Power storage device

Abstract

To provide a power storage device which makes a positive electrode tab less likely to be damaged.SOLUTION: A power storage device 100 disclosed here includes: a square case 10 having a pair of third surfaces 12b; an electrode body 20 having a positive electrode and a negative electrode; a positive electrode tab 23 provided at the positive electrode; a negative electrode tab 24 provided at the negative electrode; an electrolyte; and a liquid injection hole 15 provided in a position located on the third surface 12b of the case 10 and closer to the negative electrode tab 24 than the positive electrode tab 23.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, an electric storage device including an electrode assembly, an electrolyte, and a case that accommodates the electrode assembly and the electrolyte has been known. Prior art documents relating to the injection of an electrolyte into such an electric storage device include Japanese Patent No. 4009802 and Japanese Patent Laid-Open No. 2004-247120. For example, Japanese Patent No. 4537353 discloses a laminated battery that includes an electrode assembly having a positive electrode and a negative electrode, an electrolyte, and a case that accommodates the electrode assembly and the electrolyte. This laminated battery further includes a positive electrode tab extending from the positive electrode and a negative electrode tab extending from the negative electrode, disposed inside the case, and a liquid injection hole located midway between the positive electrode tab and the negative electrode tab. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4009802 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-247120 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the inventors' investigations, positive electrode tabs are generally softer and more easily deformed than negative electrode tabs. Therefore, if a liquid injection hole is provided near the positive electrode tab, the force of the electrolyte injection may damage the positive electrode tab. In particular, in large-capacity or large-sized batteries used in vehicles, etc., a large amount of electrolyte is used, and a large amount of electrolyte may be injected through the liquid injection hole all at once, which can cause such problems to become apparent.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electricity storage device in which the positive electrode tab is less likely to be damaged when an electrolyte is poured therein. [Means for solving the problem]

[0006] The present invention provides an electricity storage device comprising: a rectangular case having a substantially rectangular first surface having a pair of short sides and a pair of long sides, a pair of second surfaces extending from the pair of short sides, respectively, and a pair of third surfaces extending from the pair of long sides, respectively, and having areas larger than the first and second surfaces; an electrode assembly housed inside the case and having a positive electrode and a negative electrode; a positive electrode tab provided on the positive electrode; a negative electrode tab provided on the negative electrode; an electrolyte housed inside the case; and a liquid injection hole provided on the third surface of the case, the liquid injection hole being located closer to the negative electrode tab than the positive electrode tab.

[0007] In the present invention, by providing the injection hole closer to the negative electrode tab than to the positive electrode tab, damage to the positive electrode tab during injection of the electrolyte can be relatively reduced. [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 cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a partially enlarged view that schematically shows the vicinity of the negative electrode tab during injection. [Figure 5] FIG. 5 is a view corresponding to FIG. 2 according to the first modified example. [Figure 6] FIG. 6 is a view corresponding to FIG. 1 according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the technology disclosed herein will be described below with reference to the drawings as appropriate. Matters necessary for implementing the technology disclosed herein other than those specifically mentioned in this specification (e.g., the general configuration and manufacturing process of an electricity storage device that do not characterize the technology disclosed herein) can be understood as design matters of a person skilled in the art based on 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 addition, in the following drawings, components and parts that perform the same function are designated by the same reference numerals, and redundant explanations may be omitted or simplified. In addition, in this specification, the notation "A to B" indicating a range is intended to include not only the meaning of A or more and not more than B, but also the meanings of "greater than A" and "smaller than B."

[0010] [Energy storage devices] FIG. 1 is a perspective view schematically illustrating an energy storage device 100 according to an embodiment. FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic transverse sectional view taken along line III-III in FIG. 1. As shown in FIG. 1, the energy storage device 100 has a hexahedral polygonal shape (specifically, a rectangular parallelepiped shape). In the following description, the symbols F, Rr, L, R, U, and D in the drawings represent front, rear, left, right, top, and bottom, and the symbols X, Y, and Z in the drawings represent the thickness direction, width direction perpendicular to the thickness direction, and up-down direction perpendicular to the thickness direction and width direction, respectively, of the energy storage device 100. However, these directions are merely used for convenience of description and do not limit the installation form of the energy storage device 100 in any way.

[0011] As shown in FIG. 2, the electricity storage device 100 includes a case 10, an electrode assembly 20, an electrolyte (not shown), a positive electrode terminal 30, a negative electrode terminal 40, and an inlet 15 (see also FIG. 1). Here, the electricity storage device 100 is a non-aqueous electrolyte secondary battery, such as a lithium-ion secondary battery. The electricity storage device 100 is configured by accommodating the electrode assembly 20 and the electrolyte in a case 10 to which the positive electrode terminal 30 and the negative electrode terminal 40 are attached and which is provided with the inlet 15. In this specification, the term "electricity storage device" refers to a general device that can be repeatedly charged and discharged, and is a concept that encompasses secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors such as lithium-ion capacitors and electric double layer capacitors.

[0012] The case 10 is a housing that houses the electrode assembly 20 and the electrolyte. As shown in FIG. 1, the case 10 has a flat, bottomed, and rectangular shape (specifically, a rectangular parallelepiped shape). The material of the case 10 may be the same as that conventionally used, and is not particularly limited. The case 10 is preferably made of metal, and more preferably made of, for example, iron, iron alloys such as stainless steel, aluminum, aluminum alloys, or the like. The case 10 is preferably made of a metal plate.

[0013] 2, the case 10 here includes a rectangular cylindrical case body 12 having a pair of openings 12h at both ends in the width direction Y, and two sealing plates 14 that close the pair of openings 12h of the case body 12. The case 10 is integrated by joining (for example, welding) the sealing plates 14 to the peripheries of the pair of openings 12h of the case body 12. The case 10 is hermetically sealed (sealed).

[0014] 1, the case body 12 includes a substantially rectangular bottom surface 12a (first surface) having a pair of short sides and a pair of long sides, a pair of long side surfaces 12b (third surfaces) extending from the pair of long sides of the bottom surface 12a and facing each other, and a top surface 12c (fourth surface) facing the bottom surface 12a. The case body 12 is formed, for example, by bending a single metal plate into a rectangular tube shape and joining the seams (for example, by welding). In this embodiment, the bottom surface 12a is an example of the "first surface," and the long side surfaces 12b are an example of the "third surface."

[0015] The long side surface 12b (third surface) has a larger area than the bottom surface 12a (first surface) and the sealing plate 14 (second surface). The long side surface 12b is provided with a liquid inlet hole 15. The liquid inlet hole 15 will be described later. The top surface 12c (fourth surface) has the same shape and area as the bottom surface 12a. Therefore, the long side surface 12b has a larger area than the top surface 12c. The top surface 12c extends from each of the long sides of the pair of long side surfaces 12b and connects the upper ends of the pair of long side surfaces 12b.

[0016] In this specification, the term "approximately rectangular" refers not only to a perfect rectangular shape (rectangular shape), but also to shapes such as those in which the corners connecting the long and short sides of the rectangle are rounded, or those in which the corners have notches.

[0017] The pair of sealing plates 14 are plate-like members that seal the pair of openings 12h, respectively. The sealing plates 14 are substantially rectangular in plan view. The sealing plates 14 extend from a pair of short sides of the bottom surface 12a, respectively, and face each other. A positive electrode terminal 30 and a negative electrode terminal 40 are provided on each of the pair of sealing plates 14. The positive electrode terminal 30 and the negative electrode terminal 40 will be described later. In this embodiment, the sealing plates 14 are an example of a "second surface."

[0018] The dimensions of the case 10 can be changed appropriately depending on, for example, the size of the electrode assembly 20. Therefore, although not particularly limited, as shown in FIG. 2, for example, the width (length in the width direction Y) Ly of the case 10 is preferably 20 cm or more, more preferably 25 cm or more. The width Ly may be 35 cm or less, or may be 30 cm or less. Furthermore, the height (length in the vertical direction Z) Lz of the case 10 is preferably 5 cm or more, more preferably 8 cm or more. The height Lz may be 12 cm or less, or may be 10 cm or less. In large batteries in which the width Ly or height Lz of the case 10 is equal to or greater than a predetermined value, a large amount of electrolyte is used. Therefore, applying the technology disclosed herein is particularly effective.

[0019] Although not particularly limited, the internal volume of the case 10 (the spatial volume of the entire case 10 calculated by (length in the thickness direction X) × (length in the width direction Y) × (length in the vertical direction Z)) is 500 cm 3 More than 1000cm is preferable. 3 The upper limit of the internal volume of the case 10 is 3000 cm 3 Less than 1500cm is also acceptable. 3 In a large battery in which the internal volume of the case 10 is equal to or greater than a predetermined value, the amount of electrolyte used is also large. Therefore, it is particularly effective to apply the technology disclosed herein. However, the technology disclosed herein is applicable only to batteries with an internal volume of 300 cm or less. 3 or less (typically 150cm 3 It can also be applied to small batteries (see below).

[0020] As shown in FIG. 2, the electrode assembly 20 is housed inside the case 10. Although not shown, the electrode assembly 20 has a positive electrode and a negative electrode. The configuration of the electrode assembly 20 may be the same as that of a conventional electrode assembly and is not particularly limited. The positive electrode typically has a positive electrode current collector and a positive electrode active material layer fixed to the positive electrode current collector. The negative electrode typically has a negative electrode current collector and a negative electrode active material layer fixed to the negative electrode current collector. The electrode assembly 20 is housed inside the case 10 covered with a resin insulating sheet (electrode assembly holder) 50 in this example.

[0021] 3, here, two (plural) electrode assemblies 20 are housed inside one case 10. The two electrode assemblies 20 are arranged side by side along the thickness direction X. However, the number of electrode assemblies 20 housed inside one case 10 is not particularly limited, and in other embodiments, it may be one, or three or more.

[0022] Here, the electrode assembly 20 is a wound electrode assembly formed by stacking a strip-shaped positive electrode and a strip-shaped negative electrode with a strip-shaped separator interposed therebetween and winding them in the longitudinal direction around a winding axis. In this embodiment, the electrode assembly 20 is arranged inside the case 10 with the winding axis oriented approximately parallel to the width direction Y. However, in other embodiments, the electrode assembly 20 may be arranged inside the case 10 with the winding axis oriented approximately parallel to the up-down direction Z, for example. Furthermore, in other embodiments, the electrode assembly 20 may be a laminated electrode assembly formed by stacking multiple square-shaped (typically rectangular) positive electrodes and multiple square-shaped (typically rectangular) negative electrodes in an insulated state.

[0023] As shown in FIGS. 2 and 3, a positive electrode tab 23 is provided on the positive electrode of the electrode assembly 20. The positive electrode tab 23 is preferably made of metal, more preferably aluminum or an aluminum alloy. The positive electrode tab 23 is preferably made of the same metal as the positive electrode terminal 30. In this example, the positive electrode tab 23 is part of the positive electrode current collector. In this example, the positive electrode tab 23 is convex and protrudes from the electrode assembly 20 toward one side in the width direction Y (the left side in FIGS. 2 and 3). In this example, the positive electrode tab 23 protrudes toward the first sealing plate 14 (the first second surface of the sealing plate 14 on the left side in FIGS. 2 and 3). The positive electrode tab 23 is electrically connected directly or indirectly to the positive electrode terminal 30. In this example, the positive electrode tab 23 is electrically connected to the positive electrode terminal 30 via a positive electrode current collector 32.

[0024] The negative electrode tab 24 is provided on the negative electrode of the electrode assembly 20. The negative electrode tab 24 is preferably made of metal, more preferably copper or a copper alloy. The negative electrode tab 24 is preferably made of the same metal as the negative electrode terminal 40. In this example, the negative electrode tab 24 is part of the negative electrode current collector. In this example, the negative electrode tab 24 is convex and protrudes from the electrode assembly 20 toward the other side in the width direction Y (the right side in Figures 2 and 3). In this example, the negative electrode tab 24 protrudes toward the second sealing plate 14 (the right sealing plate 14, the second surface of the second electrode in Figures 2 and 3). The negative electrode tab 24 is electrically connected directly or indirectly to the negative electrode terminal 40. In this example, the negative electrode tab 24 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 42.

[0025] As shown in FIG. 3, the negative electrode tabs 24 of the two electrode assemblies 20 are each attached to the negative electrode current collecting portion 42 in a bent or curved state. Specifically, the negative electrode tab 24 of the electrode assembly 20 located on the front side in the thickness direction X is bent to form an L-shape in plan view. The negative electrode tab 24 of the electrode assembly 20 located on the rear side in the thickness direction X is bent to form a U-shape in plan view. The negative electrode tab 24 of the electrode assembly 20 located on the rear side in the thickness direction X has a curved portion 24b that curves from the first long side surface 12b (the rear long side surface 12b in FIG. 3, the first third surface) to the second long side surface 12b (the front long side surface 12b in FIG. 3, the second third surface).

[0026] The electrolyte solution is accommodated inside the case 10 together with the electrode assembly 20. The electrolyte solution may be the same as conventional ones and is not particularly limited. The electrolyte solution is typically a non-aqueous electrolyte solution containing a non-aqueous solvent and a supporting salt (electrolyte salt, for example, Li salt or Na salt). The electrolyte solution is typically liquid, but may also be gel-like. Although not particularly limited, in an on-vehicle or other power storage device 100, the amount of electrolyte solution contained in one case 10 can be, for example, 100 g or more, 200 g or more, or even 300 g or more. If the amount of electrolyte solution is large, the injection speed during injection of the electrolyte solution may be increased from the viewpoint of productivity. Therefore, it is necessary to prevent damage to the positive electrode tab during injection, and applying the technology disclosed herein is particularly effective.

[0027] The positive electrode terminal 30 is provided on the first sealing plate 14 (the left sealing plate 14 in FIGS. 2 and 3, the first second surface). The positive electrode terminal 30 is preferably made of metal, and more preferably made of aluminum or an aluminum alloy, for example. As shown in FIGS. 2 and 3, the positive electrode terminal 30 is electrically connected to the positive electrode tab 23 inside the case 10 via a positive electrode current collecting portion 32.

[0028] The negative electrode terminal 40 is provided on the second sealing plate 14 (the second second surface of the sealing plate 14 on the right side in FIGS. 2 and 3). The negative electrode terminal 40 is preferably made of metal, and more preferably made of copper or a copper alloy, for example. As shown in FIGS. 2 and 3, the negative electrode terminal 40 is electrically connected to the negative electrode tab 24 inside the case 10 via the negative electrode current collecting portion 42.

[0029] In this embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 are provided on each of the pair of sealing plates 14, but in other embodiments, the positive electrode terminal 30 and the negative electrode terminal 40 may be provided on the same sealing plate 14 or on the case body 12.

[0030] The liquid inlet 15 is for injecting the electrolyte into the case 10 after the sealing plate 14 is attached to the case body 12. After the electrolyte is injected, the liquid inlet 15 is sealed with a sealing member 16. Any conventionally known member can be used as the sealing member 16 without any particular restrictions. An example of the sealing member 16 is a metal member such as a blind rivet.

[0031] In this example, the liquid inlet hole 15 is provided on the second long side surface 12b of the case 10 (the front long side surface 12b, the second third surface in FIGS. 1 and 3). In FIG. 2, the position of the liquid inlet hole 15 is virtually indicated by an imaginary line. As shown in FIG. 3, the liquid inlet hole 15 is a through-hole that penetrates the long side surface 12b in the thickness direction X.

[0032] In the technology disclosed herein, the liquid injection hole 15 is located closer to the negative electrode tab 24 than to the positive electrode tab 23. This makes it less likely that the electrolyte will come into contact with the positive electrode tab 23 when the electrolyte is injected, thereby relatively reducing damage to the positive electrode tab 23. Furthermore, when the electrolyte is injected, the injection speed can be increased to, for example, 500 g / min or more, allowing even large batteries to be produced efficiently.

[0033] As shown in FIG. 2 , the liquid injection hole 15 is preferably provided above the negative electrode tab 24 in the vertical direction Z. This allows the electrolyte to be efficiently injected and impregnated into the electrode assembly 20. It is preferable that the electrode assembly 20 is not located directly below the liquid injection hole 15. This makes it difficult for the electrolyte to contact the electrode assembly 20 during injection, relatively reducing damage to the electrode assembly 20, such as peeling off of the separator. Furthermore, the injection speed can be increased during injection of the electrolyte, allowing efficient production of even large batteries. Furthermore, a rectifying plate (so-called baffle plate) that prevents the electrolyte from contacting the electrode assembly 20 is not required, which not only reduces the number of parts but also increases the usable area of ​​the internal volume of the case 10.

[0034] As shown in FIGS. 2 and 3 , the liquid inlet 15 is preferably provided between the second sealing plate 14 (the sealing plate 14 on the right side in FIGS. 2 and 3 , the second second surface) and the end of the electrode assembly 20 in the width direction Y (the direction in which the negative electrode tab 24 protrudes). In other words, the liquid inlet 15 is preferably provided in the region in the width direction Y where the curved portion 24b of the negative electrode tab 24 is disposed. This makes it difficult for the electrolyte to contact the electrode assembly 20 during the injection of the electrolyte, thereby relatively reducing damage to the electrode assembly 20, such as peeling of the separator. Furthermore, the injection speed can be increased during the injection of the electrolyte, allowing even large batteries to be produced efficiently. Furthermore, a rectifying plate (so-called baffle plate) that prevents the electrolyte from contacting the electrode assembly 20 is not required, thereby reducing the number of parts and increasing the usable area of ​​the internal volume of the case 10.

[0035] As shown in FIG. 3, the liquid injection hole 15 preferably directly faces the first long side surface 12b (the rear long side surface 12b, the first third surface, in FIG. 3) in the thickness direction X. FIG. 4 is a partial enlarged view schematically illustrating the vicinity of the negative electrode tab 24 during injection. As indicated by the arrow in FIG. 4, during injection of the electrolyte, the electrolyte flows into the case 10 through the liquid injection hole 15. If the liquid injection hole 15 faces the long side surface 12b, the flowing electrolyte hits the opposing long side surface 12b and typically moves downward along the inner wall surface of the long side surface 12b. Therefore, even if the injection speed is high, the force of the injection can be reduced. This increases the injection speed, enabling efficient production of even large batteries. Furthermore, the electrolyte is less likely to directly hit the negative electrode tab 24, making the negative electrode tab 24 less likely to be damaged.

[0036] 3, when the negative electrode tab 24 has a curved portion 24b that curves from the first long side surface 12b (the rear long side surface 12b in FIG. 3, the first third surface) to the second long side surface 12b (the front long side surface 12b in FIG. 3, the second third surface), the liquid inlet 15 is preferably provided on the second long side surface 12b (the second third surface). In other words, the liquid inlet 15 is preferably provided so as to face the protruding side (vertex side) of the curved portion 24b.

[0037] 4, when the liquid inlet 15 is provided so as to face the apex side of the curved portion 24b, the electrolyte that flows in from the liquid inlet 15 strikes the outer circumferential side (back side) A0 of the curved portion 24b and is more likely to move along the outer circumferential surface of the curved portion 24b. Therefore, compared to when the electrolyte that flows in from the liquid inlet 15 strikes the inner circumferential side (ventral side) Ai of the curved portion 24b, the negative electrode tab 24 is less likely to be biased by the force of the liquid injection. This makes it possible to prevent the negative electrode tab 24 from bending or moving due to the force of the liquid injection.

[0038] The case 10 may further be provided with an exhaust hole for venting gas during the injection of the electrolyte. The exhaust hole may be provided, for example, in the first long side surface 12b of the case 10 (the rear long side surface 12b, or the first third surface, in FIGS. 1 and 3), in the second long side surface 12b of the case 10 (the front long side surface 12b, or the second third surface, in FIGS. 1 and 3), or in the sealing plate 14 (the second surface of the case 10) or the top surface 12c (the fourth surface of the case 10). The exhaust hole is a second through-hole penetrating the long side surface 12b in the thickness direction X. Contrary to the injection hole 15, the exhaust hole is preferably provided closer to the positive electrode tab 23 than to the negative electrode tab 24. This facilitates the smooth injection of a large amount of electrolyte. It also promotes the impregnation of the electrolyte into the electrode assembly 20. Like the injection hole 15, the exhaust hole is preferably sealed with a sealing member after the injection of the electrolyte.

[0039] [Uses of energy storage devices] The electricity storage device 100 can be used for various purposes, and can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car, a truck, etc. The type of vehicle is not particularly limited, and examples thereof include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

[0040] Although the preferred embodiment of the present invention has been described above, the above embodiment is merely an example. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiment. For example, it is possible to replace part of the above-described embodiment with other modifications, or to add other modifications to the above-described embodiment. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0041] For example, in the electrode assembly 20 of Figures 2 and 3 described above, the positive electrode tab 23 protrudes toward the first sealing plate 14 (the sealing plate 14 on the left side in Figures 2 and 3, the first second surface), and the negative electrode tab 24 protrudes toward the second sealing plate 14 (the sealing plate 14 on the right side in Figures 2 and 3, the second second surface). In addition, the positive electrode terminal 30 is provided on the first sealing plate 14 (the sealing plate 14 on the left side in Figures 2 and 3, the first second surface), and the negative electrode terminal 40 is provided on the second sealing plate 14 (the sealing plate 14 on the right side in Figures 2 and 3, the second second surface). However, the present invention is not limited to this.

[0042] Fig. 5 is a view corresponding to Fig. 2 according to a first modified example. The electricity storage device 200 shown in Fig. 5 may be similar to the electricity storage device 100, except that it includes an electrode assembly 120, a positive electrode terminal 130, and a negative electrode terminal 140. In the electrode assembly 120, the positive electrode tab 123 and the negative electrode tab 124 both protrude toward the first sealing plate 14 (the sealing plate 14 on the right side in Fig. 5, the first second surface). Furthermore, the positive electrode terminal 130 and the negative electrode terminal 140 are provided on the same sealing plate 14, more specifically, on the first sealing plate 14 (the sealing plate 14 on the right side in Fig. 5, the first second surface). In this modification, the liquid injection hole 15 is preferably provided on the opposite side of the negative electrode tab 124 from the positive electrode tab 123, and between the first sealing plate 14 (the sealing plate 14 on the left side in FIG. 5 , the first second surface) and the end of the electrode body 120 in the width direction Y (the direction in which the positive electrode tab 123 and the negative electrode tab 124 protrude). The techniques disclosed herein can also be suitably applied to such an electricity storage device 200.

[0043] For example, in the above-described electricity storage device 100 of FIG. 1 to electricity storage device 200 of FIG. 5, the positive electrode terminals 30, 130 and the negative electrode terminals 40, 140 are provided at the ends in the width direction Y. However, this is not limiting. FIG. 6 is a view corresponding to FIG. 1 according to a second modified example. The electricity storage device 300 shown in FIG. 6 may be similar to the electricity storage device 100 to the electricity storage device 200, except that it includes a case 210, a positive electrode terminal 230, and a negative electrode terminal 240.

[0044] As shown in FIG. 6 , the case 210 includes a rectangular (box-shaped) case body 212 with a bottom and an opening on one surface (here, the upper surface), and a sealing plate 214 that closes the opening of the case body 212. The case body 212 includes a substantially rectangular first surface 212a having a pair of short sides and a pair of opposite short sides, a pair of second surfaces 212c that extend from the pair of short sides of the first surface 212a and face each other, and a pair of third surfaces 212b that extend from the pair of long sides of the first surface 212a and face each other. A liquid injection hole 215 is provided in the third surface 212b. The liquid injection hole 215 is sealed with a sealing member 216 after the electrolyte is injected. A positive electrode terminal 230 and a negative electrode terminal 240 are provided on the sealing plate 214. The technology disclosed herein can be suitably applied to such an electricity storage device 300 as well.

[0045] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: An electricity storage device comprising: a rectangular case having a substantially rectangular first surface having a pair of short sides and a pair of long sides, a pair of second surfaces extending from the pair of short sides, respectively, and a pair of third surfaces extending from the pair of long sides, respectively, and having areas larger than the first and second surfaces; an electrode assembly housed inside the case and having a positive electrode and a negative electrode; a positive electrode tab provided on the positive electrode; a negative electrode tab provided on the negative electrode; an electrolyte housed inside the case; and a liquid injection hole provided on the third surface of the case, the liquid injection hole being located closer to the negative electrode tab than the positive electrode tab. Item 2: The electricity storage device according to item 1, wherein the positive electrode tab protrudes toward the first second surface side, the negative electrode tab protrudes toward the second second surface side, and the liquid injection hole is provided between the second second surface and an end of the electrode body in the direction in which the negative electrode tab protrudes. Item 3: The electricity storage device according to item 1, wherein the positive electrode tab and the negative electrode tab both protrude toward the first second surface, and the liquid injection hole is provided on the opposite side of the positive electrode tab across the negative electrode tab, and between the first second surface and an end of the electrode body in the direction in which the positive electrode tab and the negative electrode tab protrude. Item 4: The electricity storage device according to Item 2 or 3, wherein the liquid injection hole is provided above the negative electrode tab. Item 5: The electricity storage device according to Item 2, further comprising: a positive electrode terminal connected to the positive electrode tab and provided on the first second surface; and a negative electrode terminal connected to the negative electrode tab and provided on the second second surface. Item 6: The electricity storage device according to any one of items 1 to 5, wherein the negative electrode tab has a curved portion that curves from the first third surface toward the second third surface, and the liquid injection hole is provided in the second third surface. Item 7: The electricity storage device according to item 6, wherein the liquid injection hole directly faces the first third surface. Item 8: The electricity storage device according to any one of Items 1 to 7, wherein the positive electrode tab is made of aluminum or an aluminum alloy, and the negative electrode tab is made of copper or a copper alloy. [Explanation of symbols]

[0046] 10 cases 12 Case body 12a Bottom (first side) 12b Long side (3rd side) 12c Top 14 Sealing plate (second side) 15 Liquid injection hole 20 Electrode body 23 Positive electrode tab 24 Negative electrode tab 24b Curved section 30 Positive terminal 40 Negative terminal 100 Energy storage device

Claims

1. a rectangular case having a substantially rectangular first surface having a pair of short sides and a pair of long sides, a pair of second surfaces extending from the pair of short sides, respectively, and a pair of third surfaces extending from the pair of long sides, respectively, and having areas larger than the first surface and the second surface; an electrode assembly housed inside the case and having a positive electrode and a negative electrode; a positive electrode tab provided on the positive electrode; a negative electrode tab provided on the negative electrode; an electrolyte contained inside the case; a liquid injection hole provided in the third surface of the case and at a position closer to the negative electrode tab than the positive electrode tab; Equipped with Energy storage device.

2. The positive electrode tab protrudes toward the first second surface side, The negative electrode tab protrudes toward the second surface side, the liquid injection hole is provided between the second surface and an end of the electrode body in a direction in which the negative electrode tab protrudes; The electricity storage device according to claim 1 .

3. the positive electrode tab and the negative electrode tab both protrude toward the first second surface side, the liquid injection hole is provided on the opposite side of the negative electrode tab from the positive electrode tab, and between the first second surface and an end of the electrode body in a direction in which the positive electrode tab and the negative electrode tab protrude. The electricity storage device according to claim 1 .

4. The liquid injection hole is provided above the negative electrode tab. The electricity storage device according to claim 2 or 3.

5. a positive electrode terminal connected to the positive electrode tab and provided on the first second surface; a negative electrode terminal connected to the negative electrode tab and provided on the second second surface; Further provided with The electricity storage device according to claim 2 .

6. the negative electrode tab has a curved portion curved from the first third surface toward the second third surface, The liquid injection hole is provided on the second third surface. The electricity storage device according to claim 1 .

7. the liquid injection hole directly faces the first third surface; The electricity storage device according to claim 6 .

8. the positive electrode tab is made of aluminum or an aluminum alloy, The negative electrode tab is made of copper or a copper alloy. The electricity storage device according to claim 1 .

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