Power storage device and power storage module

Abstract

A power storage device (10) is provided with: an electrode body (14) including a positive electrode (11) and a negative electrode (12); an outer can (20) that accommodates the electrode body (14) and is electrically connected to the negative electrode (12); a positive electrode cap (31) that closes an opening formed on one side in the axial direction of the outer can (20) and is electrically connected to the positive electrode (11); and a negative electrode cap (21) provided on one side of the outer can (20) in the axial direction and electrically connected to the outer can (20), the negative electrode cap (21) having a safety device provided with a protrusion (21C).

Description

Technical Field

[0001] The present invention relates to a power storage device and a power storage module. Background Art

[0002] With the popularization of electric vehicles, large-scale power storage systems, etc., power storage modules with a large battery capacity and a small resistance have become popular. A power storage module is formed by connecting a plurality of power storage devices in parallel and in series.

[0003] In a power storage module, when one power storage device becomes electrically short-circuited due to an internal short circuit or the like, there is a concern that current flows from other adjacent power storage devices connected in parallel to the short-circuited power storage device, increasing the heat generation of the short-circuited power storage device. Therefore, some safety measures are required.

[0004] For example, Patent Document 1 discloses the following technique: A spring is disposed at a terminal portion of a battery sealing body, and the tip portion of the spring is fixed to the sealing body with an adhesive in a state where the tip portion of the spring is deformed. When the battery is abnormal, heat melts the adhesive material at the tip portion of the spring, releasing the spring pressure, and the tip portion of the spring comes into contact with a can potential member disposed at a battery caulking portion, thereby short-circuiting the sealing body and the can and suppressing current from flowing into the electrode group (winding body).

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 3232767 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] The above-mentioned electric vehicles, large-scale power storage systems, etc. are systems for long-term use for 10 to 20 years or more. On the other hand, in the technique disclosed in Patent Document 1, the fixing force of an adhesive for deforming the spring inside the battery for a long time is required. However, there are concerns in terms of selecting an adhesive material that can withstand the chemical reactions inside the battery for a long time and the occurrence of creep of the spring, and there is room for improvement from the viewpoint of improving safety.

[0010] Therefore, an object of the present invention is to provide a power storage device and a power storage module that can improve safety.

[0011] The present invention provides an electricity storage device, characterized in that the electricity storage device includes: an electrode body including a first electrode and a second electrode; an outer can that houses the electrode body and is electrically connected to the second electrode; a first electrode that seals an opening formed on one side in the axial direction of the outer can and is electrically connected to the first electrode; and a second electrode that is provided on one side in the axial direction of the outer can and is electrically connected to the outer can, and the second electrode has a safety device constituted by a convex portion.

[0012] According to the electricity storage device and the electricity storage module of the present invention, safety can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a circuit diagram showing an electricity storage module of an embodiment.

[0014] Figure 2 It is a schematic cross-sectional view showing an electricity storage device of the first embodiment.

[0015] Figure 3 It is a schematic cross-sectional view showing an external insulation mechanism of the first embodiment.

[0016] Figure 4 It is a schematic cross-sectional view showing a state after the external insulation mechanism operates.

[0017] Figure 5 It is a schematic cross-sectional view showing an external insulation mechanism as another example of the first embodiment.

[0018] Figure 6 It is a schematic cross-sectional view showing a state after the external insulation mechanism operates.

[0019] Figure 7 It is a schematic cross-sectional view showing an external insulation mechanism of an electricity storage device of the second embodiment.

[0020] Figure 8 It is a schematic cross-sectional view showing an electricity storage device of the third embodiment.

[0021] Figure 9 It is a schematic cross-sectional view showing an external short-circuit mechanism of the third embodiment.

[0022] Figure 10 It is a schematic cross-sectional view showing a state after the external short-circuit mechanism operates.

[0023] Figure 11 It is a schematic cross-sectional view showing an electricity storage device of the fourth embodiment.

[0024] Figure 12 It is a schematic cross-sectional view showing an external short-circuit mechanism of the fourth embodiment.

[0025] Figure 13It is a schematic cross-sectional view showing the state after the operation of the external short-circuit mechanism.

[0026] Figure 14 It is a schematic cross-sectional view showing the external short-circuit mechanism of the power storage device according to the fifth embodiment. Detailed Embodiment

[0027] Hereinafter, an example of an embodiment of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for easy understanding of the present invention and can be appropriately changed according to uses, purposes, specifications, etc.

[0028] [Power Storage Module]

[0029] Use Figure 1 To describe the power storage module 5 of the embodiment.

[0030] The power storage module 5 is used, for example, as a power source for an electric vehicle. However, the power storage module of the present invention is not limited to being used as a power source for an electric vehicle. For example, it can also be used as a power source for motor-driven electric devices such as power tools, electric assist bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric scooters. In addition, the power storage module of the present invention can also be used, for example, as a power source for various electrical devices used indoors and outdoors, such as cleaners, wireless devices, lighting devices, digital cameras, and video cameras.

[0031] The power storage module 5 is formed by connecting a plurality of power storage devices 10 in parallel and in series. In the power storage module 5 of the present embodiment, four power storage devices 10 are connected in parallel to form one block, and three blocks are connected in series respectively. However, the power storage module of the present invention is not limited to the combination of the power storage devices 10 of the present embodiment. In addition, the details of the power storage device 10 will be described later.

[0032] The power storage module 5 includes: a positive electrode current collector plate 41, which is connected to the positive electrode cover 31 serving as an external positive electrode terminal of each of the power storage devices 10 to be described later; a negative electrode current collector plate 42, which is connected to the negative electrode cover 21 serving as an external negative electrode terminal of each of the power storage devices 10 to be described later; and a base member 43, which is provided above the positive electrode current collector plate 41 (see Figures 2 to 6 ).

[0033] [First Embodiment]

[0034] Use Figure 2 And Figure 3 To describe the power storage device 10 of the first embodiment.

[0035] The electrical storage device 10 includes: a wound electrode body 14 formed by winding a positive electrode 11 as a first electrode and a negative electrode 12 as a second electrode with a separator 13 interposed therebetween; an outer can 20 that houses the electrode body 14; and a sealing body 30 that seals an opening of the outer can 20. An electrolytic solution is housed in the outer can 20 together with the electrode body 14. The electrolytic solution of the present embodiment is a non-aqueous electrolytic solution, but may also be an aqueous electrolytic solution. Hereinafter, for the sake of convenience of explanation, the side of the electrical storage device 10 where the sealing body 30 is provided is defined as the upper side, and the side of the outer can 20 where the bottom portion 20B is formed is defined as the lower side.

[0036] The positive electrode 11, the negative electrode 12, and the separator 13 are all strip-shaped long bodies, and they are wound in a spiral shape and laminated alternately in the radial direction of the electrode body 14. In order to prevent the precipitation of lithium, the binder layer of the negative electrode 12 may be formed to be one size larger than the binder layer of the positive electrode 11 in terms of size. That is, the binder layer of the negative electrode 12 may be formed longer than the binder layer of the positive electrode 11 in the longitudinal direction and the width direction (short side direction). The separator 13 is formed to be at least one size larger than the positive electrode 11. For example, two separators 13 are arranged so as to sandwich the positive electrode 11.

[0037] The positive electrode 11 has a positive electrode core and a positive electrode binder layer formed on at least one surface of the core. For the positive electrode core, a foil of a metal such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode 11, a thin film having the metal disposed on the surface layer, etc. can be used. The positive electrode binder layer contains, for example, a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and the positive electrode binder layer is preferably formed on both surfaces of the positive electrode core. As the positive electrode active material, for example, a lithium transition metal composite oxide is used.

[0038] The negative electrode 12 has a negative electrode core and a negative electrode binder layer formed on at least one surface of the core. For the negative electrode core, a foil of a metal such as copper or copper alloy that is stable within the potential range of the negative electrode 12, a thin film having the metal disposed on the surface layer, etc. can be used. The negative electrode binder layer contains, for example, a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and the negative electrode binder layer is preferably formed on both surfaces of the negative electrode core. As the negative electrode active material, for example, graphite, a silicon-containing compound, etc. can be used. The negative electrode lead is preferably directly joined to the negative electrode core by welding or the like.

[0039] The non-aqueous electrolyte accommodated in the outer can 20 includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of them can be used. The non-aqueous solvent may contain a halogen-substituted product obtained by substituting at least a part of the hydrogen of these solvents with a halogen atom such as fluorine. As an example of the non-aqueous solvent, ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and their mixed solvents can be cited. For the electrolyte salt, for example, a lithium salt such as LiPF6 can be used. In addition, the non-aqueous electrolyte may not be an electrolytic solution but a gel electrolyte, a solid electrolyte, etc.

[0040] Above the electrode body 14, there are provided: a positive electrode lead 15 that extends upward from the upper end in the axial direction of the electrode body 14 and directly connects the positive electrode 11 constituting the electrode body 14 to the current collector plate 32 of the sealing body 30; and an upper insulating plate 16 that is disposed between the electrode body 14 and the sealing body 30. Since the positive electrode lead 15 electrically connects the positive electrode 11 and the sealing body 30, the positive electrode cap 31 of the sealing body 30 functions as a positive electrode external terminal, which is the first external terminal. The upper insulating plate 16 prevents the positive electrode 11 and the positive electrode lead 15 from contacting the outer can 20, and also prevents the positive electrode lead 15 from contacting the negative electrode 12 of the electrode body 14.

[0041] Below the electrode body 14, there are provided: a negative electrode lead that extends downward from the lower end in the axial direction of the electrode body 14 and directly connects the negative electrode 12 constituting the electrode body 14 to the bottom 20B of the outer can 20; and a lower insulating plate 17 that is disposed between the electrode body 14 and the bottom 20B of the outer can 20. The negative electrode lead electrically connects the negative electrode 12 and the outer can 20, and the outer can 20 is electrically connected to the negative electrode cap 21 described later. Therefore, the negative electrode cap 21 functions as a negative electrode external terminal, which is the second external terminal.

[0042] The outer can 20 is a bottomed cylindrical metal container that is open at one axial end (upper end). In addition, the outer can 20 is usually made of a metal mainly composed of iron, but in the case of being connected to the positive electrode 11, it can also be made of a metal mainly composed of aluminum or the like. The outer can 20 has a cylindrical portion 20A formed in a cylindrical shape, a bottom portion 20B that is circular when viewed from above, a shoulder portion 20C formed in a ring shape along the circumferential direction of the opening end of the cylindrical portion 20A, and a groove portion 20D formed along the circumferential direction of the cylindrical portion 20A. In addition, a negative electrode cap 21 serving as the second terminal is provided on the outer can 20.

[0043] The groove portion 20D is formed at a position near the opening of the outer can 20 and separated from the shoulder portion 20C by a predetermined length. The groove portion 20D is a part where a part of the cylindrical portion 20A extends inwardly of the outer can 20. For example, the groove portion 20D is formed by performing spinning on the cylindrical portion 20A from the outside. Further, at the formation position of the groove portion 20D, the outer can 20 is reduced in diameter, and a thin-line-shaped groove is formed on the outer peripheral surface of the cylindrical portion 20A. Preferably, the groove portion 20D has a substantially U-shaped cross section and is formed in a ring shape over the entire circumferential length of the cylindrical portion 20A.

[0044] The negative electrode cap 21 as the second terminal is connected to the negative electrode 12 via the outer can 20 and functions as an external negative electrode terminal. The negative electrode cap 21 is formed in a ring shape when viewed from above (when observed from the axial direction) and has a cross-sectional L shape when observed from the circumferential direction. Further, the negative electrode cap 21 may be partially missing like a C shape when viewed from above. The negative electrode cap 21 includes: an end wall 21A that faces the outer can 20 in the height direction (axial direction) and abuts against the upper end surface of the shoulder portion 20C of the outer can 20; a side wall 21B that faces the outer can 20 in the radial direction and abuts against the upper end portion of the cylindrical portion 20A of the outer can 20; and a convex portion 21C that is formed to protrude upward at the radially inner peripheral side end portion of the side wall 21B. Further, it is not necessary for both the end wall 21A and the side wall 21B to abut against the outer can 20. The negative electrode cap 21 is welded to the cylindrical portion 20A of the outer can 20 at a predetermined position of the side wall 21B of the negative electrode cap 21 and is electrically connected to the outer can 20. The end wall 21A is joined to the negative electrode current collector plate 42 by welding, and thus the negative electrode cap 21 is electrically connected to the negative electrode current collector plate 42, which will be described in detail later.

[0045] The convex portion 21C of the negative electrode cap 21 constitutes an external insulation mechanism 50, which will be described in detail later. The convex portion 21C is formed by bending the inner peripheral side end portion of the end wall 21A of the negative electrode cap 21 upward. The convex portion 21C is formed in a ring shape when viewed from above (when observed from the axial direction). The convex portion 21C is formed by flanging the inner peripheral side end portion of the end wall 21A. Flanging is a type of forming process method in which a hole is formed in a plate material and the edge of the hole is stretched into a cylindrical shape. Further, an insulating member 22 is provided on the convex portion 21C of the negative electrode cap 21.

[0046] In addition, the convex portion 21C does not necessarily have to be located at the inner peripheral side end of the end wall 21A of the negative electrode cap 21, as long as it is at least located at a position on the end wall 21A of the negative electrode cap 21 that is radially closer to the inside than the outer end of the outer can 20. Therefore, it can also be located at a position on the end wall 21A of the negative electrode cap 21 that is closer to the outside than the inner peripheral side end. At this time, the portion of the end wall 21A where the convex portion 21C is formed can be made into a thick wall, or the plate-shaped end wall 21A can be bent to form a mountain shape with a V-shaped, C-shaped, or U-shaped cross-section that protrudes from the lower surface (the surface on the side of the outer can) of the end wall 21A toward the upper surface (the surface on the side of the outside of the power storage device). With this structure, the rigidity of the entire negative electrode cap 21 is improved compared to the convex portion 21C located at the inner peripheral side end.

[0047] Moreover, especially when the negative electrode cap 21 is a metal plate with a plated surface, sometimes the inner peripheral side end in the radial direction and the like are not covered by the plating, and the non-plated inner peripheral side end is prone to rusting. Therefore, by disposing the convex portion 21C at a position closer to the outside than the inner peripheral side end, the non-rusting area of the plated end wall 21A can be used as the convex portion 21C. Thereby, the insulating member 22 can be prevented from being damaged by rust.

[0048] In addition, the convex portion 21C does not necessarily have to be annular, and the convex portion 21C can also be intermittently provided in the circumferential direction of the end wall 21A. Moreover, in the circumferential direction of the end wall 21A, the convex portion 21C can be only at one place. In addition, the above-mentioned mountain-shaped convex portion 21C can also be provided at the inner peripheral side end of the end wall 21A. In addition, the upper end of the convex portion 21C including the insulating member 22 can be located at a position higher than the upper end of the positive electrode cap 31.

[0049] The insulating member 22 is a rubber or resin member for preventing contact between the convex portion 21C of the negative electrode cap 21 and the positive electrode current collector plate 41 to ensure electrical insulation between the negative electrode cap 21 and the positive electrode current collector plate 41. The insulating member 22 is preferably a member having heat resistance that does not melt even when the power storage device 10 generates heat.

[0050] The entire sealing body 30 is formed in a disc shape and has a positive electrode cap 31, a current collector plate 32, a gasket 33, and an insulating member 34. The sealing body 30 is disposed on the groove portion 20D of the outer can 20 and fixed to the upper end portion of the outer can 20. More specifically, the shoulder portion 20C of the outer can 20 is bent inward in the radial direction and caulked to the sealing body 30, and the sealing body 30 is fixed to the upper end portion of the outer can 20 by the shoulder portion 20C and the groove portion 20D of the outer can 20, and the sealing body 30 seals the opening of the outer can 20.

[0051] The positive electrode cover 31 is connected to the positive electrode 11 via the positive electrode lead 15 and the current collector plate 32, and functions as an external terminal of the positive electrode. The positive electrode cover 31 is a disk-shaped metal member, having a raised portion 31A formed by protruding the central portion in the radial direction outward from the power storage device 10 and a flange portion 31B formed around the raised portion 31A. The positive electrode cover 31 is disposed on the upper surface side of the sealing body 30 and is exposed to the outside of the outer can 20 to form the top surface of the power storage device 10. The raised portion 31A is joined to the positive electrode current collector plate 41 by welding, thereby being electrically connected to the positive electrode current collector plate 41, which will be described in detail later.

[0052] The current collector plate 32 is connected to the positive electrode 11 via the positive electrode lead 15 and functions as a positive electrode current collector. The current collector plate 32 is a metal member having a diameter similar to that of the positive electrode cover 31. The current collector plate 32 is formed in an annular shape having an opening at the central portion in the radial direction. The current collector plate 32 is disposed at a position closer to the electrode body 14 than the positive electrode cover 31. The current collector plate 32 is welded to the positive electrode cover 31, for example, at a position on the positive electrode cover 31 where the distance from the radial center of the positive electrode cover 31 is greater than the distance from the outer peripheral edge of the positive electrode cover 31.

[0053] The gasket 33 is a rubber member or a resin member for preventing contact between the positive electrode cover 31 and the current collector plate 32 and the outer can 20 to ensure electrical insulation between the outer can 20 and the sealing body 30. In addition, the gasket 33 seals the gap between the outer can 20 and the sealing body 30 to make the inside of the power storage device 10 airtight. The gasket 33 is provided between the outer peripheral portion of the laminate of the positive electrode cover 31 and the current collector plate 32 and the outer can 20. The gasket 33 covers the upper surface of the flange portion 31B of the positive electrode cover 31, the side surfaces of the positive electrode cover 31 and the current collector plate 32, and the lower surface of the current collector plate 32 at the outer peripheral portion of the above laminate.

[0054] The insulating member 34 is a rubber member or a resin member for preventing contact between the positive electrode cover 31 and the negative electrode cover 21 to ensure electrical insulation between the positive electrode cover 31 and the negative electrode cover 21. The insulating member 34 is formed in an annular shape having an opening at the central portion in the radial direction. The insulating member 34 is disposed between the upper surface of the flange portion 31B of the positive electrode cover 31 and the lower surface of the end wall 21A of the negative electrode cover 21. In addition, when viewed from the axial direction, the insulating member 34 is disposed between the raised portion 31A of the positive electrode cover 31 and the shoulder 20C of the outer can 20.

[0055] As described above, the positive electrode current collector plate 41 is joined to the raised portion 31A of the positive electrode cover 31 by welding. Thus, the positive electrode current collector plate 41 is electrically connected to the positive electrode cover 31. The positive electrode current collector plate 41 is a rectangular conductive metal member and is disposed above the positive electrode cover 31.

[0056] In addition, a negative current collector plate 42 is joined to the end wall 21A of the negative electrode cap 21 by welding. Thus, the negative current collector plate 42 is electrically connected to the negative electrode cap 21. The negative current collector plate 42 is a rectangular conductive metal member and is disposed above the negative electrode cap 21.

[0057] [External insulation mechanism (external current cut-off mechanism)]

[0058] Use Figure 3 and Figure 4 to describe the external insulation mechanism 50 (current cut-off mechanism) of the first embodiment.

[0059] The external insulation mechanism 50 is a mechanism that insulates the positive current collector plate 41 from the power storage device 10 outside the outer can 20 when the internal pressure of the power storage device 10 rises during an abnormality of the power storage device 10. According to the external insulation mechanism 50, the safety of the power storage module 5 can be improved, which will be described in detail later.

[0060] As Figure 3 shown, the external insulation mechanism 50 is composed of a convex portion 21C of the negative electrode cap 21, an insulating member 22, and the positive current collector plate 41. That is, the external insulation mechanism 50 is formed outside the outer can 20. Therefore, when the positive current collector plate 41 is insulated from the power storage device 10 by the external insulation mechanism 50, the influence of this insulation on the inside of the power storage device 10 can be reduced.

[0061] As Figure 4 shown, when the internal pressure of the power storage device 10 rises during an abnormality of the power storage device 10, the outer can 20 expands and the negative electrode cap 21 deforms upward. At this time, the positive current collector plate 41 is lifted upward by the insulating member 22, and the welded portion between the positive electrode cap 31 and the positive current collector plate 41 breaks, so that the positive electrode cap 31 is electrically insulated from the positive current collector plate 41, and the power storage device 10 is insulated from the power storage module 5.

[0062] According to the external insulation mechanism 50, the safety of the power storage module 5 can be improved. More specifically, according to the external insulation mechanism 50, the power storage device 10 is insulated outside the outer can 20, so that the power storage device 10 can be insulated while reducing the influence on the inside of the power storage device 10. Thus, the abnormal power storage device 10 can be electrically disconnected from the power storage module 5, and current flowing into the abnormal power storage device 10 can be avoided, which may cause an increase in heat generation. In addition, although the output of the power storage module 5 decreases, the system connected to the power storage module 5 can be measured and operated.

[0063] In addition, according to the external insulation mechanism 50, there is no need to use a complicated mechanism such as an adhesive or a spring inside the power storage device 10, and the insulation mechanism can be realized only by forming the convex portion 21C of the negative electrode cap 21.

[0064] Further, according to the external insulation mechanism 50, an insulation mechanism can be achieved without additionally providing components on the conduction path from the positive electrode 11 to the positive electrode cover 31 or from the negative electrode 12 to the negative electrode cover 21. Thus, an insulation path can be achieved while maintaining the power storage device 10 at a low resistance.

[0065] Use Figure 5 and Figure 6 The external insulation mechanism 60 as another example of the first embodiment will be described. Hereinafter, a structure different from the above-described power storage device 10 and external insulation mechanism 50 will be described, and the description of the same structures and effects as the above-described power storage device 10 and external insulation mechanism 50 will be omitted.

[0066] As Figure 5 shown, the external insulation mechanism 60 includes a convex portion 21C of the negative electrode cover 21, an insulating member 22, a positive electrode current collector plate 41, and a base member 43 provided above the positive electrode current collector plate 41. That is, the external insulation mechanism 60 is formed outside the outer can 20. Therefore, when the positive electrode current collector plate 41 is insulated from the power storage device 10 (current is cut off) by the external insulation mechanism 60, the influence of the insulation is less likely to affect the potential and electrolyte inside the power storage device 10.

[0067] The base member 43 has an end face 43A on the side of the negative electrode cover 21. The base member 43 is provided at a position where the insulating member 22 slides on the end face 43A when the outer can 20 expands and the negative electrode cover 21 deforms upward. The base member 43 of the present embodiment is provided, for example, at the bottom portion of the exhaust passage. The exhaust passage is formed above the inside of the housing of the power storage module 5 that houses the power storage device 10 and communicates with the outside of the housing, and discharges the gas inside the power storage device 10 to the outside of the housing 40 when the power storage device 10 is abnormal. In addition, the base member of the present invention is not limited to the base member 43 of the present embodiment, and may be provided above the inside of the housing 40.

[0068] As Figure 6 shown, when the internal pressure of the power storage device 10 rises when the power storage device 10 is abnormal, the outer can 20 expands and the negative electrode cover 21 deforms upward. At this time, the positive electrode current collector plate 41 is pressed against the base member 43 by the insulating member 22, and the insulating member 22 slides on the end face 43A of the base member 43, whereby the positive electrode current collector plate 41 is cut off. Thus, the positive electrode current collector plate 41 is electrically insulated from the power storage device 10, and the power storage device 10 is insulated from the power storage module 5.

[0069] [Second Embodiment]

[0070] Use Figure 7To describe the external insulation mechanism 250 of the power storage device 210 according to the second embodiment. Hereinafter, structures different from those of the above-described power storage device 10 and external insulation mechanism 50 will be described, and descriptions of the same structures and effects as those of the above-described power storage device 10 and external insulation mechanism 50 will be omitted.

[0071] The power storage device 210 includes: an electrode body 214 formed by winding a positive electrode 211 as a first electrode plate and a negative electrode 212 as a second electrode plate with a strip-shaped spacer 213 interposed therebetween; an electrolyte (not shown); an outer can 220 that houses the electrode body 214 and the electrolyte; a negative electrode cap 221 as a second external terminal; and a rivet 231 as a first external terminal. In addition, in the present embodiment, as an example, an opening is provided at the other end of the outer can 220 (not shown), and the opening is sealed by joining a lid that closes the opening to the opening by welding. And this lid is connected to the negative electrode 212 of the electrode body 214.

[0072] The rivet 231 is fixed to an opening formed on the upper end face in the axial direction of the outer can 220 with an insulating plate 234 interposed therebetween. Above the electrode body 214, there are provided: a positive electrode lead 215 that extends from the upper end in the axial direction of the electrode body 214 and directly connects the positive electrode 211 constituting the electrode body 214 to the rivet 231; and an upper insulating plate 216 that is disposed between the electrode body 214 and the rivet 231.

[0073] A positive electrode current collector plate 241 is joined to the rivet 231 by welding. Thus, the positive electrode current collector plate 241 is electrically connected to the rivet 231. In addition, a negative electrode current collector plate 242 is joined to the end wall portion 221A of the negative electrode cap 221 by welding.

[0074] The external insulation mechanism 250 is composed of a convex portion 221C of the negative electrode cap 221, an insulating member 222, and the positive electrode current collector plate 241. When the internal pressure of the power storage device 210 rises in the case of an abnormality of the power storage device 210, the outer can 220 expands and the negative electrode cap 221 deforms upward in the axial direction. At this time, the convex portion 221C of the negative electrode cap 221 and the insulating member 222 lift the positive electrode current collector plate 241 upward, and the welded portion between the rivet 231 and the positive electrode current collector plate 241 breaks, electrically insulating the rivet 231 from the positive electrode current collector plate 241, and insulating the power storage device 210 from the power storage module.

[0075] [Third Embodiment]

[0076] Use Figure 8 and Figure 9 To describe the power storage device 310 according to the third embodiment.

[0077] The electricity storage device 310 includes: a wound electrode body 314 formed by winding a positive electrode 311 as a first electrode and a negative electrode 312 as a second electrode with a separator 313 interposed therebetween; an exterior can 320 that houses the electrode body 314; and a sealing body 330 that seals an opening of the exterior can 320. An electrolytic solution is housed in the exterior can 320 together with the electrode body 314. The electrolytic solution in the present embodiment is a non-aqueous electrolytic solution, but it may also be an aqueous electrolytic solution. Hereinafter, for the sake of convenience of explanation, the side where the sealing body 330 of the electricity storage device 310 is provided is defined as the upper side, and the side where the bottom 320B of the exterior can 320 is formed is defined as the lower side.

[0078] The positive electrode 311, the negative electrode 312, and the separator 313 are all strip-shaped long bodies, and they are wound in a spiral shape and laminated alternately in the radial direction of the electrode body 314. In order to prevent the precipitation of lithium, the binder layer of the negative electrode 312 may be formed to be one size larger than the binder layer of the positive electrode 311 in terms of circumference. That is, the binder layer of the negative electrode 312 may be formed longer than the binder layer of the positive electrode 311 in the longitudinal direction and the width direction (short side direction). The separator 313 is formed to be at least one size larger than the positive electrode 311 in terms of circumference. For example, two separators 313 are arranged so as to sandwich the positive electrode 311.

[0079] The positive electrode 311 has a positive electrode core body and a positive electrode binder layer formed on at least one surface of the core body. For the positive electrode core body, it is possible to use, for example, a foil of a metal such as aluminum or an aluminum alloy that is stable within the potential range of the positive electrode 311, a thin film in which the metal is disposed on the surface layer, etc. The positive electrode binder layer contains, for example, a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and the positive electrode binder layer is preferably formed on both surfaces of the positive electrode core body. For the positive electrode active material, for example, a lithium transition metal composite oxide is used.

[0080] The negative electrode 312 has a negative electrode core body and a negative electrode binder layer formed on at least one surface of the core body. For the negative electrode core body, it is possible to use, for example, a foil of a metal such as copper or a copper alloy that is stable within the potential range of the negative electrode 312, a thin film in which the metal is disposed on the surface layer, etc. The negative electrode binder layer contains, for example, a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and the negative electrode binder layer is preferably formed on both surfaces of the negative electrode core body. For the negative electrode active material, for example, graphite, a silicon-containing compound, etc. can be used. The negative electrode lead is preferably directly joined to the negative electrode core body by welding or the like.

[0081] The non-aqueous electrolyte accommodated in the outer can 320 includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of them can be used. The non-aqueous solvent may contain a halogen-substituted body obtained by substituting at least a part of the hydrogen of these solvents with halogen atoms such as fluorine. As an example of the non-aqueous solvent, ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and their mixed solvents can be cited. For the electrolyte salt, for example, lithium salts such as LiPF6 can be used. In addition, the non-aqueous electrolyte may not be an electrolytic solution but a gel electrolyte, a solid electrolyte, etc.

[0082] Above the electrode body 314, there are provided: a positive electrode lead 315 that extends from the upper end in the axial direction of the electrode body 314 and directly connects the positive electrode 311 constituting the electrode body 314 to the current collector plate 332 of the sealing body 330; and an upper insulating plate 316 that is disposed between the electrode body 314 and the sealing body 330. Since the positive electrode lead 315 electrically connects the positive electrode 311 and the sealing body 330, the positive electrode cap 331 of the sealing body 330 functions as a positive electrode external terminal, and this positive electrode external terminal is the first external terminal. The upper insulating plate 316 prevents the positive electrode 311 and the positive electrode lead 315 from contacting the outer can 320, and prevents the positive electrode lead 315 from contacting the negative electrode 312 of the electrode body 314.

[0083] Below the electrode body 314, there are provided: a negative electrode lead that extends from the lower end in the axial direction of the electrode body 314 and directly connects the negative electrode 312 constituting the electrode body 314 to the bottom 320B of the outer can 320; and a lower insulating plate 317 that is disposed between the electrode body 314 and the bottom 320B of the outer can 320. The negative electrode lead electrically connects the negative electrode 312 and the outer can 320, and the outer can 320 is electrically connected to the negative electrode cap 321 described later, so the negative electrode cap 321 functions as a negative electrode external terminal, and this negative electrode external terminal is the second external terminal.

[0084] The outer can 320 is a bottomed cylindrical metal container with one axial end (upper end) open. In addition, the outer can 320 is usually made of a metal mainly composed of iron, but in the case of connecting to the positive electrode 311, it can also be made of a metal mainly composed of aluminum or the like. The outer can 320 has a cylindrical portion 320A formed in a cylindrical shape, a bottom portion 320B that is circular when viewed from above, a shoulder portion 320C formed in a ring shape along the circumferential direction of the opening end of the cylindrical portion 320A, and a groove portion 320D formed along the circumferential direction of the cylindrical portion 320A. In addition, a negative electrode cap 321 as the second terminal is provided on the outer can 320.

[0085] The groove portion 320D is formed at a position near the opening of the outer can 320 and separated from the shoulder portion 320C by a predetermined length. The groove portion 320D is a part where a portion of the cylindrical portion 320A extends inwardly of the outer can 320. For example, the groove portion 320D is formed by performing spinning on the cylindrical portion 320A from the outside. In addition, at the formation position of the groove portion 320D, the outer can 320 is reduced in diameter, and a thin linear groove is formed on the outer peripheral surface of the cylindrical portion 320A. Preferably, the groove portion 320D has a substantially U-shaped cross section and is formed in a ring shape over the entire circumferential length of the cylindrical portion 320A.

[0086] The negative electrode cap 321 as the second terminal is connected to the negative electrode 312 via the outer can 320 and functions as an external negative electrode terminal. The negative electrode cap 321 is formed in a ring shape when viewed from above (when observed from the axial direction) and has a cross-sectional L shape when viewed from the circumferential direction. The negative electrode cap 321 includes: an end wall 321A that faces the outer can 320 in the height direction (axial direction) and abuts against the upper end surface of the shoulder portion 320C of the outer can 320; a side wall 321B that faces the outer can 320 in the radial direction and abuts against the upper end portion of the cylindrical portion 320A of the outer can 320; and a convex portion 321C that is formed to protrude downward at the radially inner peripheral side end portion of the end wall 321A. In addition, it is not necessary for both the end wall 321A and the side wall 321B to abut against the outer can 320. The negative electrode cap 321 is welded to the cylindrical portion 320A of the outer can 320 at a predetermined position of the side wall 321B of the negative electrode cap 321 and is electrically connected to the outer can 320.

[0087] The convex portion 321C of the negative electrode cap 321 constitutes an external short-circuit mechanism 350 which will be described in detail later. The convex portion 321C is formed by bending the inner peripheral side end portion of the end wall 321A of the negative electrode cap 321 downward. The convex portion 321C is formed in a ring shape when viewed from above (when observed from the axial direction). The convex portion 321C is formed by flanging the inner peripheral side end portion of the end wall 321A.

[0088] In addition, the convex portion 321C does not necessarily have to be located at the inner peripheral side end portion of the end wall 321A of the negative electrode cap 321, as long as it is at least located at a position on the end wall 321A of the negative electrode cap 321 that is radially inward of the outer end of the outer can 320 in the electric storage device 310. Therefore, it can also be located at a position on the end wall 321A of the negative electrode cap 321 that is outward of the inner peripheral side end portion. In this case, the formation portion of the convex portion 321C on the end wall 321A can be made thick-walled, or the plate-shaped end wall 321A can be bent to form a mountain shape with a V-shaped, C-shaped, or U-shaped cross section that protrudes from the upper surface (the surface on the outside of the electric storage device) of the end wall 321A toward the lower surface (the surface on the side of the outer can). With this structure, the overall rigidity of the negative electrode cap 321 is improved compared to the convex portion 321C located at the inner peripheral side end portion.

[0089] In addition, the convex portion 321C does not necessarily have to be annular, and the convex portion 321C may be intermittently provided in the circumferential direction of the end wall 321A. Moreover, in the circumferential direction of the end wall 321A, the convex portion 321C may be only one place. In the case where the convex portion 321C is intermittently provided, a through hole may also be formed at the top of the mountain-shaped convex portion 321C. In addition, the above-mentioned mountain-shaped convex portion 321C may also be provided at the inner circumferential side end portion of the end wall 321A.

[0090] The entire sealing body 330 is formed in a disc shape and includes a positive electrode cap 331, a current collector plate 332, a gasket 333, and an insulating member 334. The sealing body 330 is disposed on the groove portion 320D of the outer can 320 and fixed to the upper end portion of the outer can 320. More specifically, the shoulder portion 320C of the outer can 320 is bent inward in the radial direction and caulked to the sealing body 330, and the sealing body 330 is fixed to the upper end portion of the outer can 320 by the shoulder portion 320C and the groove portion 320D of the outer can 320, and the sealing body 330 seals the opening of the outer can 320.

[0091] The positive electrode cap 331 is connected to the positive electrode 311 via the positive electrode lead 315 and the current collector plate 332, and functions as an external positive electrode terminal. The positive electrode cap 331 is a disc-shaped metal member and has a raised portion 31A in which the central portion in the radial direction protrudes outward from the power storage device 310 and a flange portion 331B formed around the raised portion 31A. The positive electrode cap 331 is disposed on the upper surface side of the sealing body 330 and is exposed to the outside of the outer can 320 to form the top surface of the power storage device 310. The flange portion 331B constitutes an external short-circuit mechanism 350 which will be described in detail later.

[0092] The current collector plate 332 is connected to the positive electrode 311 via the positive electrode lead 315 and functions as a positive electrode current collector. The current collector plate 332 is a metal member having a diameter similar to that of the positive electrode cap 331. The current collector plate 332 is formed in an annular shape having an opening at the radial center portion. The current collector plate 332 is disposed at a position closer to the electrode body 314 than the positive electrode cap 331. The current collector plate 332 is welded to the positive electrode cap 331, for example, at a position where the distance from the radial center of the positive electrode cap 331 to the current collector plate 332 is greater than the distance from the outer peripheral edge of the positive electrode cap 331.

[0093] The gasket 333 is a rubber or resin component for preventing contact between the positive electrode lid 331 and the current collector plate 332 and the outer can 320, ensuring electrical insulation between the outer can 320 and the sealing body 330. Additionally, the gasket 333 seals the gap between the outer can 320 and the sealing body 330 to make the interior of the power storage device 310 airtight. The gasket 333 is disposed between the outer periphery of the laminate of the positive electrode lid 331 and the current collector plate 332 and the outer can 320. The gasket 333 covers the upper surface of the flange portion 331B of the positive electrode lid 331, the side surfaces of the positive electrode lid 331 and the current collector plate 332, and the lower surface of the current collector plate 332 on the outer periphery of the laminate.

[0094] The insulating member 334 is a rubber or resin component for preventing contact between the positive electrode lid 331 and the negative electrode lid 321, ensuring electrical insulation between the positive electrode lid 331 and the negative electrode lid 321. The insulating member 334 is formed in an annular shape with an opening at the radial center. The insulating member 334 is disposed between the upper surface of the flange portion 331B of the positive electrode lid 331 and the lower surface of the end wall 321A of the negative electrode lid 321. Additionally, when viewed from the axial direction, the insulating member 334 is disposed between the raised portion 31A of the positive electrode lid 331 and the shoulder portion 320C of the outer can 320.

[0095] The insulating member 334 constitutes the external short - circuit mechanism 350, which will be described in detail later. The insulating member 334 can also be formed of a raw material that melts when it reaches a specified temperature or higher. A concave portion 334A for fitting the convex portion 321C of the negative electrode lid 321 is formed on the upper surface of the insulating member 334. The concave portion 334A is formed in an annular shape when viewed from above (when viewed from the axial direction).

[0096] [External short - circuit mechanism]

[0097] Use Figure 9 and Figure 10 to describe the external short - circuit mechanism 350.

[0098] The external short - circuit mechanism 350 is a mechanism that shorts the positive electrode lid 331 and the negative electrode lid 321 when the power storage device 310 generates heat and the internal pressure of the power storage device 310 rises due to an abnormality in the power storage device 310, short - circuiting the power storage device 310 outside the outer can 320. According to the external short - circuit mechanism 350, the safety of the power storage module 5 can be improved, which will be described in detail later.

[0099] As Figure 9 shown, the external short - circuit mechanism 350 is composed of the convex portion 321C of the negative electrode lid 321, the insulating member 334, and the flange portion 331B of the positive electrode lid 331. That is, the external short - circuit mechanism 350 is formed outside the outer can 320. Therefore, when the power storage device 310 is short - circuited through the external short - circuit mechanism 350, the influence of the short - circuit is not easily spread to the potential and electrolyte inside the power storage device 310.

[0100] As Figure 10 shown, when the power storage device 310 generates heat and the internal pressure of the power storage device 310 rises in the event of an abnormality in the power storage device 310, the insulating member 334 melts due to the heat generated by the power storage device 310, the outer can 320 expands due to the rise in the internal pressure of the power storage device 310, and the positive electrode lid 331 deforms upward in the axial direction. At this time, the convex portion 321C of the negative electrode lid 321 penetrates below the concave portion 334A of the melted insulating member 334 and contacts the flange portion 331B of the positive electrode lid 331, and the positive electrode lid 331 and the negative electrode lid 321 are electrically connected, and the power storage device 310 is short-circuited. In addition, when the external short-circuit mechanism 350 operates, it is not necessary for the insulating member 334 to melt. For example, it may be that the insulating member 334 is actively brought into contact with the convex portion 321C by the force of the expansion of the positive electrode lid 331, and the convex portion 321C penetrates the insulating member 334.

[0101] According to the external short-circuit mechanism 350, the safety of the power storage module 5 can be improved. More specifically, according to the external short-circuit mechanism 350, the power storage device 310 is short-circuited outside the outer can 320, so that the power storage device 310 can be short-circuited without being affected by the electrolyte and potential of the power storage device 310. As a result, it is possible to suppress the following situation: current flows from other adjacent power storage devices 310 connected in parallel with the short-circuited power storage device 310 into the short-circuited power storage device 310, and the calorific value of the short-circuited power storage device 310 increases.

[0102] In addition, when the power storage device 310 is short-circuited by the external short-circuit mechanism 350 in the event of an abnormality in the power storage device 310, a large current flows through the system to which the power storage module 5 is connected, and the fuse provided in the system melts, suppressing the current from flowing into the short-circuited power storage device 310.

[0103] In addition, according to the external short-circuit mechanism 350, there is no need to use a complicated mechanism such as an adhesive or a spring inside the power storage device 310, and the short-circuit mechanism can be realized only by forming the convex portion 321C of the negative electrode lid 321.

[0104] Moreover, according to the external short-circuit mechanism 350, the short-circuit mechanism can be realized without additionally providing a member on the conduction path from the positive electrode 311 to the positive electrode lid 331 or the conduction path from the negative electrode 312 to the negative electrode lid 321. As a result, a short-circuit path can be realized while maintaining the power storage device 310 at a low resistance.

[0105] [Fourth Embodiment]

[0106] Use Figure 11 and Figure 12 to describe the power storage device 410 of the fourth embodiment.

[0107] The power storage device 410 includes: a wound electrode body 414 formed by winding a positive electrode 411 as a first electrode and a negative electrode 412 as a second electrode with a separator 413 interposed therebetween; an exterior can 420 that houses the electrode body 414; and a sealing body 430 that seals an opening of the exterior can 420. An electrolytic solution is housed in the exterior can 420 together with the electrode body 414. The electrolytic solution in the present embodiment is a non-aqueous electrolytic solution, but it may also be an aqueous electrolytic solution. Hereinafter, for the sake of convenience of explanation, the side of the power storage device 410 where the sealing body 430 is provided is defined as the upper side, and the side of the exterior can 420 where the bottom 420B is formed is defined as the lower side.

[0108] The positive electrode 411, the negative electrode 412, and the separator 413 are all strip-shaped long bodies, and they are wound in a spiral shape and laminated alternately in the radial direction of the electrode body 414. In order to prevent the precipitation of lithium, the binder layer of the negative electrode 412 can be formed to be one size larger than the binder layer of the positive electrode 411 in terms of circumference. That is, the binder layer of the negative electrode 412 can be formed longer than the binder layer of the positive electrode 411 in the longitudinal direction and the width direction (short side direction). The separator 413 is formed to be at least one size larger than the positive electrode 411. For example, two separators 413 are arranged so as to sandwich the positive electrode 411.

[0109] The positive electrode 411 has a positive electrode core body and a positive electrode binder layer formed on at least one surface of the core body. For the positive electrode core body, for example, a foil of a metal such as aluminum or an aluminum alloy that is stable within the potential range of the positive electrode 411, a thin film in which the metal is disposed on the surface layer, etc. can be used. The positive electrode binder layer contains, for example, a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride. The positive electrode binder layer is preferably formed on both surfaces of the positive electrode core body. For the positive electrode active material, for example, a lithium transition metal composite oxide is used.

[0110] The negative electrode 412 has a negative electrode core body and a negative electrode binder layer formed on at least one surface of the core body. For the negative electrode core body, for example, a foil of a metal such as copper or a copper alloy that is stable within the potential range of the negative electrode 412, a thin film in which the metal is disposed on the surface layer, etc. can be used. The negative electrode binder layer contains, for example, a negative electrode active material and a binder such as styrene-butadiene rubber (SBR). The negative electrode binder layer is preferably formed on both surfaces of the negative electrode core body. For the negative electrode active material, for example, graphite, a silicon-containing compound, etc. can be used. The negative electrode lead is preferably directly joined to the negative electrode core body by welding or the like.

[0111] The non-aqueous electrolyte contained in the outer can 420 includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of them can be used. The non-aqueous solvent may contain a halogen-substituted body obtained by substituting at least a part of the hydrogen of these solvents with a halogen atom such as fluorine. As an example of the non-aqueous solvent, ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and their mixed solvents can be cited. For the electrolyte salt, for example, a lithium salt such as LiPF6 can be used. In addition, the non-aqueous electrolyte may not be an electrolytic solution but a gel electrolyte, a solid electrolyte, etc.

[0112] Above the electrode body 414, there are provided: a positive electrode lead 415 that extends from the upper end in the axial direction of the electrode body 414 and directly connects the positive electrode 411 constituting the electrode body 414 to the current collector plate 432 of the sealing body 430; and an upper insulating plate 416 that is disposed between the electrode body 414 and the sealing body 430. Since the positive electrode lead 415 electrically connects the positive electrode 411 and the sealing body 430, the positive electrode cap 431 of the sealing body 430 functions as a positive electrode external terminal, and this positive electrode external terminal is the first external terminal. The upper insulating plate 416 prevents the positive electrode 411 and the positive electrode lead 415 from contacting the outer can 420, and prevents the positive electrode lead 415 from contacting the negative electrode 412 of the electrode body 414.

[0113] Below the electrode body 414, there are provided: a negative electrode lead that extends from the lower end in the axial direction of the electrode body 414 and directly connects the negative electrode 412 constituting the electrode body 414 to the bottom 420B of the outer can 420; and a lower insulating plate 417 that is disposed between the electrode body 414 and the bottom 420B of the outer can 420. The negative electrode lead electrically connects the negative electrode 412 and the outer can 420, and the outer can 420 is electrically connected to the negative electrode cap 421 described later, so the negative electrode cap 421 functions as a negative electrode external terminal, and this negative electrode external terminal is the second external terminal.

[0114] The outer can 420 is a bottomed cylindrical metal container with one end (upper end) axially open. In addition, the outer can 420 is usually made of a metal mainly composed of iron, but in the case of connecting to the positive electrode 411, it can also be made of a metal mainly composed of aluminum, etc. The outer can 420 has a cylindrical portion 420A formed in a cylindrical shape, a bottom portion 420B that is circular when viewed from above, a shoulder portion 420C formed in a ring shape along the circumferential direction of the opening end of the cylindrical portion 420A, and a groove portion 420D formed along the circumferential direction of the cylindrical portion 420A. In addition, a negative electrode cap 421 as the second terminal is provided on the outer can 420.

[0115] The groove portion 420D is formed at a position near the opening of the outer can 420 and separated from the shoulder portion 420C by a predetermined length. The groove portion 420D is a part where a part of the cylindrical portion 420A extends inwardly of the outer can 420. For example, the groove portion 420D is formed by performing spinning on the cylindrical portion 420A from the outside. Further, at the formation position of the groove portion 420D, the outer can 420 is reduced in diameter, and a thin-line-shaped groove is formed on the outer peripheral surface of the cylindrical portion 420A. Preferably, the groove portion 420D has a substantially U-shaped cross section and is formed in a ring shape over the entire circumferential length of the cylindrical portion 420A.

[0116] The negative electrode cap 421 as the second terminal is connected to the negative electrode 412 via the outer can 420 and functions as an external negative electrode terminal. The negative electrode cap 421 is formed in a ring shape when viewed from above (when observed from the axial direction) and has a cross section in an L shape when viewed from the circumferential direction. In addition, the negative electrode cap 421 may be partially missing like a C shape when viewed from above. The negative electrode cap 421 has: an end wall 421A that faces the outer can 420 in the height direction (axial direction) and abuts against the upper end surface of the shoulder portion 420C of the outer can 420; a side wall 421B that faces the outer can 420 in the radial direction and abuts against the upper end portion of the cylindrical portion 420A of the outer can 420; and a convex portion 421C that is formed to protrude upward at the radially inner peripheral side end portion of the end wall 421A. Further, it is not necessary for both the end wall 421A and the side wall 421B to abut against the outer can 420. The negative electrode cap 421 is welded to the cylindrical portion 420A of the outer can 420 at a predetermined position of the side wall 421B of the negative electrode cap 421 and is electrically connected to the outer can 420. The end wall 421A is joined to the negative electrode current collector plate 442 by welding, which will be described in detail later. Thus, the negative electrode cap 421 is electrically connected to the negative electrode current collector plate 442.

[0117] The convex portion 421C of the negative electrode cap 421 constitutes an external short-circuit mechanism 450, which will be described in detail later. The convex portion 421C is formed by bending the inner peripheral side end portion of the end wall 421A of the negative electrode cap 421 upward. The convex portion 421C is formed in a ring shape when viewed from above (when observed from the axial direction). The convex portion 21C is formed by performing flanging on the inner peripheral side end portion of the end wall 421A.

[0118] In addition, the convex portion 421C does not necessarily have to be located at the inner peripheral side end of the end wall 421A of the negative electrode cap 421, as long as it is at least located at a position on the end wall 421A of the negative electrode cap 421 that is radially closer to the inside than the outer end of the outer can 420. Therefore, it can also be located at a position on the end wall 421A of the negative electrode cap 421 that is closer to the outside than the inner peripheral side end. In this case, the portion of the end wall 421A where the convex portion 421C is formed can be made into a thick wall, or the plate-shaped end wall 421A can be bent to form a mountain shape with a V-shaped, C-shaped, or U-shaped cross-section that protrudes from the lower surface (the side facing the outer can) of the end wall 421A toward the upper surface (the side outside the power storage device). With this structure, the rigidity of the entire negative electrode cap 421 is increased compared to the convex portion 421C located at the inner peripheral side end.

[0119] Moreover, especially when the negative electrode cap 421 is a metal plate with a plated surface, sometimes the inner peripheral side end in the radial direction and the like are not covered by the plating, and the non-plated inner peripheral side end is prone to rusting. Therefore, by arranging the convex portion 421C at a position closer to the outside than the inner peripheral side end, the non-rusting area of the plated end wall 421A can be used as the convex portion 421C. In addition, the convex portion 421C does not necessarily have to be annular, and the convex portion 421C can also be intermittently provided in the circumferential direction of the end wall 421A.

[0120] Also, in the circumferential direction of the end wall 421A, the convex portion 421C can be only one place. In the case where the convex portion 421C is intermittently provided, a through hole can also be formed at the top of the mountain-shaped convex portion 421C. In addition, the above-mentioned mountain-shaped convex portion 421C can also be provided at the inner peripheral side end of the end wall 421A. In addition, the upper end of the convex portion 421C can be located at a position higher than the upper end of the positive electrode cap 431.

[0121] The entire sealing body 430 is formed in a disk shape and includes a positive electrode cap 431, a current collector plate 432, a gasket 433, and an insulating member 434. The sealing body 430 is disposed on the groove portion 420D of the outer can 420 and fixed to the upper end portion of the outer can 420. More specifically, the shoulder portion 420C of the outer can 420 is bent inward in the radial direction and caulked to the sealing body 430, and the sealing body 430 is fixed to the upper end portion of the outer can 420 through the shoulder portion 420C and the groove portion 420D of the outer can 420, and the sealing body 430 seals the opening of the outer can 420.

[0122] The positive electrode cap 431 is connected to the positive electrode 411 via the positive electrode lead 415 and the current collector plate 432, and functions as an external terminal of the positive electrode. The positive electrode cap 431 is a disk-shaped metal member, and has a raised portion 431A formed by protruding the radial central portion outward from the power storage device 410 and a flange portion 431B formed around the raised portion 431A. The positive electrode cap 431 is disposed on the upper surface side of the sealing body 430 and is exposed to the outside of the outer can 420 to form the top surface of the power storage device 410. The raised portion 431A is joined to the positive electrode current collector plate 441 by welding, which will be described in detail later. Thus, the positive electrode cap 431 is electrically connected to the positive electrode current collector plate 441.

[0123] The current collector plate 432 is connected to the positive electrode 411 via the positive electrode lead 415 and functions as a positive electrode current collector. The current collector plate 432 is a metal member having a diameter similar to that of the positive electrode cap 431. The current collector plate 432 is formed in a ring shape having an opening at the radial central portion. The current collector plate 432 is disposed at a position closer to the electrode body 414 than the positive electrode cap 431. The current collector plate 432 is welded to the positive electrode cap 431, for example, at a position where the distance from the radial center of the positive electrode cap 431 is greater than the distance from the outer peripheral edge of the positive electrode cap 431.

[0124] The gasket 433 is a rubber or resin member for preventing contact between the positive electrode cap 431 and the current collector plate 432 and the outer can 420, and ensuring electrical insulation between the outer can 420 and the sealing body 430. In addition, the gasket 433 seals the gap between the outer can 420 and the sealing body 430 to make the inside of the power storage device 410 airtight. The gasket 433 is provided between the outer peripheral portion of the laminate of the positive electrode cap 431 and the current collector plate 432 and the outer can 420. The gasket 433 covers the upper surface of the flange portion 431B of the positive electrode cap 431, the side surfaces of the positive electrode cap 431 and the current collector plate 432, and the lower surface of the current collector plate 432 at the outer peripheral portion of the laminate.

[0125] The insulating member 434 is a rubber or resin member for preventing contact between the positive electrode cap 431 and the negative electrode cap 421 and ensuring electrical insulation between the positive electrode cap 431 and the negative electrode cap 421. The insulating member 434 is formed in a ring shape having an opening at the radial central portion. The insulating member 434 is disposed between the upper surface of the flange portion 431B of the positive electrode cap 431 and the lower surface of the end wall 421A of the negative electrode cap 421. In addition, when viewed from the axial direction, the insulating member 434 is disposed between the raised portion 431A of the positive electrode cap 431 and the shoulder portion 420C of the outer can 420.

[0126] As described above, the positive electrode current collector plate 441 is joined to the raised portion 431A of the positive electrode cap 431 by welding. Thus, the positive electrode current collector plate 441 is electrically connected to the positive electrode cap 431. The positive electrode current collector plate 441 is a rectangular conductive metal member and is disposed above the positive electrode cap 431.

[0127] In addition, a negative electrode current collector plate 442 is joined to the end wall 421A of the negative electrode lid 421 by welding. Thus, the negative electrode current collector plate 442 is electrically connected to the negative electrode lid 421. The negative electrode current collector plate 442 is a rectangular conductive metal member and is disposed above the negative electrode lid 421.

[0128] [External short-circuit mechanism]

[0129] Use Figure 12 and Figure 13 to describe the external short-circuit mechanism 450.

[0130] The external short-circuit mechanism 450 is a mechanism that shorts the positive electrode current collector plate 441 and the negative electrode lid 421 when the internal pressure of the power storage device 410 rises in the case of an abnormality of the power storage device 410, thereby shorting the power storage device 410 outside the outer can 420. According to the external short-circuit mechanism 450, the safety of the power storage module 5 can be improved, which will be described in detail later.

[0131] As Figure 12 shown, the external short-circuit mechanism 450 is composed of a convex portion 421C of the negative electrode lid 421 and the positive electrode current collector plate 441. That is, the external short-circuit mechanism 450 is formed outside the outer can 420. Therefore, when the power storage device 410 is short-circuited by the external short-circuit mechanism 450, the influence of the short circuit on the potential and electrolyte inside the power storage device 410 can be reduced.

[0132] As Figure 13 shown, when the internal pressure of the power storage device 410 rises in the case of an abnormality of the power storage device 410, the outer can 420 expands and the negative electrode lid 421 deforms upward in the axial direction. At this time, the convex portion 421C of the negative electrode lid 421 comes into contact with the positive electrode current collector plate 441, the negative electrode lid 421 is electrically connected to the positive electrode current collector plate 441, and the power storage device 410 is short-circuited.

[0133] According to the external short-circuit mechanism 450, the safety of the power storage module 5 can be improved. More specifically, according to the external short-circuit mechanism 450, the power storage device 410 is short-circuited outside the outer can 420, so that the power storage device 410 can be short-circuited without being affected by the electrolyte and potential of the power storage device 410. Thus, it is possible to suppress current from flowing from other adjacent power storage devices 410 connected in parallel with the short-circuited power storage device 410 into the short-circuited power storage device 410, and to suppress the heat generation amount of the short-circuited power storage device 410.

[0134] In addition, when the power storage device 410 is short-circuited by the external short-circuit mechanism 450 in the case of an abnormality of the power storage device 410, a large current flows through the system to which the power storage module 5 is connected, and the fuse provided in the system melts to suppress current from flowing into the short-circuited power storage device 410.

[0135] In addition, according to the external short-circuit mechanism 450, there is no need to use complex mechanisms such as adhesives or springs inside the power storage device 410. The short-circuit mechanism can be achieved only by forming the convex portion 421C of the negative electrode cap 421.

[0136] Moreover, according to the external short-circuit mechanism 450, the short-circuit mechanism can be achieved without additionally providing components on the conduction path from the positive electrode 411 to the positive electrode cap 431 or on the conduction path from the negative electrode 412 to the negative electrode cap 421. Thus, a short-circuit path can be achieved while maintaining the power storage device 410 at a low resistance.

[0137] [Fifth Embodiment]

[0138] Use Figure 14 The external short-circuit mechanism 550 of the power storage device 510 as another example of the fifth embodiment will be described. Hereinafter, the structures different from those of the above-described power storage device 410 and external short-circuit mechanism 450 will be described, and the description of the same structures and effects as those of the above-described power storage device 410 and external short-circuit mechanism 450 will be omitted.

[0139] The power storage device 510 includes: an electrode body 514 formed by winding a positive electrode 511 as a first electrode plate and a negative electrode 512 as a second electrode plate with a strip-shaped spacer 513 interposed therebetween; an electrolyte (not shown); an outer can 520 that houses the electrode body 514 and the electrolyte; a negative electrode cap 521 as a second external terminal; and a rivet 531 as a first external terminal. In addition, in this embodiment, as an example, an opening is provided at the other end of the outer can 520 not shown, and the opening is sealed by joining a lid that seals the opening to the opening by welding. And this lid is connected to the negative electrode 512 of the electrode body 514.

[0140] The rivet 531 is fixed to an opening formed on the upper end surface in the axial direction of the outer can 520 with an insulating plate 534 interposed therebetween. Above the electrode body 514, there are provided: a positive electrode lead 515 that extends upward from the upper end in the axial direction of the electrode body 514 and directly connects the positive electrode 511 constituting the electrode body 514 to the rivet 531; and an upper insulating plate 516 that is disposed between the electrode body 514 and the rivet 531.

[0141] A positive electrode current collector plate 541 is joined to the rivet 531 by welding. Thus, the positive electrode current collector plate 541 is electrically connected to the rivet 531. In addition, a negative electrode current collector plate 542 is joined to the negative electrode cap 521 by welding.

[0142] The external short-circuit mechanism 550 is composed of the convex portion 521C of the negative electrode lid 521 and the positive electrode current collector plate 541. When the internal pressure of the power storage device 510 rises during an abnormality of the power storage device 510, the outer can 520 expands and the negative electrode lid 521 deforms upward in the axial direction. At this time, the convex portion 521C of the negative electrode lid 521 comes into contact with the positive electrode current collector plate 541, the negative electrode lid 521 is electrically connected to the positive electrode current collector plate 541, and the power storage device 510 is short-circuited.

[0143] In addition, the present invention is not limited to the above-described embodiments and their modified examples, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

[0144] Explanation of reference numerals

[0145] 5. Battery storage module; 10. Battery storage device; 11. Positive electrode; 12. Negative electrode; 13. Spacer; 14. Electrode body; 15. Positive electrode lead; 16. Upper insulating plate; 17. Lower insulating plate; 20. Outer can; 20A. Cylindrical part; 20B. Bottom; 20C. Shoulder; 20D. Groove part; 21. Negative electrode cover; 21A. End wall; 21B. Side wall; 21C. Protrusion; 30. Sealing body; 31. Positive electrode cover; 31A. Raised part; 31B. Flange part; 31C. Protrusion; 32. Current collector plate; 33. Gasket; 34. Insulating member; 41. Positive electrode current collector plate; 42. Negative electrode current collector plate; 43. Base member; 43A. End face; 50. External insulation mechanism; 60. External insulation mechanism; 210. Battery storage device; 211. Positive electrode; 212. Negative electrode; 213. Spacer; 214. Electrode body; 215. Positive electrode lead; 216. Upper insulating plate; 220. Outer can; 221. Negative electrode cover; 221A. End wall; 221B. Side wall; 221C. Protrusion; 231. Rivet; 234. Insulating member; 241. Positive electrode current collector plate; 242. Negative electrode current collector plate; 250. External insulation mechanism; 310. Battery storage device; 311. Positive electrode; 312. Negative electrode; 313. Spacer; 314. Electrode body; 315. Positive electrode lead; 316. Upper insulating plate; 317. Lower insulating plate; 320. Outer can; 320A. Cylindrical part; 320B. Bottom; 320C. Shoulder; 320D. Groove part; 321. Negative electrode cover; 321A. End wall; 321B. Side wall; 321C. Protrusion; 330. Sealing body; 331. Positive electrode cover; 331A. Raised part; 331B. Flange part; 331C. Protrusion; 332. Current collector plate; 333. Gasket; 334. Insulating member; 334A. Concave part; 350. External short-circuit mechanism; 410. Battery storage device; 411. Positive electrode; 412. Negative electrode; 413. Spacer; 414. Electrode body; 415. Positive electrode lead; 416. Upper insulating plate; 417. Lower insulating plate; 420. Outer can; 420A. Cylindrical part; 420B. Bottom; 420C. Shoulder; 420D. Groove part; 421. Negative electrode cover; 421A. End wall; 421B. Side wall; 421C. Protrusion; 430. Sealing body; 431. Positive electrode cover; 431A. Raised part; 431B. Flange part; 431C. Protrusion; 432. Current collector plate; 433. Gasket; 434. Insulating member; 441. Positive electrode current collector plate; 442. Negative electrode current collector plate; 450. External short-circuit mechanism; 510. Battery storage device; 511. Positive electrode; 512. Negative electrode; 513. Spacer; 514. Electrode body; 515. Positive electrode lead; 516. Upper insulating plate; 520. Outer can; 521. Negative electrode cover; 521A. End wall; 521B. Side wall; 521C. Protrusion; 531. Rivet; 534. Insulating member; 541. Positive electrode current collector plate; 542. Negative electrode current collector plate; 550. External short-circuit mechanism.

Claims

1. A power storage device, wherein, the power storage device includes: an electrode body including a first electrode and a second electrode; an outer can that houses the electrode body and is electrically connected to the second electrode; a first terminal that seals an opening formed on one side in the axial direction of the outer can and is electrically connected to the first electrode; and a second terminal that is provided on one side in the axial direction of the outer can and is electrically connected to the outer can, the second terminal has a safety device provided with a convex portion.

2. The power storage device according to claim 1, wherein, the convex portion that protrudes toward a first current collector plate connected to the first terminal is provided on the second terminal, and an insulating member that covers the convex portion is provided on the convex portion.

3. The power storage device according to claim 2, wherein, the second terminal deforms upward in the axial direction due to the expansion of the outer can, the first current collector plate is lifted by the insulating member, and the connection between the first current collector plate and the first terminal is broken.

4. The power storage device according to claim 2, wherein, the second terminal deforms upward in the axial direction due to the expansion of the outer can, and the insulating member slides on an end face of a base member provided above the first current collector plate, so that the first current collector plate is cut off.

5. The power storage device according to any one of claims 2 to 4, wherein, the convex portion is located radially inside the outer end of the outer can.

6. The power storage device according to any one of claims 2 to 5, wherein, the convex portion is formed by bending an end portion on the inner peripheral side of the second terminal upward.

7. The power storage device according to any one of claims 2 to 6, wherein, the convex portion is formed in a ring shape in a plan view.

8. A power storage module having the power storage device according to any one of claims 2 to 7, wherein, the power storage module is formed by connecting the power storage devices in parallel and in series, the power storage module has the first current collector plate connected to the first terminal of the power storage device.

9. A power storage module having the power storage device according to any one of claims 2 to 7, wherein, the power storage module is formed by connecting the power storage devices in parallel and in series, the power storage module includes: the first current collector plate connected to the first terminal of the power storage device; and a base member provided above the first current collector plate.

10. The power storage device according to claim 1, wherein, the power storage device further includes an insulating member provided between the first terminal and the second terminal, and the convex portion that protrudes toward the first terminal is provided on the second terminal.

11. The power storage device according to claim 10, wherein, the first terminal deforms toward one side in the axial direction due to the expansion of the outer can, so that the convex portion contacts the first terminal.

12. The power storage device according to claim 10 or 11, wherein, the convex portion is located radially inside the outer end of the outer can.

13. The power storage device according to any one of claims 10 to 12, wherein, The convex portion is formed by bending the end portion on the inner peripheral side of the second terminal.

14. The power storage device according to any one of claims 10 to 13, wherein The convex portion is formed in a ring shape in a plan view.

15. The power storage device according to any one of claims 10 to 14, wherein The insulating member is provided with a concave portion into which the convex portion is fitted.

16. The power storage device according to claim 15, wherein The concave portion is formed in a ring shape in a plan view.

17. A power storage module having the power storage device according to any one of claims 10 to 16, wherein The power storage module is formed by connecting the power storage devices in parallel and in series.

18. The power storage device according to claim 1, wherein The second terminal is provided with the convex portion that protrudes toward the first current collector plate connected to the first terminal.

19. The power storage device according to claim 18, wherein The second terminal deforms toward one side in the axial direction due to the expansion of the outer can, so that the convex portion contacts the first current collector plate.

20. The power storage device according to claim 18 or 19, wherein The convex portion is located radially inside the outer end of the outer can.

21. The power storage device according to any one of claims 18 to 20, wherein The convex portion is formed by bending the end portion on the inner peripheral side of the second terminal upward.

22. The power storage device according to any one of claims 18 to 21, wherein The convex portion is formed in a ring shape in a plan view.

23. A power storage module having the power storage device according to any one of claims 18 to 22, wherein The power storage module is formed by connecting the power storage devices in parallel and in series, The power storage module has the first current collector plate connected to the first terminal of the power storage device.

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