other. The first bent portion is joined to the first wall of the housing body via the first welded joint.

2. The energy storage device as described in claim 1, wherein, The opening described above is surrounded by a pair of long sides and a pair of short sides. The aforementioned pair of first walls constitute the aforementioned pair of long sides.

3. The energy storage device as described in claim 2, wherein, The aforementioned sidewalls also have a pair of second walls. The aforementioned second wall constitutes the aforementioned pair of short sides. The sealing body has a pair of second bends that extend from the base portion along the pair of second walls of the shell body and face each other.

4. The energy storage device as described in claim 3, wherein, The second bend is joined to the second wall of the housing body via the second welded joint.

5. The energy storage device as described in claim 1, wherein, The first bent portion is joined to the inner surface of the first wall of the housing body via the first welded joint.

6. The energy storage device as described in claim 1, wherein, The first bent portion is joined to the outer surface of the first wall of the housing body via the first welded joint.

7. The energy storage device according to any one of claims 1 to 6, wherein, In the lamination direction of the lamination portion of the electrode body, the base portion of the sealing body is in direct or indirect contact with the electrode body.

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