Energy storage devices

Abstract

Providing a technology to suppress uneven surface pressure in the electrode body. [Solution] The energy storage device disclosed herein comprises an electrode body in which positive electrodes and negative electrodes are alternately stacked with a separator in between, a case for housing the electrode body, and a spacer disposed between the case and the electrode body. The outer surface of the electrode body has a first surface at one end in the stacking direction of the positive and negative electrodes, a second surface at the other end in the stacking direction, and a third surface between the first and second surfaces. The first surface, the second surface, and the third surface are composed of a separator. The first end of the separator in the longitudinal direction is located on the third surface. The separator has a first region that includes the first end and is located on the third surface. The first region covers a part of the spacer and has a joint with the spacer.

Description

Technical Field

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

Background Art

[0002] As an example of a power storage device, a secondary battery such as a lithium-ion secondary battery can be mentioned. In recent years, this type of power storage device has been suitably used, for example, as a power source for driving vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs).

[0003] The secondary battery disclosed in Japanese Patent No. 7448357 includes a plurality of flat positive electrodes, a plurality of flat negative electrodes, a strip-shaped separator provided between the positive electrode and the negative electrode, an exterior material that houses the stacked positive electrode, negative electrode, and separator, and an adhesive tape that fixes the start or end of the separator strip. The positive electrode and the negative electrode are alternately stacked with the separator interposed therebetween. The separator is zigzag-folded so as to be interposed between the positive electrode and the negative electrode. The folded portion of the zigzag fold of the separator is provided such that at least a predetermined length is separated from the folded portion to the end of the negative electrode. The separator covers at least a part of the upper surface of the electrode located in the uppermost layer in the stacking direction or at least a part of the lower surface of the electrode located in the lowermost layer in the stacking direction of the stacked positive electrode and negative electrode, with a portion on the start side or the end side of the separator strip. The entire separator covering the electrode located in the outermost layer in the stacking direction is covered with an adhesive tape. The separator covering the electrode located in the outermost layer in the stacking direction is a portion on the start side or the end side of the separator strip. The publication describes that according to such a configuration, it is possible to suppress the occurrence of adverse effects caused by the folded portion of the zigzag-folded separator.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] As described in the prior art documents cited above, in conventional electrode bodies, the entire separator covering the electrode located in the outermost layer in the stacking direction of the positive and negative electrodes was covered with adhesive tape. When adhesive tape is placed at the ends in the stacking direction of the positive and negative electrodes, for example, the step created by the adhesive tape increases the risk of uneven surface pressure occurring in the electrode body during restraint. Uneven surface pressure is undesirable because it can lead to factors such as Li deposition.

[0006] Therefore, the inventors of this invention want to suppress the unevenness of the surface pressure in the electrode body. [Means for solving the problem]

[0007] The technology disclosed herein provides an energy storage device. This energy storage device comprises an electrode body in which positive electrodes and negative electrodes are alternately stacked with separators in between; a case for housing the electrode body; and a spacer disposed between the case and the electrode body. The outer surface of the electrode body has a first surface at one end in the stacking direction of the positive and negative electrodes, a second surface at the other end in the stacking direction, and a third surface between the first and second surfaces. The first surface, the second surface, and the third surface are composed of separators. The first end of the separator in the longitudinal direction is located on the third surface. The separator has a first region that includes the first end and is located on the third surface. The first region covers a portion of the spacer and has a joint with the spacer.

[0008] This configuration makes it possible to suppress unevenness in the surface pressure on the electrode body. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of the energy storage device 1. [Figure 2] Figure 2 is a perspective view of the energy storage device 1. [Figure 3] Figure 3 is a cross-sectional view taken along line III-III in Figure 1. [Figure 4] Figure 4 is a schematic cross-sectional view of the electrode body 30. [Figure 5] Figure 5 is a perspective view of the spacer 40. [Figure 6] Figure 6 is a cross-sectional view of the joint W. [Figure 7] Figure 7 is a perspective view of the electrode body 230. [Modes for carrying out the invention]

[0010] An embodiment of the energy storage device disclosed herein is described below. The embodiment described herein is not limited to 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. Components and parts that perform the same function are appropriately denoted by the same reference numerals, and redundant explanations may be omitted. The reference numerals "X", "Y", and "Z" in the drawings indicate the "first direction", "second direction", and "third direction" in this specification, respectively. The reference numerals "X1", "X2", "Y1", "Y2", "Z1", and "Z2" in the drawings indicate the orientation in the drawings. However, these directions are defined for the convenience of explanation and do not limit the installation method of the energy storage device in any way. 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".

[0011] 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 and negative electrodes) via an electrolyte. 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. An energy storage device may be, for example, a lithium-ion secondary battery.

[0012] Figures 1 and 2 are perspective views of the energy storage device 1. Figure 1 shows the energy storage device 1 with the Z1 side as the upper side in the drawing. In Figure 1, the top surface 12 of the energy storage device 1 is positioned at the top of the drawing. Figure 2 shows the energy storage device 1 with the Z2 side as the upper side in the drawing. In Figure 2, the bottom surface 11 of the energy storage device 1 is positioned at the top of the drawing. Figure 3 is a cross-sectional view taken along line III-III in Figure 1. Figure 3 shows the cross-sectional structure of the energy storage device 1 with one of the first side surfaces 13 (here, the first side surface 13 on the Y1 side) positioned as the front.

[0013] As shown in Figures 1 to 3, the energy storage device 1 comprises a case 10, a positive electrode terminal 22, a negative electrode terminal 24, an electrode body 30, a spacer 40, a resin film 50, and an electrolyte (not shown). In this case, the energy storage device 1 is a lithium-ion secondary battery.

[0014] As shown in Figures 1 to 3, the case 10 has a bottom surface 11, a top surface 12, a pair of opposing first sides 13, and a pair of opposing second sides 14. In this embodiment, the case 10 is hexahedral. In this embodiment, the bottom surface 11 and the top surface 12 are rectangular and face each other. In the configurations shown in Figures 1 and 2, the pair of opposing first sides 13 extend from a pair of opposing long sides 11a on the bottom surface 11 and have a relatively large area. The pair of opposing second sides 14 extend from a pair of opposing short sides 11b on the bottom surface 11 and have a relatively small area.

[0015] As shown in FIGS. 1 to 3, the case 10 includes a case body 10A, a first sealing plate 10B, and a second sealing plate 10C. The case body 10A is, for example, a rectangular tube shape and has a bottom surface 11, an upper surface 12, and a pair of opposing first side surfaces 13. In this embodiment, in the case body 10A, the portion surrounded by the bottom surface 11, the upper surface 12, and the pair of opposing first side surfaces 13 is an opening. As shown in FIG. 3, the power storage device 1 has two openings 15.

[0016] The case body 10A can be produced, for example, by bending a single metal plate into a tubular shape and joining the seams (for example, by welding). Therefore, as shown in FIG. 1, the case body 10A has a joint portion 16 extending along the first direction X on the upper surface 12. The case body 10A is not particularly limited, but is preferably made of a metal such as aluminum, an aluminum alloy, iron, or an iron alloy.

[0017] As shown in FIG. 2, the case body 10A has a safety valve 17 on the bottom surface 11. The safety valve 17 is, for example, a thin-walled portion designed to break when the internal pressure of the case 10 reaches a predetermined value and release the internal pressure. Note that the safety valve 17 does not necessarily have to be provided on the bottom surface 11. In other embodiments, the safety valve 17 may be provided on the upper surface 12 or the first side surface 13.

[0018] The first sealing plate 10B is, for example, a member that seals one of the openings 15. The first sealing plate 10B is, for example, a substantially rectangular plate-like member. In this embodiment, the first sealing plate 10B is fitted into one of the openings 15 and joined by welding (for example, laser welding). As shown in FIGS. 1 and 3, a positive electrode terminal 22 is attached to the first sealing plate 10B.

[0019] In this embodiment, the first sealing plate 10B has a liquid injection portion 19. The liquid injection portion 19 has a liquid injection hole 19A and a sealing plug 19B. Here, the liquid injection hole 19A is a portion where the electrolytic solution is injected into the case 10 in the manufacturing process of the power storage device 1. In this embodiment, the liquid injection hole 19A is provided in the first sealing plate 10B close to the upper surface 12. The sealing plug 19B is a member that closes the liquid injection hole 19A here.

[0020] The second sealing plate 10C is, for example, a member that seals the other opening 15. The second sealing plate 10C is, for example, a substantially rectangular plate-like member. In this embodiment, the second sealing plate 10C is fitted into the other opening 15 and joined by welding (for example, laser welding). As shown in FIGS. 2 and 3, a negative electrode terminal 24 is attached to the second sealing plate 10C.

[0021] In the form shown in FIGS. 1 to 3, the first sealing plate 10B and the second sealing plate 10C constitute a pair of opposing second side surfaces 14. The first sealing plate 10B and the second sealing plate 10C are preferably made of the same metal material as the metal material constituting the case body 10A, for example.

[0022] The positive electrode terminal 22 is electrically connected to the positive electrode 32 (see FIG. 4) of the electrode body 30, for example. As shown in FIGS. 1 and 3, the positive electrode terminal 22 is attached to the first sealing plate 10B. As shown in FIG. 3, the positive electrode terminal 22 is electrically connected to the positive electrode tab 33 of the electrode body 30 via the positive electrode current collecting portion 23. The positive electrode terminal 22 is made of metal, for example, and is preferably made of aluminum or an aluminum alloy. Note that the positive electrode terminal 22 may constitute the positive electrode current collecting portion 23.

[0023] The negative electrode terminal 24 is electrically connected to, for example, the negative electrode 34 of the electrode body 30 (see Figure 4). As shown in Figures 2 and 3, the negative electrode terminal 24 is attached to the second sealing plate 10C. As shown in Figure 3, the negative electrode terminal 24 is electrically connected to the negative electrode tab 35 of the electrode body 30 via the negative electrode current collector 25. The negative electrode terminal 24 is made of, for example, metal, preferably copper or a copper alloy. The negative electrode terminal 24 may also constitute the negative electrode current collector 25.

[0024] The electrode body 30 is, for example, a power generation element in the energy storage device 1. As shown in Figure 3, the electrode body 30 is housed in the case 10. Figure 4 is a schematic cross-sectional view of the electrode body 30. Figure 4 schematically shows the cross-sectional structure of the electrode body 30 as seen from the side of the first sealing plate 10B (see Figure 3). The electrode body 30 is, for example, flattened.

[0025] As shown in Figure 4, the electrode body 30 comprises a positive electrode 32, a negative electrode 34, and a separator 36 interposed between the positive electrode 32 and the negative electrode 34. In this embodiment, the electrode body 30 is a flat electrode body having a zigzag structure in which a long strip-shaped separator 36 is folded back alternately at predetermined intervals, and a plurality of positive electrodes 32 and a plurality of negative electrodes 34 are alternately sandwiched between the zigzag-folded separator 36.

[0026] As shown in Figures 3 and 4, the outer surface of the electrode body 30 has a first surface 301, a second surface 302, a third surface 303, and a fourth surface 304. The first surface 301 is located at one end in the stacking direction of the positive electrode 32 and the negative electrode 34, and is on the Y1 side of the second direction Y in Figure 4. The second surface 302 is located at the other end in the stacking direction of the positive electrode 32 and the negative electrode 34, and is on the Y2 side of the second direction Y in Figure 4. The third surface 303 is located between the first surface 301 and the second surface 302, and is on the Z1 side of the third direction Z in Figure 4. As shown in Figure 3, the third surface 303 faces the top surface 12. The fourth surface 304 is located between the first surface 301 and the second surface 302, and is on the Z2 side of the third direction Z in Figure 4. As shown in Figure 3, the fourth surface 304 faces the bottom surface 11.

[0027] In the configuration shown in Figure 4, the separator 36 is wrapped around the outermost periphery of the zigzag structure and constitutes the outer surface of the electrode body 30. In this embodiment, the separator 36 is wrapped around the outermost electrode (in this embodiment, the negative electrode 34 (see Figure 4)) within the electrode body 30 at least once. As shown in Figure 4, the first surface 301, the second surface 302, the third surface 303, and the fourth surface 304 are composed of the separator 36. In this embodiment, the first end portion 36e1 in the longitudinal direction of the separator 36 is located on the third surface 303. The separator 36 has a first region 361 which includes the first end portion 36e1 and is located on the third surface 303. The first region 361 here includes the first end portion 36e1 and the portion adjacent to the first end portion 36e1 that is located on the third surface 303. In this embodiment, no tape is applied to the first end 36e1. However, the technology disclosed herein is not limited thereto, and in other embodiments, tape may be applied to the first end 36e1. The second end 36e2 in the longitudinal direction of the separator 36 is located within the electrode body 30.

[0028] As shown in Figure 3, the electrode body 30 has a first end face 30A at one end in the short direction of the separator 36 and a second end face 30B at the other end. In this embodiment, the first end face 30A and the second end face 30B are the laminated surfaces of the electrode and the separator 36, and are open surfaces that open outwards toward the outside of the electrode body 30. As shown in Figure 3, the first end face 30A faces the first sealing plate 10B. The second end face 30B faces the second sealing plate 10C.

[0029] In the configuration shown in Figure 3, the electrode body 30 has a positive electrode tab 33 connected to a positive electrode 32 on its first end face 30A. The electrode body 30 has a negative electrode tab 35 connected to a negative electrode 34 on its second end face 30B. The positive electrode tabs 33 are provided on each positive electrode 32 included in the electrode body 30. The positive electrode tabs 33 provided on each positive electrode 32 (multiple positive electrode tabs 33) can be stacked, for example, to form a group of positive electrode tabs. The negative electrode tabs 35 are provided on each negative electrode 34 included in the electrode body 30. The negative electrode tabs 35 provided on each negative electrode 34 (multiple negative electrode tabs 35) can be stacked, for example, to form a group of negative electrode tabs.

[0030] The positive electrode 32 may be, for example, a rectangular sheet-shaped positive electrode sheet. In this embodiment, the positive electrode 32 comprises a rectangular sheet-shaped positive electrode current collector foil and a positive electrode active material layer provided on the surface of the positive electrode current collector foil. The positive electrode current collector foil is preferably made of, for example, aluminum or an aluminum alloy. In the embodiment shown in Figure 3, a positive electrode tab 33 is provided at the end of the positive electrode current collector foil (the end on the X1 side in the figure). The positive electrode tab 33 has, for example, an exposed region where the positive electrode current collector foil is exposed. The exposed portion of the positive electrode tab 33 is joined to, for example, the positive electrode current collector portion 23. The positive electrode active material layer contains, for example, a positive electrode active material. The positive electrode active material is, for example, a material that can reversibly absorb and release charge carriers. As the positive electrode active material, for example, a material used as the positive electrode active material in this type of energy storage device can be used without particular limitation. The positive electrode active material layer may contain components other than the positive electrode active material (e.g., binder, conductive material, etc.).

[0031] The negative electrode 34 may be, for example, a rectangular sheet-shaped negative electrode sheet. In this embodiment, the negative electrode 34 comprises a rectangular sheet-shaped negative electrode current collector foil and a negative electrode active material layer provided on the surface of the negative electrode current collector foil. The negative electrode current collector foil is preferably made of, for example, copper or a copper alloy. In the embodiment shown in Figure 3, a negative electrode tab 35 is provided at the end of the negative electrode current collector foil (the end on the X2 side in the figure). The negative electrode tab 35 has, for example, an exposed region where the negative electrode current collector foil is exposed. The exposed portion of the negative electrode tab 35 is joined to, for example, the negative electrode current collector portion 25. The negative electrode active material layer contains, for example, a negative electrode active material. The negative electrode active material is, for example, a material that can reversibly absorb and release charge carriers. As the negative electrode active material, for example, a material used as the negative electrode active material for this type of energy storage device can be used without particular limitation. The negative electrode active material layer may contain components other than the negative electrode active material (e.g., binder, thickener, dispersant, etc.).

[0032] As the separator 36, for example, a separator from this type of energy storage device can be used without particular limitation. The separator 36 may be a single-layer structure, or it may be a structure of two or more layers with different properties and characteristics (thickness, porosity, etc.), for example, a three-layer structure. The separator 36 is made of resin, for example, and is preferably made of polyolefin resin. The polyolefin resin may be polyethylene, polypropylene, or a mixture thereof.

[0033] As the electrolyte, for example, the electrolyte used in this type of energy storage device can be used without particular limitation. The electrolyte is, for example, a non-aqueous electrolyte containing a non-aqueous solvent (organic solvent) and a supporting salt. Examples of non-aqueous solvents include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as lithium hexafluoride phosphate (LiPF6).

[0034] The spacer 40 is a component that is placed, for example, between the case 10 and the electrode body 30. In the configuration shown in Figure 3, the spacer 40 is placed between the case 10 and the first end face 30A of the electrode body 30. As shown in Figure 3, the spacer 40 is placed between the first sealing plate 10B and the electrode body 30 (first end face 30A on the X1 side), and between the second sealing plate 10C and the electrode body 30 (first end face 30A on the X2 side). The spacer 40 may be made of an insulating resin (for example, polyamide resin, etc.) that has been conventionally used in this type of energy storage device.

[0035] Figure 5 is a perspective view of the spacer 40. Figure 5 shows a spacer 40 assumed to be positioned on the side of the second sealing plate 10C. As shown in Figure 5, the spacer 40 has a first spacer 41, a second spacer 42, and a connecting portion 43. The first spacer 41 is, for example, the part positioned on the side of the upper surface 12 (see Figure 3) of the case 10. As shown in Figure 5, the first spacer 41 has a first opposing portion 411 and a first wall portion 412. The first opposing portion 411 is, for example, the part that faces the electrode body 30 (for example, the first end face 30A of the electrode body 30). The first opposing portion 411 is, in this case, a roughly rectangular flat plate. In the configuration shown in Figure 5, the first opposing portion 411 has a through hole 41h to facilitate the flow of electrolyte into the electrode body 30. The first wall portion 412 is, for example, the part that supports the first opposing portion 411 with respect to the second sealing plate 10C. In this embodiment, the first wall portion 412 extends from the periphery of the first opposing portion 411 toward the second sealing plate 10C. In this embodiment, the tip of the first wall portion 412 contacts the second sealing plate 10C.

[0036] The second spacer 42 is, for example, a portion located on the bottom surface 11 (see Figure 3) side of the case 10. As shown in Figure 5, the second spacer 42 has a second opposing portion 421 and a second wall portion 422. The second opposing portion 421 is, for example, a portion facing the electrode body 30 (for example, the first end face 30A of the electrode body 30). The second opposing portion 421 is, in this case, a substantially rectangular flat plate. In the configuration shown in Figure 5, the second opposing portion 421 has a through hole 42h to facilitate the flow of electrolyte into the electrode body 30. The second wall portion 422 is, for example, a portion that supports the second opposing portion 421 with respect to the second sealing plate 10C. The second wall portion 422 extends from the periphery of the second opposing portion 421 toward the second sealing plate 10C. In this embodiment, the tip of the second wall portion 422 contacts the second sealing plate 10C.

[0037] The connecting portion 43 is, for example, a portion that connects the first spacer 41 and the second spacer 42. The connecting portion 43 is, for example, plate-shaped. As shown in Figure 5, the connecting portion 43 connects the first spacer 41 and the second spacer 42 on one of the first side surfaces 13 of the case 10 (in Figure 5, the first side surface 13 on the Y2 side (see also Figures 1 and 3)). In this embodiment, the connecting portion 43 connects the first wall portion 412 and the second wall portion 422 on one of the first side surfaces 13 of the case 10 (in Figure 5, the first side surface 13 on the Y2 side (see also Figures 1 and 3)). The connecting portion 43 is not provided on the other first side surface 13 (in Figure 5, the first side surface 13 on the Y1 side (see also Figures 1 and 3)). Note that in other embodiments, the connecting portion 43 may not be provided. In this case, the first spacer 41 and the second spacer 42 are not integrated.

[0038] In the case 10, the first spacer 41 and the second spacer 42 are not connected on the other first side surface 13 side. In this embodiment, the spacer 40 is provided with a recess 40r that is recessed from the other first side surface 13 side of the case 10 toward the first side surface 13 side. Here, a negative electrode tab 35 (group of negative electrode tabs) is placed in the recess 40r.

[0039] When the spacer 40 is positioned on the first sealing plate 10B side, the first wall portion 412 and the second wall portion 422 extend toward the first sealing plate 10B. A positive electrode tab 33 (group of positive electrode tabs) is positioned in the recess 40r.

[0040] Figure 6 is a cross-sectional view of the joint W. Figure 6 schematically shows the cross-sectional structure of the spacer 40, separator 36, and resin film 50 at the joint W as viewed from the first sealing plate 10B side. As shown in Figure 6, the first region 361 of the separator 36 covers a part of the spacer 40. Here, both ends of the first region 361 in the short direction of the separator 36 are positioned on the spacer 40. In this embodiment, the first region 361 has a joint W with the spacer 40. At the joint W, the first end 36e1 of the separator 36 is joined to the spacer 40. Although not particularly limited, at the joint W, the separator 36 and the spacer 40 may be welded together, for example. Such welding means may be ultrasonic welding, heat welding, etc.

[0041] From the viewpoint of realizing the effects of the technology disclosed herein, when the length of the separator 36 in the short direction is taken as 100%, the first region 361 is joined to the spacer 40 in portions of preferably 0.03% to 3%, more preferably 0.05% to 2%, and even more preferably 0.1% to 1% at both ends in the same direction. From a similar viewpoint, when the thickness of the electrode body 30 is taken as 100%, the first region 361 is joined to the spacer 40 in portions of preferably 20% to 80%, more preferably 30% to 70% in the same direction. Here, "thickness of the electrode body 30" refers to the shortest distance between the first surface 301 and the second surface 302.

[0042] The resin film 50 is, for example, a component that insulates the case 10 from the electrode body 30. As shown in Figures 3 and 6, the resin film 50 is arranged to surround the outer circumference of the electrode body 30. In this embodiment, the resin film 50 is cylindrical and houses the electrode body 30 inside. Preferably, the resin film 50 houses a portion of the spacer 40 inside. As the resin material constituting the resin film 50, for example, the resin material constituting the resin film included in this type of energy storage device may be used. Such resin materials may be, for example, polyamide resin, polyolefin resin (polyethylene, polypropylene, etc.).

[0043] In this embodiment, the resin film 50 covers the electrode body 30 and a portion of the spacer 40. As shown in Figure 6, a portion of the resin film 50 is joined to the spacer 40. Here, at the joint W, the resin film 50, the separator 36, and the spacer 40 are joined to each other.

[0044] 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).

[0045] As described above, the energy storage device 1 comprises an electrode body 30 in which positive electrodes 32 and negative electrodes 34 are alternately stacked with separators 36 in between, a case 10 that houses the electrode body 30, and a spacer 40 disposed between the case 10 and the electrode body 30. The outer surface of the electrode body 30 has a first surface 301 at one end in the stacking direction of the positive electrodes 32 and negative electrodes 34, a second surface 302 at the other end in the stacking direction, and a third surface 303 between the first surface 301 and the second surface 302. The first surface 301, the second surface 302, and the third surface 303 are composed of separators 36. The first end 36e1 in the longitudinal direction of the separator 36 is located on the third surface 303. The separator 36 has a first region 361 which includes the first end 36e1 and is located on the third surface 303. The first region 361 covers a portion of the spacer 40 and has a joint W with the spacer 40.

[0046] The energy storage device 1 includes a spacer 40 positioned between the case 10 and the electrode body 30. This prevents the electrode body 30 from moving within the case 10. The first surface 301, the second surface 302, and the third surface 303, which are included in the outer surface of the electrode body 30, are composed of a separator 36. The first longitudinal end 36e1 of the separator 36 is positioned on the third surface 303. Here, the first end 36e1 is the winding end of the separator 36. In other words, the winding end of the separator 36 is not positioned on either the first surface 301 or the second surface 302 in the stacking direction of the positive electrode 32 and the negative electrode 34. This eliminates the need to apply tape to either the first surface 301 or the second surface 302. Therefore, it is possible to prevent the occurrence of steps on the first surface 301 and the second surface 302. Furthermore, the first region 361 of the separator 36, which includes the first end portion 36e1 and is positioned on the third surface 303, covers a portion of the spacer 40 and is joined to the spacer 40. This eliminates the need to apply tape to fix the first end portion 36e1 to the electrode body 30, or at least reduces the amount of tape used. As a result, the energy storage device 1 can suppress uneven surface pressure on each surface of the electrode body 30.

[0047] The electrode body 30 may have a zigzag structure in which a long strip-shaped separator 36 is folded back alternately at predetermined intervals, and a plurality of positive electrodes 32 and a plurality of negative electrodes 34 are alternately sandwiched between the zigzag separator 36 and stacked. The zigzag structure of the electrode body 30 makes it easier to stably position the first end 36e1 of the separator 36 on the third surface 303. Therefore, the effects of the technology disclosed herein can be better realized.

[0048] The first end 36e1 of the separator 36 may be joined to the spacer 40. This, in addition to the effects described above, can better suppress the curling of the separator 36.

[0049] At the joint W between the separator 36 and the spacer 40, the separator 36 and the spacer 40 may be welded together. This can further increase the joint strength between the separator 36 and the spacer 40.

[0050] The separator 36 may be wrapped around the outermost electrode (in this case, the negative electrode 34) within the electrode body 30 at least once. In addition to the effects described above, this prevents the separator 36 from peeling back and exposing the electrode to the outside.

[0051] The case 10 may include a case body 10A having an opening 15 and sealing plates (here, a first sealing plate 10B and a second sealing plate 10C) that seal the opening 15. The spacer 40 may be placed between the sealing plates (here, the first sealing plate 10B and the second sealing plate 10C) and the electrode body 30. This prevents the electrode body 30 from moving between the electrode body 30 and the sealing plates. Therefore, the risk of a short circuit between the electrode body 30 and the sealing plates can be better reduced.

[0052] The electrode body 30 may have a positive electrode tab 33 electrically connected to the positive electrode 32 on the first end face 30A in the short direction of the separator 36, and a negative electrode tab 35 electrically connected to the negative electrode 34 on the second end face 30B in the short direction. A spacer 40 may be placed between the case 10 and the first end face 30A or the second end face 30B. In this case, the first end face 30A and the second end face 30B of the electrode body 30 are not covered by the separator 36. In other words, the electrodes are exposed outside the electrode body 30 at the first end face 30A and the second end face 30B. Therefore, by placing the spacer 40 between the case 10 and the first end face 30A or the second end face 30B, the risk of a short circuit between the electrode body 30 and the case 10 can be better reduced.

[0053] The energy storage device 1 may further include a resin film 50. The resin film 50 may cover the electrode body 30 and a portion of the spacer 40. This can better reduce the risk of a short circuit occurring between the electrode body 30 and the case 40.

[0054] At least a portion of the resin film 50 may be bonded to the spacer 40. This can further enhance the effects described above. In this case, for example, when the resin film 50 is wrapped around the electrode body 30 and a portion of the spacer 40, it is preferable to bond the resin film 50 and the separator 36 to the spacer 40. This eliminates the need for bonding steps, thereby improving the productivity of the energy storage device 1.

[0055] The embodiments of the technology disclosed herein have been described above, but these embodiments are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes, for example, various modifications and changes to the following specific examples.

[0056] For example, in the above embodiment, the energy storage device 1 included an electrode body 30 having a zigzag structure. However, the technology disclosed herein is not limited thereto. Figure 7 is a perspective view of the electrode body 230. The energy storage device 1 may include the electrode body 230 shown in Figure 7 instead of the electrode body 30. The electrode body 230 is, for example, a flat wound electrode body in which a long strip-shaped positive electrode 232 and a long strip-shaped negative electrode 234 are stacked with a long strip-shaped separator 236 interposed between them and wound in the longitudinal direction. The electrode body 230 is arranged in the case 10 such that the winding axis is parallel to the bottom surface 11 and the top surface 12 (see Figure 3). As shown in Figure 7, the electrode body 230 has a positive electrode tab 233 on the first end face 230A in the short direction of the separator 236, and a negative electrode tab 235 on the second end face 230B in the same direction.

[0057] As shown in Figure 7, the outer surface of the electrode body 230 has a first surface 2301, a second surface 2302, a third surface 2303, and a fourth surface 2304. The first surface 2301 and the second surface 2302 are rectangular surfaces located at the respective ends in the electrode stacking direction (in this embodiment, the thickness direction of the electrode body 230) of the electrode body 230. The third surface 2303 and the fourth surface 2304 are curved surfaces that curve outward from the electrode body 230, respectively, located between the first surface 2301 and the second surface 2302.

[0058] In the configuration shown in Figure 7, the first surface 2301, the second surface 2302, the third surface 2303, and the fourth surface 2304 are all composed of separators 236. In this embodiment, the first end portion 236e1 in the longitudinal direction of the separator 236 is positioned on the third surface 2303. The separator 236 has a first region 2361 that includes the first end portion 236e1 and is positioned on the third surface 2303. The first region 2361 covers a portion of the spacer 40 and may have a joint with the spacer 40 (see Figure 3).

[0059] In the wound electrode body 230, the first end 236e1 of the separator 236 is easily positioned on the third surface 2303 during the manufacturing process. For this reason, the wound electrode body is preferred for realizing the effects of the technology disclosed herein.

[0060] The technologies disclosed herein may include the technologies described in the following sections. Section 1: An electrode body in which positive and negative electrodes are alternately stacked with a separator in between, A case for housing the electrode body, A spacer is disposed between the case and the electrode body, A power storage device comprising, The outer surface of the electrode body is The first surface located at one end of the stacking direction between the positive electrode and the negative electrode, The second surface at the other end in the stacking direction, The third surface is located between the first surface and the second surface, It has, The first surface, the second surface, and the third surface are formed by the separator, The first end of the separator in the longitudinal direction is positioned on the third surface, The separator has a first region which includes the first end and is located on the third surface, The first region covers a portion of the spacer and has a joint with the spacer, wherein the energy storage device. Section 2: The electrode body has a zigzag structure in which a long strip-shaped separator is folded back alternately at predetermined intervals, and a plurality of positive electrodes and a plurality of negative electrodes are alternately sandwiched between the zigzag-folded separators and stacked. The energy storage device described in item 1. Section 3: The electrode body is a flat electrode body formed by stacking a long, strip-shaped positive electrode and a long, strip-shaped negative electrode with a long, strip-shaped separator in between, and winding them in the longitudinal direction. The energy storage device described in item 1. Section 4: The first end of the separator is joined to the spacer. A power storage device described in any one of items 1 to 3. Section 5: At the joint between the separator and the spacer, the separator and the spacer are welded together. A power storage device described in any one of items 1 to 4. Item 6: The separator is wrapped around the outermost electrode within the electrode body at least once. A power storage device described in any one of items 1 to 5. Section 7: The case includes a case body having an opening and a sealing plate that seals the opening. The spacer is positioned between the sealing plate and the electrode body. A power storage device as described in any one of items 1 to 6. Section 8: The electrode body has a positive electrode tab electrically connected to the positive electrode on the first end face in the short direction of the separator, and a negative electrode tab electrically connected to the negative electrode on the second end face in the same short direction. The spacer is positioned between the case and the first end face or the second end face. A power storage device described in any one of items 1 through 7. Section 9: Furthermore, it is equipped with a resin film, The resin film covers the electrode body and a part of the spacer. A power storage device described in any one of items 1 to 8. Section 10: At least a portion of the resin film is bonded to the spacer. The energy storage device described in item 9. [Explanation of symbols]

[0061] 1. Energy storage device 10 cases 30, 230 electrode body 301, 2301 1st page 302, 2302 2nd page 303, 2303 3rd page 32 Positive electrode 33 Positive Tab 34 Negative electrode 35 Negative Electrode Tabs 36,236 separators 361, 2361 1st area 36e1, 236e1 1st end 40 Spacers 50 resin film W joint

Claims

1. An electrode body in which positive and negative electrodes are alternately stacked with a separator in between, A case for housing the electrode body, A spacer is placed between the case and the electrode body, A power storage device comprising, The outer surface of the electrode body is The first surface located at one end of the stacking direction between the positive electrode and the negative electrode, The second surface at the other end in the stacking direction, A third surface located between the first surface and the second surface, It has, The first surface, the second surface, and the third surface are formed by the separator, The first end of the separator in the longitudinal direction is positioned on the third surface, The separator has a first region which includes the first end and is located on the third surface, The first region covers a portion of the spacer and has a joint with the spacer, wherein the energy storage device.

2. The electrode body has a zigzag structure in which a long strip-shaped separator is folded back alternately at predetermined intervals, and a plurality of positive electrodes and a plurality of negative electrodes are alternately sandwiched between the zigzag-folded separators and stacked. The energy storage device according to claim 1.

3. The electrode body is a flat electrode body formed by stacking a long, strip-shaped positive electrode and a long, strip-shaped negative electrode with a long, strip-shaped separator in between, and winding them in the longitudinal direction. The energy storage device according to claim 1.

4. The first end of the separator is joined to the spacer. The energy storage device according to any one of claims 1 to 3.

5. At the joint between the separator and the spacer, the separator and the spacer are welded together. The energy storage device according to any one of claims 1 to 3.

6. The separator is wrapped around the outermost electrode within the electrode body at least once. The energy storage device according to any one of claims 1 to 3.

7. The case includes a case body having an opening and a sealing plate that seals the opening. The spacer is positioned between the sealing plate and the electrode body. The energy storage device according to any one of claims 1 to 3.

8. The electrode body has a positive electrode tab electrically connected to the positive electrode on the first end face in the short direction of the separator, and a negative electrode tab electrically connected to the negative electrode on the second end face in the same short direction. The spacer is positioned between the case and the first end face or the second end face. The energy storage device according to any one of claims 1 to 3.

9. Furthermore, it is equipped with a resin film, The resin film covers the electrode body and a part of the spacer. The energy storage device according to any one of claims 1 to 3.

10. At least a portion of the resin film is bonded to the spacer. The energy storage device according to claim 9.

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