Energy storage devices

Abstract

To provide a technique of suppressing the adhesion of an electrolyte solution near a liquid injection hole on an inner surface of a sealing plate.SOLUTION: A power storage device 1 includes an electrode body 20, an electrolyte solution, and a case 10 that accommodates the electrode body 20 and the electrolyte solution. The case 10 includes a case main body 12 that has an opening 12h, and a rectangular sealing plate 14 that seals the opening 12h. The sealing plate 14 has a liquid injection hole 17 for injecting the electrolyte solution on a first short-side part side relative to a line CL passing a middle point M1 of a first long-side part and a middle point M2 of a second long-side part. Here, the sealing plate 14 has a pair of projecting parts 90 projecting from an inner surface 142 to the inward of the case 10. The pair of projecting parts 90 are provided at portions symmetrical to the liquid injection hole 17 on the inner surface 142 in a long-side direction of the sealing plate 14.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] The power storage element disclosed in Japanese Patent Application Laid-Open No. 2016-76346 includes a container provided with a liquid injection hole for injecting an electrolytic solution in a partition wall, an electrode body accommodated in the container, and a plug member for sealing the liquid injection hole, the plug member having a head larger than the inner diameter of the liquid injection hole and a shaft portion inserted into the liquid injection hole. In this power storage element, a first recess surrounding the liquid injection hole or a convex portion surrounding the liquid injection hole is formed on the inner surface of the partition wall. The publication describes that with such a configuration, it is possible to suppress the amount of the electrolytic solution that adheres to the inner surface of the partition wall and moves to the outside through the space between the shaft portion of the plug member and the inner peripheral surface of the liquid injection hole.

[0003] Japanese Patent Application Laid-Open No. 2013-191450 discloses a method for manufacturing a rectangular secondary battery having a battery can for accommodating an electrode group, a battery lid for closing an opening of the battery can, a liquid injection port having a recess recessed on the surface of the battery lid and a through hole that opens on the bottom surface of the recess of the recess and penetrates the battery lid, and a sealing plug that is fitted into the recess and welded to the battery lid in a state of contacting the bottom surface of the recess to seal the liquid injection port after the electrolytic solution is injected into the battery can from the liquid injection port. This manufacturing method includes an injection step of mounting a nozzle head for injecting an electrolytic solution to the liquid injection port, connecting the electrolytic solution to the inside of the battery can in a state where a head body made of an elastic material of the nozzle head is brought into contact with the bottom surface of the recess and sealed to the through hole. The publication describes that with such a configuration, when injecting the electrolytic solution into the battery can, adhesion of the electrolytic solution to the recess of the liquid injection port is prevented, and welding defects caused by adhesion of the electrolytic solution when sealing the liquid injection port can be eliminated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Incidentally, the inventors of this invention want to prevent the electrolyte from adhering to the injection hole on the inner surface of the sealing plate. [Means for solving the problem]

[0006] The energy storage device disclosed herein comprises an electrode body, an electrolyte, and a case housing the electrode body and the electrolyte. The case has a case body having a rectangular bottom surface, an opening opposite the bottom surface, a pair of opposing wide surfaces extending from a pair of opposing long sides on the bottom surface, and a pair of opposing narrow surfaces extending from a pair of opposing short sides on the bottom surface, and a rectangular sealing plate that seals the opening. The sealing plate has a first long side portion and a second long side portion that are opposite to each other, and a first short side portion and a second short side portion that are opposite to each other. The sealing plate also has an injection hole for injecting the electrolyte, located on the first short side side of a straight line CL passing through the midpoint M1 of the first long side portion and the midpoint M2 of the second long side portion. Here, the sealing plate has a pair of protrusions projecting inward from the inner surface on the bottom side of the case. The pair of protrusions are provided on the inner surface of the sealing plate in the direction of its long side, symmetrically with respect to the liquid injection hole. With this configuration, it is possible to suppress the adhesion of electrolyte to the liquid injection hole on the inner surface of the sealing plate. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a cross-sectional view of the energy storage device 1. [Figure 2] Figure 2 is a magnified view of a portion of Figure 1. [Figure 3] Figure 3 is a plan view of the sealing plate 14. [Figure 4] Figure 4 is a schematic diagram of the electrode body 20. [Figure 5]Figure 5 is a partial cross-sectional view of the energy storage device 2. [Modes for carrying out the invention]

[0008] The following describes one embodiment of the technology disclosed herein. The embodiment described herein is not intended to limit the technology disclosed herein. Unless otherwise specified, the technology disclosed herein is not limited to the embodiment described herein. The drawings are schematic and do not necessarily reflect the actual objects. In addition, the same reference numerals are used appropriately for members and parts that perform the same function, and redundant explanations are omitted. In the drawings, the numerals "R", "L", "U", "D", "F", and "Rr" indicate "right", "left", "up", "down", "front", and "back", respectively. In addition, the notation "A~B" indicating a numerical range means "A or more and B or less" unless otherwise specified, and also includes the meaning of "greater than A and less than B".

[0009] In this specification, "energy storage device" refers to a device in which charging and discharging occur through the movement of a charge carrier between a pair of electrodes (positive electrode and negative electrode) via an electrolyte. Such energy 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. Below, an embodiment of a lithium-ion secondary battery will be described as an example of the energy storage device described above.

[0010] Figure 1 is a cross-sectional view of the energy storage device 1. Figure 1 shows the cross-sectional structure of the energy storage device 1 along the wide surface 12a. Figure 2 is a partially enlarged view of Figure 1. Figure 2 shows a partially enlarged view of the cross-sectional structure near the liquid injection hole 17 in Figure 1. As shown in Figure 1, the energy storage device 1 comprises a case 10, an electrode body 20, a positive electrode terminal 30, a negative electrode terminal 40, a current collector member 50 on the positive electrode side, a current collector member 60 on the negative electrode side, an insulating film 70, an insulating member 80, and an electrolyte (not shown).

[0011] Case 10 is, for example, a component that houses the electrode body 20 and the electrolyte. While not particularly limited, for example, case 10 may be made of aluminum or an aluminum alloy, respectively, from the viewpoint of reducing weight and ensuring the required rigidity.

[0012] As shown in Figures 1 and 2, 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, for example, housing the electrode body 20 inside. 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 here faces the opening 12h. The bottom surface 12c here is rectangular and has a pair of opposing long sides and a pair of opposing short sides. The pair of opposing wide surfaces 12a are surfaces extending from the pair of opposing long sides on the bottom surface 12c. The pair of opposing narrow surfaces 12b are surfaces extending from the pair of opposing short sides on the bottom surface 12c. In this specification, the term "rectangular" or "rectangle" includes shapes in which the 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 curved, uneven, or bent and composed of multiple straight or curved lines, etc.

[0013] The opening 12h is, for example, the area where the sealing plate 14 is fitted. Here, the 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 is rectangular in shape. The sealing plate 14 is fitted into the opening 12h and joined (for example, by welding), thereby integrating the case body 12 and the sealing plate 14, and the case 10 is airtightly sealed.

[0014] Figure 3 is a plan view of the sealing plate 14. Figure 3 shows the structure of the sealing plate 14 as seen from the outside of the case 10. The sealing plate 14 is, for example, a flat plate-shaped member that seals the opening 12h. For this reason, the shape of the sealing plate 14 is preferably 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. As shown in Figure 3, the sealing plate 14 has a first long side portion 14a and a second long side portion 14b that face each other, and a first short side portion 14c and a second short side portion 14d that face each other. In the form shown in Figure 3, the first long side portion 14a is the front (F) long side portion of the pair of opposing long sides. The second long side portion 14b is the rear (Rr) long side portion of the pair of opposing long sides. The first short side portion 14c is the right (R) long side portion of the pair of opposing short sides. The second short side portion 14d is the left (L) long side portion of the pair of opposing short sides.

[0015] As shown in Figure 3, the sealing plate 14 has mounting holes (not shown), a discharge valve 15, and an injection hole 17. The mounting holes are, for example, through holes for attaching electrode terminals. For this reason, the sealing plate 14 preferably has mounting holes for attaching the positive electrode terminal 30 and mounting holes for attaching the negative electrode terminal 40. A portion of the electrode terminal is inserted through these mounting holes. The discharge valve 15 is, for example, a thin-walled portion. Here, the discharge valve 15 is configured to rupture when the pressure inside the case 10 exceeds a predetermined value, thereby discharging gas from inside the case 10 to the outside. The injection hole 17 is the part into which the electrolyte is injected. As shown in Figures 1 to 3, a sealing member 16 is attached to the injection hole 17. In this embodiment, the injection hole 17 is located on the side of the first short side 14c (to the right in Figure 3) relative to the straight line CL passing through the midpoint M1 of the first long side 14a and the midpoint M2 of the second long side 14b.

[0016] The sealing member 16 may be made of metal, for example. In the embodiment shown in Figure 3, the sealing member 16 has a flange portion 161 and an insertion portion 162. The flange portion 161 is plate-shaped and is positioned on the sealing plate 14 and welded to the sealing plate 14. The insertion portion 162 is axial or projection-shaped and is inserted into the liquid injection hole 17. The shape of the sealing member 16 is not limited to this. In other embodiments, the sealing member 16 may consist only of the flange portion 161.

[0017] Incidentally, during the welding of the sealing member 16 and the sealing plate 14, for example, the sealing member 16 (here, the flange portion 161) is welded to the outer surface 141 of the sealing plate 14 (see Figures 2 and 3). At this time, in the sealing plate 14, for example, the temperature rise is greater near the injection hole 17 than in other areas. Therefore, if electrolyte is adhering to the vicinity of the injection hole 17, the electrolyte may vaporize due to the temperature rise caused by welding. The inventors wanted to suppress the vaporization of the electrolyte near the injection hole 17 during welding. The inventors thought that by suppressing the adhesion of electrolyte to the injection hole 17 on the inner surface 142 of the sealing plate 14 (see Figure 2), it would be possible to suppress the vaporization of the electrolyte in that area during welding, and consequently reduce the risk of problems (e.g., welding defects) caused by the vaporization of the electrolyte.

[0018] In the form shown in FIGS. 1 to 3, the sealing plate 14 has a pair of protruding portions 90. Here, the pair of protruding portions 90 protrude inward from the inner surface 142 on the bottom surface 12c side of the case 10. The protruding direction of the protruding portion 90 can be defined, for example, by a straight line L1 connecting the proximal end 90B and the distal end 90E of the protruding portion 90. The proximal end 90B of the protruding portion 90 is here the boundary between the inner surface 142 and the protruding portion 90. In this embodiment, the pair of protruding portions 90 are provided at positions symmetric with respect to the liquid injection hole 17 on the inner surface 142 in the long side direction of the sealing plate 14. The long side direction of the sealing plate 14 here refers to the direction in which the first long side portion 14a extends, and in FIGS. 1 to 3, it is the left-right direction. Also, in this specification, "the pair of protruding portions 90 are symmetric with respect to the liquid injection hole 17 in the long side direction of the sealing plate 14" means that in the long side direction of the sealing plate 14, the pair of protruding portions 90 sandwich the liquid injection hole 17, and the shortest distance from one protruding portion 90 to the liquid injection hole 17 is equal to the shortest distance from the other protruding portion 90 to the liquid injection hole 17. For the sake of convenience of explanation, in the following description, the left protruding portion 90 in FIGS. 2 and 3 may be referred to as the first protruding portion 901, and the right protruding portion 90 in the same figure may be referred to as the second protruding portion 902.

[0019] In the form shown in FIGS. 1 and 2, the protruding portion 90 is plate-shaped. As shown in FIG. 2, the protruding portion 90 has a first surface 91 and a second surface 92. The first surface 91 is here a flat surface and is the surface on the side of the other protruding portion 90. The "surface on the side of the other protruding portion 90" here means any surface provided on the side of the other protruding portion 90, and depending on the size of the angle θ (see FIG. 2) described later, it does not necessarily face the other protruding portion 90. As shown in FIG. 2, the first surface 91 of the first protruding portion 901 is the surface on the side of the second protruding portion 902. The first surface 91 of the second protruding portion 902 is the surface on the side of the first protruding portion 901. The second surface 92 is here a flat surface and is the surface on the side opposite to the first surface 91. As shown in FIG. 2, the second surface 92 of the first protruding portion 901 is the surface facing the side opposite to the second protruding portion 902. The second surface 92 of the second protruding portion 902 is the surface facing the side opposite to the first protruding portion 901.

[0020] In this embodiment, the protruding portion 90 is inclined with respect to the inner surface 142 of the sealing plate 14. Here, the other protruding portion 90 side (the angle on the injection hole 17 side) of the angle formed by the protruding portion 90 and the inner surface 142 of the sealing plate 14 is less than 90 degrees. In the form shown in FIG. 2, the angle θ formed by the line segment LS and the straight line L1 is less than 90 degrees. The line segment LS is, here, the line segment connecting the base end 90B of the first protruding portion 901 and the base end 90B of the second protruding portion 902 at the shortest distance. The angle θ is, for example, preferably 80 degrees or less, more preferably 70 degrees or less, still more preferably 60 degrees or less, further more preferably 50 degrees or less, and particularly preferably 40 degrees or less. The angle θ is generally preferably 3 degrees or more, more preferably 5 degrees or more, and still more preferably 10 degrees or more.

[0021] The shortest distance W1 between the injection hole 17 and the protruding portion 90 is not particularly limited as long as the effects of the technology disclosed here are achieved. The shortest distance W1 is, for example, the shortest distance between the center P of the injection hole 17 and the base end 90B of the protruding portion 90 (see FIG. 3). When the shortest distance W2 (outer dimension, see FIG. 3) between the first short side portion 14c and the second short side portion 14d is taken as 1, the shortest distance W1 is, for example, 0.02 or more, preferably 0.04 or more, and more preferably 0.06 or more. Also, when the shortest distance W2 is taken as 1, the shortest distance W1 is, for example, 0.17 or less, preferably 0.15 or less, and more preferably 0.13 or less. In one example, when the shortest distance W2 is 120 mm, the shortest distance W1 is preferably 7 mm to 15 mm. In this case, the shortest distance W3 between the base end 90B of the second protruding portion 902 and the first short side portion 14c is preferably 31 mm or more and 39 mm or less.

[0022] In this embodiment, the protruding portion 90 is provided continuously and integrally with the sealing plate 14. In this case, the protruding portion 90 is preferably made of the same material as the sealing plate 14. Although not particularly limited, the protruding portion 90 is preferably provided on the sealing plate 14 by pressing.

[0023] Figure 4 is a schematic diagram of the electrode body 20. The electrode body 20 is a power generation element of the energy storage device 1, for example, having a positive electrode and a negative electrode. The electrode body 20 has a laminated structure in which a sheet-shaped positive electrode 22 and a sheet-shaped negative electrode 24 are stacked with a separator 23 in between. The electrode body 20 is housed in the case 10 with the stacking direction of the sheet-shaped positive electrode 22 and the sheet-shaped negative electrode 24 facing a pair of wide surfaces 12a.

[0024] As shown in Figure 4, the electrode body 20 is a wound electrode body in which, for example, a sheet-shaped positive electrode 22 and a sheet-shaped negative electrode 24 are laminated with a separator 23 in between, and wound in the longitudinal direction LD of the sheet. The electrode body 20 can be manufactured, for example, by winding the positive electrode 22, the negative electrode 24 and the separator 23 to form a cylindrical body, and then press-molding this cylindrical body. For this reason, the electrode body 20 has a flattened shape. The electrode body 20 has, for example, a pair of opposing flattened surfaces 20a (see Figure 1).

[0025] Furthermore, one end face 20b of the electrode body 20 faces one narrow surface 12b (the left narrow surface 12b in Figure 1), and the other end face 20c faces the other narrow surface 12b (the right narrow surface 12b in Figure 1). End face 20b is the laminated surface of the uncoated portion 22c1 of the positive electrode current collector foil 22c and is an open surface. End face 20c is the laminated surface of the uncoated portion 24c1 of the negative electrode current collector foil 24c and is an open surface. As shown in Figures 1 and 4, the electrode body 20 is housed in the case body 12 such that the winding axis direction WD and the left-right direction of the energy storage device 1 are substantially parallel. Also, the winding axis WL of the electrode body 20 is substantially perpendicular to the wide surface 12a and the narrow surface 12b, and substantially parallel to the sealing plate 14.

[0026] As shown in Figure 4, the positive electrode 22 comprises 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 of the positive electrode 22 in the winding axis direction WD, if necessary. The constituent materials of the positive electrode active material layer 22a and the protective layer may be those used in this type of energy storage device (in this embodiment, a lithium-ion secondary battery) without any particular limitations.

[0027] One end of the positive electrode current collector foil 22c in the winding axis direction WD (the left end in Figure 4) is provided with a strip-shaped uncoated portion 22c1 along the longitudinal direction LD. The uncoated portion 22c1 is part of the positive electrode current collector foil 22c. The uncoated portion 22c1 is the portion of the positive electrode current collector foil 22c where the positive electrode active material layer 22a is not coated. In this embodiment, the uncoated portion 22c1 protrudes further than the separator 23 in the winding axis direction WD. The uncoated portion 22c1 is laminated at one end in the winding axis direction WD (the left end in Figure 4). As shown in Figure 1, the current collector member 50 is joined to the uncoated portion 22c1.

[0028] As shown in Figure 4, the negative electrode 24 has a long, strip-shaped negative electrode current collector foil 24c (for example, copper foil) and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector foil 24c. The constituent material of the negative electrode active material layer 24a may be any material used in this type of energy storage device (in this embodiment, a lithium-ion secondary battery) without any particular limitations.

[0029] One end of the negative electrode current collector foil 24c in the winding axis direction WD (the right end in Figure 4) is provided with a strip-shaped uncoated portion 24c1 along the longitudinal direction LD. The uncoated portion 24c1 is part of the negative electrode current collector foil 24c. The uncoated portion 24c1 is the 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 than the separator 23 in the winding axis direction WD. For example, the uncoated portion 24c1 is laminated at one end in the winding axis direction WD (the right end in Figure 4). As shown in Figure 1, the current collector member 60 is joined to the uncoated portion 22c1.

[0030] The separator 23 is a component 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 constitutes the outer surface of the electrode body 20. As the separator 23, for example, a porous sheet made of polyolefin resin such as polyethylene (PE) or polypropylene (PP) is used.

[0031] The positive electrode terminal 30 is, for example, a component that is electrically connected to the positive electrode 22 of the electrode body 20. As described above, the positive electrode terminal 30 is inserted through a mounting hole provided in the sealing plate 14 and is positioned on both the outside and inside of the case body 12. For this reason, the positive electrode terminal 30 preferably has, for example, a portion positioned on the outside of the case 10, a portion inserted through the mounting hole, and a portion positioned on the inside of the case 10. The positive electrode terminal 30 is made of, for example, aluminum or an aluminum alloy.

[0032] The positive electrode current collector 50 is, for example, a member that electrically connects the positive electrode 22 and the positive electrode terminal 30 inside the case 10. In the configuration shown in Figure 1, the current collector 50 is plate-shaped and extends from the sealing plate 14 toward the electrode body 20. Here, the current collector 50 is connected to the positive electrode terminal 30 at one end (the upper end in Figure 1) and to the electrode body 20 at the other end (the lower end in Figure 1). In this embodiment, the connection between the current collector 50 and the positive electrode terminal 30 is achieved by joining (for example, welding) one end of the current collector 50 to the positive electrode terminal 30. In this embodiment, the connection between the current collector 50 and the electrode body 20 is achieved by joining (for example, welding) the other end of the current collector 50 to the unpainted portion 22c1. The current collector 50 is made of, for example, aluminum or an aluminum alloy.

[0033] The negative electrode terminal 40 is, for example, a component that is 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 a configuration similar to that of the positive electrode terminal 30. For this reason, a description of the configuration of the negative electrode terminal 40 is omitted here. The current collector member 60 on the negative electrode side is, for example, a component that electrically connects the negative electrode 24 and the negative electrode terminal 40 inside the case 10. The current collector member 60 is made of, for example, copper or a copper alloy. The current collector member 60 on the negative electrode side may have a configuration similar to that of the current collector member 50 on the positive electrode side. For this reason, a description of the configuration of the current collector member 60 is omitted here.

[0034] The insulating film 70 is, for example, a component that covers the electrode body 20. The insulating film 70 is, for example, bag-shaped with a portion open. As shown in Figure 1, the insulating film 70 is closed at the lower end and open at the upper end. In this embodiment, the insulating film 70 is housed in the case 10 with the electrode body 20 contained inside.

[0035] As shown in Figures 1 and 2, insulating members 80 are placed between the positive terminal 30 and the sealing plate 14, and between the negative terminal 40 and the sealing plate 14. The insulating members 80 are placed, for example, between the positive terminal 30 and the outer surface of the sealing plate 14, between the positive terminal 30 and the inner surface of the sealing plate 14, and along the inner circumferential surface of the mounting hole. The same applies to the negative terminal side, where the insulating member 80 is placed, for example, between the negative terminal 40 and 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 molded, or it may be a combination of multiple molded parts.

[0036] The electrolyte solution contains, for example, an electrolyte salt and a non-aqueous solvent. An example of an electrolyte salt is 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), monofluoromethyldifluoromethyl carbonate (F-DMC), and trifluorodimethyl carbonate (TFDMC). These can be used individually or in combination of two or more.

[0037] The energy storage device 1 can be used for various purposes, but it is particularly suitable for use as a power source (driving power supply) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but preferred examples include plug-in hybrid vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0038] As described above, the energy storage device 1 comprises an electrode body 20, an electrolyte, and a case 10 that houses the electrode body 20 and the electrolyte. The case 10 comprises a case body 12 having a rectangular bottom surface 12c, an opening 12h facing the bottom surface 12c, a pair of opposing wide surfaces 12a extending from a pair of opposing long sides on the bottom surface 12c, and a pair of opposing narrow surfaces 12b extending from a pair of opposing short sides on the bottom surface 12c, and a rectangular sealing plate 14 that seals the opening 12h. The sealing plate 14 has a first long side portion 14a and a second long side portion 14b that face each other, and a first short side portion 14c and a second short side portion 14d that face each other. The sealing plate 14 has an injection hole 17 for injecting electrolyte solution on the side of the first short side 14c, relative to the straight line CL passing through the midpoint M1 of the first long side 14a and the midpoint M2 of the second long side 14b.

[0039] Here, the sealing plate 14 has a pair of protrusions 90 (here, a first protrusion 901 and a second protrusion 902) that project inward from the inner surface 142 on the bottom surface 12c side of the case 10. Furthermore, the pair of protrusions 90 are provided on the inner surface 142 in the long side direction of the sealing plate 14, in a position symmetrical with respect to the liquid injection hole 17.

[0040] In the energy storage device 1, a pair of protrusions 90 are provided on the inner surface 142 of the sealing plate 14, such that they are symmetrical in the long-side direction relative to the liquid injection hole 17. In other words, on the inner surface 142 of the sealing plate 14, the liquid injection hole 17 is sandwiched between the pair of protrusions 90. Therefore, for example, in the manufacturing process of the energy storage device 1, if the case 10 containing the electrode body 20 and electrolyte before sealing moves, the protrusions 90 can block the electrolyte that bounces back from the inner wall surface (e.g., the narrow side 12b) of the case body 12. This prevents the electrolyte from adhering to the vicinity of the liquid injection hole 17 on the inner surface 142 of the sealing plate 14. And, for example, it can suppress the occurrence of defects that may be caused by the electrolyte adhering to the vicinity of the liquid injection hole 17 (e.g., welding defects between the sealing member 16 and the sealing plate 14).

[0041] Furthermore, it is preferable that the protrusion 90 has a flat surface (in this case, the second surface 92) facing the opposite side of the other protrusion 90. By making the surface of the protrusion 90 opposite to the other protrusion 90 a flat surface without irregularities, the electrolyte that bounces back from the inner wall surface of the case body 12 can flow more smoothly into the case 10. This makes it possible to enhance the effect of suppressing the adhesion of the electrolyte to the injection hole 17 on the inner surface 142 of the sealing plate 14.

[0042] Furthermore, the protrusion 90 is preferably plate-shaped. The protrusion 90 preferably has a flat first surface 91 on the other side of the protrusion 90 and a flat second surface 92 on the opposite side of the first surface 91. In this case, the fact that the second surface 92 is a flat surface makes it possible to suppress the scattering of electrolyte inside the case 10 when the electrolyte is poured into the case 10. This makes it possible to further enhance the effect of suppressing the adhesion of electrolyte to the pouring hole 17 on the inner surface 142 of the sealing plate 14.

[0043] Furthermore, the protrusion 90 is preferably inclined with respect to the inner surface 142 of the sealing plate 14. The angle θ on the other side of the angle formed between the protrusion 90 and the inner surface 142 is preferably less than 90 degrees. This further enhances the effect of suppressing the adhesion of electrolyte to the injection hole 17 on the inner surface 142 of the sealing plate 14.

[0044] Furthermore, when the shortest distance W2 between the first short side portion 14c and the second short side portion 14d is set to 1, the shortest distance W1 from the liquid injection hole 17 to the protruding portion 90 should be between 0.06 and 0.13. This further enhances the effect of suppressing the adhesion of electrolyte to the liquid injection hole 17 on the inner surface 142 of the sealing plate 14.

[0045] Furthermore, the protrusion 90 is preferably provided continuously and integrally with the sealing plate 14. This eliminates the need to prepare a separate member for providing the protrusion 90. Therefore, in addition to the effect of suppressing the adhesion of electrolyte to the liquid injection hole 17, the ease of forming the energy storage device 1 can be improved.

[0046] In the above embodiment, the protrusion 90 was integrally formed with the sealing plate 14. However, it is not limited to this. Figure 5 is a partial cross-sectional view of the energy storage device 2. Figure 5 shows a partially enlarged view of the cross-sectional structure of the energy storage device 2 near the liquid injection hole 17. As shown in Figure 5, in the energy storage device 2, the sealing plate 14 has a pair of protrusions 290 that project inward from the inner surface 142 into the case 10. The pair of protrusions 290 are provided on the inner surface 142 in the long-side direction of the sealing plate 14, in a position symmetrical with respect to the liquid injection hole 17.

[0047] In this embodiment, the sealing plate 14 is provided with an insulating member 280 extending along its inner surface 142. A portion of the insulating member 280 also constitutes a protrusion 290. Similar to the insulating member 80 in the above embodiment, the insulating member 280 in this embodiment has the function of insulating the positive terminal 30 from the inner surface 142 of the sealing plate 14, and also the function of insulating the negative terminal 40 from the inner surface 142 of the sealing plate 14. As shown in Figure 5, the insulating member 280 located on the positive terminal side (left side of Figure 5, see Figure 1) has a protrusion 290 at the end on the liquid injection hole 17 side (right end in Figure 5). Similarly, the insulating member 280 located on the negative terminal side (right side of Figure 5, see Figure 1) also has a protrusion 290 at the end on the liquid injection hole 17 side (right end in Figure 5). In this embodiment, the protrusion 290 is made of an insulating material (for example, a resin material). Therefore, in addition to the effect of suppressing the adhesion of electrolyte to the injection hole 17, it is possible to achieve the effect of reducing the risk of contact between the electrode body 20 and the sealing plate 14.

[0048] The following describes examples of studies (tests) conducted by the inventors regarding the technology disclosed herein. However, these test examples are not intended to limit the technology disclosed herein. For reference to the part numbers in the following test examples, please refer to Figures 1 to 3 as appropriate.

[0049] <Design of evaluation samples> Regarding the protrusion 90 in this test example, each sample shown in Table 1 below was designed. However, in this test example, only the protrusion 90 on the first short side 14c side was designed, and the protrusion 90 on the second short side 14d side was not designed. For each sample, a simulation regarding the adhesion of the electrolyte to the injection hole 17 was performed using CAE (computer-aided engineering) analysis. In the CAE analysis, a test assembly in which the electrode body 20 and the electrolyte are housed in the case body 12 and a sealing plate 14 is attached to the opening 12h was transported to the left from the narrow surface 12b corresponding to the first short side 14c, and when decelerated at a predetermined timing, it was evaluated whether or not the electrolyte adhered to the injection hole 17. Here, the electrolyte was accelerated from a stationary state. The analysis was performed by decelerating from constant acceleration to obtain the same result as accelerating from a stationary state. At this time, the electrolyte is in a stationary state. The transport speed of the test assembly in the CAE analysis was 1000 mm / s. The acceleration during deceleration (i.e., deceleration) was 1.2 × 9.8 m / s². 2 That was the case.

[0050] The dimensional relationships of each sample were designed as follows: • Longest side length of sealing plate 14 (outer dimensions): 120mm (inner dimensions: 119mm) • Case body height (external dimensions): 65mm • Electrolyte level (distance from the outer surface 141 of the sealing plate 14): 8 mm • Thickness of protrusion 90: 0.5 mm • Width of the protrusion 90 (length along the short side of the sealing plate 14): 10.5 mm • Distance X: As shown in Table 1. • Distance Z: As shown in Table 1. • Angle θ: As shown in Table 1. Note that "Distance X" corresponds to the shortest distance W3 shown in Figure 3. "Distance Z" is the distance from the inner surface 142 of the sealing plate 14 to the tip 90E of the protrusion 90, as shown in Figure 2. "Angle θ" is the angle formed by the line segment LS and the straight line L1, as shown in Figure 2.

[0051] <Rating> The evaluation criteria for each sample are as follows: "○": On the inner surface 142 of the sealing plate 14, no electrolyte adhered to the injection hole 17 (there was an effect in suppressing the adhesion of electrolyte to the injection hole 17). "×" On the inner surface 142 of the sealing plate 14, electrolyte adhered to the injection hole 17 (there was no effect in suppressing the adhesion of electrolyte to the injection hole 17).

[0052] [Table 1]

[0053] When the protrusion 90 is provided only on the first short side 14c of the sealing plate 14, it was found that the smaller the angle θ, the more likely the effects of the disclosed technology are to be realized, as shown in Table 1. It was also found that the smaller the distance Z, the more likely the effects of the disclosed technology are to be realized. Furthermore, it was found that the closer the protrusion 90 is provided to the liquid injection hole 17 (i.e., the larger the distance X), the more likely the effects of the disclosed technology are to be realized.

[0054] As described above, specific embodiments of the technology disclosed herein include those described in the following sections. Section 1: Electrode body and Electrolyte and A case for housing the electrode body and the electrolyte, A case body having a rectangular base, an opening opposite the base, a pair of opposing wide surfaces extending from a pair of opposing long sides on the base, and a pair of opposing narrow surfaces extending from a pair of opposing short sides on the base, A rectangular sealing plate that seals the aforementioned opening, Cases equipped with, A power storage device comprising, The aforementioned sealing plate is Mutually opposing first long side and second long side, Mutually opposing first short side portion and second short side portion, It has, The device has an injection hole for injecting the electrolyte on the side of the first short side, relative to the straight line CL passing through the midpoint M1 of the first long side and the midpoint M2 of the second long side. Here, The sealing plate has a pair of protrusions that project inward from the inner surface on the bottom side of the case. A power storage device wherein the pair of protrusions are provided on the inner surface of the sealing plate in the direction of the long side, symmetrically with respect to the liquid injection hole. Section 2: The energy storage device according to item 1, wherein the projection has a flat surface facing away from the other projection. Section 3: The aforementioned protrusion is It is plate-shaped, The energy storage device according to claim 1 or 2, having a flat first surface on the other side of the protruding portion and a flat second surface on the opposite side of the first surface. Section 4: The aforementioned protrusion is inclined with respect to the inner surface of the sealing plate, The energy storage device according to any one of items 1 to 3, wherein the angle on the side of the other of the angle formed between the protruding portion and the inner surface is less than 90 degrees. Section 5: The energy storage device according to any one of items 1 to 4, wherein, when the shortest distance between the first short side portion and the second short side portion is 1, the shortest distance from the liquid injection hole to the protruding portion is 0.06 or more and 0.13 or less. Item 6: The energy storage device according to any one of claims 1 to 5, wherein the protruding portion is provided continuously and integrally with the sealing plate. Section 7: The energy storage device according to any one of claims 1 to 5, wherein the sealing plate is provided with an insulating member extending along the inner surface, and a portion of the insulating member constitutes the protrusion.

[0055] While embodiments of the technology disclosed herein have been described above, the technology disclosed herein is not intended to be limited to the embodiments described herein. The technology disclosed herein can also be implemented in other embodiments. The technology described in the claims includes various modifications and changes to the embodiments exemplified above. For example, it is possible to replace parts of the above embodiments with other modifications, and it is also possible to add other modifications to the above embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate. [Explanation of Symbols]

[0056] 1,2 Energy storage devices 10 cases 12 Case body 12h opening 14 Sealing plate 141 External surface 142 Inner surface 17 Liquid injection hole 20 Electrode body 30 Positive terminal 40 Negative terminal 50,60 Current collector 70 Insulating film 80,280 Insulating materials 90,290 Protrusion

Claims

1. Electrode body and Electrolyte and A case for housing the electrode body and the electrolyte, A case body having a rectangular base, an opening opposite the base, a pair of opposing wide surfaces extending from a pair of opposing long sides on the base, and a pair of opposing narrow surfaces extending from a pair of opposing short sides on the base, A rectangular sealing plate that seals the aforementioned opening, Cases equipped with, A power storage device comprising, The aforementioned sealing plate is Mutually opposing first long side and second long side, Mutually opposing first short side portion and second short side portion, It has, The device has an injection hole for injecting the electrolyte on the first short side side, relative to the straight line CL passing through the midpoint M1 of the first long side and the midpoint M2 of the second long side. Here, The sealing plate has a pair of protrusions that project inward from the inner surface on the bottom side of the case. The pair of protrusions are provided on the inner surface of the sealing plate in the direction of the long side, symmetrically with respect to the liquid injection hole. When the shortest distance between the first short side portion and the second short side portion is set to 1, the shortest distance from the liquid injection hole to the protruding portion is 0.06 or more and 0.13 or less. Energy storage device.

2. Electrode body and Electrolyte and A case for housing the electrode body and the electrolyte, A case body having a rectangular base, an opening opposite the base, a pair of opposing wide surfaces extending from a pair of opposing long sides on the base, and a pair of opposing narrow surfaces extending from a pair of opposing short sides on the base, A rectangular sealing plate that seals the aforementioned opening, Cases equipped with, A power storage device comprising, The aforementioned sealing plate is Mutually opposing first long side and second long side, Mutually opposing first short side portion and second short side portion, It has, The device has an injection hole for injecting the electrolyte on the first short side side, relative to the straight line CL passing through the midpoint M1 of the first long side and the midpoint M2 of the second long side. Here, The sealing plate has a pair of protrusions, including a first protrusion and a second protrusion, that project inward from the inner surface on the bottom side of the case. The pair of protrusions are provided on the inner surface of the sealing plate in the direction of the long side, symmetrically with respect to the liquid injection hole. Both the first protrusion and the second protrusion are inclined with respect to the inner surface of the sealing plate. The angle between the line segment connecting the base end of the first projection and the base end of the second projection by the shortest distance, and the straight line connecting the tip and base end of the first projection by the shortest distance; and, The angle between the aforementioned line segment and the straight line connecting the tip and base of the second projection with the shortest distance. All of them are less than 90 degrees, When the shortest distance between the first short side portion and the second short side portion is set to 1, the shortest distance from the liquid injection hole to the protruding portion is 0.06 or more and 0.13 or less. Energy storage device.

3. The energy storage device according to claim 1, wherein the aforementioned protrusion has a flat surface facing away from the other aforementioned protrusion.

4. The aforementioned protrusion is It is plate-shaped, The energy storage device according to claim 1, further comprising a flat first surface on the other side of the protruding portion and a flat second surface on the opposite side of the first surface.

5. The aforementioned protrusion is inclined with respect to the inner surface of the sealing plate, The energy storage device according to claim 1, wherein the angle on the side of the other side of the angle formed by the protruding portion and the inner surface is less than 90 degrees.

6. The energy storage device according to any one of claims 1 to 5, wherein the protruding portion is provided continuously and integrally with the sealing plate.

7. The energy storage device according to any one of claims 1 to 5, wherein the sealing plate is provided with an insulating member extending along the inner surface, and a part of the insulating member constitutes the protruding portion.

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