Energy storage device

Abstract

To provide an energy storage device that can suppress the breakage of the outer casing. [Solution] The energy storage device comprises a rectangular parallelepiped energy storage module having a plurality of electrodes and having a first main surface and a second main surface facing opposite directions in a first direction, a first side surface and a second side surface facing opposite directions in a second direction, and a third side surface and a fourth side surface facing opposite directions in a third direction, a cover member, and an outer casing having a housing section in which the energy storage module and the cover member are housed and arranged. The cover member is fixed to the outer casing, the inside of the outer casing is depressurized below atmospheric pressure, the housing section has a side facing the first side surface, and the cover member has a hollow main body positioned between the energy storage module and the side so as not to overlap with the energy storage module when viewed from the first direction, and a plate-shaped projection that protrudes from the main body in a second direction and overlaps with the gap between the main body and the energy storage module when viewed from the first or third direction.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a power storage device. This power storage device includes an electrode laminate in which a plurality of bipolar electrodes are stacked, and an exterior body that seals the electrode laminate. The exterior body seals a structural member together with the electrode laminate. The structural member sandwiches the electrode laminate in the planar direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the exterior body houses inclusions such as an electrode laminate and performs vacuum sealing, if there are gaps on the surface of the inclusions such as a large electrode laminate, the exterior body may fall into the gaps, causing stress to concentrate in a partial region of the exterior body and potentially breaking the exterior body.

[0005] The present disclosure provides a power storage device capable of suppressing breakage of the exterior body.

Means for Solving the Problems

[0006] The energy storage device according to this disclosure includes a rectangular parallelepiped energy storage module having a plurality of electrodes stacked along a first direction, a first main surface and a second main surface facing opposite directions in the first direction, a first side surface and a second side surface facing opposite directions in a second direction intersecting the first direction, and a third side surface and a fourth side surface facing opposite directions in a third direction intersecting the first and second directions; a cover member; and an outer casing having a housing section in which the energy storage module and the cover member are housed and arranged. The cover member is fixed to the outer casing, the inside of the outer casing is depressurized below atmospheric pressure, the housing section has a side facing the first side surface, and the cover member has a hollow main body positioned between the energy storage module and the side section so as not to overlap with the energy storage module when viewed from the first direction, and a plate-shaped projection that protrudes from the main body in a second direction and overlaps with the gap between the main body and the energy storage module when viewed from the first or third direction.

[0007] In the above-described energy storage device, the plate-shaped protrusions on the cover member cover the gap between the cover member and the energy storage module. This prevents the outer casing from falling into the gap. As a result, stress is concentrated in a part of the outer casing, which prevents the outer casing from fracturing.

[0008] The protrusions may cover the gaps.

[0009] The cover member comprises a first cover member and a second cover member arranged side by side in a third direction, and the projection of the first cover member may cover a portion of the third side surface.

[0010] The projection may have a first projection that covers a portion of the first main surface.

[0011] The projection may further have a second projection that covers a portion of the second main surface.

[0012] The cover member is composed of a first part and a second part arranged adjacent to each other in a first direction, and the projection may include projections of the first part and projections of the second part.

[0013] The tip of the projection has a bent portion, and the bent portion may have an R-shape.

[0014] The tip of the projection may have a tapered shape that becomes thinner towards the tip.

[0015] The protrusion does not need to be in contact with the energy storage module.

[0016] The above-described energy storage device further comprises a connecting component attached to the first side surface, and the cover member may be adjacent to the connecting component in a third direction, with the projection protruding in the third direction as well and covering the connecting component.

[0017] The energy storage module has an internal space that holds an electrolyte between adjacent electrodes in a first direction, and the first side surface has a region provided with a communication hole that communicates with the internal space, and the energy storage module has a resin member that covers the region, and the resin member includes a resin main body attached to the first side surface, a first overhang portion that extends from the resin main body onto a first main surface, and a second overhang portion that extends from the resin main body onto a second main surface, and the projection may cover the entire first overhang portion in a second direction. [Effects of the Invention]

[0018] According to this disclosure, it is possible to provide an energy storage device that can suppress the fracture of the outer casing. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a schematic plan view showing an energy storage device according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram showing the first side view of the energy storage module. [Figure 3] Figure 3 is a cross-sectional view along the line III-III in Figure 2. [Figure 4] Figure 4 is a cross-sectional view along the line IV-IV in Figure 1. [Figure 5] Figure 5 is a cross-sectional view along the VV line in Figure 1. [Figure 6] Figure 6 is a cross-sectional view taken along line VI-VI of Figure 1. [Figure 7] Figure 7 is a plan view schematically showing a part of the power storage device. [Figure 8] Figure 8 is a perspective view showing the cover member and the power storage module. [Figure 9] Figure 9 is a perspective view showing a cover member of an example. [Figure 10] Figure 10 is a perspective view showing a cover member of an example. [Figure 11] Figure 11 is a perspective view showing a cover member of an example. [Figure 12] Figure 12 is a plan view schematically showing a part of the power storage device according to a modified example. [Figure 13] Figure 13 is a plan view schematically showing a part of the power storage device according to the second embodiment. [Figure 14] Figure 14 is a cross-sectional view taken along line XIV-XIV of Figure 13. [Figure 15] Figure 15 is a cross-sectional view taken along line XV-XV of Figure 13. [Figure 16] Figure 16 is a perspective view showing an example of the second part of the cover member. [Figure 17] Figure 17 is a perspective view showing an example of the second part of the cover member.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, an embodiment will be described with reference to the drawings. In the description of the drawings, the same or equivalent elements may be denoted by the same reference numerals, and redundant descriptions may be omitted. Also, in the description, a rectangular coordinate system defined by the X-axis, Y-axis, and Z-axis shown in the drawings may be referred to.

[0021] (First Embodiment) Figure 1 is a schematic plan view showing a power storage device according to the first embodiment. The power storage device 1 can be used, for example, in the batteries of various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 is a secondary battery, such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage device 1 may be an electric double-layer capacitor or an all-solid-state battery. Here, we show the case where the power storage device 1 is a lithium-ion secondary battery.

[0022] The energy storage device 1 comprises an energy storage module 2, a cover member 3 (first cover member), a cover member 4 (second cover member), a pair of cover members 5, an outer casing 6, and a connector unit 7 (connecting component). The energy storage module 2 has a rectangular parallelepiped shape. The energy storage module 2 has a first main surface 2a and a second main surface 2b (see Figure 3) facing opposite directions in the Z-axis direction, a first side surface 2c and a second side surface 2d facing opposite directions in the Y-axis direction, and a third side surface 2e and a fourth side surface 2f facing opposite directions in the X-axis direction. The X-axis, Y-axis, and Z-axis directions intersect (in this case, are orthogonal).

[0023] The cover members 3 and 4 are positioned opposite the first side surface 2c so as to cover the first side surface 2c. The cover members 3 and 4 are positioned so as to cover the first side surface 2c when viewed from the Y-axis direction. In the Y-axis direction, a gap G may be formed between the cover members 3 and 4 and the first side surface 2c. The cover members 3 and 4 are adjacent to each other in the X-axis direction.

[0024] The pair of cover members 5 are positioned opposite each other on the second side surface 2d so as to cover the second side surface 2d. The pair of cover members 5 are positioned so as to cover the second side surface 2d when viewed from the Y-axis direction. A gap G may be formed between the pair of cover members 5 and the second side surface 2d in the Y-axis direction. The pair of cover members 5 are adjacent to each other in the X-axis direction.

[0025] The connector unit 7 is attached to the first side surface 2c. The connector unit 7 is positioned between the cover member 3 and the cover member 4 in the X-axis direction. The connector unit 7 is adjacent to both the cover member 3 and the cover member 4 in the X-axis direction. The connector unit 7 is positioned on the negative side of the X-axis direction relative to the cover member 3. The connector unit 7 is positioned on the positive side of the X-axis direction relative to the cover member 4. The cover members 3 to 5 are formed from a non-conductive material such as resin.

[0026] Figure 2 is a schematic diagram showing the first side surface 2c of the energy storage module 2. Figure 3 is a schematic cross-sectional view of an example of the energy storage module 2, showing a cross-section along line III-III in Figure 2. The first side surface 2c of the energy storage module 2 includes a region R1 to which the additional member 50, described later, is attached, and regions R2 and R3 adjacent to region R1. In the example shown in Figure 2, region R2 is located on the negative side in the X-axis direction compared to region R1, and region R3 is located on the positive side in the X-axis direction compared to region R1. Region R2 is adjacent to the fourth side surface 2f. Region R3 is adjacent to the third side surface 2e. The additional member 50 includes an injection port 53A used when injecting electrolyte into the energy storage module 2.

[0027] As shown in Figure 3, the energy storage module 2 includes an electrode stack 10 and a sealing body 30 that surrounds the electrode stack 10 when viewed from the Z-axis direction. The electrode stack 10 includes a plurality of electrodes stacked along the Z-axis direction. The Z-axis direction is the direction in which the electrodes are stacked and is the height direction of the energy storage device 1. The electrode stack 10 has a rectangular parallelepiped shape. The electrode stack 10 has an upper surface and a lower surface that face opposite each other in the Z-axis direction. The upper surface of the electrode stack 10 constitutes part of the first main surface 2a of the energy storage module 2. The lower surface of the electrode stack 10 constitutes part of the second main surface 2b of the energy storage module 2. The electrode stack 10 is large, for example, its length in the longitudinal direction (Y-axis direction) is 80 cm or more.

[0028] The multiple electrodes include multiple bipolar electrodes 11, a positive terminal electrode 12, and a negative terminal electrode 13. Separators 14 are interposed between adjacent electrodes. The positive terminal electrode 12 includes the upper surface (first main surface 2a) of the electrode stack 10. The negative terminal electrode 13 includes the lower surface (second main surface 2b) of the electrode stack 10.

[0029] The bipolar electrode 11 comprises a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 is rectangular in shape when viewed from the Z-axis direction and is in the form of a sheet. The active material layers (positive electrode active material layer 16, negative electrode active material layer 17) are located in the center of the current collector 15 when viewed from the Z-axis direction and are not located on the peripheral edge 15c of the current collector 15. The positive electrode active material layer 16 is located on the first surface 15a of the current collector 15. The negative electrode active material layer 17 is located on the second surface 15b of the current collector 15. The first surface 15a of the current collector 15 is the surface facing the negative side in the Z-axis direction (the side where the negative electrode terminal electrode 13 is located in Figure 3). The second surface 15b of the current collector 15 is the surface facing the positive side in the Z-axis direction (the side where the positive electrode terminal electrode 12 is located in Figure 3). Multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one adjacent bipolar electrode 11 and the negative electrode active material layer 17 of the other bipolar electrode 11 face each other in the stacking direction.

[0030] The positive terminal electrode 12 comprises a current collector 15 and a positive electrode active material layer 16 provided on the first surface 15a of the current collector 15. The second surface 15b of the current collector 15 of the positive terminal electrode 12 does not have an active material layer. The positive terminal electrode 12 is laminated on the bipolar electrode 11 at the positive end of the electrode stack 10 in the Z-axis direction. The positive terminal electrode 12 is laminated on the bipolar electrode 11 such that its positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11.

[0031] The negative electrode terminal electrode 13 comprises a current collector 15 and a negative electrode active material layer 17 provided on the second surface 15b of the current collector 15. The first surface 15a of the current collector 15 of the negative electrode terminal electrode 13 does not have an active material layer. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 at the negative end of the electrode laminate 10 in the Z-axis direction. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 such that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0032] The separator 14 is positioned between adjacent bipolar electrodes 11, between the positive terminal electrode 12 and the bipolar electrode 11, and between the negative terminal electrode 13 and the bipolar electrode 11. The separator 14 is interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17, separating them. The separator 14 prevents short circuits caused by contact between adjacent electrodes while allowing charge carriers such as lithium ions to pass through.

[0033] The current collector 15 is a chemically inert electrical conductor that allows current to continue flowing through the positive electrode active material layer 16 and the negative electrode active material layer 17 during the discharge or charging of the lithium-ion secondary battery. The material of the current collector 15 is, for example, a metal material, a conductive resin material, or a conductive inorganic material. Examples of conductive resin materials include conductive polymer materials or resins to which conductive fillers are optionally added to non-conductive polymer materials. The current collector 15 may comprise multiple layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material or conductive resin material. In this embodiment, the current collectors 15 of the bipolar electrode 11, the positive electrode terminal electrode 12, and the negative electrode terminal electrode 13 are identical to each other, but they may be different from each other.

[0034] A coating layer may be formed on the surface of the current collector 15. This coating layer may be formed by known methods such as plating or spray coating. The current collector 15 may be in the form of a plate, foil (e.g., metal foil), film, or mesh. Examples of metal foils include aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The current collector 15 may be an alloy foil or clad foil of the above metals. If the current collector 15 is in the form of a foil, its thickness may be, for example, 1 μm or more and 100 μm or less. In this embodiment, the current collector 15 is a foil in which aluminum foil and copper foil are integrated, or aluminum foil.

[0035] The positive electrode active material layer 16 contains a positive electrode active material capable of intercalating and releasing charge carriers such as lithium ions. Examples of positive electrode active materials include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, and polyanionic compounds. The positive electrode active material can be any material suitable for use in lithium-ion secondary batteries. The positive electrode active material layer 16 may contain multiple positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0036] The negative electrode active material layer 17 contains a negative electrode active material capable of intercalating and releasing charge carriers such as lithium ions. The negative electrode active material may be an element, an alloy, or a compound. Examples of negative electrode active materials include Li, carbon, and metal compounds. The negative electrode active material may also be an element or compound thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, hard carbon (carbon that is difficult to graphitize), or soft carbon (carbon that is easily graphitized). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon or tin. In this embodiment, the negative electrode active material layer 17 contains graphite as a carbon-based material.

[0037] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 (hereinafter sometimes simply referred to as the "active material layer") may further contain, as necessary, conductive additives, binders, electrolytes (polymer matrix, ion-conducting polymer, electrolyte solution, etc.), electrolyte-supporting salts (lithium salts) to enhance ionic conductivity, etc. Conductive additives are added to enhance the conductivity of each electrode (bipolar electrode 11, positive electrode terminal electrode 12, negative electrode terminal electrode 13). Examples of conductive additives include acetylene black, carbon black, or graphite.

[0038] Examples of binders include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins such as acrylic acid or methacrylic acid; styrene-butadiene rubber (SBR); alginates such as carboxymethylcellulose, sodium alginate, and ammonium alginate; water-soluble cellulose ester crosslinked polymers; and starch-acrylic acid graft polymers. These binders can be used individually or in combination. Examples of solvents include water and N-methyl-2-pyrrolidone (NMP).

[0039] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains electrolytes. Examples of materials for the separator 14 include polypropylene, polyethylene, polyolefin, and polyester. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer structure may include, for example, a ceramic layer as an adhesive layer or a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The separator 14 may be composed of an electrolyte such as a polymer electrolyte or an inorganic electrolyte. Examples of electrolytes impregnated into the separator 14 include a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, or a polymer gel electrolyte containing an electrolyte held in a polymer matrix.

[0040] When the separator 14 is impregnated with an electrolyte, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 may be used as the electrolyte salt. Furthermore, known solvents such as cyclic carbonates, cyclic esters, linear carbonates, linear esters, and ethers may be used as the non-aqueous solvent. Two or more of these known solvent materials may be used in combination.

[0041] The sealing body 30 includes a sealing main body 20 and an additional member 50 (resin member). The sealing main body 20 is formed in a frame shape on the periphery of the electrode stack 10 so as to surround the periphery of the electrode stack 10 when viewed from the Z-axis direction. The sealing main body 20 can be joined to the first surface 15a and the second surface 15b of each current collector 15 at the peripheral edge 15c of each current collector 15. The sealing main body 20 can form an internal space S between adjacent current collectors 15 in the Z-axis direction and can seal each of these internal spaces S. In this embodiment, each internal space S holds an electrolyte (not shown). That is, the sealing main body 20 cooperates with adjacent current collectors 15 in the Z-axis direction to define an internal space S that holds the electrolyte. The sealing main body 20 can suppress the outflow of the electrolyte held in the internal space S to the outside.

[0042] The sealing body portion 20 can suppress the intrusion and discharge of air, moisture, etc., between the outside and the internal space S of the electrode stack 10. The sealing body portion 20 can, for example, suppress the leakage of gas generated at each electrode due to charge-discharge reactions, etc., to the outside of the energy storage module 2. The edges of the separator 14 are joined to the sealing body portion 20. The sealing body portion 20 contains an insulating material. Examples of materials for the sealing body portion 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile styrene resin.

[0043] One example of a sealing body 20 includes a plurality of sealing materials 21, a pair of end sealing materials 24, and a plurality of spacers 22. The sealing materials 21, end sealing materials 24, and spacers 22 may be frame-shaped members formed in a sheet-like manner. The sealing body 20 also has a welded end 23. The sealing material 21 is frame-shaped when viewed from the Z-axis direction and is provided along the peripheral edge 15c of the current collector 15. The sealing material 21 is provided so as to extend from the first surface 15a of the current collector 15 through the end surface to the second surface 15b, covering the peripheral edge 15c.

[0044] The sealing material 21 has an inner portion that overlaps the current collector 15 when viewed from the Z direction, and an outer portion that is located outside the edge of the current collector 15, on the first surface 15a and the second surface 15b of the current collector 15. A pair of adjacent sealing materials 21 on either side of the current collector 15 are connected by their outer portions. The sealing material 21 can be welded to at least one of the first surface 15a and the second surface 15b of the current collector 15. In this embodiment, the sealing material 21 is welded to both the first surface 15a and the second surface 15b of the current collector 15.

[0045] The end seal material 24 has a frame shape when viewed from the Z-axis direction and is provided along the peripheral edge 15c of the current collector 15 that constitutes the positive terminal electrode 12 and the negative terminal electrode 13, respectively. Therefore, the end seal material 24 is arranged to sandwich the multiple seal materials 21 from the Z-axis direction. The end seal material 24 can be welded to at least one of the first surface 15a and the second surface 15b of the current collector 15. In this embodiment, the end seal material 24 is welded to both the first surface 15a and the second surface 15b of the current collector 15.

[0046] The surface of the end seal material 24 joined to the positive terminal electrode 12, opposite to the spacer 22, constitutes a part of the first main surface 2a. The surface of the end seal material 24 joined to the negative terminal electrode 13, opposite to the spacer 22, constitutes a part of the second main surface 2b.

[0047] The spacer 22 has a frame shape when viewed from the Z-axis direction and is positioned along the peripheral edge 15c of the current collector 15. The spacer 22 is positioned to be interposed between adjacent sealing materials 21 in the Z-axis direction. Furthermore, the spacer 22 is positioned to be interposed between adjacent sealing materials 21 and end sealing materials 24 in the Z-axis direction. The spacer 22 can maintain the distance between adjacent current collectors 15 in the Z-axis direction. That is, the spacer 22, sealing materials 21 and end sealing materials 24 define an internal space S between adjacent current collectors 15 in the Z-axis direction.

[0048] The welded end portion 23 is formed by welding together the ends of multiple sealing materials 21, a pair of end sealing materials 24, and multiple spacers 22 that are opposite to the internal space S, thereby integrating them. When viewed from the Z-axis direction, the welded end portion 23 has a frame-like shape that surrounds the electrode stack 10. The side of the welded end portion 23 opposite to the internal space S extends along the Z-axis direction and constitutes the outer surface of the sealing body portion 20. In other words, the sealing body portion 20 includes the outer surface opposite to the internal space S. The outer surface of the sealing body portion 20 includes the first side 2c, second side 2d, third side 2e, and fourth side 2f of the energy storage module 2.

[0049] The sealing body portion 20 has a plurality of communication holes 27 that communicate with each of the plurality of internal spaces S. For example, the communication holes 27 are notched portions formed in the spacer 22 and are formed to penetrate the welded end portion 23. The communication holes 27 have one opening in the internal space S and the other opening in the first side surface 2c of the sealing body portion 20.

[0050] The additional member 50 is formed to cover the region R1 of the first side surface 2c in which the communication holes 27 are provided. As described above, the communication holes 27 communicate with the internal space S between adjacent electrodes in the Z-axis direction. By being molded into a predetermined shape, the additional member 50 provides a liquid injection port portion 53A having a plurality of liquid injection ports that each communicate with a plurality of communication holes 27. The additional member 50 is joined to the welded end portion 23. For example, the additional member 50 is integrally joined to the welded end portion 23 by injection molding. An example of the additional member 50 includes a resin body portion 51, a first overhang portion 55, and a second overhang portion 57.

[0051] The resin body portion 51 is partially attached to the first side surface 2c so as to cover the entire region R1. In the example shown in Figure 2, 30 communication holes 27 corresponding to the 30 layers of internal space S formed between each current collector 15 are arranged discretely in the X-axis and Z-axis directions. More specifically, the communication holes 27 corresponding to the 1st to 10th layers of internal space S are arranged evenly spaced along the X-axis direction, with the positive electrode terminal electrode 12 side as the base end. The communication holes 27 corresponding to the 11th to 20th layers of internal space S, and the communication holes 27 corresponding to the 21st to 30th layers of internal space S are arranged sequentially in the Z-axis direction below the 1st to 10th layers of internal space S. The resin body portion 51 extends in a rectangular shape along the X-axis and Z-axis directions to cover the region R1 in which these 30 communication holes 27 are formed.

[0052] The resin body portion 51 is formed in the shape of a rectangular plate with a predetermined thickness in the Y-axis direction. The resin body portion 51 has openings 52 at positions corresponding to the communication holes 27. The resin body portion 51 also has protruding frame portions 53 that project in the Y-axis direction, intersecting (orthogonal to) the first side surface 2c. When viewed from the Y-axis direction, the protruding frame portions 53 surround each opening 52 and function as partitions separating each opening 52. In the example in Figure 2, ten protruding frame portions 53 are arranged in the X-axis direction, each having three spaces to separate three vertically aligned openings 52.

[0053] The protruding frame portion 53 is used, for example, when injecting electrolyte into each of the internal spaces S. For example, when injecting electrolyte, the nozzle of the injection device is brought into close contact with the top surface of the protruding frame portion 53, and the electrolyte is introduced into the space of each protruding frame portion 53 from the nozzle. This makes it possible to inject electrolyte into the internal space S from the opening 52 and the communication hole 27.

[0054] In one example, the resin body portion 51 includes a terminal portion 58 for voltage detection (see Figure 2). The terminal portion 58 is formed in the resin body portion 51 at a position offset to the positive side in the X-axis direction from the liquid injection port portion 53A, which is formed by a plurality of protruding frame portions 53. For example, the terminal portion 58 is provided adjacent to the protruding frame portion 53 formed at the positive end in the X-axis direction, via a flat surface 51a. In one example, the terminal portion 58 is provided at the positive end in the X-axis direction of the resin body portion 51.

[0055] The terminal section 58 provides multiple terminals 58a that are electrically connected to multiple current collectors 15. One end of each terminal 58a is connected to the corresponding current collector 15, and the other end of each terminal 58a is exposed from the resin body 51. The terminals 58a only need to be electrically connected to the current collectors 15, and may be, for example, metal pins. A connector unit 7 (see Figure 1) is fixed to the terminal section 58. An example of a connector unit 7 includes a housing 8 having multiple contacts connected to the multiple terminals 58a, and a connector 9 connected to the housing 8. A flexible circuit board that is brought out to the outside of the outer casing 6 may be connected to the connector 9.

[0056] The first overhang portion 55 and the second overhang portion 57 are formed by connecting to both ends of the resin body portion 51 in the Z-axis direction. The first overhang portion 55 partially covers one end of the welded end portion 23 in the Z-axis direction (the positive Z-axis side). For example, the first overhang portion 55 partially covers the end seal material 24 joined to the positive electrode terminal electrode 12. The first overhang portion 55 protrudes from the resin body portion 51 onto the first main surface 2a (the end seal material 24 joined to the positive electrode terminal electrode 12).

[0057] In the illustrated example, the edge 55a of the first overhang portion 55 extends from the edge of the welded end portion 23 to a position outside the inner edge 22a of the spacer 22 and the inner edge 21a of the sealing material 21 when viewed from the Z-axis direction, but this is not limited to that. The first overhang portion 55 may be formed in the shape of a rectangular plate having the same length as the resin main body portion 51 in the X-axis direction.

[0058] Similar to the first overhang portion 55, the second overhang portion 57 partially covers the other edge of the welded end portion 23 in the Z-axis direction (the negative side in the Z-axis direction). The second overhang portion 57 extends from the resin body portion 51 onto the second main surface 2b (the end sealing material 24 joined to the negative electrode terminal electrode 13).

[0059] Figure 4 is a cross-sectional view along line IV-IV in Figure 1. Figure 5 is a cross-sectional view along line VV in Figure 1. Figure 6 is a cross-sectional view along line VI-VI in Figure 1. Note that in Figures 4 to 6, the energy storage module 2 included in the energy storage device 1 is depicted in a simplified manner. An example of an outer casing 6 includes a first outer casing pack 6A and a second outer casing pack 6B that are arranged facing each other in the vertical direction. The first outer casing pack 6A is positioned opposite the first main surface 2a of the energy storage module 2. The second outer casing pack 6B is positioned opposite the second main surface 2b of the energy storage module 2. The first outer casing pack 6A and the second outer casing pack 6B have similar configurations to each other.

[0060] The first outer pack 6A and the second outer pack 6B each have recesses 60 (housing sections) formed therein. The recesses 60 provide space for housing the energy storage module 2, cover members 3-5, and connector unit 7. The outer body 6 houses the energy storage module 2, cover members 3-5, and connector unit 7 in each recess 60.

[0061] The recess 60 has a first side portion 61 (side portion), a second side portion 62, a third side portion 63, a fourth side portion 64, and a bottom portion 65. The first side portion 61 and the second side portion 62 face each other in the Y-axis direction and extend in the X-axis direction and the Z-axis direction, respectively. The third side portion 63 and the fourth side portion 64 face each other in the X-axis direction and extend in the Y-axis direction and the Z-axis direction, respectively.

[0062] The bottom portion 65 is adjacent to and continuous with each of the first side portion 61, the second side portion 62, the third side portion 63, and the fourth side portion 64. The bottom portion 65 extends in the X-axis direction and the Y-axis direction. The first side portion 61 and the third side portion 63 are adjacent to and continuous with each other. The third side portion 63 and the second side portion 62 are adjacent to and continuous with each other. The second side portion 62 and the fourth side portion 64 are adjacent to and continuous with each other. The fourth side portion 64 and the first side portion 61 are adjacent to and continuous with each other.

[0063] The first side portion 61 faces the first side surface 2c of the energy storage module 2 and is positioned to cover the first side surface 2c. The second side portion 62 faces the second side surface 2d of the energy storage module 2 and is positioned to cover the second side surface 2d. The third side portion 63 faces the third side surface 2e of the energy storage module 2 and is positioned to cover the third side surface 2e. The fourth side portion 64 faces the fourth side surface 2f of the energy storage module 2 and is positioned to cover the fourth side surface 2f. The bottom portion 65 faces the first main surface 2a or the second main surface 2b of the energy storage module 2 and is positioned to cover the said main surface.

[0064] The first outer packaging 6A and the second outer packaging 6B each have a flange portion 66 that extends outward and is provided around the recess 60. The flange portion 66 is continuous with the edge opposite the bottom portion 65 of the first side portion 61, the second side portion 62, the third side portion 63, and the fourth side portion 64. The flange portion 66 is provided parallel to the bottom portion 65.

[0065] The first outer packaging 6A and the second outer packaging 6B each include a conductive member 67 and an outer film 68. The conductive member 67 has a rectangular shape in plan view and forms the center of the bottom portion 65. The conductive member 67 of the first outer packaging 6A abuts against the second surface 15b of the current collector 15 of the positive terminal electrode 12 which constitutes the first main surface 2a, and is electrically connected to the positive terminal electrode 12. The conductive member 67 of the second outer packaging 6B abuts against the first surface 15a of the current collector 15 of the negative terminal electrode 13 which constitutes the second main surface 2b, and is electrically connected to the negative terminal electrode 13. The conductive member 67 may be, for example, a metal foil, and one example may be aluminum foil. The planar size of the conductive member 67 may be the same as or smaller than that of the current collector 15.

[0066] The outer film 68 constitutes the periphery of the bottom portion 65, the first side portion 61, the second side portion 62, the third side portion 63, and the fourth side portion 64. The outer film 68 is configured to surround the outer periphery of the contents (in this case, the energy storage module 2, cover members 3-5, and connector unit 7) when viewed from the Z-axis direction. The outer film 68 is connected to the periphery of the conductive member 67. The outer film 68 has a rectangular frame shape. For example, the outer film 68 may be formed by welding together four strip-shaped sheet members along each of the four sides that make up the rectangle.

[0067] The outer film 68 is processed (for example, by press forming) so that its outer edge is further away from the conductive member 67 than its inner edge. This processing forms a recess 60 in the outer film 68 with the conductive member 67 as its bottom. The inner edge of the outer film 68, which forms a rectangular frame shape when viewed from the Z-axis direction, is located inside the periphery of the conductive member 67. The inner edge of the outer film 68 and the periphery of the conductive member 67 are joined together in an overlapping manner.

[0068] In one example, the inner edge of the outer film 68 and the periphery of the conductive member 67 may be joined to each other by a resin material 69. The resin material 69 may be a rectangular frame-shaped sealing resin formed in a sheet. For example, the inner edge of the rectangular frame-shaped resin material 69 may be located inside the inner edge of the outer film 68, and the outer edge of the resin material 69 may coincide with the periphery of the conductive member 67. The outer edge of the outer film 68 is located outside the periphery of the contents when viewed from the Z-axis direction.

[0069] The outer film 68 may be, for example, a laminate film including a metal layer. That is, the outer film 68 may be a sheet-like member in which both sides of a metal layer 68a, such as aluminum, are covered with resin layers 68b and 68c. The resin layers 68b and 68c may be formed from the same resin as the sealant 30.

[0070] In the first outer packaging 6A and the second outer packaging 6B, the outer edges of the outer film 68 are joined together. For example, the flange portions 66 of the outer film 68 may be welded together. By sealing the outer edges of the outer film 68 together, a sealed space is formed inside the outer packaging 6. After the energy storage module 2 etc. are housed in the outer packaging 6, the outer packaging 6 is sealed under reduced pressure. As a result, the pressure inside the outer packaging 6 is lower than atmospheric pressure.

[0071] Next, cover members 3 to 5 will be described. Figure 7 is a schematic plan view showing a part of the energy storage device. In Figure 7, the first outer pack 6A is not shown. Cover members 3 to 5 are housed in the outer body 6 together with the energy storage module 2 and the connector unit 7. Cover members 3 and 4 are arranged side by side in the X-axis direction between the first side surface 2c of the energy storage module 2 and the first side portion 61 of the outer body 6. The pair of cover members 5 are arranged side by side in the X-axis direction between the second side surface 2d of the energy storage module 2 and the second side portion 62 of the outer body 6.

[0072] Figure 8 is a perspective view showing the cover member 3 and the energy storage module 2. As shown in Figures 7 and 8, the cover member 3 has a main body 31 and a projection 32. The main body 31 is positioned between the first side surface 2c and the first side portion 61 so as not to overlap with the energy storage module 2 when viewed from the Z-axis direction. The main body 31 is a hollow member and has a hollow space H1 inside. The projection 32 protrudes from the main body 31 in the Y-axis direction so as to cover the gap G between the hollow main body 31 and the energy storage module 2 (first side surface 2c). When viewed from the X-axis direction, the projection 32 overlaps with the gap G. The gap G may be extremely small, and the main body 31 and the energy storage module 2 may be in partial contact. The projection 32 covers a portion of the third side surface 2e. The projection 32 is formed in a plate shape parallel to the third side surface 2e. The projection 32 is not in contact with the third side surface 2e, but may be in contact.

[0073] The cover member 4 has a main body portion 33 and a projection portion 34. The main body portion 33 is positioned between the first side surface 2c and the first side portion 61 so as not to overlap with the energy storage module 2 when viewed from the Z-axis direction. The main body portion 33 is a hollow member and has a hollow space H2 inside. The projection portion 34 protrudes from the main body portion 33 in the Y-axis direction so as to cover the gap G between the hollow main body portion 33 and the energy storage module 2 (first side surface 2c). When viewed from the X-axis direction, the projection portion 34 overlaps with the gap G. The gap G may be extremely small, and the main body portion 33 and the energy storage module 2 may be in partial contact. The projection portion 34 covers a portion of the fourth side surface 2f. The projection portion 34 is formed in a plate shape parallel to the fourth side surface 2f. The projection portion 34 is not in contact with the fourth side surface 2f, but may be in contact.

[0074] Each cover member 5 has a main body 35 and a projection 36. The main body 35 is positioned between the second side surface 2d and the second side portion 62 so as not to overlap with the energy storage module 2 when viewed from the Z-axis direction. The main body 35 is a hollow member and has a hollow space H3 inside. The projection 36 protrudes from the main body 35 in the Y-axis direction so as to cover the gap G between the hollow main body 35 and the energy storage module 2 (second side surface 2d). When viewed from the X-axis direction, the projection 36 overlaps with the gap G. The gap G may be extremely small, and the main body 35 and the energy storage module 2 may be in partial contact. The projection 36 covers a portion of the third side surface 2e or the fourth side surface 2f. The projection 36 is formed in a plate shape parallel to the third side surface 2e or the fourth side surface 2f. The projection 36 does not contact the third side surface 2e and the fourth side surface 2f, but may contact them.

[0075] The cover member 3 includes a first portion 110 and a second portion 120 that are arranged adjacent to each other in the Z-axis direction. The cover member 3 is formed by combining the first portion 110 and the second portion 120. The first portion 110 is fixed to the outer film 68 of the second outer pack 6B. The second portion 120 is fixed to the outer film 68 of the first outer pack 6A. Figures 9 and 10 are perspective views showing the first portion 110. Figure 11 is a perspective view showing the second portion 120.

[0076] The first part 110 includes a base wall 111 extending along the Y-axis direction (more specifically, the XY plane), and side walls 112 and 113 projecting toward the second part 120 from both ends of the base wall 111 in the Y-axis direction. The outer surface 111b of the base wall 111 faces the bottom 65 of the second outer packaging 6B, and the outer surface 112b of the side walls 112 faces the first side 61 of the second outer packaging 6B.

[0077] The first part 110 has side walls 114 and 115 that extend toward the second part 120 from both ends of the base wall 111 in the X-axis direction. The base wall 111 intersects in the Z-axis direction, side walls 112 and 113 intersect in the Y-axis direction, and side walls 114 and 115 intersect in the X-axis direction. The outer surface 114b of side wall 114 faces the third side portion 63 of the second outer packaging pack 6B. Side wall 114 has a projection 114a that protrudes from side wall 113 in the Y-axis direction.

[0078] In the illustrated example, the base wall 111 has a notched portion 111c formed at the edge where the side wall 115 is formed, for positioning the connector unit 7. As a result, the connection portion between the side wall 112 and the side wall 115 is formed in an inward corner shape. Therefore, the side wall 115 is divided into two parts in the center in the Y-axis direction. Also, the side wall 112 is divided into two parts in the X-axis direction at a position close to the side wall 115.

[0079] In one example, the connection portion 118a between the base wall 111 and the side wall 112, and the connection portion 118b between the base wall 111 and the side wall 114, are curved with a predetermined curvature. Furthermore, the connection portion 118c between the side wall 112 and the side wall 114 is curved with an even greater curvature. That is, these connection portions 118a, 118b, and 118c are formed in an R-shape with chamfered corners.

[0080] The first part 110 has a plurality of ribs 117. The ribs 117 are plate-like and extend along the YZ plane, and are connected to the base wall 111, side wall 112, and side wall 113. The height of the ribs 117 in the Z-axis direction may be the same as that of the side walls 112, side wall 113, side wall 114, and side wall 115. The plurality of ribs 117 are spaced apart from each other in the X-axis direction. The plurality of ribs 117 may be spaced equally or at different intervals in the X-axis direction.

[0081] The base wall 111 of the first part 110 has an inner surface 111a that extends in the Y-axis direction (more specifically, the XY plane) and faces toward the second part 120. The inner surface 111a is provided with support columns 119 that extend along the Z-axis direction and project toward the second part 120. In the illustrated example, the inner surface 111a has a plurality of support columns 119. The positions of the plurality of support columns 119 are not particularly limited. For example, a pair of support columns 119 may be formed adjacent to each other in the Y-axis direction between a pair of adjacent ribs 117 in the X-axis direction.

[0082] As shown in Figure 10, a welding plate 108 is fixed to the outer surface 111b of an example base wall 111. In the illustrated example, a rectangular recess 111d is formed on the outer surface 111b of the base wall 111 in plan view. The welding plate 108 has a plate shape with the same planar shape as the recess 111d and is placed inside the recess 111d. For example, the welding plate 108 and the recess 111d may be fixed to each other by the fitting of a projection 108a provided on the welding plate 108 and a hole 111e provided on the recess 111d.

[0083] When the welding plate 108 is fixed in the recess 111d, the outer surface of the base wall 111 and the surface of the welding plate 108 may be flush. The welding plate 108 is the part that is welded to the outer film 68 of the second outer pack 6B, and is made of the same material as the resin layer 68b of the outer film 68. If the first part 110 is made of the same material as the resin layer 68b, the first part 110 does not need to have the welding plate 108.

[0084] In this embodiment, cover members 3 to 5 are arranged between the sealant 30 and the outer casing 6. The coefficient of linear expansion of cover members 3 to 5 is closer to the coefficient of linear expansion of the outer casing 6 than to the coefficient of linear expansion of the resin used in the sealant 30. Therefore, it is possible to suppress the generation of stress in the outer casing 6 by the sealant 30 which has expanded due to the temperature change of the energy storage device 1. For example, cover members 3 to 5 may be resin materials such as polyphenylene sulfide blended with fillers such as glass fibers, or they may be resin materials with a relatively small coefficient of linear expansion such as polyphenylene sulfide.

[0085] The resin layer 68b of the outer film 68 is formed of the same resin as the sealant 30. For example, the resin layer 68b may be made of polypropylene. In this case, the cover member has a welding plate 108 as described above, and this welding plate 108 may be made of polypropylene. In this embodiment, gaps G are provided between the cover members 3, 4 and the first side surface 2c, and between the pair of cover members 5 and the second side surface 2d. This makes it difficult for the expansion of the sealant 30 in the Y-axis direction to affect the outer body 6.

[0086] The welded plate 108 of the first part 110 is welded to the opposing outer film 68 with the outer surface 111b of the base wall 111 in contact with the outer film 68 constituting the bottom 65 of the second outer pack 6B, and the outer surface 112b of the side wall 112 in contact with the outer film 68 constituting the first side 61 of the second outer pack 6B. In this case, the outer surface 114b of the side wall 114 may be in contact with the third side 63 of the second outer pack 6B. When the base wall 111, side wall 112 and side wall 114 are in contact with the inner surface of the opposing recess 60, the connection portion 118a between the base wall 111 and the side wall 112 may be in contact with the connection portion between the bottom 65 and the first side 61 on the inner surface of the recess 60.

[0087] Similarly, the connection portion 118b between the base wall 111 and the side wall 114 may abut the connection portion between the bottom 65 and the third side portion 63 on the inner surface of the recess 60. The connection portion 118c between the side wall 112 and the side wall 114 may abut the connection portion between the first side portion 61 and the third side portion 63 on the inner surface of the recess 60. That is, the connection portion 118a between the base wall 111 and the side wall 112 and the connection portion between the bottom 65 and the first side portion 61 may have equal curvature. The connection portion 118b between the base wall 111 and the side wall 114 and the connection portion between the bottom 65 and the third side portion 63 may have equal curvature. The connection portion 118c between the side wall 112 and the side wall 114 and the connection portion between the first side portion 61 and the third side portion 63 may have equal curvature.

[0088] The basic structure of the second part 120 is the same as that of the first part 110. The second part 120 has a base wall 121, side walls 122, 123, 124, and 125. The base wall 121 of the second part 120 corresponds to the base wall 111 of the first part 110 and extends along the Y-axis direction (more specifically, the XY plane) so as to face the base wall 111. A welding plate 108 is provided on the outer surface of the base wall 121, similar to the first part 110. When viewed from the Z-axis direction, the base wall 111 of the first part 110 and the base wall 121 of the second part 120 have the same shape.

[0089] The side walls 122, 123, 124, and 125 of the second part 120 face the side walls 112, 113, 114, and 115 of the first part 110 in the Z-axis direction, and protrude toward the first part 110 from the edge of the base wall 121. The side wall 124 has a projection 124a that protrudes from the side wall 123 in the Y-axis direction. The projection 124a, together with the projection 114a, forms a projection 32. The second part 120 has a plurality of ribs 127. The ribs 127 are parts corresponding to the ribs 117 and face the ribs 117 of the first part 110 in the Z-axis direction.

[0090] Unlike the first part 110, the second part 120 does not have a support column 119. The support column 119 in the first part 110 described above is formed to be higher in the Z-axis direction than the side walls 112, 113, 114, and 115 of the first part 110. In one example, the inner surface 121a of the base wall 121 of the second part 120 faces the inner surface 111a of the first part 110 and may be in contact with the tip of the support column 119 of the first part 110.

[0091] Similar to the first part 110, the second part 120 is fixed to the first outer pack 6A by welding a welding plate 108 provided on the base wall 121 to the outer film 68. In this case, the outer surface 121b of the base wall 121 may abut against the outer film 68 that constitutes the bottom 65 of the first outer pack 6A, the outer surface 122b of the side wall 122 may abut against the outer film 68 that constitutes the first side 61 of the first outer pack 6A, and the outer surface 124b of the side wall 124 may abut against the third side 63 of the first outer pack 6A. When the base wall 121, side wall 122 and side wall 124 abut against the inner surface of the opposite recess 60, the connection portion 128a between the base wall 121 and the side wall 122 may abut against the connection portion between the bottom 65 and the first side 61 on the inner surface of the recess 60.

[0092] Similarly, the connection portion 128b between the base wall 121 and the side wall 124 may abut the connection portion between the bottom 65 and the third side portion 63 on the inner surface of the recess 60. The connection portion 128c between the side wall 122 and the side wall 124 may abut the connection portion between the first side portion 61 and the third side portion 63 on the inner surface of the recess 60. That is, the connection portion 128a between the base wall 121 and the side wall 122 and the connection portion between the bottom 65 and the first side portion 61 may have equal curvature. The connection portion 128b between the base wall 121 and the side wall 124 and the connection portion between the bottom 65 and the third side portion 63 may have equal curvature. The connection portion 128c between the side wall 122 and the side wall 124 and the connection portion between the first side portion 61 and the third side portion 63 may have equal curvature.

[0093] The cover member 4 has the same configuration as the cover member 3 and includes a first part 130 and a second part 140. The structure of the first part 130 and the second part 140 is the same as that of the first part 110 and the second part 120, differing only in their planar shape, so a detailed explanation is omitted. The first part 130 is fixed to the second outer packaging pack 6B by a welding plate 108. Similarly, the second part 140 is fixed to the first outer packaging pack 6A by a welding plate 108.

[0094] The cover member 5 has the same configuration as the cover member 3 and includes a first portion 150 and a second portion 160. The structure of the first portion 150 and the second portion 160 is the same as that of the first portion 110 and the second portion 120, differing only in their planar shape, so a detailed explanation is omitted. As shown in Figures 1 and 6, in this embodiment, a pair of cover members 5 are arranged adjacent to each other in the X-axis direction. The first portion 150 is fixed to the second outer packaging 6B by a welding plate 108. Similarly, the second portion 160 is fixed to the first outer packaging 6A by a welding plate 108.

[0095] From the standpoint of preventing short circuits, non-conductive materials such as resin are used for the cover members 3 to 5. Since the energy storage module 2 is not fixed to the outer casing 6, while the cover members 3 to 5 are fixed to the outer casing 6, a gap G is created between the cover members 3 to 5 and the energy storage module 2 due to the dimensional tolerances of the energy storage module 2 and the outer casing 6. When the energy storage module 2 and cover members 3 to 5 are sealed under reduced pressure by the outer casing 6 while the gap G exists, stress concentrates in the region of the outer casing 6 that faces the gap G. If the energy storage device 1 is enlarged with this configuration, the difference in the coefficients of linear expansion of the cover members 3 to 5 and the outer casing 6 may cause the cover members 3 to 5 to interfere with the stress concentration area of ​​the outer casing 6 (i.e., the region of the outer casing 6 that faces the gap G), potentially causing the outer casing 6 to break.

[0096] In the energy storage device 1, the cover member 3 has a plate-shaped projection 32 that protrudes from the main body 31 in the Y-axis direction and covers a portion of the third side surface 2e. When viewed from the X-axis direction, the projection 32 overlaps with the gap G. The projection 32 covers the gap G between the cover member 3 and the energy storage module 2. The cover member 4 has a plate-shaped projection 34 that protrudes from the main body 33 in the Y-axis direction and covers a portion of the fourth side surface 2f. When viewed from the X-axis direction, the projection 34 overlaps with the gap G. The projection 34 covers the gap G between the cover member 4 and the energy storage module 2. The cover member 5 has a plate-shaped projection 36 that protrudes from the main body 35 in the Y-axis direction and covers a portion of the third side surface 2e or the fourth side surface 2f. When viewed from the X-axis direction, the projection 36 overlaps with the gap G. The projection 36 covers the gap G between the cover member 4 and the energy storage module 2. Therefore, the energy storage device 1 can prevent the outer casing 6 from falling into or becoming embedded in the gap G. This prevents stress from concentrating in a portion of the outer casing 6 (i.e., the portion facing the gap G), thus preventing the outer casing 6 from fracturing.

[0097] The protrusions 32, 34, and 36 do not come into contact with the energy storage module 2. Therefore, damage to the energy storage module 2 is suppressed. The protrusions 32, 34, and 36 may each come into surface contact with the energy storage module 2. In this case, even if the protrusions 32, 34, and 36 come into contact with the energy storage module 2, damage to the energy storage module 2 is unlikely.

[0098] (modified version) Figure 12 is a schematic plan view showing a part of a modified energy storage device. In Figure 12, the first outer packaging 6A is not shown. In the modified energy storage device 1A, the tip portion 32a of the projection 32 of the cover member 3 has a tapered shape that becomes thinner towards the tip 32b. The tip portion 32a has a tapered surface 32c that approaches the third side surface 2e towards the tip 32b. The tapered surface 32c is inclined with respect to the third side surface 2e. This reduces the step caused by the thickness of the projection 32. Therefore, the fracture of the outer packaging 6 can be further suppressed. Although not shown, in the energy storage device 1A, the projection 34 of the cover member 4 and the projection 36 of the cover member 5 may also each have tapered tip portions.

[0099] (Second Embodiment) Figure 13 is a schematic plan view showing the energy storage device according to the second embodiment. Figure 14 is a cross-sectional view along the line XIV-XIV in Figure 13. Figure 15 is a cross-sectional view along the line XV-XV in Figure 13. In Figure 13, the first outer packaging 6A is not shown. In Figure 14, the outer casing 6 is not shown. In Figure 15, the energy storage module 2 included in the energy storage device 1B is depicted in a simplified manner. The energy storage device 1B according to the second embodiment differs from the energy storage device 1 according to the first embodiment in that the cover member 3 has a pair of protrusions 37, the cover member 4 has a pair of protrusions 38, and the cover member 5 has a pair of protrusions 39.

[0100] The pair of projections 37 are positioned opposite each other in the Z-axis direction. The projections 37 protrude from the main body 31 in the Y-axis direction and overlap with the gap G between the energy storage module 2 and the cover member 3 when viewed from the Z-axis direction. The projections 37 cover the gap G. The pair of projections 37 are continuous with the base walls 111 and 121 of the main body 31. The thickness of the pair of projections 37 may be thinner than the thickness of the base walls 111 and 121.

[0101] The projection 37A protrudes from the main body 31 on the negative side in the Y-axis direction and covers a portion of the first main surface 2a of the energy storage module 2. The projection 37A is plate-shaped and parallel to the first main surface 2a, but the tip portion 37a on the negative side in the Y-axis direction of the projection 37A has a bent portion 37c in which the tip 37b faces the first main surface 2a. The bent portion 37c has an R-shape.

[0102] The projection 37A also protrudes from the main body 31 on the negative side in the X-axis direction, covering a portion of the connector unit 7 and the additional member 50. The tip portion of the projection 37A on the negative side in the X-axis direction has the same structure as the tip portion 37a. The projection 37A covers the entire first overhang portion 55 in the Y-axis direction.

[0103] In the energy storage device 1B, the base wall 121 of the second part 120 protrudes from the side wall 123 in the Y-axis direction and from the side wall 125 in the X-axis direction, forming a projection 37A. The positive end 37d of the projection 37A in the Y-axis direction covers the side surface of the connector unit 7 extending in the Z-axis direction. The projection 37A has a bent portion 37e adjacent to the end 37d, which is bent along the corner of the connector unit 7. The bent portion 37e has an R-shape.

[0104] The projection 37B protrudes from the main body 31 on the negative side in the Y-axis direction and covers a portion of the second main surface 2b of the energy storage module 2. The projection 37B protrudes from the main body 31 on the negative side in the X-axis direction and covers a portion of the connector unit 7 and the additional member 50. The projection 37B covers the entire second overhang portion 57 in the Y-axis direction. Since the projection 37B has the same structure as the projection 37A, a detailed explanation is omitted.

[0105] In the energy storage device 1B, the base wall 111 of the first part 110 protrudes from the side wall 113 in the Y-axis direction and from the side wall 115 in the X-axis direction, forming a projection 37B. The positive end 37d of the projection 37B in the Y-axis direction covers the side surface of the connector unit 7 extending in the Z-axis direction. The projection 37B has a bent portion 37e adjacent to the end 37d, which is bent along the corner of the connector unit 7. The bent portion 37e has an R-shape.

[0106] The projection 37 covers the gap G between the energy storage module 2 and the cover member 3, and the gap G between the connector unit 7 and the cover member 3, thereby suppressing the breakage of the outer casing 6. The rounded bent portion 37c further suppresses the breakage of the outer casing 6. The surface of the bent portion 37c is an R-shaped curved surface, but it may also have a chamfered shape consisting of a combination of flat surfaces. The projection 37 also covers the gap G between components such as the housing 8 and connector 9 that constitute the connector unit 7, as well as the corners of the components, further suppressing the breakage of the outer casing 6.

[0107] Since the additional member 50 is formed by injection molding, the corners of the first overhang portion 55 and the second overhang portion 57 may have a sharp shape. Even in this case, the corners of the first overhang portion 55 and the second overhang portion 57 are covered by the projection 37, so the fracture of the outer casing 6 is suppressed. Since the projection 37 is not in contact with the energy storage module 2, damage to the energy storage module 2 is suppressed. The projection 37 may be in contact with the energy storage module 2.

[0108] The pair of projections 38 are positioned opposite each other in the Z-axis direction. The projections 38 protrude from the main body 33 in the Y-axis direction and overlap with the gap G between the energy storage module 2 and the cover member 4 when viewed from the Z-axis direction. The projections 38 cover the gap G. The pair of projections 38 are continuous with the pair of base walls 131, 141 (see Figure 5) of the main body 33. The thickness of the pair of projections 38 may be formed to be thinner than the thickness of the pair of 131, 141 of the main body 33.

[0109] The pair of projections 38 protrude from the main body 33 on the negative side in the Y-axis direction and cover a portion of the first main surface 2a and the second main surface 2b of the energy storage module 2. The pair of projections 38 also protrude from the main body 33 on the positive side in the X-axis direction and cover a portion of the connector unit 7 and the additional member 50. The pair of projections 38 cover the entirety of the first overhang portion 55 and the second overhang portion 57 in the Y-axis direction. Since the projections 38 have the same structure as the projections 37, a detailed explanation is omitted.

[0110] The cover member 5 has a pair of projections 39 that protrude on the positive side in the Y-axis direction and cover a portion of the first main surface 2a and the second main surface 2b of the energy storage module 2. The projections 39 protrude from the main body 35 in the Y-axis direction and overlap with the gap G between the energy storage module 2 and the cover member 5 when viewed from the Z-axis direction. The projections 39 cover the gap G. The pair of projections 39 are continuous with the pair of base walls 151, 161 of the main body 35. The thickness of the pair of projections 39 may be thinner than the thickness of the pair of base walls 151, 161 of the main body 35.

[0111] Examples of each form of this disclosure have been described above with reference to the drawings, but this disclosure is not limited to the above forms.

[0112] For example, cover member 3 may have both projections 32 and 37 and cover a portion of the first main surface 2a, second main surface 2b, and third side surface 2e of the energy storage module 2. Cover member 4 may have both projections 34 and 38 and cover a portion of the first main surface 2a, second main surface 2b, and fourth side surface 2f of the energy storage module 2. In addition to projection 36, the pair of cover members 5 may further have projections that cover a portion of the first main surface 2a and second main surface 2b of the energy storage module 2.

[0113] Figure 16 is a perspective view showing an example of the second part of the cover member. As shown in Figure 16, the side wall 124 has a projection 124a that protrudes from the side wall 123 in the Y-axis direction. The projection 124a, together with the projection 114a, forms a projection 32. The base wall 121 has a projection 37 that protrudes from the side wall 123 in the Y-axis direction. By using this second part 120, a cover member 3 having both projections 32 and 37 can be obtained.

[0114] Figure 17 is a perspective view showing an example of a second part of the cover member. The second part 120 shown in Figure 17 does not have a side wall 123. In this second part 120, the extent of the projection 124a and projection 37 may be defined, for example, by the tip position of the rib 127.

[0115] In the energy storage device 1, it is sufficient that at least one of the protrusions 32, 34, or 36 is provided.

[0116] In the outer casing 6, recesses 60 are formed in the first outer casing pack 6A and the second outer casing pack 6B, respectively. However, recesses 60 may be formed in only one of the first outer casing pack 6A or the second outer casing pack 6B. In this case, the recess 60 has a depth sufficient to accommodate the entire energy storage module 2 in the Z-axis direction. The other of the first outer casing pack 6A and the second outer casing pack 6B, which does not have a recess 60, may be flat.

[0117] The above embodiments and modifications may be combined as appropriate.

[0118] The form of this disclosure may be shown as follows: [Clause 1] A rectangular parallelepiped energy storage module comprising a plurality of electrodes stacked along a first direction, having a first main surface and a second main surface facing opposite directions in the first direction, a first side surface and a second side surface facing opposite directions in a second direction intersecting the first direction, and a third side surface and a fourth side surface facing opposite directions in a third direction intersecting the first and second directions, Cover member and An exterior body having a housing section formed therein, which houses and arranges the energy storage module and the cover member, Equipped with, The cover member is fixed to the exterior body, The inside of the aforementioned outer casing is reduced to a pressure lower than atmospheric pressure. The housing portion has a side portion facing the first side portion, The cover member is A hollow main body is positioned between the energy storage module and the side portion so as not to overlap with the energy storage module when viewed from the first direction, The main body portion has a plate-shaped projection that protrudes in the second direction and overlaps with the gap between the main body portion and the energy storage module when viewed from the first or third direction, Energy storage device. [Clause 2] The aforementioned projection covers the gap. The energy storage device described in Clause 1. [Clause 3] The cover member has a first cover member and a second cover member arranged side by side in the third direction, The projection of the first cover member covers a portion of the third side surface, The projection of the second cover member covers a portion of the fourth side surface. Energy storage devices as described in Clause 1 or 2. [Clause 4] The projection has a first projection that covers a portion of the first main surface. Energy storage devices as described in Clause 1 or 2. [Clause 5] The aforementioned projection further has a second projection that covers a portion of the second main surface. Energy storage device as described in Clause 4. [Clause 6] The cover member is formed by combining a first portion and a second portion that are arranged adjacent to each other in the first direction. The projection includes the projection of the first portion and the projection of the second portion. A power storage device as described in any one of clauses 1 to 5. [Clause 7] The tip portion of the aforementioned projection has a bent portion, The aforementioned bent portion has an R shape. A power storage device as described in any one of clauses 1 to 6. [Clause 8] The tip portion of the aforementioned projection has a tapered shape that becomes thinner towards the tip. A power storage device as described in any one of clauses 1 to 6. [Clause 9] The device further comprises a connecting component attached to the first side surface, The cover member is adjacent to the connecting component in the third direction, The aforementioned projection also protrudes in the third direction and covers the connecting component. A power storage device as described in any one of clauses 1 to 8. [Clause 10] The energy storage module has an internal space for holding an electrolyte between adjacent electrodes in the first direction, The first side surface has a region in which a communication hole is provided that communicates with the internal space, The energy storage module has a resin member that covers the area, The resin member includes a resin body portion attached to the first side surface, a first overhang portion extending from the resin body portion onto the first main surface, and a second overhang portion extending from the resin body portion onto the second main surface. The projection covers the entire first overhang in the second direction. A power storage device as described in any one of clauses 1 to 9. [Explanation of Symbols]

[0119] 1, 1A, 1B... Energy storage device, 2... Energy storage module, 2a... First main surface, 2b... Second main surface, 2c... First side surface, 2d... Second side surface, 2e... Third side surface, 2f... Fourth side surface, 3-5... Cover member, 6... Outer casing, 7... Connector unit (connecting part), 11... Bipolar electrode, 12... Positive terminal electrode, 13... Negative terminal electrode, 27... Communication hole, 31, 33, 35... Main body, 32, 34, 36, 3 7, 38, 39... projections, 32a, 37a... tip portions, 32b, 37b... tip, 37c... bent portion, 50... additional member (resin member), 51... resin main body, 55... first overhang portion, 57... second overhang portion, 60... recess, 61... first side portion (side portion), 110... first part, 114a... projection, 120... second part, 124a... projection, G... gap, R1... region, S... internal space.

Claims

1. A rectangular parallelepiped energy storage module comprising a plurality of electrodes stacked along a first direction, having a first main surface and a second main surface facing opposite directions in the first direction, a first side surface and a second side surface facing opposite directions in a second direction intersecting the first direction, and a third side surface and a fourth side surface facing opposite directions in a third direction intersecting the first and second directions, Cover member and An exterior body having a housing section formed therein, which houses and arranges the energy storage module and the cover member, Equipped with, The cover member is fixed to the exterior body, The inside of the aforementioned outer casing is reduced to a pressure lower than atmospheric pressure. The housing portion has a side portion facing the first side portion, The cover member is A hollow main body is positioned between the energy storage module and the side portion so as not to overlap with the energy storage module when viewed from the first direction, The main body has a plate-shaped projection that protrudes from the main body in the second direction and overlaps with the gap between the main body and the energy storage module when viewed from the first or third direction, Energy storage device.

2. The aforementioned projection covers the gap. The energy storage device according to claim 1.

3. The cover member has a first cover member and a second cover member arranged side by side in the third direction. The projection of the first cover member covers a portion of the third side surface, The projection of the second cover member covers a portion of the fourth side surface. The energy storage device according to claim 1.

4. The projection has a first projection that covers a portion of the first main surface. The energy storage device according to claim 1.

5. The aforementioned projection further includes a second projection that covers a portion of the second main surface. The energy storage device according to claim 4.

6. The cover member is formed by combining a first portion and a second portion that are arranged adjacent to each other in the first direction. The projection includes the projection of the first portion and the projection of the second portion. The energy storage device according to any one of claims 1 to 5.

7. The tip portion of the aforementioned projection has a bent portion, The aforementioned bent portion has an R shape. The energy storage device according to any one of claims 1 to 5.

8. The tip portion of the aforementioned projection has a tapered shape that becomes thinner towards the tip. The energy storage device according to any one of claims 1 to 5.

9. The device further comprises a connecting component attached to the first side surface, The cover member is adjacent to the connecting component in the third direction, The aforementioned projection also protrudes in the third direction and covers the connecting component. The energy storage device according to any one of claims 1 to 5.

10. The energy storage module has an internal space for holding an electrolyte between adjacent electrodes in the first direction, The first side surface has a region in which a communication hole is provided that communicates with the internal space, The energy storage module has a resin member that covers the area, The resin member includes a resin body portion attached to the first side surface, a first overhang portion extending from the resin body portion onto the first main surface, and a second overhang portion extending from the resin body portion onto the second main surface. The projection covers the entirety of the first overhang in the second direction. The energy storage device according to any one of claims 1 to 5.

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