power storage module

Abstract

A power storage device (1) (power storage module) includes a laminate (5) including a plurality of power storage units (2) stacked along a stacking direction, and a sealing member (50) for enclosing the laminate (5), the laminate (5) including a plurality of outer side surfaces (P) extending along the stacking direction, the sealing member (50) being disposed in contact with the plurality of outer side surfaces (P), the power storage unit (2) including a positive electrode (11), a negative electrode (12), and a separator (14), at least the sealing member (50) disposed on one of the outer side surfaces (P) being a low elastic modulus portion (L) having a smaller elastic modulus than the separator (14).

Description

Technical Field

[0001] This invention relates to energy storage modules. Background Technology

[0002] As a conventional energy storage module, there is the energy storage module used in the bipolar battery cell described in Patent Document 1. The bipolar battery cell described in Patent Document 1 includes: a first current collector; a second current collector; an inner sealing layer disposed between the first current collector and the second current collector and disposed at an edge; and an outer sealing layer disposed outside the resin layer formed as the aforementioned inner sealing layer.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-175778 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the aforementioned energy storage module, the first current collector, negative electrode layer, insulating layer, positive electrode layer, and second current collector can be considered as being stacked in this order and enclosed by an internal sealing layer to form an energy storage unit. For example, if gas is generated inside such an energy storage unit, the unit may expand due to the gas. If the energy storage unit expands, peeling may occur at the joints between the first and second current collectors and the sealing layer, compromising the unit's seal.

[0008] This invention was made to solve the above-mentioned problems, and its purpose is to provide an energy storage module that can improve sealing performance.

[0009] Solution for solving the problem

[0010] The energy storage module of the present invention comprises: a laminate including a plurality of energy storage units stacked along a first direction; and a sealing member for sealing the laminate, the laminate including a plurality of laminate side surfaces extending as outer side surfaces along the first direction, the sealing member being disposed in contact with the plurality of laminate side surfaces, and the energy storage unit including: a first electrode including a first electrode plate and a first active material layer, the first electrode plate including a first surface intersecting the first direction, the first active material layer being disposed on the first surface; and a second electrode including a second electrode plate and a second active material layer. The first electrode plate includes a second surface intersecting the first direction, a second active material layer disposed on the second surface having a different polarity from the first active material layer, and a second electrode stacked on the first electrode such that the second active material layer is opposite to the first active material layer; and a spacer disposed between the first electrode plate and the second electrode plate such that it surrounds the first active material layer and the second active material layer when viewed from the first direction, and at least one portion of the sealing member disposed on the side of one of the laminates is a low elastic modulus portion having an elastic modulus smaller than that of the spacer.

[0011] In this energy storage module, the laminate includes a plurality of energy storage cells stacked along a first direction. Each energy storage cell includes a first electrode and a second electrode stacked on top of each other, and a spacer disposed between them. On the other hand, sealing members for sealing the laminate are provided on the sides of the plurality of laminates extending along the first direction. Furthermore, at least one portion of the sealing member disposed on a side of the laminate is a low elastic modulus portion having an elastic modulus smaller than that of the spacer constituting the energy storage cell. With this configuration, when the energy storage cell undergoes deformation such as expansion or displacement due to some reason, the relatively easily deformable sealing member can both ensure sealing and deform sufficiently to follow the deformation. Therefore, according to this energy storage module, sealing performance can be improved.

[0012] Alternatively, in the energy storage module of the present invention, the first electrode plate includes a third surface opposite to the first surface, and the second electrode plate includes a fourth surface opposite to the second surface. The stack is constructed by stacking multiple energy storage units such that the third surface of the first electrode plate of one energy storage unit overlaps with the fourth surface of the second electrode plate of another energy storage unit. In this case, portions of the electrode plates overlapping each other are created between adjacent energy storage units. Therefore, since the energy storage units may misalign with each other during stacking, a relatively easily deformable sealing member is more effective in ensuring sealing performance.

[0013] Alternatively, the energy storage module of the present invention may also include a detection line located between two adjacent third and fourth surfaces and connected to at least one of the first and second electrode plates for detecting the state of the energy storage unit. The detection line protrudes outward from a sealing member, and at least a portion of the sealing member disposed on the side of the laminate with the protruding detection line is a low-modulus portion. In this case, the root of the detection line protruding from the side of the laminate can be supported by the relatively soft portion of the sealing member. Therefore, vibration of the detection line can be absorbed by the sealing member, suppressing breakage of the detection line.

[0014] Alternatively, in the energy storage module of the present invention, the portion of the sealing member located on the side of the laminate protruding the detection line has a smaller elastic modulus than the portions located on the sides of other laminates. In this case, the portions of the sealing member located on the sides of the laminate other than the side protruding the detection line have a relatively high elastic modulus. Therefore, it is possible to suppress the breakage of the detection line while ensuring the overall rigidity of the energy storage module.

[0015] Alternatively, the energy storage module of the present invention may further include a pair of current collectors respectively disposed at one end and the other end of the laminate in the first direction, and a groove extending in the direction intersecting the first direction when viewed from a second direction intersecting the side surface of the laminate. In this case, due to the groove, the surface distance between the sides of the laminate between the current collectors is extended. As a result, for example, compared to the case where the sealing member is flat overall, water generated on the surface of the sealing member due to condensation or the like is more likely to be interrupted midway along the side surface of the laminate. As a result, short circuits between the current collectors are suppressed.

[0016] Alternatively, in the energy storage module of the present invention, the groove extends obliquely relative to the first direction when viewed from the second direction. This allows water generated on the surface of the sealing member due to condensation or the like to be guided in a desired direction.

[0017] Alternatively, in the energy storage module of the present invention, the spacer includes an inner side facing the space between the first electrode plate and the second electrode plate, and an outer side opposite to the inner side. The thickness of the sealing member in the direction intersecting the side of the laminate is thinner than the thickness between the inner and outer sides of the spacer. In this case, both the increase in size and cost of the energy storage module can be suppressed, and the sealing performance can be ensured.

[0018] Alternatively, in the energy storage module of the present invention, the melting point of the sealing member is lower than that of the spacer. In this case, when the sealing member is formed by welding or casting, the thermal impact on the spacer can be reduced, and the decrease in sealing performance can be suppressed.

[0019] Invention Effects

[0020] According to the present invention, it is possible to provide an energy storage module that can improve sealing performance. Attached Figure Description

[0021] Figure 1 This is a schematic cross-sectional view showing one embodiment of an energy storage device.

[0022] Figure 2 Yes, yes Figure 1 A schematic top view of the energy storage device shown.

[0023] Figure 3 yes Figure 1 A side view of a portion of the energy storage device shown.

[0024] Figure 4 It is Figure 1 A cross-sectional view of a portion of the energy storage device shown is enlarged.

[0025] Figure 5 (a) and (b) are side views showing the groove of the modified example.

[0026] Figure 6 (a) and (b) are cross-sectional views showing the groove in the modified example. Detailed Implementation

[0027] Hereinafter, one embodiment of the energy storage module will be described with reference to the accompanying drawings. Furthermore, in the description of the drawings, the same reference numerals are sometimes used to denote the same elements or equivalent elements, and repeated descriptions are omitted. Additionally, orthogonal coordinate systems including the X-axis, Y-axis, and Z-axis are sometimes shown in the figures.

[0028] Figure 1 This is a schematic cross-sectional view showing one embodiment of an energy storage device. Figure 1 The energy storage device 1 (energy storage module) shown is, for example, an energy storage module used in batteries of various vehicles such as forklifts, hybrid vehicles, and electric vehicles. Energy storage device 1 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery. Energy storage device 1 can also be an electric double-layer capacitor or an all-solid-state battery. In this embodiment, the case where energy storage device 1 is a lithium-ion secondary battery is illustrated.

[0029] The energy storage device 1 comprises a stack 5 in which a plurality of energy storage cells 2 are stacked in a stacking direction (first direction). Here, the stacking direction of the energy storage cells 2 is set as the Z-axis direction. Each energy storage cell 2 includes: a positive electrode (first electrode) 11, a negative electrode (second electrode) 12, a separator 13, and a spacer 14. The positive electrode 11 includes a first electrode plate 20 and a positive electrode active material layer (first active material layer) 22 disposed on one surface (first surface) 20a of the first electrode plate 20. The positive electrode 11 is, for example, a rectangular electrode. One surface (first surface) 20a intersects the first direction.

[0030] The negative electrode 12 includes a second electrode plate 21 and a negative electrode active material layer (a second active material layer of different polarity from the first active material layer) 23 disposed on one surface (second surface) 21a of the second electrode plate 21. The negative electrode 12 is, for example, a rectangular electrode. One surface (second surface) 21a intersects the first direction. In a battery storage unit 2, the negative electrode 12 is stacked on the positive electrode 11 such that the negative electrode active material layer 23 faces the positive electrode active material layer 22. In this embodiment, the stacking direction of the positive electrode 11 and the negative electrode 12 is consistent with the stacking direction of the battery storage unit 2 (the Z-axis direction). Hereinafter, the stacking direction of the battery storage unit 2 and the stacking direction of the positive electrode 11 and the negative electrode 12 are sometimes simply referred to as the "stacking direction". In this embodiment, both the positive electrode active material layer 22 and the negative electrode active material layer 23 are formed in a rectangular shape. The negative electrode active material layer 23 is formed to be one size larger than the positive electrode active material layer 22. When viewed from above (when viewed from the stacking direction), the formation area of ​​the positive electrode active material layer 22 is entirely located within the formation area of ​​the negative electrode active material layer 23.

[0031] The first electrode plate 20 has another side (third side) 20b, which is the side opposite to one side 20a. No positive electrode active material layer 22 is formed on the other side 20b. The second electrode plate 21 has another side (fourth side) 21b, which is the side opposite to one side 21a. No negative electrode active material layer 23 is formed on the other side 21b. The laminate 5 is constructed by stacking multiple energy storage units 2 such that the other side 20b of the first electrode plate 20 of one energy storage unit 2 overlaps with the other side 21b of the second electrode plate 21 of another energy storage unit 2 adjacent to one energy storage unit 2 in the stacking direction.

[0032] Thus, in the laminate 5, multiple energy storage units 2 are electrically connected in series. In the laminate 5, a pseudo-bipolar electrode 10 is formed by adjacent energy storage units 2 in the stacking direction, with a first electrode plate 20 and a second electrode plate 21 connected to each other as electrode bodies. That is, one bipolar electrode 10 includes: a first electrode plate 20, a second electrode plate 21, a positive electrode active material layer 22, and a negative electrode active material layer 23. The first electrode plate 20 (positive electrode 11) is arranged at one end in the stacking direction as a terminal electrode. The second electrode plate 21 (negative electrode 12) is arranged at the other end in the stacking direction as a terminal electrode. Furthermore, here, the direction along one surface 20a, 21a and the other surface 20b, 21b is set as the X-axis direction and the Y-axis direction. In addition, the bipolar electrode 10 can also be formed by providing a positive electrode active material layer 22 and a negative electrode active material layer 23 on both sides of one electrode plate. In this case, energy storage units 2 are respectively formed between the electrode plates of adjacent bipolar electrodes 10.

[0033] The first electrode plate 20 and the second electrode plate 21 (hereinafter sometimes simply referred to as "electrode plates") are each chemically inert conductors used to continuously allow current to flow to the positive electrode active material layer 22 and the negative electrode active material layer 23 during the discharge or charging of the lithium-ion secondary battery. Materials constituting the electrode plates can include, for example, metallic materials, conductive resin materials, and conductive inorganic materials. Examples of conductive resin materials include resins in which conductive polymers or non-conductive polymers have conductive fillers added as needed. The electrode plates may also have multiple layers comprising one or more layers, wherein the one or more layers include the aforementioned metallic materials or conductive resin materials. The surface of the electrode plates may also be covered with a known protective layer. The surface of the electrode plates may also be treated by known methods such as plating.

[0034] The electrode plate may be in the form of foil, sheet, film, wire, rod, mesh, or clad material. Besides aluminum foil and copper foil, the electrode plate may also be a metal foil such as nickel foil, titanium foil, or stainless steel foil. From the viewpoint of ensuring mechanical strength, the electrode plate may be a stainless steel foil (e.g., SUS304, SUS316, SUS301, SUS304, etc. as specified in JIS G 4305:2015). The electrode plate may also be an alloy foil of the aforementioned metals. The first electrode plate 20 may also be a foil comprising a substrate covered by an aluminum film. In this embodiment, the first electrode plate 20 is an aluminum foil, and the second electrode plate 21 is a copper foil. The second electrode plate 21 may also be a foil comprising a substrate covered by a copper film. In the case of a foil-shaped electrode plate, the thickness of the electrode plate may be in the range of 1 μm to 100 μm.

[0035] The positive electrode active material layer 22 contains a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. As the positive electrode active material, any material suitable for use as a positive electrode active material in lithium-ion secondary batteries, such as lithium composite metal oxides with a layered rock salt structure, metal oxides with a spinel structure, or polyanionic compounds, can be used. Alternatively, two or more positive electrode active materials can be used simultaneously. In this embodiment, the positive electrode active material layer 22 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0036] The negative electrode active material layer 23 can be made of any element, alloy, or compound capable of absorbing and releasing charge carriers such as lithium ions, and is not particularly limited. Examples of negative electrode active materials include Li, carbon, metal compounds, elements or compounds that can alloy with lithium, etc. Examples of carbon include natural black lead, artificial black lead, hard carbon (difficult to blacken) or soft carbon (easy to blacken). Examples of artificial black lead include highly oriented graphite, mesophase carbon microspheres, etc. Examples of elements that can alloy with lithium include silicon and tin. In this embodiment, the negative electrode active material layer 23 includes black lead as a carbon-based material.

[0037] The positive electrode active material layer 22 and the negative electrode active material layer 23 (hereinafter sometimes simply referred to as "active material layers") may each, as needed, include conductive additives to improve electrical conductivity, binders, electrolytes (polymer matrix, ion-conducting polymer, electrolyte solution, etc.), and electrolyte support salts (lithium salts) to improve ion conductivity. The components contained in the active material layer, their mixing ratio, and the thickness of the active material layer are not particularly limited, and can be appropriately referenced to previously known insights regarding lithium-ion secondary batteries. The thickness of the active material layer is, for example, 2–150 μm. Previously known methods such as roller coating can also be used to form the active material layer on the surface of the electrode plate. To improve the thermal stability of the positive electrode 11 or the negative electrode 12, a heat-resistant layer may be provided on the surface of the electrode plate (one side or both sides) or the surface of the active material layer. The heat-resistant layer may contain, for example, inorganic particles and binders, and may also contain additives such as thickeners.

[0038] Conductive additives are added to improve the conductivity of the positive electrode 11 or the negative electrode 12. Therefore, conductive additives can be added arbitrarily if the conductivity of the positive electrode 11 or the negative electrode 12 is insufficient, and can be omitted if the conductivity of the positive electrode 11 or the negative electrode 12 is sufficiently good. Examples of conductive additives include acetylene black, carbon black, and graphite.

[0039] The binder serves to bind the active material or conductive additive to the surface of the electrode plate. Examples of binders include fluorinated resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamide-imide; resins containing alkoxysilyl groups; acrylic resins containing monomer units such as acrylic acid or methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinks; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. Solvents such as water and N-methyl-2-pyrrolidone (NMP) are also used.

[0040] The separator 13 isolates the positive electrode 11 from the negative electrode 12, preventing short circuits caused by contact between the two electrodes while allowing charge carriers such as lithium ions to pass through. In a battery storage unit 2, the separator 13 is disposed between the positive electrode 11 and the negative electrode 12. The separator 13 prevents short circuits between adjacent bipolar electrodes 10, 10 when the battery storage units 2 are stacked.

[0041] The separator 13 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the electrolyte. As a material constituting the separator 13, a porous membrane including polypropylene (PP) may be used, for example. The material constituting the separator 13 may also be a woven or nonwoven fabric including polypropylene or methylcellulose. The separator 13 may have a single-layer or multi-layer structure. A multi-layer structure may, for example, include a ceramic layer as a heat-resistant layer. An electrolyte may also be impregnated in the separator 13. The separator 13 itself may also be composed of an all-solid electrolyte (polymer solid electrolyte, inorganic solid electrolyte, etc.).

[0042] As the electrolyte impregnated in the separator 13, specifically, as conventionally known materials, liquid electrolytes (electrolytes) and polymeric gel electrolytes can be used. Electrolytes contain non-aqueous solvents and electrolytes dissolved in the non-aqueous solvents. Polymeric gel electrolytes contain electrolytes retained within a polymer matrix.

[0043] The electrolyte comprises a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent. Known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used as the non-aqueous solvent. These materials can be used alone or in combination. Known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 can be used as the electrolyte.

[0044] A spacer 14 is formed at least between the first electrode plate 20 and the second electrode plate 21, and is joined or fixed to at least one of the first electrode plate 20 and the second electrode plate 21 (e.g., both the first electrode plate 20 and the second electrode plate 21, or only either the first electrode plate 20 or the second electrode plate 21). The spacer 14 contains an insulating material to prevent short circuits by insulating the first electrode plate 20 and the second electrode plate 21. In this embodiment, the spacer 14 contains polyethylene (PE) as an insulating material. Examples of resin materials constituting the spacer 14, besides polyethylene (PE), include polystyrene, ABS resin, modified polypropylene (modified PP), and acrylonitrile styrene (AS) resin.

[0045] In this embodiment, the spacer 14 extends along the edge 20e of the first electrode plate 20 or the edge 21e of the second electrode plate 21. The spacer 14 is a frame surrounding the positive electrode active material layer 22 or the negative electrode active material layer 23 when viewed from the stacking direction.

[0046] In this embodiment, the spacer 14 also functions as a frame-shaped enclosure that seals the space S between the first electrode plate 20 and the second electrode plate 21. In this embodiment, the spacer 14 disposed in each energy storage unit 2 has a portion disposed between a pair of electrode plates and a portion extending outwards compared to the edges of the electrode plates. An electrolyte (electrolyte) impregnated with the separator 13 is contained in the space S surrounded by the spacer 14, the first electrode plate 20, and the second electrode plate 21. In this embodiment, the spacer 14 is rectangular in shape when viewed from above, and is fused to the edges 20e of the first electrode plate 20 and the edges 21e of the second electrode plate 21.

[0047] The spacer 14, by sealing the space S between the positive electrode 11 and the negative electrode 12, prevents electrolyte leakage. Furthermore, by sealing the space S between the positive electrode 11 and the negative electrode 12, the spacer 14 prevents moisture from entering the space S from the outside of the energy storage device 1. Moreover, the spacer 14, for example, prevents gas generated from the positive electrode 11 or the negative electrode 12 due to charging and discharging reactions from leaking to the outside of the energy storage device 1. Additionally, the separator 13 is embedded in the spacer 14 at its edge 13e. Here, the spacers 14 adjacent to each other along the stacking direction are separated from each other. Therefore, when viewed from a second direction intersecting the stacking direction (e.g., the X-axis direction or the Y-axis direction), the side end faces of the first electrode plate 20 and the second electrode plate 21 are exposed between the adjacent spacers 14.

[0048] The energy storage device 1 also includes a pair of positive and negative current collectors respectively disposed at one end and the other end of the laminate 5 in the stacking direction. More specifically, a positive current collector 30, which is rectangular in shape when viewed from the stacking direction, is disposed at one end of the laminate 5. A negative current collector 40, which is rectangular in shape when viewed from the stacking direction, is disposed at the other end of the laminate 5. One surface 30a of the positive current collector 30 is in contact with the other surface 20b of the first electrode plate 20, which is configured as a terminal electrode. One surface 40a of the negative current collector 40 is in contact with the other surface 21b of the second electrode plate 21, which is configured as a terminal electrode.

[0049] Both the positive current collector 30 and the negative current collector 40 (hereinafter sometimes simply referred to as "current collectors") are made of a material with good electrical conductivity. For example, the same material used for the electrode plates may be used as the constituent material of the current collector. The thickness of the current collector may also be greater than the thickness of the electrode plates used in the laminate 5. Here, the current collector is configured to be larger than the laminate 5 (energy storage unit 2) when viewed from the lamination direction, and protrudes outward compared to the outer surface 14b of the spacer 14. Furthermore, the outer surface 14b of the spacer 14 is the opposite side of the inner surface 14a of the spacer 14 facing the space S. However, the current collector may also be configured to be smaller than the laminate 5 (energy storage unit 2) when viewed from the lamination direction (or configured to the same extent). In this case, the outer edge of the current collector may be located inward compared to the outer surface 14b of the spacer 14 when viewed from the lamination direction.

[0050] As an example, the current collector described above, by providing terminals, can be used to charge and discharge the energy storage device 1 through these terminals. Alternatively, by stacking multiple energy storage devices 1 with the current collector in between, the current collector can be used to electrically connect the multiple energy storage devices 1. Furthermore, the current collector can have a cooling function for cooling the stacked body 5 (energy storage unit 2). In this case, the current collector may, for example, have a flow path extending in the in-plane direction, through which a cooling medium flows to exchange heat with the stacked body 5.

[0051] To ensure good conductive contact between the first electrode plate 20 disposed at one end of the laminate 5 and the positive current collector 30, or between the second electrode plate 21 disposed at the other end of the laminate 5 and the negative current collector 40, a conductive layer (not shown) may also be provided. In this case, the conductive layer may be in close contact with the other side 20b, 21b of the electrode plate. The conductive layer may, for example, have a hardness lower than that of the electrode plate. The conductive layer may be a layer containing carbon such as acetylene black or graphite, or a plating layer containing Au.

[0052] Figure 2 yes Figure 1 A schematic top view of the energy storage device shown. Figure 2The current collectors located at one and the other ends of the stacked body 5 are omitted. For example... Figure 1 , Figure 2 As shown, the laminate 5 has an outer surface (laminate side) P extending along the lamination direction. Since the laminate 5 is quadrilateral when viewed from the lamination direction, it has four outer surfaces (laminate sides) P1, P2, P3, and P4, each corresponding to one of the four sides of the quadrilateral. The outer surface P is composed of the outer surfaces 14b of a plurality of spacers 14 arranged along the lamination direction and the side end faces of electrode plates exposed between adjacent spacers 14. The energy storage device 1 also includes a sealing member 50 provided on the outer surface P.

[0053] The sealing member 50 is a component used to seal the insulation of the laminate 5. The sealing member 50 is integrally formed on all outer surfaces P1 to P4. The sealing member 50 is disposed (contacts) on the outer surface P, i.e., the outer surface 14b of the spacer 14, and the side end faces of the electrode plates exposed between adjacent spacers 14. That is, the sealing member 50 seals the side end faces (interfaces) of the first electrode plate 20 and the second electrode plate 21 between adjacent energy storage cells 2 by entering between adjacent spacers 14. Furthermore, the sealing member 50 extends from the positive current collector 30 to the negative current collector 40 in the lamination direction. In this case, the outer surface 14b of the spacer 14 is located on the outer side compared to the side end faces of the electrode plates. Alternatively, the sealing member 50 may only contact the outer surface 14b of the spacer 14.

[0054] Furthermore, the sealing member 50 contacts one surface 30a of the positive current collector 30 at one end of the laminate 5, and contacts one surface 40a of the negative current collector 40 at the other end of the laminate 5. Thus, the sealing member 50 surrounds and seals the entire laminate 5 containing each energy storage unit 2. Additionally, the sealing member 50 includes: a portion 51 disposed on the outer surface P1, a portion 52 disposed on the outer surface P2, a portion 53 disposed on the outer surface P3, and a portion 54 disposed on the outer surface P4.

[0055] The sealing member 50 can be made of materials such as silicone rubber, polyolefin, or urethane rubber. In particular, the material of the sealing member 50 can be selected such that at least one of the portions 51-54 has a lower elastic modulus than the spacer 14. In other words, in the sealing member 50, at least one portion provided on at least one of the plurality of outer surfaces P1-P4 is designated as a low elastic modulus portion L having an elastic modulus smaller than that of the spacer 14. Here, as an example, all portions 51-54 of the sealing member 50 have the same elastic modulus and are designated as low elastic modulus portions L. Furthermore, the elastic modulus of the low elastic modulus portion L of the sealing member 50 is between 10 MPa and 600 MPa, and the elastic modulus of the spacer 14 is between 100 MPa and 2000 MPa.

[0056] Such a sealing member 50 can be formed, for example, by stacking multiple energy storage units 2 to form a laminate 5, and after placing current collectors at both ends of the laminate 5, applying the aforementioned uncured material to the outer surface P of the laminate 5 and then curing it. When the sealing member 50 is formed by applying a molten material to the spacer 14, in order to reduce the thermal impact on the spacer 14 during the formation of the sealing member 50, the material constituting the sealing member 50 can be set to a material with a lower melting point than the material constituting the spacer 14.

[0057] Figure 3 yes Figure 1 A side view of a portion of the energy storage device shown. Figure 1 , Figure 3 As shown, a plurality of grooves 60 are provided on the outer surface 50s of the sealing member 50. The outer surface 50s of the sealing member 50 is the side of the sealing member 50 opposite to the side facing (contacting) the outer surface 14b of the spacer 14. The plurality of grooves 60 are parallel to each other and extend in a direction orthogonal to the stacking direction when viewed from a direction intersecting the stacking direction (second direction). As an example, grooves 60 are provided in all portions 51 to 54 of the sealing member 50. Furthermore, each groove 60 is configured such that the thickness of the sealing member 50 (the dimension in the direction intersecting the outer surface P) gradually increases along the stacking direction, the thickest portion 60a of the sealing member 50 has the thickest thickness, the portion of the sealing member 50 has the thickest thickness gradually decreases along the stacking direction, and the thinnest portion 60b of the sealing member 50 has the thinnest thickness.

[0058] Therefore, the sealing member 50 does not include a flat portion with a constant thickness along the stacking direction, but it may include a flat portion. For example, the thickness of the sealing member 50 may not gradually increase or decrease along the stacking direction, but rather change in a step-like (gradual) manner. Furthermore, the groove 60 may not be provided, and the overall thickness of the sealing member 50 may be constant. Additionally, the relatively thick portion of the sealing member 50 contacts one surface 30a of the positive current collector 30 and one surface 40a of the negative current collector 40. Specifically, the groove 60 is formed such that the portion of the sealing member 50 that contacts one surface 30a or one surface 40a is the thickest portion 60a. Moreover, the relatively thick portion of the sealing member 50 is disposed on the side end face of the electrode plate exposed between adjacent spacers 14. Specifically, the groove 60 is formed such that the thickest portion 60a aligns with the interface between the first electrode plate 20 and the second electrode plate 21 between adjacent energy storage units 2. That is, in this embodiment, the number of slots 60 is set to be the same as the number of stacked energy storage units 2. Furthermore, the number of slots 60 is arbitrary. When the number of slots 60 is different from the number of stacked energy storage units 2, it is preferable to provide the slots 60 in such a way that the interface between the thinnest portion 60b and the first electrode plate 20 and the second electrode plate 21 between adjacent energy storage units 2 is not consistent.

[0059] In this embodiment, the thickness of the sealing member 50 at its thickest portion 60a is thinner than the thickness between the inner side 14a and the outer side 14b of the spacer 14. As an example, the thickness of the sealing member 50 at its thinnest portion can be set to 1 mm.

[0060] Figure 4 It is Figure 1 A cross-sectional view of a portion of the energy storage device shown is enlarged. (See diagram below.) Figure 2 , Figure 4 As shown, in the energy storage device 1, each energy storage unit 2 is provided with a voltage detection line 55. Here, the voltage detection line 55 is used to detect the voltage of each energy storage unit 2 as the state of the energy storage unit 2. The voltage detection line 55 is configured to pass from the outside of the sealing member 50 through the spacer 14 between two adjacent energy storage units 2 to the inside of the laminate 5.

[0061] More specifically, the voltage detection line 55 includes one end 55a and another end 55b opposite to the first end 55a. One end 55a of the voltage detection line 55 is disposed inside the laminate 5, and the other end 55b is disposed outside the sealing member 50. The outside of the sealing member 50 refers to the portion outside the outer peripheral surface of the sealing member 50 when viewed from the lamination direction (opposite side of the laminate 5). Therefore, the voltage detection line 55 includes a portion between one end 55a and the other end 55b that overlaps with the spacer 14 and the sealing member 50 when viewed from the lamination direction. Each voltage detection line 55 protrudes from the outer surface 50s of the sealing member 50.

[0062] One end 55a of the voltage detection line 55 is located between another surface 20b (of the first electrode plate 20) of one of the adjacent energy storage cells 2 and another surface 21b (of the second electrode plate 21) of the other energy storage cell 2, and is in contact with these other surfaces 20b and 21b. Thus, the voltage detection line 55 is electrically connected to the first electrode plate 20 of one of the adjacent energy storage cells 2 and the second electrode plate 21 of the other energy storage cell 2. Furthermore, one end 55a is located only in the regions of the first electrode plate 20 and the second electrode plate 21 where no active material layer is provided, so as not to reach the areas where the positive electrode active material layer 22 and the negative electrode active material layer 23 are opposite when viewed from the stacking direction.

[0063] In this embodiment, the leads of the voltage detection lines 55 from the sealing member 50 are gathered into a portion of the sealing member 50. As an example, all voltage detection lines 55 extend from the portion 51 of the sealing member 50 located on the outer surface P1. As described above, all portions 51 to 54 of the sealing member 50 are configured as low-modulus portions L. Therefore, the portion 51 of the sealing member 50 located on the outer surface P1 where the voltage detection lines 55 protrude becomes a low-modulus portion L. Furthermore, to avoid contact between adjacent voltage detection lines 55, the leads of the voltage detection lines 55 in the sealing member 50 are offset from each other along a direction intersecting the lamination direction (i.e., repetition is avoided from the lamination direction). Additionally, the voltage detection lines 55 extend from the relatively thicker portion (thickest portion 60a) of the sealing member 50.

[0064] As explained above, in the energy storage device 1, the laminate 5 includes a plurality of energy storage units 2 stacked along the stacking direction. Each energy storage unit 2 includes a positive electrode 11 and a negative electrode 12 stacked together, and a spacer 14 disposed between them. On the other hand, sealing members 50 for sealing the laminate 5 are provided on a plurality of outer surfaces P extending along the stacking direction of the laminate 5. Furthermore, the sealing members 50 provided on all outer surfaces P are low-modulus portions L having a lower modulus of elasticity than the spacers 14 constituting the energy storage units 2. With this configuration, when the energy storage units 2 deform due to expansion or deviation for some reason, the relatively easily deformable sealing members 50 can both ensure sealing and deform sufficiently to follow the deformation. Therefore, according to this energy storage device 1, sealing performance can be improved.

[0065] Furthermore, in the energy storage device 1, the first electrode plate 20 includes another surface 20b opposite to one surface 20a, and the second electrode plate 21 includes another surface 21b opposite to one surface 21a. The laminate 5 is constructed by stacking multiple energy storage units 2 such that the other surface 20b of the first electrode plate 20 of one energy storage unit 2 overlaps with the other surface 21b of the second electrode plate 21 of another energy storage unit 2. Therefore, portions of the electrode plates overlapping each other are created between adjacent energy storage units 2. Therefore, since the energy storage units 2 may misalign with each other during stacking, the relatively easily deformable sealing member 50 is more effective in ensuring sealing.

[0066] Furthermore, the energy storage device 1 also includes a voltage detection line 55, which is located between two adjacent surfaces 20b and 21b and is connected to at least one of the first electrode plate 20 and the second electrode plate 21, thereby detecting the state of the energy storage unit 2. The voltage detection line 55 protrudes outward from the sealing member 50, and at least one portion of the sealing member 50 provided on the outer surface P where the voltage detection line 55 protrudes is a low elastic modulus portion L. Therefore, the root of the voltage detection line 55 protruding from the outer surface P can be supported by the relatively soft portion of the sealing member 50. Thus, the sealing member 50 can absorb the vibration of the voltage detection line 55 and suppress the breakage of the voltage detection line 55.

[0067] Furthermore, the energy storage device 1 also includes a positive current collector 30 and a negative current collector 40 respectively disposed at one end and the other end of the laminate 5 in the lamination direction, and a groove 60 extending in the direction intersecting the lamination direction when viewed from the direction intersecting the outer surface P is formed in the sealing member 50. In this case, due to the groove 60, the surface distance of the outer surface P between the positive current collector 30 and the negative current collector 40 is extended. Therefore, for example, compared to the case where the sealing member 50 is flat overall, water generated on the surface of the sealing member 50 due to condensation or the like is more likely to be interrupted in the middle of the outer surface P. As a result, short circuits between the positive current collector 30 and the negative current collector 40 are suppressed.

[0068] Furthermore, as described above, when the current collector is configured to be smaller than the stacked body 5 (energy storage unit 2) when viewed from the stacking direction, and as a result, the outer edge of the current collector is located inside the outer surface 14b of the spacer 14, it is less likely to cause a short circuit between the current collectors compared to the case where the outer edge of the current collector is located outside the outer surface 14b of the spacer 14. However, even in this case, since the groove 60 described above is provided on the outer surface 50s of the sealing member 50, the surface distance of the outer surface P between the positive current collector 30 and the negative current collector 40 is also extended, and as a result, short circuits between the positive current collector 30 and the negative current collector 40 can be suppressed more reliably.

[0069] Furthermore, in the energy storage device 1, the spacer 14 includes an inner side 14a facing the space S between the first electrode plate 20 and the second electrode plate 21, and an outer side 14b opposite to the inner side 14a. The thickness of the sealing member 50 in the direction intersecting the outer side 14a is thinner than the thickness between the inner side 14a and the outer side 14b of the spacer 14. Therefore, it is possible to both suppress the enlargement of the energy storage device 1 and ensure airtightness.

[0070] Furthermore, in the energy storage device 1, the melting point of the sealing member 50 is lower than that of the spacer 14. Therefore, when the sealing member 50 is formed by welding or casting, the thermal impact on the spacer 14 can be reduced, and the decrease in sealing performance can be suppressed.

[0071] The above embodiments illustrate one aspect of the present invention. Therefore, the present invention is not limited to the above embodiments and can be modified in any way.

[0072] In the above embodiment, from the perspective of the direction intersecting the stacking direction (the second direction), the groove 60 extends in a direction orthogonal to the stacking direction, but the direction in which the groove 60 extends can be various. Figure 5 This is a side view showing a modified example of the groove. For example, it can also be as follows: Figure 5As shown in (a) and (b), viewed from the direction intersecting the stacking direction (the second direction), the grooves 60 are parallel to each other and extend at an angle relative to the stacking direction. The angle of inclination of the grooves 60 can be set to any angle for guiding water moving along the grooves 60, but in the illustrated example it is about 45 degrees. Here, in at least one part (parts 51 to 54) of the sealing member 50, all the grooves 60 extend in the same direction.

[0073] On the other hand, for example, it can also be like Figure 5 As shown in (b), multiple sets of grooves 60A and 60B with different inclination angles are formed in at least one portion (parts 51-54) of the sealing member 50. Here, viewed from a direction intersecting the stacking direction (the second direction), at least one portion of the sealing member 50 is formed with: a first set comprising multiple grooves 60A arranged along the stacking direction and inclined in one direction relative to the stacking direction; and a second set comprising multiple grooves 60B arranged along the stacking direction and inclined in another direction relative to the stacking direction. In the illustrated example, the inclination angle of the grooves 60B is set to be orthogonal to the inclination angle of the grooves 60A. In this case, moisture can be guided toward the boundaries of these sets. By forming such grooves 60, 60A, and 60B, water generated on the outer surface 50s of the sealing member 50 due to condensation, etc., can be guided to a desired direction.

[0074] exist Figure 5 In the variations shown in (a) and (b), similarly to the embodiments described above, multiple grooves 60 are formed in parallel. The angle at which the grooves 60 are tilted relative to the stacking direction can be appropriately varied, as long as the desired effect of the present invention is achieved. In the energy storage device 1 of this variation, by forming such grooves 60, water generated on the surface of the sealing member 50 due to condensation or the like can be guided to a desired direction. Thus, by guiding the condensed water towards a well-draining drain outlet, for example, the dewatering of the outer surface 50s of the sealing member 50 becomes effective. Therefore, according to the above configuration, short circuits between the positive current collector 30 and the negative current collector 40 are more reliably suppressed.

[0075] Furthermore, in the above embodiment, the groove 60 is constructed by alternating portions of the sealing member 50 whose thickness gradually increases and decreases along the stacking direction. However, the configuration of the groove 60 is not limited to this. For example, it can also be constructed as follows: Figure 6 As shown in (a), the groove 60 is formed by alternating portions of the sealing member 50 whose thickness gradually increases along the stacking direction with portions that decrease discontinuously. Alternatively, it can be as follows: Figure 6As shown in (b), the groove 60 is formed by alternating between portions of the sealing member 50 that gradually increase in thickness and portions that gradually decrease in thickness, and by smoothly forming (beveling) the connection between them.

[0076] Furthermore, in the above embodiment, all portions 51 to 54 of the sealing member 50 are provided with the same elastic modulus, and are provided with a low elastic modulus portion L having an elastic modulus lower than that of the spacer 14. However, it is sufficient that at least one portion of the portions 51 to 54 of the sealing member 50 is a low elastic modulus portion L, while the other portions may have an elastic modulus equal to, for example, that of the spacer 14. As an example, from the viewpoint of protecting the voltage detection line 55, it is sufficient that at least the portion 51 of the portions 51 to 54 of the sealing member 50 provided on the outer surface P1 protruding from the voltage detection line 55 is a low elastic modulus portion L. Moreover, it is also possible to distribute the elastic modulus among all portions 51 to 54 of the sealing member 50. In this case, it is sufficient that the portion 51 of the sealing member 50 provided on the outer surface P1 protruding from the voltage detection line 55 has a smaller elastic modulus than the portions 52 to 54 provided on the other outer surfaces P2 to P4. In this case, portions 52 to 54 of the sealing member 50 located on the outer surfaces P2 to P4, excluding the outer surface P1 where the voltage detection line 55 protrudes, have a relatively high modulus of elasticity compared to portion 51. Therefore, it is possible to suppress the breakage of the voltage detection line 55 while ensuring overall rigidity. Furthermore, in this case, all portions 51 to 54 of the sealing member 50 may be low modulus portions L, or only a portion may not be a low modulus portion L.

[0077] Explanation of reference numerals in the attached figures

[0078] 1. Energy storage device (energy storage module)

[0079] 2. Energy Storage Unit

[0080] 5-layered structure

[0081] 11 Positive electrode (Electrode 1)

[0082] 12 Negative Electrode (Second Electrode)

[0083] 14 Spacers

[0084] 14a Inner surface

[0085] 14b Outer surface

[0086] 20 First electrode plate

[0087] 20a, one face (face 1)

[0088] 20b Another side (side 3)

[0089] 21. Second electrode plate

[0090] 21a, one face (the second face).

[0091] 21b Another side (side 4)

[0092] 22 Positive electrode active material layer (first active material layer)

[0093] 23. Negative electrode active material layer (second active material layer)

[0094] 30 Positive current collector (current collector)

[0095] 40 Negative current collector (current collector)

[0096] 50 sealing components

[0097] 55V voltage detection cable (detection cable)

[0098] 60 groove

[0099] L Low elastic modulus section

[0100] P outer surface (side of the laminate)

[0101] S-space.

Claims

1. A power storage module, characterized in that, have: A stack comprising a plurality of energy storage cells stacked along a first direction; and Sealing member, which is used to close the laminate. The laminate includes a plurality of laminated side surfaces that serve as outer side surfaces extending along the first direction. The sealing member is disposed in contact with the side surfaces of the plurality of laminated bodies. The energy storage unit includes: The first electrode includes a first electrode plate and a first active material layer, the first electrode plate including a first surface intersecting the first direction, and the first active material layer disposed on the first surface; A second electrode includes a second electrode plate and a second active material layer. The second electrode plate includes a second surface intersecting the first direction. The second active material layer is disposed on the second surface and has a different polarity from the first active material layer. The second electrode is stacked on the first electrode such that the second active material layer is opposite to the first active material layer. A spacer is disposed between the first electrode plate and the second electrode plate such that it surrounds the first active material layer and the second active material layer when viewed from the first direction. At least one portion of the sealing member disposed on the side of one of the laminates is a low elastic modulus portion having a smaller elastic modulus than the spacer.

2. The energy storage module according to claim 1, wherein, The first electrode plate includes a third surface opposite to the first surface. The second electrode plate includes a fourth surface opposite to the second surface. The stack is constructed by stacking multiple energy storage units in such a way that the third surface of the first electrode plate of one energy storage unit is overlapped with the fourth surface of the second electrode plate of another energy storage unit.

3. The energy storage module according to claim 2, wherein, It also includes a detection line located between the adjacent third and fourth surfaces and connected to at least one of the first and second electrode plates, thereby used to detect the state of the energy storage unit. The detection line protrudes outward from the sealing member. At least one portion of the sealing member disposed on the side of the laminate protruding from the detection line is the low elastic modulus portion.

4. The energy storage module according to claim 3, wherein, The portion of the sealing member located on the side of the laminate protruding the detection line has a smaller elastic modulus than the portions located on the other sides of the laminate.

5. The energy storage module according to any one of claims 1 to 4, wherein, It also includes a pair of current collectors respectively disposed at one end and the other end of the laminate in the first direction. The sealing member has a groove that extends in a direction intersecting the first direction when viewed from a second direction that intersects the side of the laminate.

6. The energy storage module according to claim 5, wherein, Viewed from the second direction, the groove extends at an angle relative to the first direction.

7. The energy storage module according to any one of claims 1 to 6, wherein, The spacer includes: an inner side facing the space between the first electrode plate and the second electrode plate, and an outer side opposite to the inner side. The thickness of the sealing member in the direction intersecting the side of the laminate is thinner than the thickness between the inner and outer sides of the spacer.

8. The energy storage module according to any one of claims 1 to 7, wherein, The melting point of the sealing member is lower than that of the spacer.

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