Energy storage devices

Abstract

To provide a power storage device with which space efficiency is improved and an increase in electrical resistance is suppressed at the same time.SOLUTION: A power storage device comprises a case 10 having a wide rectangular first face 12a, a pair of second faces 12b, 12c facing each other, a pair of third faces 12d, 12e facing each other, an outer package 12 having an opening 12h, and a wide rectangular sealing plate 14 that seals the opening 12h. A cathode 22 and an anode 24 have a plurality of tabs 22t, 24t protruding at one end in the winding axis direction of an electrode body 20, and have through-holes 18, 19 in one surface of the second face 12b, with terminals 30, 40 inserted through the through-holes 18, 19. Also included is a metal junction 50 that is located inside of the case 10 so that a wide face 20a of the electrode body 20 faces the sealing plate 14 and the first face 12a, and the tabs 22t, 24t face the second face 12b, and that connects the terminals 30, 40 and the tags 22t, 24t together.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, there is known an electric storage device that includes an electrode body having a pair of opposing wide surfaces, a case that houses the electrode body, and a terminal that is electrically connected to the electrode body. For example, Patent Document 1 discloses a technology for a battery (electric storage device) that includes an electrode body, a battery case (case), and a current collector terminal, and that aims to improve space efficiency within the case and prevent damage to the electrode current collector (tab) portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-44958 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the inventor's intensive study, there is room for improvement in the above-mentioned conventional technology. More specifically, since the above-mentioned electricity storage device includes a current collecting terminal (hereinafter also referred to as a "current collector"), the number of parts increases, which increases the electrical resistance.

[0005] The technology disclosed herein has been made in view of the above circumstances, and its purpose is to provide an electricity storage device that achieves both improved space efficiency and suppression of increases in electrical resistance. [Means for solving the problem]

[0006] The energy storage device disclosed herein comprises an electrode body in which a long, sheet-like positive electrode and a long, sheet-like negative electrode are wound in the longitudinal direction of the sheet with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a hexahedral case that houses the electrode body, the case having a wide, rectangular first surface and an opening facing the first surface, a pair of opposing second surfaces extending from the outer edge of the first surface toward the opening, and a pair of opposing third surfaces extending from the outer edge of the first surface toward the opening; a wide, rectangular sealing plate that seals the opening and faces the first surface; and a terminal that is electrically connected to the electrode body. Here, the positive electrode and the negative electrode each have a plurality of protruding tabs at one end in the winding axis direction of the electrode body, have a through hole on one side of the second surface, the terminal is inserted into the through hole, the electrode body is arranged inside the case so that the wide surface faces the sealing plate and the first surface and the tab faces the second surface to which the terminal is attached, and has a metal joint connecting the terminal and the tab.

[0007] According to this configuration, the tab and the terminal of the electrode body are electrically connected directly by a metal joint without using a current collector, thereby suppressing an increase in electrical resistance. Furthermore, by using a case with the above configuration, the electrode body can be easily housed in the case. This allows the volume of the electrode body to be increased. Increasing the volume of the electrode body reduces the range of movement of the electrode body within the case. This effectively reduces the risk of breakage of the tab. Therefore, it is possible to achieve both an improvement in the capacity of the electricity storage device (higher volumetric energy density) and electrical conductivity reliability. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically illustrating an electricity storage device according to one embodiment. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic vertical cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic diagram of an electrode assembly according to one embodiment. [Figure 5] FIG. 5 is a schematic diagram illustrating an electrode assembly accommodating step and a tab joining step according to one embodiment. [Figure 6] FIG. 6 is a schematic diagram illustrating a sealing step according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the drawings. Matters not mentioned in this specification but necessary for implementing the technology disclosed herein can be understood as design matters for those skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In the following drawings, components and parts that perform the same function are denoted by the same reference numerals. Furthermore, dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships. In this specification, a numerical range expressed as "A to B" includes A and B, and also encompasses the meanings of "preferably greater than A" and "preferably smaller than B."

[0010] In this specification, the term "electricity storage device" refers to a device that can be charged and discharged. Electricity storage devices include batteries generally referred to as lithium ion batteries and lithium secondary batteries, as well as lithium polymer batteries and lithium ion capacitors. A secondary battery generally refers to a battery that can be repeatedly charged and discharged by the movement of charge carriers between the positive and negative electrodes. Here, a lithium ion secondary battery is exemplified as one form of electricity storage device.

[0011] <Electricity storage device 1> FIG. 1 is a perspective view schematically illustrating an electricity storage device 1 according to one embodiment. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic longitudinal cross-sectional view taken along line III-III in FIG. 1. In FIG. 3, for ease of explanation, the number of negative electrode tabs 24t is shown as 11, but this is not limiting. In the following explanation, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom (the direction of gravity). In the drawings, the symbol X indicates the short-side direction (also referred to as the thickness direction) of the electricity storage device 1, the symbol Y indicates the long-side direction of the electricity storage device 1, and the symbol Z indicates the vertical direction (also referred to as the height direction). However, these directions are merely used for ease of explanation and do not limit the installation form of the electricity storage device 1 in any way.

[0012] 1 and 2, the electricity storage device 1 includes a case 10, an electrode assembly 20, a positive electrode terminal 30, and a negative electrode terminal 40. Although not shown, the electricity storage device 1 further includes an electrolyte solution. The electricity storage device 1 is preferably a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

[0013] The case 10 is, for example, a hexahedral member that houses the electrode assembly 20. As shown in Figures 1 and 2, the case 10 includes an exterior body 12 and a sealing plate 14. The case 10 is typically made of a metal such as aluminum, an aluminum alloy, or stainless steel.

[0014] The exterior body 12 is, for example, the main body of the case 10 that houses the electrode assembly 20. As shown in FIGS. 1 and 2, the exterior body 12 has an opening 12h, a first surface 12a, a pair of opposing second surfaces 12b and 12c, and a pair of opposing third surfaces 12d and 12e. In this embodiment, the first surface 12a has a wide rectangular shape and faces the opening 12h. The pair of second surfaces 12b and 12c extend from a pair of opposing long sides of the first surface 12a. As shown in FIGS. 1 and 2, the lower second surface 12c forms the bottom surface of the energy storage device 1. The upper second surface 12b is the top surface facing the bottom surface and is the mounting surface for the positive electrode terminal 30 and the negative electrode terminal 40. The pair of third surfaces 12d and 12e extend from a pair of opposing short sides of the first surface 12a. In this specification, "rectangular" includes shapes in which straight long and short sides are joined to each other via a curve, shapes in which at least one of the long and short sides is not straight but is curved, uneven, or bent and composed of multiple straight or curved lines, and the like.

[0015] Opening 12h is, for example, a location where sealing plate 14 is attached. Here, opening 12h is formed by being surrounded by the upper edges of the pair of second surfaces 12b, 12c and the upper edges of the pair of third surfaces 12d, 12e, and has a wide rectangular shape. As shown in FIG. 3 , opening 12h has a recessed step 121 along its inner edge. Here, sealing plate 14 is fitted into step 121. Furthermore, sealing plate 14 is welded to step 121 of exterior body 12, thereby integrating exterior body 12 and sealing plate 14, and hermetically sealing case 10.

[0016] As shown in FIG. 2, the second surface 12b is provided with a drain valve 123, a liquid inlet 16, a first terminal mounting portion 124, and a second terminal mounting portion 125. The drain valve 123 is, for example, a thin-walled portion. Here, the drain valve 123 is configured to break when the pressure inside the case 10 reaches a predetermined value or higher, thereby discharging gas inside the case 10 to the outside. The liquid inlet 16 is a through-hole for injecting electrolyte into the case 10 after the sealing plate 14 is attached to the exterior body 12. Here, the liquid inlet 16 is sealed with a sealing member 16a after the electrolyte is injected. The first terminal mounting portion 124 is, for example, a portion where the positive electrode terminal 30 is attached. In the embodiment shown in FIG. 2, the first terminal mounting portion 124 is a step recessed from the second surface 12b. A through-hole 18 through which the positive electrode terminal 30 is inserted is provided at the bottom of the first terminal mounting portion 124. The second terminal mounting portion 125 is a portion where, for example, the negative electrode terminal 40 is mounted. In the embodiment shown in Fig. 2, the second terminal mounting portion 125 is a step recessed from the second surface 12b. A through-hole 19 through which the negative electrode terminal 40 is inserted is provided at the bottom of the second terminal mounting portion 125.

[0017] The sealing plate 14 is, for example, a flat plate-like member that seals the opening 12h. Therefore, the shape of the sealing plate 14 may be a shape that corresponds to the shape of the opening 12h. In this embodiment, the sealing plate 14 has a wide rectangular shape. Here, when the sealing plate 14 is attached to the opening 12h, the sealing plate 14 faces the first surface 12a.

[0018] As the electrolyte, any known electrolyte may be used without any particular limitation. For example, a non-aqueous electrolyte in which a supporting salt (electrolyte salt) is dissolved in a non-aqueous solvent (organic solvent) is preferably used. Examples of non-aqueous solvents include carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as LiPF6. The electrolyte may contain additives as needed.

[0019] The positive electrode terminal 30 is a member electrically connected to the positive electrode 22 of the electrode assembly 20. As shown in FIG. 2, the positive electrode terminal 30 is inserted through the through-hole 18 and exposed to the outside of the exterior housing 12. Here, the positive electrode terminal 30 has a shaft portion 30a and a base portion 30b. The shaft portion 30a is, for example, cylindrical and is the portion inserted through the through-hole 18. The base portion 30b is, for example, flat and is the portion disposed along the outer surface of the exterior housing 12 (here, the second surface 12b). As shown in FIG. 2, the positive electrode terminal 30 is here crimped to the peripheral portion surrounding the through-hole 18 of the exterior housing 12 by crimping, and a crimped portion is formed at the end of the shaft portion 30a inside the exterior housing 12. The positive electrode terminal 30 is preferably made of metal, more preferably aluminum or an aluminum alloy. The positive electrode terminal 30 is an example of a "terminal" disclosed herein.

[0020] The negative electrode terminal 40 is a member electrically connected to the negative electrode 24 of the electrode assembly 20. As shown in FIG. 2, the negative electrode terminal 40 is inserted into the through-hole 19 and exposed to the outside of the exterior housing 12. Here, the negative electrode terminal 40 has a shaft portion 40a and a base portion 40b. The shaft portion 40a is, for example, cylindrical and is the portion inserted into the through-hole 19. The base portion 40b is, for example, flat and is the portion disposed along the outer surface of the exterior housing 12 (here, the second surface 12b). As shown in FIG. 2, the negative electrode terminal 40 is here crimped to the peripheral portion surrounding the through-hole 19 of the exterior housing 12 by crimping, and a crimped portion is formed at the end of the shaft portion 40a inside the exterior housing 12. The negative electrode terminal 40 is preferably made of metal, more preferably copper or a copper alloy, for example. The negative electrode terminal 40 is an example of a "terminal" disclosed herein.

[0021] The positive electrode terminal 30 and the negative electrode terminal 40 are insulated from the exterior body 12 by a gasket 92 and an internal insulating member 93, respectively. Here, the gasket 92 functions to insulate the exterior body 12 from the positive electrode terminal 30 and the negative electrode terminal 40, and also to seal (close) the through holes 18 and 19. The gasket 92 and the internal insulating member 93 are preferably made of a material with excellent chemical resistance and weather resistance. The gasket 92 and the internal insulating member 93 may be made of an electrically insulating and elastically deformable resin material, such as a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA), polyphenylene sulfide resin (PPS), or aliphatic polyamide. The gasket 92 and the internal insulating member 93 may be integrated, for example, by insert molding.

[0022] The electrode assembly 20 is a power generating element of the electricity storage device 1, having, for example, a positive electrode 22 and a negative electrode 24. FIG. 4 is a schematic diagram of the electrode assembly 20 according to one embodiment. As shown in FIG. 4, the electrode assembly 20 is a wound electrode assembly in which a long sheet-like positive electrode 22 and a long sheet-like negative electrode 24 are wound in the sheet longitudinal direction LD with a separator 23 interposed therebetween. The electrode assembly 20 can be produced, for example, by winding the positive electrode 22, the negative electrode 24, and the separator 23 into a cylindrical body and press-molding the cylindrical body. Therefore, the electrode assembly 20 has a flat shape and a pair of wide surfaces 20a (see FIGS. 2 and 3). The number of electrode assemblies 20 arranged inside one exterior housing 12 is not particularly limited and may be two or more (plural), or may be one. As shown in FIG. 3, two electrode assemblies are arranged inside the exterior housing 12.

[0023] As shown in FIGS. 2 and 3 , the electrode assembly 20 is housed in the exterior housing 12 so that the winding axis direction WD and the vertical direction (up-down direction) of the electricity storage device 1 are substantially parallel. In this embodiment, the winding axis WL of the electrode assembly 20 is substantially parallel to the first surface 12a, the third surfaces 12d and 12e, and the sealing plate 14, and substantially perpendicular to the second surfaces 12b and 12c. The wide surface 20a of the electrode assembly 20 faces the first surface 12a and the sealing plate 14. One end surface of the electrode assembly 20 faces the second surface 12b, and the other end surface faces the second surface 12c. Here, the end surface of the electrode assembly 20 is the laminated surface of the positive electrode 22, the negative electrode 24, and the separator 23, and is an open surface. The electrode assembly 20 may be housed inside the case 10 covered with an electrode assembly holder (not shown) made of an insulating resin sheet.

[0024] 4, the positive electrode 22 has a long, strip-shaped positive electrode current collector foil 22c (e.g., aluminum foil) and a positive electrode active material layer 22a fixed to at least one surface of the positive electrode current collector foil 22c. Although not particularly limited, a protective layer 22p may be provided on one side edge portion in the winding axis direction WD of the positive electrode 22, as necessary. Note that, as the constituent materials of the positive electrode active material layer 22a and the protective layer 22p, materials used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without particular limitation.

[0025] A plurality of positive electrode tabs 22t are provided at one end of the positive electrode current collector foil 22c in the winding axis direction WD (the upper end in FIG. 4). The plurality of positive electrode tabs 22t protrude toward one end of the positive electrode current collector foil 22c in the winding axis direction WD (the upper end in FIG. 4). The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction LD of the positive electrode 22. The positive electrode tabs 22t are part of the positive electrode current collector foil 22c and are portions of the positive electrode current collector foil 22c where the positive electrode active material layer 22a is not formed (active material layer unformed portions). In the embodiment shown in FIG. 4, a protective layer 22p is provided on the base end side of the positive electrode tab 22t. In this embodiment, the plurality of positive electrode tabs 22t protrude further in the winding axis direction WD than the separator 23. The shape and size of the positive electrode tabs 22t can be appropriately adjusted by, for example, their formation position, taking into consideration the state of connection to the positive electrode terminal 30. The positive electrode tabs 22t are stacked at one end in the winding axis direction WD (the upper end in FIG. 4) to form a positive electrode tab group. Therefore, the height (length in the winding axis direction WD) of each positive electrode tab 22t and the width (length in the longitudinal direction LD) of each positive electrode tab 22t do not have to be the same. The positive electrode tab 22t is an example of a "tab" disclosed herein.

[0026] 4, the negative electrode 24 has a long, strip-shaped negative electrode current collector foil 24c (e.g., copper foil) and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector foil 24c. Note that, as a constituent material of the negative electrode active material layer 24a, any material used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without any particular limitation.

[0027] A plurality of negative electrode tabs 24t are provided at one end (the upper end in FIG. 4 ) of the negative electrode current collector foil 24c in the winding axis direction WD. The plurality of negative electrode tabs 24t protrude toward one end (the upper end in FIG. 4 ) in the winding axis direction WD. The plurality of negative electrode tabs 24t are provided at intervals (intermittently) along the longitudinal direction LD of the negative electrode 24. The negative electrode tabs 24t are part of the negative electrode current collector foil 24c and are portions of the negative electrode current collector foil 24c where the negative electrode active material layer 24a is not formed (active material layer unformed portions). In this embodiment, the plurality of negative electrode tabs 24t protrude beyond the separator 23 in the winding axis direction WD. The shape and size of the negative electrode tabs 24t can be appropriately adjusted by their formation position, etc., taking into consideration, for example, the state of connection to the negative electrode terminal 40. For example, the plurality of negative electrode tabs 24t are stacked at one end (the upper end in FIG. 4 ) in the winding axis direction WD to form a negative electrode tab group. Therefore, the height (length in the winding axis direction WD) of each negative electrode tab 24t and the width (length in the longitudinal direction LD) of each negative electrode tab 24t do not need to be the same. The positive electrode tab 22t is an example of a "tab" disclosed herein.

[0028] The separator 23 is a member that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. In this embodiment, the separator 23 forms the outer surface of the electrode body 20. The separator 23 is, for example, a porous sheet made of a resin such as a polyolefin resin, such as polyethylene (PE) or polypropylene (PP).

[0029] 4, in the electrode assembly 20, the lower end P3 of the separator 23 is the lowest, followed by the lower end P2 of the negative electrode 24, and the lower end P1 of the positive electrode 22 is the highest. The widths of the sheets (in FIG. 4, the length in the winding axis direction WD, excluding the positive electrode tab 22t and the negative electrode tab 24t) are largest in the order of the separator 23, the negative electrode 24, and the positive electrode 22.

[0030] In the electricity storage device 1 disclosed herein, the electrode body 20 is disposed inside the case 10 so that the wide surface 20a faces the sealing plate 14 and the first surface 12a, and the positive electrode tab 22t and the negative electrode tab 24t face the second surface 12b to which the positive electrode terminal 30 and the negative electrode terminal 40 are attached. The positive electrode tab 22t is joined to the positive electrode terminal 30 (specifically, the shaft portion 30a) by a metal joint 50. Similarly, the negative electrode tab 24t is joined to the negative electrode terminal 40 (specifically, the shaft portion 40a) by a metal joint 50. The metal joint 50 is, for example, a portion where a tab and a terminal (here, the positive electrode tab 22t and the positive electrode terminal 30, and the negative electrode tab 24t and the negative electrode terminal 40) are joined to each other by melting and solidifying.

[0031] The exterior body 12 used in the electricity storage device 1 disclosed herein has a wide rectangular opening 12h. Therefore, the positive electrode tab 22t and the positive electrode terminal 30, and the negative electrode tab 24t and the negative electrode terminal 40 can be electrically connected by the metal joint 50 without using a current collector. In other words, the electrode body 20 is directly electrically connected to the positive electrode terminal 30 and the negative electrode terminal 40. Therefore, an increase in the electrical resistance of the electricity storage device 1 can be suppressed. The metal joint 50 can be suitably formed by, for example, laser welding, ultrasonic welding, resistance welding, or the like.

[0032] Furthermore, since the exterior body 12 has a wide rectangular opening 12h, the electrode body 20 can be easily housed inside the exterior body 12. Therefore, compared to an electricity storage device using a conventional case (see Patent Document 1), the clearance required to house the electrode body 20 is smaller. This allows the volume of the electrode body 20 to be larger. Furthermore, by increasing the volume of the electrode body 20, the range of movement of the electrode body 20 within the case 10 is reduced. This makes it possible to suitably reduce the risk of breakage of the positive electrode tab 22t and the negative electrode tab 24t. Therefore, it is possible to achieve both an improvement in the capacity of the electricity storage device 1 (higher volumetric energy density) and electrical conductivity reliability.

[0033] In some preferred embodiments, as shown in Fig. 3, a plurality of electrode assemblies 20 are arranged inside the case 10 (exterior body 12), and the metal joint 50 is formed by joining the positive electrode tabs 22t and the negative electrode tabs 24t of the plurality of electrode assemblies 20 to the positive electrode terminal 30 and the negative electrode terminal 40. This configuration makes it possible to provide an electricity storage device 1 with more preferably improved capacity. Note that, although the electricity storage device 1 includes two electrode assemblies 20 in this embodiment, the invention is not limited thereto, and the number of electrode assemblies 20 may be three or more.

[0034] In some preferred embodiments, the sealing plate 14 abuts against the surface of the wide surface 20a of the electrode assembly 20 that faces the sealing plate 14 inside the case 10 (when multiple electrode assemblies 20 are housed in the case 10, the wide surface 20a of the electrode assembly 20 that faces the sealing plate 14). In other words, when the electrode assembly 20 is housed and the sealing plate 14 is welded to the exterior body 12, the wide surface 20a of the electrode assembly 20 is pressed against the sealing plate 14. This configuration restricts movement of the electrode assembly 20 inside the case 10 even when vibrations, impacts, and the like are applied during use of the electricity storage device 1. This more effectively reduces the risk of damage to the positive electrode tab 22t and the negative electrode tab 24t. This makes it possible to provide an electricity storage device 1 with improved conduction reliability. When the electricity storage device 1 has such a configuration, it is preferable that, for example, approximately 70% or more of the wide surface 20a of the electrode body 20 abuts against the sealing plate 14, and preferably approximately 80% or more of the wide surface 20a abuts against the sealing plate 14.

[0035] <Method of Manufacturing Electricity Storage Device 1> The electricity storage device 1 can be manufactured by a manufacturing method that includes, for example, a terminal assembling step, an electrode assembly accommodating step, a metal joint forming step, a sealing plate sealing step, and a liquid injection step, typically in this order, using the above-described case 10 (exterior body 12 and sealing plate 14), electrode assembly 20 (one or more; here, two), electrolyte, positive electrode terminal 30, and negative electrode terminal 40. The manufacturing method for the electricity storage device 1 is characterized by performing the electrode assembly accommodating step, the metal joint forming step, and the sealing step using the above-described case 10 and electrode assembly 20. The remaining manufacturing processes may be the same as conventional manufacturing processes. The manufacturing method disclosed herein may also include other steps at any stage.

[0036] (Terminal assembly process) In the terminal assembling process, the positive terminal 30, the negative terminal 40, a gasket 92, and an internal insulating member 93 are assembled to the second surface 12b of the exterior body 12. The negative terminal 40 can be fixed to the second surface 12b of the exterior body 12, for example, by crimping (riveting). The crimping process is performed by sandwiching the gasket 92 between the negative terminal 40 and the second surface 12b of the exterior body 12, and further sandwiching the insulating member 80 between the second surface 12b of the exterior body 12 and the shaft portion 40a of the negative terminal 40 (see FIG. 8). This crimps the end of the shaft portion 40a of the negative terminal 40. This crimping process compresses the gasket 92 and the internal insulating member 93, integrally fixing the negative terminal 40, the second surface 12b of the exterior body 12, and the internal insulating member 93 to the second surface 12b of the exterior body 12, and sealing the through-hole 19. The assembly method for the positive electrode terminal 30 may be the same as the above-described assembly method for the negative electrode terminal 40. The terminal assembly step is not limited to this, and for example, the second surface 12b of the exterior body 12, the positive electrode terminal 30 and the negative electrode terminal 40, the gasket 92, and the internal insulating member 93 may be integrated by insert molding.

[0037] (Electrode body accommodation process) In the electrode assembly accommodating step, the electrode assembly 20 is accommodated in the exterior housing 12. FIG. 5 is a schematic diagram illustrating the electrode assembly accommodating step and the tab joining step according to one embodiment. In FIG. 5, the planned joining portion 50a (the portion where the metal joint 50 is to be formed) is indicated by a virtual line. At this time, the electrode assembly 20 is arranged so that one wide surface 20a of the electrode assembly 20 faces the first surface 12a and the positive electrode tab 22t and the negative electrode tab 24t face the second surface 12b to which the positive electrode terminal 30 and the negative electrode terminal 40 are attached. Here, the positive electrode tab 22t is curved and arranged to face the shaft portion 30a of the positive electrode terminal 30. Similarly, the negative electrode tab 24t is curved and arranged to face the shaft portion 40a of the negative electrode terminal 40. When manufacturing an electricity storage device 1 having a plurality of electrode assemblies 20, the electrode assembly accommodating step can be performed multiple times, with the tab joining step sandwiched between them. In this embodiment, as shown in Fig. 5, the electrode assembly accommodating step is first performed on one of the two electrode assemblies 20. After that, the tab joining step is performed, and then the electrode assembly accommodating step is performed on the remaining electrode assembly 20.

[0038] (Tab joining process) In the tab joining process, multiple positive electrode tabs 22t are electrically joined to the positive electrode terminal 30, and multiple negative electrode tabs 24t are electrically joined to the negative electrode terminal 40. Here, a joining method using laser welding is described as an example, but this is not limiting, and any of the joining methods described above may be used. Specifically, as shown in FIG. 5 , the negative electrode tab 24t of the electrode assembly 20 is first arranged so as to overlap the shank 40a of the negative electrode terminal 40. At this time, the negative electrode tab 24t may be bent to make it easier to overlap the shank 40a of the negative electrode terminal 40. When the energy storage device 1 has multiple electrode assemblies 20, the negative electrode tab 24t of another electrode assembly 20 may be further overlapped on one of the negative electrode tabs 24t, as shown in FIGS. 3 and 5 . Then, with the negative electrode tab 24t overlapped on the shank 40a of the negative electrode terminal 40, a laser is scanned over the intended joining portion 50a. This forms a metal joint 50, electrically connecting the negative electrode terminal 40 and the negative electrode tab 24t. The method for joining the positive electrode tab 22t and the positive electrode terminal 30 may be the same as the method for joining the negative electrode tab 24t and the negative electrode terminal 40 described above. For ease of explanation, the third surface 12e of the exterior body 12 is shown facing downward in Fig. 5, but this is not limiting. In the tab joining step, the tab joining step can be performed with the exterior body 12 tilted at an angle that makes it easy to form the metal joint 50, depending on the joining method and the jig used for joining.

[0039] (Sealing plate sealing process) In the sealing plate sealing process, the opening 12h of the exterior body 12 is sealed with the sealing plate 14. FIG. 6 is a schematic diagram illustrating the sealing plate sealing process according to one embodiment. In FIG. 6, for ease of explanation, the pressing direction of the sealing plate 14 is indicated by a hollow arrow, and the scanning path of the laser L is indicated by a virtual line. As shown in FIG. 6, the sealing plate 14 is fitted into the opening 12h of the exterior body 12, and then pressed toward the first surface 12a of the exterior body 12 (the direction of the hollow arrow in FIG. 6). Then, while maintaining the state in which the sealing plate 14 is pressed toward the first surface 12a of the exterior body 12, the sealing plate 14 and the exterior body 12 are sealed. As a result, the opening 12h of the exterior body 12 is sealed with the sealing plate 14, with the wide surface 20a of the electrode body 20 closest to the sealing plate 14 abutting against the sealing plate 14. This more suitably reduces the risk of damage to the positive electrode tab 22t and the negative electrode tab 24t. Here, the laser L is scanned along the periphery of the sealing plate 14 (here, in the direction of the imaginary line in FIG. 6). However, the sealing method is not limited to this.

[0040] The pressure strength of the sealing plate 14 in the sealing step is not particularly limited and can be changed as appropriate depending on the material, thickness, and size of the case 10, but can be, for example, 10 kN or more.

[0041] (liquid injection process) In the liquid injection step, the electrolyte is injected into the case 10 through the liquid injection hole 16. Thereafter, the liquid injection hole 16 is closed with a sealing member 16a to hermetically seal the case 10. In this manner, the electricity storage device 1 can be manufactured.

[0042] The electricity storage device 1 can be used for a variety of purposes, but is preferably used in applications that require a large capacity for the electricity storage device 1, or in applications where external forces such as vibrations and impacts may be applied during use, typically as a power source (driving power source) for motors mounted on various vehicles, such as passenger cars, trucks, etc. The type of vehicle is not particularly limited, and examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0043] Although several embodiments of the technology disclosed herein have been described above, the above embodiments are merely examples. The technology disclosed herein can be implemented in various other forms. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiments. For example, it is possible to replace part of the above-described embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0044] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: An electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a hexahedral case that houses the electrode body, the hexahedral case having a wide rectangular first surface and an opening opposing the first surface, a pair of opposing second surfaces extending from the outer edge of the first surface toward the opening, and a pair of opposing third surfaces extending from the outer edge of the first surface toward the opening; and a wide rectangular sealing plate that seals the opening and faces the first surface. an electric storage device comprising a case and terminals electrically connected to the electrode body, wherein the positive electrode and the negative electrode each have a plurality of protruding tabs at one end in a winding axis direction of the electrode body, and a through hole on one side of the second surface, the terminals are inserted into the through hole, the electrode body is disposed inside the case such that the wide surface faces the sealing plate and the first surface and the tabs face the second surface to which the terminals are attached, and the electric storage device has a metal joint connecting the terminals and the tabs. Item 2: The electricity storage device according to item 1, wherein a plurality of the electrode bodies are arranged inside the case, and the metal joint is formed by joining the tabs of the plurality of electrode bodies to the terminals. Item 3: The electricity storage device according to item 1 or 2, wherein the wide surface of the electrode assembly is pressed against the sealing plate when the sealing plate and the exterior body are welded together. [Explanation of symbols]

[0045] 1. Energy storage devices 10 cases 12 Exterior body 12a 1st page 12b, 12c 2nd side 12d, 12e 3rd side 12h opening 14 Sealing plate 18, 19 Through holes 20 Electrode body 22 Positive electrode 22t Positive electrode tab 23 Separator 24 Negative electrode 24t negative electrode tab 30 Positive terminal 40 Negative terminal 50 Metal joints 92 Gasket 93 Internal insulating material

Claims

1. An electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a hexahedral case for accommodating the electrode assembly, the case having an exterior body having a wide rectangular first surface and an opening facing the first surface, a pair of opposing second surfaces extending from an outer edge of the first surface toward the opening, and a pair of opposing third surfaces extending from the outer edge of the first surface toward the opening; and a wide rectangular sealing plate that seals the opening and faces the first surface; a terminal electrically connected to the electrode body; An electricity storage device comprising: each of the positive electrode and the negative electrode has a plurality of protruding tabs at one end in the winding axis direction of the electrode body; a through hole on one surface of the second surface; The terminal is inserted into the through hole, the electrode body is disposed inside the case such that the wide surface faces the sealing plate and the first surface and the tab faces the second surface to which the terminal is attached, and 70% or more of the wide surface of the electrode body facing the sealing plate abuts against the sealing plate; a metal joint portion connecting the terminal and the tab; When the sealing plate and the exterior body are welded together, the wide surface of the electrode body is pressed against the sealing plate. Energy storage device.

2. An electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the sheet longitudinal direction with a separator interposed therebetween, the electrode body having a pair of opposing wide surfaces; a hexahedral case for accommodating the electrode assembly, the case having an exterior body having a wide rectangular first surface and an opening facing the first surface, a pair of opposing second surfaces extending from an outer edge of the first surface toward the opening, and a pair of opposing third surfaces extending from the outer edge of the first surface toward the opening; and a wide rectangular sealing plate that seals the opening and faces the first surface; a terminal electrically connected to the electrode body; An electricity storage device comprising: each of the positive electrode and the negative electrode has a plurality of protruding tabs at one end in the winding axis direction of the electrode body; a through hole on one surface of the second surface; The terminal is inserted into the through hole, the electrode body is disposed inside the case such that the wide surface faces the sealing plate and the first surface and the tab faces the second surface to which the terminal is attached, and 70% or more of the wide surface of the electrode body facing the sealing plate abuts against the sealing plate; a metal joint portion connecting the terminal and the tab; A plurality of the electrode bodies are arranged inside the case, the metal joints are formed by joining the tabs of the plurality of electrode bodies to the terminals, When the sealing plate and the exterior body are welded together, the wide surface of the electrode body is pressed against the sealing plate. Energy storage device.

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