Energy storage devices

Abstract

To provide a technique of suppressing adhesion of an electrolyte solution in a vicinity of a liquid injection hole in a hole.SOLUTION: A power storage device 1 includes an electrode body 20, an insulating film 70, an electrolyte solution, a case 10, a positive electrode terminal 30 and a negative electrode terminal 40, and current collecting members 50 and 60. Here, the insulating film 70 includes a first side surface 70b facing a wide surface 12a of a case body 12. The insulating film 70 is closed at a lower end on a bottom surface 12c side of the case body 12 and opens at an upper end on a sealing plate 14 side. The insulating film 70 has a notch 75 at an upper end of the first side surface 70b. The notch 75 is provided under an intersection Q between a line L1 passing a center P of a liquid injection hole 17 and present along a short side direction of the sealing plate 14 and a line L2 present along the first side surface 70b in a cross-sectional view along a narrow surface 12b of the case main body 12.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Japanese Patent Publication No. 2020-95836 discloses a battery comprising a rectangular battery case, an electrode assembly housed within the battery case, and an insulating film disposed between the battery case and the electrode assembly. The battery case comprises a case body with an opening and a lid member covering the opening. The case body has a bottom surface opposite the opening and a pair of long sides extending continuously from the bottom surface. The insulating film is in the form of a single sheet and is disposed between at least the electrode assembly, the bottom surface, and the pair of long sides. The pair of ends of the insulating film in the height direction connecting the bottom surface and the lid member are located closer to the lid member than the electrode assembly. The insulating film has a notch in the thickness direction of the insulating film, located between a position corresponding to the end of the electrode assembly on the lid member side and the pair of ends, at least in a portion of the width direction perpendicular to the height direction and along the long sides. The area between the notch and the pair of ends forms an inclined surface that slopes toward the electrode assembly. The publication states that a battery with such a configuration reduces the possibility of metallic foreign matter being mixed into the electrode assembly.

[0003] The secondary battery disclosed in WO 2018 / 131417 includes an electricity storage element consisting of a metal foil with a mixture layer disposed thereon, an electrode assembly with an exposed metal foil portion, and a current collector connected to the exposed metal foil portion; an insulating film covering the electricity storage element; and a rectangular battery can containing the electricity storage element and the insulating film and having an opening, a bottom, and side surfaces. The insulating film is folded back at the bottom of the battery can to cover the electricity storage element. The insulating film has a protruding portion that protrudes from the electricity storage element and faces the side surface of the battery can, where the insulating film overlaps. A portion of the protruding portion abuts the side surface opposite the direction in which the insulating film protrudes. The tip of the protruding portion is located in the space between the electricity storage element and a corner of the rectangular battery can. The publication states that in this secondary battery, by making the insulating film between the mixture layer and the metal container into a uniform surface, it is possible to prevent distortional damage to the mixture layer and improve the insulation between the wound group and the can against external forces.

[0004] The prismatic secondary battery disclosed in International Publication No. 2016 / 088506 includes a flat electrode group formed by winding positive and negative electrodes, a flat rectangular battery can housing the electrode group, a battery lid sealing the opening of the battery can, and an insulating member secured to the battery lid and housed within the battery can. This secondary battery also includes a housing member smaller in volume than the battery can, made of a bag-shaped insulating sheet housed within the battery can and housing the electrode group together with an electrolyte solution. The insulating member is characterized by being tightly fitted to the battery lid to seal the space between the battery lid and the housing member, and being joined to the opening of the housing member to seal the opening. The publication also describes how this configuration eliminates excess electrolyte solution filling the space between the battery can and the housing member, allowing the electrolyte solution in the housing member to efficiently impregnate the electrode group. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-95836 [Patent Document 2] International Publication No. 2018 / 131417 [Patent Document 3] International Publication No. 2016 / 088506 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors wish to prevent the adhesion of electrolyte to the vicinity of the injection hole inside the case. [Means for solving the problem]

[0007] The disclosed power storage device includes an electrode assembly, a bag-shaped insulating film covering the electrode assembly, an electrolyte solution, a case containing the electrode assembly, the insulating film, and the electrolyte solution, electrode terminals attached to the case, and a current collecting member connected to the electrode assembly and the electrode terminals inside the case. The case includes a case body having a rectangular bottom, an opening facing the bottom, a pair of wide sides extending from a pair of opposing long sides of the bottom, and a pair of narrow sides extending from a pair of opposing short sides of the bottom, and a rectangular sealing plate sealing the opening. The sealing plate has mounting holes for attaching the electrode terminals and an injection hole for the electrolyte solution. The insulating film has a first side surface facing the wide side of the case body. The insulating film is closed at its lower end on the bottom side of the case body and open at its upper end on the sealing plate side. The insulating film also has a notch at the upper end of the first side surface. In a cross-sectional view along the narrow surface of the case body, the notch is located below an intersection Q of a line L1 that passes through the center P of the liquid inlet and that extends along the short side of the sealing plate, and a line L2 that extends along the first side surface. This configuration makes it possible to prevent the adhesion of electrolyte near the liquid inlet inside the case. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an electricity storage device 1. As shown in FIG. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic diagram of the electrode body 20. As shown in FIG. [Figure 5] FIG. 5 is a perspective view of the insulating film 70. As shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of the electricity storage device 1. As shown in FIG. [Figure 7] FIG. 7 is a front view of insulating film 270. As shown in FIG. [Figure 8] FIG. 8 is a front view of the insulating film 370. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the technology disclosed herein will be described below. The embodiment described herein is not intended to limit the technology disclosed herein. The technology disclosed herein is not limited to the embodiment described herein unless otherwise specified. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, identical reference symbols are used for components and parts performing the same function, and redundant explanations will be omitted. The reference symbols "R," "L," "U," "D," "F," and "Rr" in the drawings represent "right," "left," "up," "down," "front," and "rear," respectively. Furthermore, the notation "A to B" indicating a numerical range means "greater than A and less than B" unless otherwise specified, and also encompasses the meaning of "greater than A and less than B."

[0010] In this specification, the term "electricity storage device" refers to a device in which charging and discharging occur by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte. Such electricity storage devices include secondary batteries such as lithium ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries; and capacitors such as lithium ion capacitors and electric double layer capacitors. In the following, an embodiment will be described in which a lithium ion secondary battery is used as an example of the above-mentioned electricity storage device.

[0011] FIG. 1 is a cross-sectional view of an electricity storage device 1. FIG. 1 shows the cross-sectional structure of the electricity storage device 1 along a wide surface 12a. FIG. 2 is a cross-sectional view taken along II-II in FIG. 1. FIG. 2 shows the cross-sectional structure of the vicinity of the positive electrode terminal connection portion along a narrow surface 12b. FIG. 3 is a cross-sectional view taken along III-III in FIG. 1. FIG. 3 shows the cross-sectional structure of the vicinity of a liquid injection hole 17 along a narrow surface 12b. As shown in FIGS. 1 to 3, the electricity storage device 1 includes a case 10, an electrode assembly 20, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode side current collecting member 50, a negative electrode side current collecting member 60, an insulating film 70, an insulating member 80, and an electrolyte (not shown).

[0012] The case 10 is a member that houses, for example, the electrode body 20, the insulating film 70, and the electrolyte solution. Although not particularly limited, it is preferable that the case 10 be made of aluminum or an aluminum alloy, from the viewpoint of reducing weight and ensuring the required rigidity.

[0013] As shown in FIGS. 1 to 3, the case 10 has a case body 12 and a sealing plate 14. The case body 12 is the main body of the case 10, and houses, for example, the electrode assembly 20 therein. In this embodiment, the case body 12 has an opening 12h, a pair of opposing wide surfaces 12a, a pair of opposing narrow surfaces 12b, and a bottom surface 12c. The bottom surface 12c faces the opening 12h. The bottom surface 12c is rectangular and has a pair of opposing long sides and a pair of opposing short sides. The pair of opposing wide surfaces 12a extend from the pair of opposing long sides of the bottom surface 12c. The pair of opposing narrow surfaces 12b extend from the pair of opposing short sides of the bottom surface 12c. In this specification, the terms "rectangular" or "rectangle" include 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, etc.

[0014] Opening 12h is, for example, a portion where sealing plate 14 is attached. Here, opening 12h is formed by being surrounded by the upper edges of a pair of wide surfaces 12a and the upper edges of a pair of narrow surfaces 12b, and has a rectangular shape. Sealing plate 14 is fitted into opening 12h and joined (for example, welded) to integrate case body 12 and sealing plate 14, and case 10 is hermetically sealed.

[0015] 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 is rectangular. Here, when the sealing plate 14 is attached to the opening 12h, the sealing plate 14 faces, for example, the bottom surface 12c. The sealing plate 14 has a drain valve (not shown) and a liquid injection hole 17. The drain valve is, for example, a thin portion. Here, the drain valve is configured to break when the pressure inside the case 10 reaches or exceeds a predetermined value, thereby discharging gas inside the case 10 to the outside.

[0016] The liquid inlet 17 is a portion into which an electrolyte solution is injected. As shown in FIG. 3, a sealing member 16 is attached to the liquid inlet 17. The sealing member 16 may be made of, for example, metal. In the embodiment shown in FIG. 3, the sealing member 16 has a flange portion 161 and an insertion portion 162. The flange portion 161 here is plate-shaped and is disposed on the sealing plate 14, and is a portion that is joined (for example, welded) to the sealing plate 14. The insertion portion 162 is axial or protruding and is a portion that is inserted into the liquid inlet 17. Note that the shape of the sealing member 16 is not limited thereto. In other embodiments, the sealing member 16 may be made of the flange portion 161.

[0017] In this embodiment, the sealing plate 14 has mounting holes to which electrode terminals are attached. In the embodiment shown in FIG. 2, the sealing plate 14 is provided with a mounting hole 18 on the positive electrode side. Here, the mounting hole 18 is a through hole. The mounting hole 18 is a portion to which, for example, the positive electrode terminal 30 is attached. Although not shown, the sealing plate 14 is also provided with a mounting hole on the negative electrode side. Like the mounting hole 18, the negative electrode side mounting hole is a through hole. The negative electrode side mounting hole is a portion to which the negative electrode terminal 40 is attached.

[0018] 4 is a schematic diagram of the electrode body 20. The electrode body 20 is a power generating element of the electricity storage device 1, having, for example, a positive electrode and a negative electrode. The electrode body 20 has, for example, a laminated structure in which a sheet-shaped positive electrode 22 and a sheet-shaped negative electrode 24 are laminated with a separator 23 interposed therebetween. The electrode body 20 is housed in the case 10 in a state in which the sheet-shaped positive electrode 22 and the sheet-shaped negative electrode 24 are stacked such that the stacking direction faces the pair of wide surfaces 12a.

[0019] 4, the electrode assembly 20 is a wound electrode assembly in which, for example, a sheet-shaped positive electrode 22 and a sheet-shaped negative electrode 24 are stacked with a separator 23 interposed therebetween and wound in the sheet longitudinal direction LD. 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.

[0020] As shown in FIGS. 2 and 3, the electrode assembly 20 has a first curved portion 20r1, a second curved portion 20r2, and a flat portion 20f. The first curved portion 20r1 is located on the sealing plate 14 side and curves toward the inner surface of the sealing plate 14. The second curved portion 20r2 is located on the bottom surface 12c side of the case 10 and curves toward the bottom surface 12c. The flat portion 20f is a portion sandwiched between the first curved portion 20r1 and the second curved portion 20r2. In this embodiment, the electrode assembly 20 has a pair of flat surfaces 20a. The flat surfaces 20a are located at both ends in the stacking direction of the positive electrode 22 and the negative electrode 24. Here, the flat surfaces 20a are located at both ends of the flat portion 20f. The flat surfaces 20a of the electrode assembly 20 face the wide surface 12a.

[0021] Furthermore, one end face 20b of the electrode assembly 20 faces one narrow surface 12b (the left narrow surface 12b in FIG. 1), and the other end face 20c faces the other narrow surface 12b (the right narrow surface 12b in FIG. 1). The end face 20b here is the lamination surface of the uncoated portion 22c1 of the positive current collector foil 22c and is an open surface. The end face 20c here is the lamination surface of the uncoated portion 24c1 of the negative current collector foil 24c and is also an open surface. As shown in FIGS. 1 and 4, the electrode assembly 20 is housed in the case body 12 so that the winding axis direction WD and the left-right direction of the electricity storage device 1 are substantially parallel. The winding axis WL of the electrode assembly 20 is substantially perpendicular to the wide surface 12a and the narrow surface 12b and is substantially parallel to the sealing plate 14.

[0022] 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 (not shown) 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, materials used in this type of electricity storage device (in this embodiment, a lithium-ion secondary battery) may be used without particular limitation.

[0023] A band-shaped uncoated portion 22c1 is provided along the longitudinal direction LD at one end of the positive current collector foil 22c in the winding axis direction WD (the left end in FIG. 4). The uncoated portion 22c1 is a part of the positive current collector foil 22c. The uncoated portion 22c1 is a portion of the positive current collector foil 22c that is not coated with the positive active material layer 22a. In this embodiment, the uncoated portion 22c1 protrudes further in the winding axis direction WD than the separator 23. The uncoated portion 22c1 is laminated at one end of the winding axis direction WD (the left end in FIG. 4). As shown in FIG. 1, a current collecting member 50 is joined to the uncoated portion 22c1.

[0024] 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.

[0025] A band-shaped uncoated portion 24c1 is provided along the longitudinal direction LD at one end of the negative electrode current collector foil 24c in the winding axis direction WD (the right end in FIG. 4). The uncoated portion 24c1 is a part of the negative electrode current collector foil 24c. The uncoated portion 24c1 is a portion of the negative electrode current collector foil 24c where the negative electrode active material layer 24a is not formed. In this embodiment, the uncoated portion 24c1 protrudes further in the winding axis direction WD than the separator 23. For example, the uncoated portion 24c1 is laminated at one end of the winding axis direction WD (the right end in FIG. 4). As shown in FIG. 1, a current collecting member 60 is joined to the uncoated portion 24c1.

[0026] 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).

[0027] The positive electrode terminal 30 is, for example, 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 mounting hole 18 and disposed on both the outside and inside of the case body 12. Here, the positive electrode terminal 30 has a first conductive portion 31, a second conductive portion 32, and a shaft portion 33. The first conductive portion 31 is, for example, a portion disposed on the outside of the case 10. In the embodiment shown in FIGS. 1 and 2, the first conductive portion 31 is flat and disposed along the outer surface of the sealing plate 14. The second conductive portion 32 is, for example, a portion disposed on the inside of the case 10. In the embodiment shown in FIG. 2, the second conductive portion 32 is flat and disposed along the inner surface of the sealing plate 14. The shaft portion 33 is, for example, cylindrical and is inserted through the mounting hole 18 to connect the first conductive portion 31 and the second conductive portion 32. In the embodiment shown in FIG. 2, the shaft portion 33 extends from the first conductive portion 31 and is connected to the second conductive portion 32. For example, the second conductive portion 32 may be provided with a through-hole. In this case, the tip of the shaft portion 33 may be inserted into the through-hole and crimped. This allows the first conductive portion 31 and the second conductive portion 32 to be connected by the shaft portion 33. Alternatively, the first conductive portion 31, the second conductive portion 32, and the shaft portion 33 may be integrally molded. The positive electrode terminal 30 is made of, for example, aluminum or an aluminum alloy.

[0028] The current collecting member 50 on the positive electrode side is, for example, a member that electrically connects the positive electrode 22 and the positive electrode terminal 30 inside the case 10. In the embodiment shown in FIG. 1, the current collecting member 50 is plate-shaped and extends from the sealing plate 14 toward the electrode body 20. Here, the current collecting member 50 is connected at one end (the upper end in FIG. 1) to the second conductive part 32 and at the other end (the lower end in FIG. 1) to the electrode body 20. Therefore, as shown in FIG. 2, the current collecting member 50 is sandwiched between the insulating films 70 between the upper end of the electrode body 20 and the sealing plate 14. In this embodiment, the connection between the current collecting member 50 and the second conductive part 32 is achieved by joining (e.g., welding) one end of the current collecting member 50 to the second conductive part. In this embodiment, the connection between the current collecting member 50 and the electrode body 20 is achieved by joining (for example, welding) the other end of the current collecting member 50 to the uncoated portion 22c1. The current collecting member 50 is made of, for example, aluminum or an aluminum alloy.

[0029] The negative electrode terminal 40 is, for example, a member electrically connected to the negative electrode 24 of the electrode body 20. The negative electrode terminal 40 is made of, for example, copper or a copper alloy. The negative electrode terminal 40 may have the same configuration as the positive electrode terminal 30. Therefore, a description of the configuration of the negative electrode terminal 40 will be omitted here. The negative electrode side current collecting member 60 is, for example, a member that electrically connects the negative electrode 24 and the negative electrode terminal 40 inside the case 10. The current collecting member 60 is made of, for example, copper or a copper alloy. The negative electrode side current collecting member 60 may have the same configuration as the positive electrode side current collecting member 50. Therefore, a description of the configuration of the current collecting member 60 will be omitted here.

[0030] The insulating film 70 is, for example, a member that covers the electrode body 20. FIG. 5 is a perspective view of the insulating film 70. As shown in FIG. 5, the insulating film 70 is bag-shaped and partially open. As shown in FIGS. 1 to 3 and 5, the insulating film 70 is closed at the bottom end and open at the top end. In this specification, the end of the insulating film 70 on the side of the bottom surface 12c of the case body 12 is referred to as the "bottom end," and the end on the side of the sealing plate 14 is referred to as the "top end."

[0031] The insulating film 70 shown in FIG. 5 has a generally regular hexahedral shape with one side open. In this embodiment, the insulating film 70 has a bottom surface 70a, a pair of opposing first side surfaces 70b, and a pair of opposing second side surfaces 70c. The insulating film 70 also has an opening 70h facing the bottom surface 70a. The bottom surface 70a here is rectangular. As shown in FIG. 5, the pair of first side surfaces 70b extend from a pair of opposing long sides of the bottom surface 70a and are the widest surfaces of the insulating film 70. The pair of second side surfaces 70c extend from a pair of opposing short sides of the bottom surface 70a. In the embodiment shown in FIG. 2, the bottom surface 70a faces the bottom surface 12c of the case body 12 within the case 10. Here, the bottom surface 70a constitutes the lower end of the insulating film 70. The pair of first side surfaces 70b face the pair of wide surfaces 12a of the case body 12. The pair of second side surfaces 70c face the pair of narrow surfaces 12b of the case body 12. The opening 70h is disposed on the opening 12h side of the case body 12. Here, the opening 70h constitutes the upper end of the insulating film 70.

[0032] As shown in FIGS. 1, 3, and 5, the insulating film 70 has a notch 75 at the upper end of the first side surface 70b. In the cross-section shown in FIG. 3, the notch 75 is provided below the intersection Q of the straight line L1 and the straight line L2. The "cross-section shown in FIG. 3" mentioned here is a cross-section passing through the center P of the liquid injection hole 17 and along the narrow-width surface 12b of the case body 12. Also, the straight line L1 is a straight line passing through the center P of the liquid injection hole 17 and along the short side direction of the rectangular sealing plate 14 in the cross-section shown in FIG. 3. Further, the straight line L2 is a straight line along the first side surface 70b of the insulating film 70 in the cross-section shown in FIG. 3. In the forms shown in FIGS. 1, 3, and 5, the notch 75 is provided on each first side surface 70b. However, it is not limited to this. In other embodiments, the notch 75 may be provided only on one of the pair of first side surfaces 70b.

[0033] As shown in FIG. 2, the first side surface 70b faces the current collecting member 50. As shown in FIG. 1, when the lower end of the insulating film 70 is used as a reference, the height H1 of the upper end of the first side surface 70b at the facing portion with the current collecting member 50 is preferably greater than the height H2 of the deepest part 75p of the notch 75. The "deepest part 75p of the notch 75" mentioned here is the part with the smallest height in the notch 75 when the lower end of the insulating film 70 is used as a reference.

[0034] In the form shown in FIG. 3, the deepest part 75p of the notch 75 is provided between the boundary 20BD between the first curved part 20r1 and the flat part 20f and the sealing plate 14. The depth Zb from the inner surface of the sealing plate 14 to the boundary 20BD and the depth Zz from the inner surface of the sealing plate 14 to the deepest part 75p are preferably set to satisfy Zz ≦ Zb. Also, from the viewpoint of enhancing the effect of the technology disclosed here, the deepest part 75p of the notch 75 is preferably provided closer to the sealing plate 14 side than the boundary 20BD between the first curved part 20r1 and the flat part 20f. In this case, the depth Zb and the depth Zz may satisfy Zz < Zb.

[0035] FIG. 6 is a cross-sectional view of the power storage device 1. In FIG. 6, a portion near the sealing plate 14 in the cross-sectional structure along the wide surface 12a of the power storage device 1 is shown enlarged. In FIG. 6, with respect to the positional relationship among the positive electrode terminal 30, the negative electrode terminal 40, the liquid injection hole 17, and the notch 75, a preferred example for realizing the effects of the technology disclosed herein is shown. As shown in FIG. 6, inside the case 10, the distance Xp from the narrow surface 12b to the positive electrode terminal 30 and the distance Xzp from the narrow surface 12b to the end of the notch 75 on the positive electrode terminal 30 side preferably satisfy Xp≦Xzp, and more preferably satisfy Xp<Xzp. Here, the distance Xp is the shortest distance from the narrow surface 12b to the end of the second conductive portion 32 on the liquid injection hole 17 side. Also, inside the case 10, the distance Xn from the narrow surface 12b to the negative electrode terminal 40 and the distance Xzn from the narrow surface 12b to the end of the notch 75 on the negative electrode terminal 40 side preferably satisfy Xn≦Xzn, and more preferably satisfy Xn<Xzn. Here, the distance Xzn is the shortest distance from the narrow surface 12b to the end of the second conductive portion of the negative electrode terminal 40 on the liquid injection hole 17 side.

[0036] As shown in FIGS. 1 to 3, an insulating member 80 is disposed between the positive electrode terminal 30 and the sealing plate 14, and between the negative electrode terminal 40 and the sealing plate 14. The insulating member 80 is disposed, for example, between the first conductive portion 31 and the outer surface of the sealing plate 14, between the second conductive portion 32 and the inner surface of the sealing plate 14, and between the shaft portion 33 and the mounting hole 18. The same applies to the negative electrode side, and the insulating member 80 is disposed, for example, between the negative electrode terminal 40 and between the outer surface of the sealing plate 14, the inner surface of the sealing plate 14, and the mounting hole. The insulating member 80 may be integrally formed or may be a combination of members formed for each of a plurality of parts.

[0037] The electrolyte solution contains, for example, an electrolyte salt and a non-aqueous solvent. Examples of the electrolyte salt include LiPF6. The concentration of the electrolyte salt in the electrolyte solution is, for example, 0.7 mol / L to 1.3 mol / L. The non-aqueous solvent may be, for example, a carbonate. Examples of carbonates include ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (MFEC), difluoroethylene carbonate (DFEC), monofluoromethyl difluoromethyl carbonate (F-DMC), trifluorodimethyl carbonate (TFDMC), etc. These may be used alone or in combination of two or more.

[0038] The electricity storage device 1 can be used for a variety of purposes, and is particularly preferably used as a power source (driving power source) for motors mounted on vehicles such as passenger cars, trucks, etc. The type of vehicle is not particularly limited, but suitable examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0039] As described above, the electricity storage device 1 includes the electrode assembly 20, a bag-shaped insulating film 70 that covers the electrode assembly 20, an electrolyte, a case 10 that accommodates the electrode assembly 20, the insulating film 70, and the electrolyte, electrode terminals (a positive electrode terminal 30 and a negative electrode terminal 40) attached to the case 10, and current collecting members 50, 60 connected to the electrode assembly 20 and the electrode terminals (the positive electrode terminal 30 and the negative electrode terminal 40) inside the case 10. The case 10 includes a case body 12 that has a rectangular bottom surface 12c, an opening 12h facing the bottom surface 12c, a pair of wide surfaces 12a extending from a pair of opposing long sides of the bottom surface 12c, and a pair of narrow surfaces 12b extending from a pair of opposing short sides of the bottom surface 12c, and a rectangular sealing plate 14 that seals the opening 12h. The sealing plate 14 has mounting holes (for example, mounting hole 18 on the positive electrode side) to which electrode terminals (positive electrode terminal 30 and negative electrode terminal 40) are attached, and an injection hole 17 for the electrolyte.

[0040] Here, the insulating film 70 has a first side surface 70b facing the wide surface 12a of the case body 12. The insulating film 70 is closed at its lower end on the bottom surface 12c side of the case body 12 and is open at its upper end on the sealing plate 14 side. The insulating film 70 has a notch 75 at the upper end of the first side surface 70b. In a cross-sectional view along the narrow surface 12b of the case body 12, the notch 75 is located below an intersection Q of a straight line L1 that passes through the center P of the liquid injection hole 17 and that extends along the short side of the sealing plate 14, and a straight line L2 that extends along the first side surface 70b.

[0041] In the electricity storage device 1, in a cross-sectional view along the narrow surface 12b of the case body 12, a notch 75 is provided below an intersection Q between a line L1 that passes through the center P of the liquid inlet 17 and that extends along the short side of the sealing plate 14, and a line L2 that extends along the first side surface 70b of the insulating film 70. Therefore, the notch 75 separates the upper end of the insulating film 70 from the liquid inlet 17. This allows the liquid inlet 17 to be spaced apart from the upper end of the insulating film 70, through which the electrolyte has crept up due to capillary action, for example. This prevents the electrolyte from adhering to the vicinity of the liquid inlet 17 within the case 10. This in turn prevents poor bonding of the sealing member 16 to the liquid inlet 17, for example.

[0042] Furthermore, in the electricity storage device 1, the notch 75 is preferably provided closer to the center of the long side of the sealing plate 14 than the connection portion (e.g., joint portion) between the positive electrode terminal 30 and the current collecting member 50 and the connection portion (e.g., joint portion) between the negative electrode terminal 40 and the current collecting member 60. This makes it possible to appropriately maintain the effect of the insulating film 70 in suppressing contact between the positive electrode terminal 30, the negative electrode terminal 40, the current collecting member 50, the current collecting member 60, and the inner surface of the case 10 in the vicinity of the mounting hole (e.g., mounting hole 18).

[0043] The electrode assembly 20 may be 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 longitudinal direction with a long, sheet-like separator 23 interposed therebetween. The electrode assembly 20 may have a first curved portion 20r1, a second curved portion 20r2, and a flat portion 20f sandwiched between the first curved portion 20r1 and the second curved portion 20r2. The electrode assembly 20 may be housed in the case 10 so that the first curved portion 20r1 is disposed on the sealing plate 14 side and the second curved portion 20r2 is disposed on the bottom surface 12c side. The deepest portion 75p of the notch 75 may be located closer to the sealing plate 14 than a boundary 20BD between the first curved portion 20r1 and the flat portion 20f. The boundary 20BD can be said to be the portion of the electrode assembly 20 closest to the sealing plate 14 and capable of coming into contact with the case 10. Therefore, by positioning the deepest portion 75p of the notch 75 closer to the sealing plate 14 than the boundary 20BD, the effect of suppressing contact between the electrode body 20 and the case 10 can be appropriately maintained.

[0044] In the energy storage device 1, the positive electrode terminal 30 preferably includes a first conductive portion 31 disposed on the outside of the case 10, a second conductive portion 32 disposed on the inside of the case 10, and an axial portion 33 inserted through the mounting hole 18 and connecting the first conductive portion 31 and the second conductive portion 32. The current collecting member 50 preferably extends from the sealing plate 14 toward the electrode body 20, and is connected at one end to the second conductive portion 32 and at the other end to the electrode body 20. The current collecting member 50 may be sandwiched between insulating films 70 between the sealing plate 14 and a boundary 20BD between the first curved portion 20r1 and the flat portion 20f of the electrode body 20. This reduces the risk of contact between the current collecting member 50 and the case 10 due to the insulating film 70. The negative electrode terminal 40 is similar to the positive electrode terminal 30, and therefore will not be described here.

[0045] Although not particularly limited, as shown in FIGS. 1, 5, and 6, the notch 75 may be semicircular. In this case, the center of the semicircle is preferably directly below the intersection Q (see FIG. 3) of the straight lines L1 and L2. Alternatively, the notch 75 may have a shape other than semicircular, as long as the effects of the technology disclosed herein can be achieved. FIG. 7 is a front view of the insulating film 270. FIG. 7 shows the insulating film 270 as viewed from the first side surface 270b. As shown in FIG. 7, the notch 275 may be triangular. In this case, the notch 275 may be an isosceles triangle with the deepest portion 275p as its vertex. Furthermore, the deepest portion 275p is preferably directly below the intersection Q (see FIG. 3) of the straight lines L1 and L2. According to the above-mentioned shapes of the notch 75 and the notch 275, the insulating film 70 or the insulating film 270 can realize the effects of the technology disclosed herein and can enhance the effect of reducing the risk of contact between the current collecting member 50, the current collecting member 60, and the case 10.

[0046] FIG. 8 is a front view of the insulating film 370. FIG. 8 shows the insulating film 370 as viewed from the first side surface 370b. As shown in FIG. 8, the cutout 375 may be rectangular. By forming the cutout 375 in this shape, the upper end of the insulating film 370 can be spaced away from the liquid inlet 17 over a wider area. This further enhances the effect of preventing the electrolyte from adhering to the vicinity of the liquid inlet 17 inside the case 10.

[0047] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Section 1: An electrode body; a bag-shaped insulating film covering the electrode body; An electrolyte; A case that accommodates the electrode body, the insulating film, and the electrolyte solution, a case body having a rectangular bottom surface, an opening facing the bottom surface, a pair of wide surfaces extending from a pair of opposing long sides of the bottom surface, and a pair of narrow surfaces extending from a pair of opposing short sides of the bottom surface; a rectangular sealing plate that seals the opening; a case comprising: an electrode terminal attached to the case; a current collecting member connected to the electrode body and the electrode terminal inside the case; An electricity storage device comprising: the sealing plate has mounting holes to which the electrode terminals are attached and a liquid injection hole for the electrolyte, where: The insulating film is a first side surface facing the wide surface of the case body; the case body is closed at a lower end on the bottom surface side and is open at an upper end on the sealing plate side, The first side surface has a notch at the upper end thereof, In a cross-sectional view along the narrow surface of the case body, the cutout is located below an intersection Q of a straight line L1 that passes through a center P of the liquid injection hole and that is along the short side direction of the sealing plate, and a straight line L2 that is along the first side surface. Section 2: Item 2. The electricity storage device according to item 1, wherein the notch is provided closer to the center of the long side of the sealing plate than the connection portion between the electrode terminal and the current collecting member. Section 3: The electrode body is a wound electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the longitudinal direction with a long sheet-like separator interposed therebetween, The device has a first curved portion, a second curved portion, and a flat portion sandwiched between the first curved portion and the second curved portion, the first curved portion is disposed on the sealing plate side and the second curved portion is disposed on the bottom side, and the battery is housed in the case; Item 3. The electricity storage device according to item 1 or 2, wherein the deepest part of the notch is provided closer to the sealing plate than the boundary between the first curved portion and the flat portion. Section 4: The electrode terminal is a first conductive part disposed on the outside of the case; a second conductive portion disposed inside the case; a shaft portion that is inserted into the mounting hole and connects the first conductive portion and the second conductive portion; It has The current collecting member is extending from the sealing plate toward the electrode body, connected to the second conductive portion at one end and connected to the electrode body at the other end; Item 4. The electricity storage device according to item 3, wherein the insulating film is sandwiched between the boundary of the electrode body and the sealing plate. Section 5 5. The electricity storage device according to any one of items 1 to 4, wherein the cutout is semicircular or triangular.

[0048] Although the embodiments of the technology disclosed herein have been described above, it is not intended that the technology disclosed herein be limited to the above-described embodiments. The technology disclosed herein may also be implemented in other embodiments. The technology described in the claims includes various modifications and alterations of the above-described exemplary 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. [Explanation of symbols]

[0049] 1. Energy storage devices 10 cases 17 Liquid injection hole 18 Mounting holes 20 Electrode body 22 Positive electrode 23 Separator 24 Negative electrode 30 Positive terminal 40 Negative terminal 50,60 Current collecting member 70,270,370 Insulating film 75,275,375 notches

Claims

1. An electrode body; a bag-shaped insulating film covering the electrode body; An electrolyte; A case that accommodates the electrode body, the insulating film, and the electrolyte solution, a case body having a rectangular bottom surface, an opening facing the bottom surface, a pair of wide surfaces extending from a pair of opposing long sides of the bottom surface, and a pair of narrow surfaces extending from a pair of opposing short sides of the bottom surface; a rectangular sealing plate that seals the opening; a case comprising: an electrode terminal attached to the case; an insulating member disposed between the inner surface of the sealing plate and the electrode terminal; a current collecting member connected to the electrode body and the electrode terminal inside the case; An electricity storage device comprising: the sealing plate has mounting holes to which the electrode terminals are attached and a liquid injection hole for the electrolyte, where: The insulating film is a first side surface facing the wide surface of the case body; the case body is closed at a lower end on the bottom surface side and is open at an upper end on the sealing plate side, The first side surface has a notch at the upper end thereof, the notch is provided below an intersection Q of a straight line L1 that passes through a center P of the liquid injection hole and that is along a short side direction of the sealing plate, and a straight line L2 that is along the first side surface, in a cross-sectional view along the narrow surface of the case body, The upper end of the insulating film is located closer to the bottom surface of the case than the insulating member.

2. The electricity storage device according to claim 1 , wherein the notch is provided closer to the center of a long side of the sealing plate than a connection portion between the electrode terminal and the current collecting member.

3. An electrode body; a bag-shaped insulating film covering the electrode body; An electrolyte; A case that accommodates the electrode body, the insulating film, and the electrolyte solution, a case body having a rectangular bottom surface, an opening facing the bottom surface, a pair of wide surfaces extending from a pair of opposing long sides of the bottom surface, and a pair of narrow surfaces extending from a pair of opposing short sides of the bottom surface; a rectangular sealing plate that seals the opening; a case comprising: an electrode terminal attached to the case; a current collecting member connected to the electrode body and the electrode terminal inside the case; An electricity storage device comprising: the sealing plate has mounting holes to which the electrode terminals are attached and a liquid injection hole for the electrolyte, where: The insulating film is a first side surface facing the wide surface of the case body; the case body is closed at a lower end on the bottom surface side and is open at an upper end on the sealing plate side, The first side surface has a notch at the upper end thereof, the notch is provided below an intersection Q of a straight line L1 that passes through a center P of the liquid injection hole and that is along a short side direction of the sealing plate, and a straight line L2 that is along the first side surface, in a cross-sectional view along the narrow surface of the case body, The electrode body is a wound electrode body in which a long sheet-like positive electrode and a long sheet-like negative electrode are wound in the longitudinal direction with a long sheet-like separator interposed therebetween, The device has a first curved portion, a second curved portion, and a flat portion sandwiched between the first curved portion and the second curved portion, the first curved portion is disposed on the sealing plate side and the second curved portion is disposed on the bottom side, and the battery is accommodated in the case; The deepest part of the notch is located closer to the sealing plate than a boundary between the first curved portion and the flat portion.

4. The electrode terminal is a first conductive portion disposed on the outside of the case; a second conductive portion disposed inside the case; a shaft portion that is inserted into the mounting hole and connects the first conductive portion and the second conductive portion; It has The current collecting member is an insulating film extending from the sealing plate toward the electrode body, connected to the second conductive portion at one end, and connected to the electrode body at the other end; The electricity storage device according to claim 3 , wherein the electrode body is sandwiched between the insulating film and the insulating film between the boundary of the electrode body and the sealing plate.

5. An electrode body; a bag-shaped insulating film covering the electrode body; An electrolyte; A case that accommodates the electrode body, the insulating film, and the electrolyte solution, a case body having a rectangular bottom surface, an opening facing the bottom surface, a pair of wide surfaces extending from a pair of opposing long sides of the bottom surface, and a pair of narrow surfaces extending from a pair of opposing short sides of the bottom surface; a rectangular sealing plate that seals the opening; a case comprising: an electrode terminal attached to the case; a current collecting member connected to the electrode body and the electrode terminal inside the case; An electricity storage device comprising: the sealing plate has mounting holes to which the electrode terminals are attached and a liquid injection hole for the electrolyte, where: The insulating film is a first side surface facing the wide surface of the case body; the case body is closed at a lower end on the bottom surface side and is open at an upper end on the sealing plate side, The first side surface has a notch at the upper end thereof, the notch is provided below an intersection Q of a straight line L1 that passes through a center P of the liquid injection hole and that is along a short side direction of the sealing plate, and a straight line L2 that is along the first side surface, in a cross-sectional view along the narrow surface of the case body, The electricity storage device, wherein the cutout is semicircular or triangular.

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