Energy storage device

Abstract

To provide a power storage device in which a space between a current collector connected to an electrode terminal and an electrode body is reduced and a volumetric energy density is higher.SOLUTION: A power storage device includes: an electrode body having a first electrode body element and a second electrode body element; an exterior body housing the electrode body; a lid closing an opening of the exterior body; electrode terminals electrically connected to the electrode body; current collectors electrically connecting a first side first electrode plate and a second side first electrode plate of the electrode body to the electrode terminals; and insulating members disposed between the current collectors and the lid. The lid has a liquid injection hole for injecting an electrolyte into the exterior body, a first tab of the first side first electrode plate is bent toward the second electrode body element, a second tab of the second side first electrode plate is bent toward the first electrode body element, and the opening facing the lid in a hole formed in the insulating member is larger than the opening facing the electrode body, of the liquid injection hole.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] A power storage device is used as a power source for driving an electric vehicle (EV), a hybrid electric vehicle (HEV, PHEV), or the like, or as a power source for an electronic device. As this power storage device, for example, an alkaline secondary battery, a non-aqueous electrolyte secondary battery, or the like is used.

[0003] These power storage devices include, for example, an electrode body, an exterior body (case) that houses this electrode body, a lid that closes an opening of the exterior body, an electrode terminal, a liquid injection hole that is a through hole provided in the lid, and a sealing member that closes this liquid injection hole. The electrode body includes a positive electrode plate, a negative electrode plate, and a separator. The electrode terminal is connected to one of the positive electrode plate and the negative electrode plate of the electrode body and penetrates through an insertion hole provided in the lid.

[0004] Patent Document 1 discloses a power storage device in which an electrolytic solution is supplied into a case from a liquid injection hole of a lid, and after the supply of the electrolytic solution is completed, the liquid injection hole is closed with a sealing member.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the power storage device as described above, it is desired to increase the volume energy density to increase the battery capacity. For this purpose, it is conceivable to reduce the distance between the lid and the electrode body.

[0007] The purpose of this disclosure is to reduce the space between the current collector connected to the electrode terminal and the electrode body, thereby providing an energy storage device with a higher volumetric energy density. [Means for solving the problem]

[0008] An energy storage device in one aspect of the present disclosure includes an electrode body having a first electrode body element including a first side first electrode plate, a first side second electrode plate, and a first side separator interposed between the first side first electrode plate and the first side second electrode plate, a second electrode body element including a second side first electrode plate, a second side second electrode plate, and a second side separator interposed between the second side first electrode plate and the second side second electrode plate, an outer casing housing the electrode body, a lid closing the opening of the outer casing, electrode terminals electrically connected to the electrode body and partially exposed outside the outer casing from the lid, a current collector electrically connecting the first side first electrode plate and the second side first electrode plate of the electrode body to the electrode terminals, and between the current collector and the lid The energy storage device comprises an insulating member, the first electrode body element and the second electrode body element are arranged in the short direction of the lid, the lid has an injection hole for injecting electrolyte into the outer casing, the first electrode plate on the first side of the first electrode body element has a first tab that connects to a first region of the current collector, the second electrode plate on the second side of the second electrode body element has a second tab that connects to a second region of the current collector, the first tab is bent toward the second electrode body element and the second tab is bent toward the first electrode body element, and in the insulating member, a hole is formed in the region of the surface facing the lid that overlaps with the injection hole, and the opening of the hole facing the lid is larger than the opening of the injection hole facing the electrode body. [Effects of the Invention]

[0009] According to one aspect of this disclosure, the space between the current collector connected to the electrode terminal and the electrode body can be reduced, resulting in an energy storage device with a higher volumetric energy density. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing an example of an energy storage device according to the embodiments of the present disclosure. [Figure 2A] This is a cross-sectional view AA in Figure 1. [Figure 2B]This figure shows the positive electrode plate that makes up the energy storage device shown in Figure 1. [Figure 2C] This figure shows the negative electrode plates that make up the energy storage device shown in Figure 1. [Figure 2D] This figure shows the electrode elements that make up the energy storage device shown in Figure 1. [Figure 3] This is a view from above of the rightmost portion of Figure 1. [Figure 4] This is a cross-sectional view of BB in Figure 3, with some parts omitted. [Figure 5] Figure 1 is a perspective view of a current collector holder used in the energy storage device shown. [Figure 6] This is a view of Figure 5 from above. [Figure 7] Figure 6 is a cross-sectional view of CC. [Figure 8] This figure corresponds to the enlarged view of section D in Figure 2A, which shows the state in which the electrolyte is supplied into the outer casing through the injection hole. [Figure 9] This figure corresponds to part E in Figure 8 in another embodiment of the present disclosure. [Figure 10] This figure corresponds to part E in Figure 8 in another embodiment of the present disclosure. [Modes for carrying out the invention]

[0011] The following describes an embodiment of the energy storage device. The drawings referenced in the description of the embodiment are schematic, and the dimensional ratios of the components depicted in the drawings may differ from those of the actual product. In this specification, the notation "approximately identical" means that, using "approximately identical" as an example, it includes not only completely identical components but also those that are considered substantially identical. The term "end" refers to the end of the object and its vicinity. Furthermore, the shapes, materials, and quantities described below are illustrative examples for explanation purposes and can be changed depending on the specifications of the energy storage device. In the following description, similar components will be denoted by the same reference numerals.

[0012] The power storage device described below is used, for example, as a drive power source for an electric vehicle or a hybrid vehicle, or as a stationary power storage system for peak shifting of grid power.

[0013] Hereinafter, a power storage device 10 according to an example of an embodiment will be described in detail with reference to FIGS. 1 to 8. FIG. 1 is a perspective view of the power storage device 10. FIG. 2A is a cross-sectional view taken along line A-A of FIG. 1. FIG. 2B is a view showing a positive electrode plate 13 constituting the power storage device 10, FIG. 2C is a view showing a negative electrode plate 16 constituting the power storage device 10, and FIG. 2D is a view showing electrode body elements 12a and 12b constituting the power storage device 10. FIG. 3 is a view of the right-end side portion of FIG. 1 as seen from above. FIG. 4 is a cross-sectional view taken along line B-B of FIG. 3. In FIGS. 1 to 4, the longitudinal direction (lateral direction) of the exterior body 80 is indicated by X, the thickness direction is indicated by Y, and the vertical direction, which is the height direction, is indicated by Z. X, Y, and Z are orthogonal to each other. Hereinafter, in the power storage device 10, the opening side of the exterior body 80 will be described as the top and the bottom side of the exterior body 80 will be described as the bottom. Top and bottom are terms used for convenience of explanation.

[0014] As shown in FIG. 1, the power storage device 10 is a rectangular non-aqueous electrolyte secondary battery, and includes an electrode body 12 (FIG. 2A) as a power generation element, an exterior body 80, and a lid 20. The electrode body 12 includes a positive electrode plate 13 (FIG. 2B), a negative electrode plate 16 (FIG. 2C), and a separator (not shown) interposed between the positive electrode plate 13 and the negative electrode plate 16. The positive electrode plate 13 corresponds to the first electrode plate, and the negative electrode plate 16 corresponds to the second electrode plate.

[0015] The outer package 80 houses the electrode body 12 together with an electrolytic solution (not shown) corresponding to a non-aqueous electrolyte, and is in the shape of a bottomed substantially rectangular parallelepiped with an opening 81 at the upper end. An insulating sheet 82 (Fig. 2A) is interposed between the electrode body 12 and the outer package 80. The lid 20 closes the opening 81 of the outer package 80. The lid 20 is a rectangular plate having a longitudinal direction and a width direction, that is, a rectangular plate. The longitudinal direction of the lid 20 coincides with the longitudinal direction X of the outer package 80, and the width direction of the lid 20 coincides with the thickness direction Y of the outer package 80. A positive electrode terminal 30 and a negative electrode terminal 32, which are partially exposed from the lid 20 to the outside of the outer package 80, are fixed to the lid 20 and are arranged apart from each other in the longitudinal direction X of the lid 20. In the lid, a liquid injection hole 21 and an exhaust valve 25 are formed in the middle part in the longitudinal direction. The liquid injection hole 21 is arranged on the side of the positive electrode terminal 30 with respect to the exhaust valve 25. The liquid injection hole 21 is a hole for injecting the electrolytic solution into the outer package 80. The outer package 80 and the lid 20 are preferably each made of metal, for example, preferably made of aluminum or an aluminum alloy.

[0016] As shown in Fig. 4, the electrode body 12 includes two electrode body elements 12a and 12b arranged adjacent to each other. Each of the electrode body elements 12a and 12b has a plurality of positive electrode plates 13 and a plurality of negative electrode plates 16 laminated one by one alternately via separators. Thereby, in each of the electrode body elements 12a and 12b, the positive electrode plates 13 and the negative electrode plates 16 are laminated via separators. In the electrode body 12, the lamination direction of the positive electrode plates 13, the separators, and the negative electrode plates 16 is a direction orthogonal to the direction from the electrode body 12 toward the lid 20, and is the thickness direction Y which is orthogonal to the vertical direction.

[0017] A porous sheet having ion permeability and insulation is used as the separator. A preferred example of the power storage device 10 is a lithium ion battery.

[0018] As shown in Figure 2B, the positive electrode plate 13 has a main body portion 14 in which an active material mixture layer is formed on both sides of a rectangular core made of, for example, aluminum foil. A positive electrode tab 15 is provided on the positive electrode plate 13. On one longitudinal side of the main body portion 14 of the positive electrode plate 13 (right side in Figure 2B), the positive electrode core extends from the upper end, which is one end, and this extended core constitutes the extended positive electrode tab 15. The positive electrode tab 15 is electrically connected to the positive electrode terminal 30 fixed to the lid 20 via a positive electrode current collector 40 (Figure 4), which will be described later.

[0019] The positive electrode tab may be part of the core as shown, but it may also be an extended positive electrode tab by connecting another component to the core of the main body portion 14 of the positive electrode plate 13. Furthermore, as shown in Figure 2B, it is preferable that a protective layer 15a with higher electrical resistance than the active material mixture layer is provided in the portion of the positive electrode tab 15 adjacent to the active material mixture layer. This protective layer 15a preferably contains ceramic particles such as alumina, silica, or zirconia, and a binder. It is even more preferable that the protective layer 15a contains conductive particles such as carbon material.

[0020] The active material mixture layer of the positive electrode plate 13 includes, for example, an active material, a conductive agent, and a binder. Lithium nickel cobalt manganese composite oxide can be used as the active material of the positive electrode plate 13, polyvinylidene fluoride (PVdF) as the binder, a carbon material as the conductive agent, and N-methylpyrrolidone (NMP) as the dispersion medium.

[0021] Next, the method for manufacturing the positive electrode plate 13 will be described. First, a slurry containing the above-mentioned active material, conductive agent, binder, and dispersant is prepared. This slurry is applied to both sides of the core body of the positive electrode plate. Then, by drying it, the dispersion medium in the slurry is removed, and an active material mixture layer is formed on the core body. After that, the active material mixture layer is compressed to a predetermined thickness. The positive electrode plate 13 obtained in this way is then cut into a predetermined shape.

[0022] As shown in Figure 2C, the negative electrode plate 16 has a main body portion 17 in which an active material mixture layer is formed on both sides of a rectangular core made of, for example, copper foil. The negative electrode plate 16 is provided with a negative electrode tab 18. On the other longitudinal side of the main body portion 17 of the negative electrode plate 16 (left side in Figure 2C), the negative electrode core extends from one end, which is the upper end, and this extended core constitutes the extended negative electrode tab 18. The negative electrode tab 18 is electrically connected to a negative electrode terminal 32 fixed to the cover 20 via a negative electrode current collector 50 (Figure 2A), which will be described later.

[0023] While the negative electrode tab may be part of the core as described above, it may also be an extended negative electrode tab made by connecting another component to the core of the main body 17 of the negative electrode plate 16.

[0024] The active material mixture layer of the negative electrode plate 16 includes, for example, an active material, a conductive agent, a binder, and a thickener. Graphite can be used as the active material of the negative electrode plate 16, styrene-butadiene rubber (SBR) as the binder, carboxymethylcellulose (CMC) as the thickener, and water as the dispersion medium.

[0025] Next, the method for manufacturing the negative electrode plate 16 will be described. First, a slurry containing the above-mentioned active material, conductive agent, binder, and thickener is prepared. This slurry is applied to both sides of the core body of the negative electrode plate. Then, by drying it, the dispersion medium in the slurry is removed, and an active material mixture layer is formed on the core body. After that, the active material mixture layer is compressed to a predetermined thickness. The negative electrode plate 16 obtained in this way is then cut into a predetermined shape.

[0026] Multiple positive electrode plates 13 (e.g., 50 plates) and multiple negative electrode plates 16 (e.g., 51 plates) are manufactured using the method described above. These positive and negative electrode plates are then laminated with rectangular separators made of polyolefin to produce two laminated electrode elements 12a and 12b (Figure 2D). The two electrode elements 12a and 12b are manufactured such that each positive electrode tab 15 is laminated on one side of the upper end of each electrode element in the longitudinal direction X, and each negative electrode tab 18 is laminated on the other side of the upper end of each electrode element in the longitudinal direction X. Separators are placed on both sides of the two electrode elements 12a and 12b in the thickness direction Y, and the laminated state of the positive electrode plates 13, negative electrode plates 16 and separators can be fixed with tape or the like. Alternatively, an adhesive layer may be provided on the separator so that the separator and the positive electrode plate 13, and the separator and the negative electrode plate 16 are bonded together. Figure 4 shows only some of the positive electrode tabs 15 out of a total of multiple positive electrode tabs 15.

[0027] As shown in Figures 2A and 4, the energy storage device 10 further includes a positive electrode terminal 30 and a negative electrode terminal 32 that penetrate two holes in the lid 20, a positive electrode current collector 40 and a negative electrode current collector 50, a current collector holder 60, and a safety device 90. The positive electrode terminal 30 and the negative electrode terminal 32 correspond to electrode terminals. The positive electrode current collector 40 electrically connects the positive electrode terminal 30 to the electrode body 12 via the safety device 90. The negative electrode current collector 50 (Figure 2A) electrically connects the negative electrode terminal 32 to the electrode body 12.

[0028] At the upper end of the electrode body 12, which is the end on the lid 20 side, multiple positive electrode tabs 15 and negative electrode tabs 18 are stacked on top of each other and connected to the positive electrode current collector 40 and the negative electrode current collector 50. The positive electrode tabs 15 are connected to the positive electrode current collector 40, and the negative electrode tabs 18 are connected to the negative electrode current collector 50.

[0029] As shown in Figure 2A, the positive electrode current collector 40 includes a first current collector plate 41 connected to the positive electrode tab 15, and a second current collector plate 45 connected to the first current collector plate 41 and the safety device 90. The first current collector plate 41 and the second current collector plate 45 are connected by overlapping their edges and welding them together.

[0030] The negative electrode current collector 50 includes a first current collector plate 51 connected to the negative electrode tab 18, and a second current collector plate 54 connected to the first current collector plate 51 and the negative electrode terminal 32. The first current collector plate 51 and the second current collector plate 54 are connected by overlapping their edges and welding them together.

[0031] A positive electrode tab 15 is connected to the lower surface of the first current collector plate 41 of the positive electrode current collector 40, which faces the electrode body 12, and the positive electrode tab 15 is curved. Similarly, a negative electrode tab 18 is connected to the lower surface of the first current collector plate 51 of the negative electrode current collector 50, which faces the electrode body 12, and the negative electrode tab 18 is curved. This reduces the space between each current collector 40, 50 and the electrode body 12, enabling the realization of a secondary battery with a higher volumetric energy density.

[0032] The current collector holder 60 is positioned and provided between the first current collector plate 41 of the positive electrode current collector 40 and the lid 20. The current collector holder 60 corresponds to an insulating member. The current collector holder 60 is located in a position that coincides with the positive electrode tab 15 in the longitudinal direction X, and includes a cylindrical body 66 formed to surround the opening of the liquid injection hole 21 on the lower surface of the lid 20, which is the electrode body 12 side. The cylindrical body 66 extends from the lid 20 toward the electrode body 12. Furthermore, a shielding portion 70 interposed between the electrode body 12 and the lid 20 is connected to the electrode body 12 side end of the cylindrical body 66. This makes it possible to obtain a power storage device 10 with high volumetric energy density and high reliability, as will be described later. The current collector holder 60 will be described in detail later.

[0033] The positive terminal 30 is fixed to the lid 20 via a resin outer insulating member 100. A through hole 31 is formed in the positive terminal 30, and this through hole 31 is sealed by a sealing member 33. The negative terminal 32 is fixed to the lid 20 via a resin outer insulating member 101. The positive terminal 30 and the negative terminal 32 are made of metal, for example. The positive terminal 30 is made of aluminum or an aluminum alloy, for example. The negative terminal 32 is made of copper or a copper alloy, for example. It is even more preferable that the negative terminal 32 has a portion made of copper or a copper alloy on the inside side of the casing 80 and a portion made of aluminum or an aluminum alloy on the outside side of the casing 80.

[0034] Furthermore, it is preferable that the surface of the negative electrode terminal 32 is nickel-plated or otherwise treated. A hole 55 is formed in the second current collector plate 54 of the negative electrode current collector 50, and the lower end of the negative electrode terminal 32 is inserted into this hole 55 and the lower end is crimped to fix the second current collector plate 54 to the lid 20. At this time, the second current collector plate 54 is fixed to the lid 20 with an insulating plate 102 interposed between the lid 20 and the second current collector plate 54. This insulating plate 102 extends toward the first current collector plate 51 so that it is also interposed between the first current collector plate 51 of the negative electrode current collector 50 and the lid 20.

[0035] The safety device 90 shown in Figure 2A is a current interruption mechanism that activates, for example, when the pressure inside the outer casing 80 exceeds a predetermined value, and interrupts the conductive path between the positive electrode plate 13 (Figure 2B) of the electrode body 12 and the positive electrode terminal 30.

[0036] The safety device 90 includes a bowl-shaped conductive member 91 fixed to the portion of the positive terminal 30 that protrudes below the lid 20 at its lower end, and a reversing plate 93. The conductive member 91 has a hole 92 in the bottom of its bowl shape, into which the lower part of the positive terminal 30 is inserted and crimped, thereby fixing the conductive member 91 to the lid 20 together with the positive terminal 30. At this time, the conductive member 91 is fixed to the lid 20 with an insulating plate 103 interposed between the lid 20 and the conductive member 91.

[0037] The reversing plate 93 is a disc with a projection in its center. The reversing plate 93 is positioned to close the opening on the lower side of the conductive member 91, and the periphery of the reversing plate 93 and the opening end of the conductive member 91 are joined by welding. The projection in the center of the reversing plate 93 is connected to the second current collector plate 45 of the positive electrode current collector 40 by fitting into a hole provided in the second current collector plate 45. In this way, the reversing plate 93 is electrically connected to the conductive member 91 and the second current collector plate 45. Note that the projection in the center of the reversing plate 93 does not need to be fitted into the hole in the second current collector plate; the projection may be electrically connected by welding to the surface of the second current collector plate 45 facing the cover 20.

[0038] The safety device 90 may be provided in the conductive path between the negative electrode plate 16 of the electrode body 12 and the negative electrode terminal 32. The conductive member 91 and the inverting plate 93 are made of metal, and when connected to the positive electrode terminal 30, the conductive member 91 and the inverting plate 93 are made of, for example, aluminum or an aluminum alloy. When the conductive member and the inverting plate are connected to the negative electrode terminal 32, the conductive member and the inverting plate are made of, for example, copper or a copper alloy.

[0039] While it is preferable for the energy storage device 10 to be equipped with a safety device, it is not mandatory to provide a safety device in this disclosure, and the safety device may be omitted.

[0040] Furthermore, the lid 20 is equipped with an exhaust valve 25 that ruptures when the pressure inside the outer casing 80 exceeds a predetermined value, thereby releasing the gas inside the outer casing 80 to the outside. The operating pressure of the exhaust valve 25 is set to a value greater than the operating pressure of the safety device 90.

[0041] The lid 20 is further provided with an injection hole 21 (Figure 4). After the electrolyte is injected into the outer casing 80 through the injection hole 21, the injection hole 21 is sealed with a rivet stopper 26 (Figure 2A). When injecting the electrolyte, a straw-shaped (tubular) nozzle 105 (Figure 4) is inserted into the injection hole 21, and the electrolyte is injected into the outer casing 80 through this nozzle 105.

[0042] As shown in Figures 2A, 4, and 8, the energy storage device 10 further includes a resin current collector holder 60 having a first insulating portion 61 and a second insulating portion 64. Figure 5 is a perspective view of the current collector holder 60. Figure 6 is a view of Figure 5 from above. Figure 7 is a cross-sectional view of section CC of Figure 6. Figure 8 is a diagram corresponding to an enlarged view of section D in Figure 2A, showing the state in which electrolyte is supplied into the outer casing 80 through the injection hole 21.

[0043] The first insulating portion 61 of the current collector holder 60 is interposed between the second current collector plate 45 and the reversing plate 93 of the positive electrode current collector 40. The second insulating portion 64 of the current collector holder 60 is interposed between the first current collector plate 41 of the positive electrode current collector 40 and the lid 20. In Figures 5 to 7, the longitudinal direction of the current collector holder 60 is shown by a, the width direction by b, and the height direction by c. a, b, and c are orthogonal to each other. The current collector holder 60 is positioned below the lid 20 such that its longitudinal direction a coincides with the longitudinal direction X of the energy storage device 10, its width direction b coincides with the thickness direction Y of the energy storage device 10, and its height direction c coincides with the vertical direction Z.

[0044] A second current collector plate 45 (Figure 2A) is supported below the first insulating portion 61. The first insulating portion 61 is locked to the outside of a cylindrical body 104 formed on the insulating plate 103. A bowl-shaped conductive member 91 is fitted inside this cylindrical body 104. As a result, the positive electrode current collector 40 is fixed to the lid 20. Specifically, on the back surface of the first insulating portion 61, which is the surface opposite to the surface facing the second current collector plate 45 (upper surface in Figure 2A, lower surface in Figure 5), multiple claws (not shown) are formed at various positions. Each of the multiple claws clamps the outer peripheral flange (not shown) formed on the lower end of the conductive member 91 or the outer circumference of the reversing plate 93 from both above and below with a portion different from the claw on the upper surface of the first insulating portion 61. In addition, on the first insulating portion 61, wall-shaped locking portions 63 (Figure 5) are formed on both side edges in the width direction b of the back surface, extending toward the lid 20. Then, the outer surface of the cylindrical body 104 of the insulating plate 103 is locked to the locking portion 63 by projections (not shown) formed on the inner surface of each of these locking portions 63. In this way, the current collector holder 60 is fixed to the lid 20 via the insulating plate 103. The first insulating portion 61 is further formed with a hole 61a (Figures 5 and 6) that penetrates in the height direction c, and the projection at the center of the reversing plate 93 and the second current collector plate 45 are connected through this hole 61a.

[0045] Furthermore, a plurality of cylindrical protrusions 61b are formed on the electrode body side surface of the first insulating portion 61, surrounding the hole 61a. The plurality of protrusions 61b are inserted into a plurality of holes 46 (Figure 2A) provided in the second current collector plate 45. After the plurality of protrusions 61b are inserted into the plurality of holes 46 of the second current collector plate 45, the portion of the protrusions 61b that penetrates the holes 46 is deformed by heat crimping, thereby fixing the second current collector plate 45 to the first insulating portion 61.

[0046] As shown in Figure 8, the second insulating portion 64 of the current collector holder 60 and the first current collector plate 41 of the positive electrode current collector 40 are positioned near the periphery of the liquid injection hole 21 of the lid 20. The first current collector plate 41 has a through hole 42 that penetrates in the vertical direction Z on the surface facing the second insulating portion 64. Furthermore, as shown in Figures 6 and 8, the second insulating portion 64 has a hole 65 that penetrates in the height direction c and the vertical direction Z at a position that aligns with the through hole 42 of the first current collector plate 41. This hole 65 is an oval shape that is elongated in the longitudinal direction a of the current collector holder 60. On the electrode body 12 side surface of the second insulating portion 64, a cylindrical body 66 is formed at the opening periphery of the hole 65, extending from the lid 20 side toward the electrode body 12 side. The cylindrical body 66 has two planar portions 67 parallel to its outer surface, corresponding to the shape of the hole 65, and its cross-sectional shape is an oval shape that is elongated in the longitudinal direction a. As a result, the cylindrical body 66 extends downward from the lid 20 toward the electrode body 12, surrounding the opening of the liquid injection hole 21 on the lower surface of the lid 20, which is the electrode body side. The cylindrical body 66 is also positioned between the upper surface, which is the outer surface of the lid 20, and the electrode body 12. Furthermore, this cylindrical body 66 is inserted into the through hole 42 of the first current collector plate 41. When the positive electrode tab 15 is joined to the surface of the first current collector plate 41 facing the electrode body 12, the tip of the positive electrode tab 15 faces the flat portion 67 on the outer circumferential surface, which is the side surface of the cylindrical body 66.

[0047] This cylindrical body 66 prevents the tip of the positive electrode tab 15 from being mistakenly positioned below the through hole 42 of the first current collector plate 41 when the positive electrode tab 15 is joined to the first current collector plate 41. It also prevents the positive electrode tab 15 from blocking the lower side of the through hole 42 and the fluid injection hole 21.

[0048] In the cylindrical body 66 described above, a shielding portion 70 interposed between the electrode body 12 and the injection hole 21 is connected to the open end on the electrode body 12 side. Specifically, two substantially parallel plate-shaped protrusions 68 are formed on the electrode body 12 side of the cylindrical body 66, extending downward toward the electrode body 12 from two positions with a 180-degree phase difference. The ends of these two protrusions 68 are connected at both ends in the first direction, the width direction b, by an elongated flat shielding portion 70, and the shielding portion 70 consists of a plate extending linearly in the width direction b. The width direction b is parallel to the width direction of the lid 20 (Figures 1 and 2A) and corresponds to the first direction. As a result, the shielding portion 70 is formed on the electrode body 12 side of the cylindrical body 66, at the end on the electrode body 12 side of the ends in the direction from the lid 20 toward the electrode body 12. Furthermore, the shielding portion 70 has two openings 73 formed between the electrode body 12 side end of the cylindrical body 66 and the shielding portion 70. Each opening 73 is an outlet that ejects the electrolyte flowing from the lid 20 side to the electrode body 12 side into the cylindrical body 66. As shown in Figures 4 and 8, with the current collector holder 60 assembled on the lower side of the lid 20, both sides of the shielding portion 70 in the vertical direction Z are parallel to a plane perpendicular to the vertical direction Z. The shielding portion 70 is the part that changes the flow of electrolyte that collides from above, on the lid 20 side, to a direction different from the downward direction on the electrode body 12 side.

[0049] When supplying electrolyte into the outer casing 80 through the injection hole 21, for example, as shown in Figure 8, the nozzle 105 is inserted into the injection hole 21 from the upper side of the lid 20. At this time, the lower end of the nozzle 105 is positioned opposite the upper surface of the shielding portion 70 with a gap between them. In this state, the electrolyte is flowed into the nozzle 105 from above in the direction indicated by arrow α in Figure 8. The electrolyte ejected from the lower end of the nozzle 105 collides with the upper surface of the shielding portion 70, and the flow of the electrolyte is changed from the direction of arrow α in Figure 8 to the direction of arrow β in Figure 8, which is approximately the longitudinal direction X. The electrolyte is then ejected to the outside of the cylindrical body approximately in the longitudinal direction X through the two openings 73 and flows downwards.

[0050] Next, using Figure 2A, the method for attaching the positive electrode terminal 30, safety device 90, and positive electrode current collector 40 to the lid 20 will be explained. The positive electrode terminal 30 is inserted into the hole in the lid 20 via the outer insulating member 100, and the electrode body 12 side of the positive electrode terminal 30 is inserted into the insulating plate 103 and the hole 92 of the conductive member 91. Then, the electrode body 12 side end of the positive electrode terminal 30 is crimped to fix the positive electrode terminal 30 to the lid 20. The periphery of the reversing plate 93 is then joined to the open end of the conductive member 91. After that, the conductive member 91 is fixed to the first insulating part 61 by the claws of the first insulating part 61 of the current collector holder 60. At the same time, the locking part 63 (Figure 5) of the first insulating part 61 is locked to the insulating plate 103. Furthermore, after inserting the protrusion 61b of the first insulating part 61 into the hole 46 of the second current collector plate 45 of the positive electrode current collector 40, the tip of the protrusion 61b is heat-crimped. Then, the projection of the reversing plate 93 is fitted into the hole of the second current collector plate 45, and the interface between these holes and the projection is joined by laser welding.

[0051] Furthermore, a positive electrode tab 15 is joined to the surface of the first current collector plate 41 of the positive electrode current collector 40 that faces the electrode body 12. With the cylindrical body 66 of the current collector holder 60 inserted into the through hole 42 of the first current collector plate 41, the first current collector plate 41 with the positive electrode tab 15 joined to it is placed in the second insulating part 64. At this time, a part of the edge of the first current collector plate 41 overlaps with a part of the edge of the second current collector plate 45, and this overlapping portion is joined by welding. After that, a cover (not shown) can be provided to cover the surface of the second current collector plate 45 that faces the electrode body 12.

[0052] As shown in Figure 4, the electrode body 12 is composed of two divided electrode body elements 12a and 12b, and each electrode body element 12a and 12b is connected to the positive electrode current collector 40 and the negative electrode current collector 50 (Figure 2A). As a result, on the first current collector plate 41, the positive electrode tabs 15 extending from each electrode body element 12a and 12b are joined to the electrode body 12 side of the first current collector plate 41 with the cylindrical body 66 positioned between the positive electrode tabs 15.

[0053] According to the above-described energy storage device 10, when the electrolyte is supplied into the outer casing 80 through the injection hole 21, the electrolyte can flow towards the electrode body 12 within the outer casing 80 with its flow velocity reduced by colliding with the shielding portion 70. Therefore, the flow velocity of the electrolyte when it collides with the upper end of the electrode body 12 within the outer casing 80 can be reduced. Consequently, damage, peeling, and slippage of the electrode body 12 material can be suppressed. Furthermore, the gap between the lid 20 and the electrode body can be reduced. As a result, an energy storage device 10 with high volumetric energy density and high reliability can be obtained.

[0054] Furthermore, in the electrode body 12, a positive electrode plate 13 and a negative electrode plate 16 are stacked with a separator in between, and the stacking direction of the positive electrode plate 13, separator and negative electrode plate in the electrode body 12 is perpendicular to the vertical direction Z, which is the direction from the electrode body toward the lid. As a result, the electrolyte tends to collide with the overlapping edges of the positive electrode plate 13, separator and negative electrode plate 16, but even in this case, peeling and sliding of the material can be suppressed, so the effects of this disclosure are significant. For example, in a configuration where the stacking direction of the positive electrode plate 13, negative electrode plate 16 and separator is perpendicular to the vertical direction Z, the edges of the stacked positive electrode plate, negative electrode plate and separator will be located at the upper end of the electrode body 12. In such a configuration, if the electrolyte collides with the edge of the electrode body 12 at a high speed, the separator adhered to the electrode plate may peel off from the electrode plate, or the active material layer of the electrode plate may slide off. According to the configuration of this disclosure, such problems can be suppressed. Therefore, even if the electrode body used in the energy storage device of this disclosure is not a stacked electrode body but a wound electrode body in which the winding axis extends from the electrode body toward the lid, the stacking direction of the positive electrode plate, negative electrode plate, and separator will be perpendicular to the vertical direction Z, thus the effect of suppressing damage to the electrode body can be fully obtained.

[0055] Furthermore, in the shielding portion 70 described above, the portion facing the electrode body 12 and the injection hole 21 is plate-shaped, and the first direction in which this facing portion extends is parallel to the width direction of the lid 20. As a result, the direction in which the electrolyte is ejected from the bottom of the cylindrical body 66 is approximately the longitudinal direction X in the inner space of the rectangular parallelepiped outer casing 80 corresponding to the shape of the lid 20, so that the electrolyte can be ejected toward a wider space within the outer casing 80. Therefore, the flow velocity of the electrolyte when it collides with the electrode body 12 can be further reduced.

[0056] Furthermore, the two openings 73 formed at the end of the cylindrical body 66 on the electrode body 12 side are separated in the longitudinal direction X, a by the shielding portion 70. This configuration allows the electrolyte flowing toward the electrode body 12 within the outer casing 80 to be dispersed, further suppressing damage, peeling, and slippage of the electrode body 12. At this time, by making a part of the edge of each opening 73 higher than the upper surface of the shielding portion 70, the electrolyte ejected from the opening 73 can be spread and dispersed over a wider area before flowing toward the electrode body 12, making it easier to further reduce the flow velocity of the electrolyte when it collides with the electrode body 12.

[0057] Furthermore, the shielding portion 70 does not need to consist of only one piece; it may be configured as multiple pieces connected to the cylindrical body 66. In this case, the multiple shielding portions may be provided at different height positions on the cylindrical body 66. For example, the shielding portion may extend in the width direction, with both ends connected at two locations on the cylindrical body in the first direction, the width direction. Alternatively, the end of the cylindrical body 66 on the electrode body 12 side may be sealed with a plate-shaped shielding portion 70, and openings for ejecting the electrolyte may be formed at at least one location on the outer circumferential surface of the cylindrical body 66.

[0058] Furthermore, the shielding portion 70 may be provided at the lower end of the cylindrical body 66, for example, near the lower end. This configuration allows the nozzle of the supply source that supplies electrolyte into the cylindrical body 66 through the injection hole 21. As a result, it is possible to suppress the scattering of electrolyte supplied from the nozzle outside the outer casing 80. Moreover, it is easy to prevent the nozzle from hitting the shielding portion, and it is easier to secure the distance between the nozzle and the shielding portion. As a result, it is easy to secure a flow path for the electrolyte from the nozzle to the shielding portion, and it is possible to suppress obstruction of the supply of electrolyte from the nozzle into the outer casing 80.

[0059] Furthermore, the cylindrical body 66 has an oval cross-section with two planar portions 67 parallel to its outer surface, allowing the positive electrode tab 15 to come into contact with the planar portions 67 of the cylindrical body 66 before joining it to the first current collector plate 41 of the positive electrode current collector 40. This stabilizes the position of the positive electrode tab 15 before joining. In addition, it is possible to suppress the rotation of the first current collector plate 41 around the cylindrical body 66 after the cylindrical body 66 has been inserted into the through hole 42 of the first current collector plate 41.

[0060] Figures 9 and 10 are diagrams corresponding to section E in Figure 8, respectively, in another embodiment of the present disclosure. In the configuration of the other embodiment shown in Figure 9, the shielding portion 70a connected to the cylindrical body 66 of the current collector holder 60a has a projection 74 on its upper surface, which is the surface facing the liquid injection hole 21 (Figure 8). The projection 74 has a roughly mountain-shaped cross-section, with an intermediate planar portion 75a parallel to the vertical direction on its upper surface, and two outer planar portions 75b adjacent to both sides of the intermediate planar portion 75a and inclined with respect to the vertical direction. Each outer planar portion 75b corresponds to an inclined surface. As a result, the projection 74 has a trapezoidal cross-sectional shape perpendicular to the first direction (width direction b). Therefore, the flow of electrolyte that has flowed through the nozzle 105 is changed from the downward direction (arrow α) to the diagonally downward direction (arrow γ), and is ejected into the outer casing 80 (Figures 2A and 8) from the two openings 73.

[0061] In the alternative configuration shown in Figure 10, the shielding portion 70b connected to the cylindrical body 66 of the current collector holder 60b has a projection 76 on its upper surface, which is the side facing the liquid injection hole 21 (Figure 8). The projection 76 has a mountain-shaped cross-section with two planar portions 76a on its upper surface that are inclined in opposite directions with respect to the vertical direction. As a result, the projection 76 has a triangular cross-sectional shape perpendicular to the first direction (width direction b). Each planar portion 76a corresponds to an inclined surface. Therefore, the flow of electrolyte that has flowed through the nozzle 105 is changed from the downward direction (arrow α) to the diagonally downward direction (arrow δ) and ejected into the outer casing 80 (Figures 2A and 8) from the two openings 73.

[0062] Furthermore, the end of the shielding portion 70 in the first direction (width direction b), which is the extending direction, may be positioned to face the positive electrode tab 15 or the negative electrode tab 18. With this configuration, the electrolyte ejected from the opening 73 is more likely to be ejected parallel to the surface of the tab facing the shielding portion 70, thereby suppressing the ejection of electrolyte toward the tab. In addition, since the ejection of electrolyte toward the tab from the cylindrical body 66 is suppressed, it becomes easier to position the tab and the cylindrical body 66 facing each other. As a result, when the tab and the cylindrical body 66 are facing each other, damage to the electrode plate connected to the tab facing the cylindrical body 66 (the tab closest to the cylindrical body 66 among multiple tabs) is suppressed, especially in the tab. And in particular, damage to the active material layer on the surface of the electrode plate facing the cylindrical body 66 or the separator facing the active material layer can be reduced.

[0063] The shapes of the shielding portions 70, 70a, and 70b constituting the structure of the present disclosure are not limited to the configurations of the above examples. For example, the shielding portion may have a projection on its upper surface, and the projection may have a curved surface such as a curved surface that bulges upward along a curve. For example, the projection may have a curved surface in which the shape of the cross section perpendicular to the first direction, which is the extending direction of the shielding portion, is an arc shape, for example, a semicircle.

[0064] The above describes a case where the electrode body 12 is divided into two electrode body elements 12a and 12b, with a positive electrode tab 15 and a negative electrode tab 18 extending from each electrode body element. On the other hand, the electrode body 12 can also be composed of only one electrode body element having a positive electrode tab and a negative electrode tab.

[0065] In the above embodiment, the case in which the cylindrical body 66 and shielding portions 70, 70a, and 70b are part of the current collector holders 60, 60a, and 60b was described, but the energy storage device of this disclosure is not limited to this configuration. For example, the second insulating portion 64 and the first current collector plate 41 of the current collector holder may not be located near the periphery of the liquid injection hole 21, and the second insulating portion 64 and the first current collector plate 41 may be located away from the periphery of the liquid injection hole 21. In this case, the energy storage device of this disclosure may be configured by providing a current collector holder without a cylindrical body and shielding portions, and an insulating member having a cylindrical body and shielding portions, and arranging the insulating member near the liquid injection hole 21. In this case as well, the cylindrical body is arranged between the outer surface of the lid and the electrode body. Furthermore, a part of the insulating plates 102 and 103 may be extended to the vicinity of the liquid injection hole 21, and the cylindrical body 66 may be fixed to the extended portion. Moreover, the cylindrical body does not need to be made of an insulating material. For example, it may consist of a metal cylinder and a shielding portion. Therefore, the cylinder may be provided integrally with the lid on the electrode body side, positioned between the outer surface of the lid and the electrode body, and extending from the lid toward the electrode body so as to surround the opening of the liquid injection hole on the electrode body side surface of the lid. Thus, the cylinder may be provided as a separate component from the lid, or it may be an integral part of the lid. [Explanation of Symbols]

[0066] 10 Energy storage device, 12 Electrode body, 12a, 12b Electrode body elements, 13 Positive electrode plate, 14 Main body, 15 Positive electrode tab, 15a Protective layer, 16 Negative electrode plate, 17 Main body, 18 Negative electrode tab, 20 Cover, 21 Liquid injection hole, 24 Exhaust valve, 25 Exhaust valve, 26 Plug, 30 Positive electrode terminal, 32 Negative electrode terminal, 33 Sealing member, 40 Positive electrode current collector, 41 First current collector plate, 42 Through hole, 45 Second current collector plate, 46 Hole, 50 Negative electrode current collector, 51 First current collector plate, 54 Second current collector plate, 55 Hole, 60, 60a, 60b Current collector holder, 61 First insulating part, 61a Hole, 61b Protrusion, 63 Locking part, 64 Second insulating part, 65 Hole, 66 Cylindrical body, 67 flat part, 68 protruding part, 70,70a,70b shielding part, 73 opening, 74 protruding part, 75a intermediate flat part, 75b outer flat part, 76 protruding part, 76a flat part, 80 exterior body, 81 opening, 82 insulating sheet, 90 safety device, 91 conductive member, 92 hole, 93 Inversion plate, 100,101 Outer insulation member, 102,103 Insulation plate, 104 Cylindrical body, 105 Nozzle.

Claims

[Claim 1] An electrode body comprising a first electrode body element including a first side first electrode plate, a first side second electrode plate, and a first side separator interposed between the first side first electrode plate and the first side second electrode plate, and a second electrode body element including a second side first electrode plate, a second side second electrode plate, and a second side separator interposed between the second side first electrode plate and the second side second electrode plate, An outer casing housing the electrode body, A cover that closes the opening of the exterior body, An electrode terminal electrically connected to the electrode body, with a portion of it exposed outside the outer casing from the cover, A current collector electrically connects the first electrode plate on the first side and the first electrode plate on the second side of the electrode body with the electrode terminals, The system comprises an insulating member positioned between the current collector and the lid, The first electrode element and the second electrode element are arranged in the short-side direction of the lid, The lid has an injection hole for injecting electrolyte into the outer casing, The first electrode plate on the first side of the first electrode element has a first tab that connects to the first region of the current collector, The second side first electrode plate of the second electrode element has a second tab that connects to the second region of the current collector, The first tab is bent toward the second electrode element, The second tab is bent toward the first electrode element, In the insulating member, a hole is formed in the region of the surface facing the lid that overlaps with the liquid injection hole. The opening in the hole facing the lid is larger than the opening of the injection hole facing the electrode body. The joints between the current collector and the first tab and the second tab, and the electrode terminals are separated in the longitudinal direction of the lid, and the joints between the current collector and the first tab and the second tab are positioned further inward in the longitudinal direction of the lid than the electrode terminals. Energy storage device.

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