Energy storage module

Abstract

To provide a power storage module capable of suppressing local increase in thickness of a laminate while suppressing deformation of a current collector.SOLUTION: A power storage module 1 includes an electrode stack 10 configured by stacking electrodes having a current collector 15 and a detection line 30 in a first direction D1, and a sealing body 20 that seals an internal space S between the current collectors 15 provided in the electrode stack 10 and adjacent in the first direction D1, and the sealing body 20 includes a plurality of sealants 21 welded to each of the plurality of electrodes, a plurality of resin spacers 22 arranged between the sealing materials 21 and forming the internal space S, and an outer surface 20s formed by a first end surface 21s of the sealing material 21 and a second end surface 22s of the spacer 22, and the detection line 30 extends from the current collector 15 and is drawn out from the outer surface 20s.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to a power storage module.

Background Art

[0002] Patent Document 1 describes a bipolar secondary battery. In this secondary battery, a bipolar electrode having a positive electrode layer formed on one surface of a current collector and a negative electrode layer formed on the other surface is arranged in series with a plurality of electrolyte layers interposed therebetween, thereby forming a battery element in a form in which single battery layers each having a laminated structure of a positive electrode layer, an electrolyte layer, and a negative electrode layer are laminated. Further, a sealing material for insulating between current collectors is provided on the outer peripheral portion of the single battery layer. The sealing material is provided on an extending portion that extends outward from the positive electrode layer and the negative electrode layer of the current collector. A detection element for voltage measurement or temperature detection is arranged and brought into contact with the current collector.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When welding a resin sealing material to a metal current collector during the manufacture of a bipolar secondary battery or the like described in Patent Document 1, there is a difference between the linear expansion coefficient of the sealing material and the linear expansion coefficient of the current collector. Therefore, deformation such as wrinkles may occur in the current collector due to the shrinkage of the sealing material after welding. On the other hand, the thinner the sealing material is, the smaller the influence of the shrinkage of the sealing material on the current collector becomes. Therefore, it is considered desirable to make the thickness of the sealing material as thin as possible.

[0005] On the other hand, when a laminate is constructed by stacking electrodes including a current collector and a detection wire that serves as a detection element joined to the current collector, the thickness of the detection wire is accumulated at the joint of the detection wire, which may locally increase the thickness of the laminate. In this case, it is conceivable to increase the thickness of the sealing material to ensure sufficient elastic deformation of the sealing material, and to absorb the increase in the thickness of the detection wire through the elastic deformation of the sealing material. In other words, in this case, it is desirable to increase the thickness of the sealing material to suppress the localized increase in the thickness of the laminate.

[0006] The present disclosure aims to provide an energy storage module that can suppress deformation of the current collector while suppressing localized increases in the thickness of the laminate. [Means for solving the problem]

[0007] The energy storage module according to this disclosure comprises an electrode stack comprising a plurality of electrodes stacked along a first direction, each electrode having a current collector with an active material layer and a detection wire joined to the current collector; and a sealing body provided on the electrode stack so as to surround the electrode stack and for sealing the internal space between adjacent current collectors in the first direction. The sealing body comprises a plurality of resin sealing materials welded to each of the plurality of electrodes; a plurality of resin spacers positioned between adjacent sealing materials in the first direction and forming an internal space together with the sealing materials; and an outer surface formed by a first end face opposite to the internal space of the sealing material and a second end face opposite to the internal space of the spacer, by welding the sealing materials and spacers to each other. Each of the plurality of sealing materials is welded to a current collector and a detection wire joined to the current collector, and the detection wire extends from the current collector and is drawn out from the outer surface along a second direction intersecting the first direction.

[0008] In this energy storage module, an electrode stack is constructed by stacking electrodes, each having a current collector and a detection wire joined to the current collector, along a first direction. The electrode stack is provided with a sealant to seal the internal space between the current collectors. The sealant includes a sealing material joined to the current collector and the detection wire, and a spacer positioned between adjacent sealing materials in the first direction to form an internal space together with the sealing material. The detection wire is drawn out from the outer surface of the sealant, which is formed by welding the sealing material and the spacer together. Thus, in this energy storage module, a sealing material is provided as a resin member welded to the current collector (and detection wire), while a spacer is provided as another resin member between the sealing materials. Therefore, it is possible to reduce the impact on the current collector due to the shrinkage of the sealing material by making it thin, while ensuring the amount of elastic deformation of the resin member with the spacer and absorbing the increase in the thickness of the detection wire. Thus, in this energy storage module, it is possible to suppress the deformation of the current collector while suppressing the local increase in the thickness of the electrode stack.

[0009] In the energy storage module according to this disclosure, the outer surface may include a protrusion that projects in a second direction at the portion where the detection wire leads out from the outer surface. When the outer surface is formed by welding the sealing material and the spacer, heat escapes to the detection wire around the portion where the detection wire leads out, which may prevent the sealing material and the spacer from welding sufficiently, potentially reducing the sealing performance. Therefore, in this case, by providing a protrusion on the outer surface of the sealing body relative to the portion where the detection wire leads out to ensure a larger amount of resin, the sealing material and spacer can be welded together more reliably even around the portion where the detection wire leads out, thereby improving the sealing performance.

[0010] In the energy storage module according to this disclosure, the lead portions of multiple detection wires are distributed to multiple positions in the third direction, such that adjacent lead portions in the first direction are provided at different positions in the third direction where they intersect the first and second directions, and the protrusions may be formed with a width that spans multiple positions in the third direction. In this case, by having adjacent lead portions of detection wires in the first direction at different positions in the third direction, separation between detection wires in the first direction is ensured. Furthermore, by forming the protrusions in the sealing material with a width that spans multiple positions where the lead portions of detection wires are provided, the preparation of the sealing material becomes easier compared to manufacturing multiple types of sealing materials, each with a protrusion corresponding to one of the multiple positions of the lead portion.

[0011] In the energy storage module according to this disclosure, at least two of the multiple detection lines are arranged to overlap each other when viewed from a first direction, and the protrusions at the leading portions of the overlapping detection lines may be spaced apart from each other in the first direction. In this case, the formation of irregularities on the leading portions of the detection lines on the outer surface increases the creepage distance between adjacent detection lines in the first direction, thereby suppressing short circuits between detection lines.

[0012] In the energy storage module according to this disclosure, the current collector and the detection wire are made of different metals, and the thermal conductivity of the metal constituting the detection wire may be lower than that of the metal constituting the current collector. In this case, the heat generated when forming the outer surface by welding the sealing material and the spacer is suppressed from escaping to the current collector through the detection wire, thereby suppressing welding defects between the sealing material and the spacer.

[0013] In the energy storage module according to this disclosure, the current collector and detection wire are made of metal, and the sealing material may be made of an acid-modified resin. In this case, the bonding strength between the sealing material and the current collector and detection wire is ensured, improving sealing performance.

[0014] In the energy storage module according to this disclosure, the detection wire may be embedded in the sealing material in the portion where the sealing material and the spacer overlap along the first direction. In this case, the detection wire is embedded in the sealing material, which is made of an acid-modified resin that can be suitably bonded to metal, in the portion where the sealing material and the spacer overlap. Therefore, even if the spacer is not made of an acid-modified resin, reliable sealing can be achieved in that portion due to its compatibility with the sealing material.

[0015] In the energy storage module according to this disclosure, a notch may be provided in the portion of the detection wire sandwiched between the current collector and the sealing material along the first direction. In this case, the anchoring effect of the notch suppresses the detection wire from coming loose. In particular, since the notch is provided in the portion of the detection wire sandwiched between the current collector and the sealing material, the anchoring effect is exerted from the moment the sealing material is welded to the current collector and the detection wire, suppressing the detection wire from coming loose. [Effects of the Invention]

[0016] According to this disclosure, it is possible to provide an energy storage module that can suppress deformation of the current collector while suppressing localized increases in the thickness of the laminate. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic plan view of the energy storage module according to this embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a plan view showing the relationship between the current collector, the detection wire, and the sealing material. [Modes for carrying out the invention]

[0018] Hereinafter, a power storage module according to an embodiment will be described with reference to the drawings. In the description of each figure, the same or corresponding elements may be denoted by the same reference numerals, and redundant descriptions may be omitted. In addition, each figure may show an orthogonal coordinate system composed of a first axis defining a first direction D1, a second axis defining a second direction D2, and a third axis defining a third direction D3.

[0019] FIG. 1 is a schematic plan view of a power storage module according to the present embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1. The power storage module 1 shown in FIGS. 1 and 2 is a power storage module used for batteries of various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage module 1 is a secondary battery such as a nickel-hydrogen secondary battery or a lithium-ion secondary battery. The power storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, the case where the power storage module 1 is a lithium-ion secondary battery is exemplified.

[0020] The power storage module 1 includes an electrode laminate 10 and a sealing body 20. The electrode laminate 10 includes a plurality of electrodes laminated along the first direction D1. The plurality of electrodes include a plurality of bipolar electrodes 11, a positive electrode terminal electrode 12, and a negative electrode terminal electrode 13. A separator 14 is interposed between adjacent electrodes.

[0021] The bipolar electrode 11 has a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 has, for example, a rectangular sheet shape. The positive electrode active material layer 16 is provided on one surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the other surface 15b of the current collector 15. The plurality of bipolar electrodes 11 are laminated such that the positive electrode active material layer 16 of one bipolar electrode 11 faces the negative electrode active material layer 17 of another bipolar electrode 11. Here, one surface 15a of the current collector 15 is a surface facing one side in the first direction D1, and the other surface 15b of the current collector 15 is a surface facing the other side in the first direction D1.

[0022] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from the first direction D1. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the first direction D1. That is, in a plan view when viewed from the first direction D1, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17.

[0023] The positive electrode terminal electrode 12 has a current collector 15 and a positive electrode active material layer 16 provided on one surface 15a of the current collector 15. The positive electrode terminal electrode 12 does not have the positive electrode active material layer 16 and the negative electrode active material layer 17 on the other surface 15b of the current collector 15. That is, no active material layer is provided on the other surface 15b of the current collector 15 of the positive electrode terminal electrode 12. The positive electrode terminal electrode 12 is laminated on the bipolar electrode 11 at one end of the electrode laminate 10 in the first direction D1. The positive electrode 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.

[0024] The negative electrode terminal electrode 13 has a current collector 15 and a negative electrode active material layer 17 provided on the other surface 15b of the current collector 15. The negative electrode terminal electrode 13 does not have the positive electrode active material layer 16 and the negative electrode active material layer 17 on one surface 15a of the current collector 15. That is, no active material layer is provided on one surface 15a of the current collector 15 of the negative electrode terminal electrode 13. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 at the end of the electrode laminate 10 in the first direction D1 opposite to the positive electrode terminal electrode 12. 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.

[0025] The separator 14 is disposed between adjacent bipolar electrodes 11, between the positive electrode terminal electrode 12 and the bipolar electrode 11, and between the negative electrode 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. The separator 14 separates the positive electrode active material layer 16 and the negative electrode active material layer 17, thereby preventing a short circuit due to contact between adjacent electrodes while allowing charge carriers such as lithium ions to pass through.

[0026] The current collector 15 is a chemically inert electrical conductor that allows current to continue to flow 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 and / or conductive resin material.

[0027] 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 of the above metals or a foil formed by integrating multiple metal foils. If the current collector 15 is in the form of a foil, its thickness may be, for example, 1 μm to 200 μm. In this embodiment, the current collector 15 is a foil formed by integrating aluminum foil and copper foil.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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 electrolyte impregnated into the separator 14 is a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0033] As the electrolyte salt of the electrolyte solution, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 may be used. Furthermore, as the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, linear carbonates, linear esters, and ethers may be used. In addition, two or more of these known solvent materials may be used in combination.

[0034] Here, the current collector 15 is provided with detection wires 30. The detection wires 30 are positioned and joined (e.g., ultrasonically welded) on the other side 15b of the current collector 15. As an example, one detection wire 30 is provided on each current collector 15 for all electrodes. This makes it possible for the energy storage module 1 to detect the battery state (e.g., voltage) of cells composed of adjacent electrodes using a pair of adjacent detection wires 30 along the first direction D1. One example of a detection wire 30 is a voltage detection wire.

[0035] The detection wire 30 is a long, foil-like structure and is made of, for example, metal. More specifically, the current collector 15 and the detection wire 30 may be made of different metals, in which case the thermal conductivity of the metal constituting the detection wire 30 may be lower than that of the metal constituting the current collector 15. In this embodiment, the detection wire 30 is stainless steel foil.

[0036] The sealant 20 is formed in a frame shape on the periphery of the electrode stack 10 so as to surround the electrode stack 10. The sealant 20 can be joined (welded) to one side 15a and the other side 15b of each current collector 15 at their respective periphery 15c. The sealant 20 is intended to form an internal space S between adjacent current collectors 15 in the first direction D1 and to seal each of these internal spaces S. An electrolyte (e.g., electrolyte solution) is contained in each internal space S. The sealant 20 can prevent the electrolyte solution from permeating to the outside.

[0037] Furthermore, the sealant 20 can suppress the intrusion of moisture and other substances from the outside of the electrode stack 10 into the internal space S. The sealant 20 can prevent gases generated at each electrode due to charge-discharge reactions, for example, from leaking to the outside of the energy storage module 1. The edges of the separator 14 are joined to the sealant 20. The sealant 20 contains an insulating material. Examples of materials for the sealant 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile styrene resin.

[0038] The sealing body 20 includes a plurality of resin sealing materials 21, a plurality of resin spacers 22, and a welded end 23. The sealing materials 21 are provided on each of the current collectors 15. Therefore, the sealing materials 21 are stacked on top of each other along the first direction D1. The sealing material 21 is frame-shaped (here, rectangular frame-shaped) when viewed from the first direction D1 and is provided on the peripheral edge 15c of the current collector 15. The sealing material 21 is provided so as to extend from one side 15a of the current collector 15 through the end face to the other side 15b, covering the peripheral edge 15c. The sealing material 21 can be welded to one side 15a and the other side 15b of the current collector 15. Here, the sealing material 21 is welded to the current collector 15 and the detection wire 30 joined to the current collector 15.

[0039] The spacer 22 is positioned between adjacent sealing materials 21 in the first direction D1. This allows the spacer 22 to maintain space between adjacent sealing materials 21, i.e., between adjacent current collectors 15, and together with the sealing materials 21, form an internal space S. The spacer 22 has a frame-like shape (here, a rectangular frame shape) when viewed from the first direction D1, and is positioned on the peripheral edge 15c of the current collector 15 when viewed from the first direction D1. Here, the end of the separator 14 is held in place, sandwiched between the sealing material 21 and the spacer 22. The separator 14 can be welded to at least one of the sealing material 21 and the spacer 22.

[0040] The welded end 23 is formed by welding together the ends of the multiple sealing materials 21 and the multiple spacers 22 opposite to the internal space S, thereby integrating them. When viewed from the first direction D1, the welded end 23 has a frame-like shape that surrounds the electrode stack 10 and constitutes the outer periphery of the sealant 20. Therefore, the sealant 20 has an outer surface 20s (outer surface of the welded end 23) formed by the first end face 21s of the sealing material 21 opposite to the internal space S and the second end face 22s of the spacer 22 opposite to the internal space S, as the sealing materials 21 and the spacers 22 are welded together.

[0041] The detection wire 30 extends from the current collector 15 and is drawn out from the outer surface 20s along a second direction D2 that intersects (is perpendicular to) the first direction D1. Here, the outer surface 20s has a rectangular cylindrical shape according to the outer shape of the sealing material 21 and the spacer 22, and has four surfaces. The portion 20p of the detection wire 30 that leads out from the outer surface 20s is concentrated on one of the four surfaces that make up the outer surface 20s.

[0042] On the other hand, the lead portions 20p of adjacent detection lines 30 in the first direction are provided at different positions with respect to the third direction D3, which intersects (is perpendicular to) the first direction D1 and the second direction D2. In the illustrated example, the lead portions 20p of the detection lines 30 are arranged along the first direction D1 such that their positions with respect to the third direction D3 are staggered. That is, the lead portions 20p of the detection lines 30 are distributed at multiple (two in this case) positions with respect to the third direction D3. On the other hand, at least two of the multiple detection lines 30 (half in the illustrated example) are arranged so as to overlap each other when viewed from the first direction D1.

[0043] Furthermore, the portion of the detection line 30 that is on the electrode stack 10 side of the outer surface 20s is embedded in the sealant 21 where the sealant 21 and spacer 22 overlap along the first direction D1. Here, the detection line 30 is terminated inside the sealant 21, and the entire portion of the detection line 30 that is on the electrode stack 10 side of the outer surface 20s is embedded in and covered by the sealant 21. As a result, the detection line 30 does not come into contact with spacer 22.

[0044] Furthermore, the material of the sealing material 21 can be appropriately selected from the materials of the sealing body 20 described above, but one example is an acid-modified resin. This ensures the bonding strength between the sealing material 21 and the current collector 15 and detection wire 30 when the current collector 15 and detection wire 30 are made of metal. On the other hand, the material of the spacer 22 can also be appropriately selected from the materials of the sealing body 20 described above, but it does not have to be an acid-modified resin.

[0045] Here, the outer surface 20s of the sealant 20 includes a projection 21k that protrudes in the second direction D2 (the direction in which the detection line 30 is drawn out) toward the side opposite to the electrode stack 10 at the lead portion 20p of the detection line 30. The projection 21k can be formed, for example, by making the first end face 21s of the sealant 21 protrude in the second direction D2 before forming the welded end 23. As described above, the lead portion 20p of the detection line 30 is concentrated on one of the four faces that make up the outer surface 20s.

[0046] Therefore, the protrusion 21k is formed on only one of the four surfaces that make up the outer surface 20s. Furthermore, the protrusion 21k is formed with a width that spans multiple (two in this case) positions where the lead-out portions 20p are provided in the third direction D3. Here, when viewed from the first direction D1, one protrusion 21k is provided so as to span the lead-out portions 20p of all detection lines 30.

[0047] The protrusions 21k (overlapping protrusions 21k when viewed from the first direction D1) at each of the leading portions 20p of the detection lines 30 that overlap each other when viewed from the first direction D1 are spaced apart with respect to the first direction D1. Therefore, on the outer surface 20s of the sealant 20, recesses 22k are formed that are recessed toward the electrode laminate 10 side along the second direction D2 in the region between these adjacent protrusions 21k (for example, the region corresponding to the second end face 22s of the spacer 22). When forming the welded end 23, the molten sealant 21 and spacer 22 are compatible with each other, so the molten resin flows from the protrusions 21k to the recesses 22k, ensuring a large amount of resin between the sealant 21 and the spacer 22. In addition, the protrusions 21k and the recesses 22k are smoothly connected.

[0048] Figure 3 is a plan view showing the relationship between the current collector, the detection line, and the sealing material. In Figure 3, the sealing material 21 is shown by a dashed line. As shown in Figure 3, the sealing material 21 includes a first region AR1 that overlaps with the current collector 15 and is welded to the current collector 15 when viewed from the first direction D1, and a second region AR2 that is located outside the current collector 15 when viewed from the first direction D1. The second region AR2 is the region that constitutes the welded end 23 by compatibility with the spacer 22. The second region AR2 may be spaced apart from the outer edge of the current collector 15, as shown in the illustrated example. That is, only a portion of the part of the sealing material 21 located outside the current collector 15, from the first end face 21s, may constitute the welded end 23 by compatibility with the spacer 22. Furthermore, when welding the sealing material 21 and the spacer 22 to form the welded end 23, heat escapes to the detection line 30 around the leading portion 20p of the detection line 30, which can reduce the area in which the sealing material 21 and the spacer 22 are compatible. Therefore, as shown in Figures 2 and 3, the width of the welded end 23 in the second direction D2 may be reduced around the leading portion 20p of the detection line 30.

[0049] The detection line 30 includes a first portion 31 and a second portion 32. The second portion 32 is narrower than the first portion 31 when viewed from the first direction D1. As a result, a step portion 33 is formed between the first portion 31 and the second portion 32 of the detection line 30. The first portion 31 of the detection line 30 is positioned from the first region AR1 to the second region AR2 of the sealing material 21, and the second portion 32 of the detection line 30 is positioned from the second region AR2 of the sealing material 21 to the outside of the sealing material 21. The step portion 33 is located in the second region AR2.

[0050] The first portion 31 is provided with notches 34. In the illustrated example, a pair of notches 34 are formed to recess inward from the outer edge of the first portion 31 along a third direction D3 that intersects the second direction D2, which is the direction in which the detection line 30 is drawn out. The notches 34 are located in the first region AR1 of the sealing material 21. That is, the portion of the detection line 30 sandwiched between the current collector 15 and the sealing material 21 along the first direction D1 (the portion of the first portion 31 that overlaps with the first region AR1) is provided with notches 34.

[0051] Here, when manufacturing the energy storage module 1, the following steps may be taken. Specifically, an electrode unit consisting of the electrode and the sealant 21 is formed by welding the sealant 21 to the electrode, which includes the current collector 15 and the detection line 30. Subsequently, the electrode units are stacked via spacers 22. After that, the welded end 23 is formed by welding the sealant 21 and the spacers 22.

[0052] As described above, the notch 34 of the detection line 30 is located in the first region AR1 where it is welded to the current collector 15 (electrode) of the sealing material 21. Therefore, the notch 34 exerts an anchoring effect on the sealing material 21 from the moment the sealing material 21 is welded to the electrode and the electrode unit is formed, contributing to the suppression of the detection line 30 coming loose.

[0053] On the other hand, the stepped portion 33 of the detection line 30 is located in the second region AR2 of the sealing material 21 used for welding to the spacer 22. Therefore, when the welded end 23 is formed by welding the sealing material 21 and the spacer 22, the stepped portion 33 exerts an anchoring effect on the welded end 23, contributing to the suppression of the detection line 30 coming loose.

[0054] As described above, in the energy storage module 1, the electrode stack 10 is constructed by stacking electrodes, each having a current collector 15 and a detection wire 30 joined to the current collector 15, along a first direction D1. The electrode stack 10 is provided with a sealant 20 for sealing the internal space S between the current collectors 15. The sealant 20 includes a sealing material 21 welded to the current collector 15 and the detection wire 30, and a spacer 22 positioned between adjacent sealing materials 21 in the first direction D1 to form the internal space S together with the sealing material 21. The detection wire 30 is drawn out from the outer surface 20s of the sealant 20 formed by welding the sealing material 21 and the spacer 22 together.

[0055] Thus, in the energy storage module 1, a sealing material 21 is provided as a resin member welded to the current collector 15 (and detection wire 30), and a spacer 22 is provided as another resin member between the sealing materials 21. Therefore, it is possible to make the sealing material 21 thinner to reduce the impact on the current collector 15 due to the shrinkage of the sealing material 21, while the spacer 22 ensures the amount of elastic deformation of the resin members and absorbs the increase in the thickness of the detection wire 30. Thus, in the energy storage module 1, it is possible to suppress the deformation of the current collector 15 while suppressing the local increase in the thickness of the electrode laminate 10.

[0056] Furthermore, in the energy storage module 1, the outer surface 20s of the sealant 20 includes a protrusion 21k that protrudes in the second direction D2 at the lead-out portion 20p of the detection wire 30 from the outer surface 20s. When the sealant 21 and the spacer 22 are welded together to form the outer surface 20s, heat escapes to the detection wire 30 around the lead-out portion 20p of the detection wire 30, which may prevent the sealant 21 and the spacer 22 from being sufficiently welded together, potentially reducing the sealing performance. In contrast, by providing a protrusion 21k on the outer surface 20s of the sealant 20 with respect to the lead-out portion 20p of the detection wire 30, and ensuring a larger amount of resin, the sealant 21 and the spacer 22 can be welded together more reliably even around the lead-out portion 20p, thereby improving the sealing performance.

[0057] Furthermore, when welding the sealing material 21 and the spacer 22, a heat source may be positioned to face the first end face 21s and the second end face 22s for heating. In this case, because the detection line 30 has good heat dissipation, the resin may not melt easily around the detection line 30. In contrast, in the energy storage module 1, by providing a protrusion 21k around the detection line 30, it becomes possible to position the resin closer to the heat source, thereby improving sealing performance.

[0058] Furthermore, in the energy storage module 1, the lead portions 20p of the multiple detection lines 30 are distributed to multiple positions in the third direction D3, such that adjacent lead portions 20p in the first direction D1 are located at different positions in the third direction D3. The protruding portion 21k is formed with a width that spans these multiple positions in the third direction D3. In this way, by having adjacent lead portions 20p of the detection lines 30 in the first direction D1 located at different positions in the third direction D3, a separation between the detection lines 30 in the first direction D1 is ensured.

[0059] Furthermore, by forming the protrusions 21k on the sealing material 21 over a width that spans multiple positions where the lead-out portion 20p of the detection line 30 is provided, the preparation of the sealing material 21 becomes easier compared to the case where multiple types of sealing material 21 are manufactured, each having a protrusion 21k corresponding to one of the multiple positions of the lead-out portion 20p.

[0060] Furthermore, in the energy storage module 1, the current collector 15 and the detection wire 30 may be made of different metals, and the thermal conductivity of the metal constituting the detection wire 30 may be lower than that of the metal constituting the current collector 15. In this case, the heat generated when forming the outer surface 20s by welding the sealing material 21 and the spacer 22 is suppressed from escaping to the current collector 15 through the detection wire 30, thereby suppressing welding defects between the sealing material 21 and the spacer 22.

[0061] Furthermore, in the energy storage module 1, the current collector 5 and the detection wire 30 may be made of metal, and the sealing material 21 may be made of an acid-modified resin. In this case, the bonding strength between the sealing material 21 and the current collector 15 and the detection wire 30 is ensured, improving sealing performance.

[0062] Furthermore, in the energy storage module 1, the detection line 30 is embedded in the sealant 21 in the portion where the sealant 21 and the spacer 22 overlap along the first direction D1. Therefore, in the portion where the sealant 21 and the spacer 22 overlap, the detection line 30 is embedded in the sealant 21, which is made of an acid-modified resin that can be suitably bonded to metal. Thus, even if the spacer 22 is not made of an acid-modified resin, reliable sealing can be achieved in that portion due to its compatibility with the sealant 21.

[0063] Furthermore, in the energy storage module 1, at least two of the multiple detection lines 30 are arranged to overlap each other when viewed from the first direction D1, and the protrusions 21k at each of the lead-out portions 20p of the detection lines 30 that overlap each other when viewed from the first direction D1 are spaced apart with respect to the first direction D1. As a result, irregularities are formed on the lead-out portions 20p of the detection lines 30 on the outer surface 20s, which increases the creepage distance between adjacent detection lines 30 in the first direction D1, thereby suppressing short circuits between the detection lines 30.

[0064] Furthermore, in the energy storage module 1, a notch 34 is provided in the portion of the detection wire 30 sandwiched between the current collector 15 and the sealing material 21 along the first direction D1. As a result, the anchoring effect of the notch suppresses the detection wire 30 from coming loose. In particular, since the notch 34 is provided in the portion of the detection wire 30 sandwiched between the current collector 15 and the sealing material 21, the anchoring effect is exerted from the moment the sealing material 21 is welded to the current collector 15 and the detection wire 30, suppressing the detection wire 30 from coming loose.

[0065] The above embodiments describe one aspect of an energy storage module. Therefore, the energy storage module 1 described above can be modified as needed.

[0066] For example, in the above embodiment, a notch 34 was provided in the detection line 30 that was recessed along the third direction D3. However, the direction in which the notch 34 is recessed is arbitrary and may be, for example, the second direction D2.

[0067] Furthermore, in the above embodiment, a configuration was described in which a protrusion 21k is provided on the leading portion 20p of the detection line 30 on the outer surface 20s of the sealing body 20. However, the protrusion 21k does not have to be provided on the outer surface 20s of the sealing body 20. If the welding end 23 can be formed with a sufficient welding width by increasing the amount of heat during welding of the sealing material 21 and the spacer 22 around the leading portion 20p of the detection line 30, then the protrusion 21k does not have to be provided.

[0068] Furthermore, the thermal conductivity of the detection wire 30 may be greater than or equal to that of the current collector 15, and the current collector 15 and the detection wire 30 may be made of the same material.

[0069] Furthermore, in the above embodiment, the case in which the detection line 30 is a voltage detection line was illustrated. However, the detection line 30 may also be a temperature detection line connected to a temperature sensor provided within the electrode stack 10.

[0070] The embodiments described above are described below.

[0071] The energy storage module is an electrode stack comprising: [1] an electrode stack comprising a plurality of electrodes stacked along a first direction, each having a current collector having an active material layer and a detection wire joined to the current collector; and a sealing body provided on the electrode stack so as to surround the electrode stack and for sealing the internal space between adjacent current collectors in the first direction, wherein the sealing body comprises a plurality of resin sealing materials welded to each of the plurality of electrodes; a plurality of resin spacers positioned between adjacent sealing materials in the first direction and forming the internal space together with the sealing materials; and an outer surface formed by a first end face of the sealing material opposite to the internal space and a second end face of the spacer opposite to the internal space, by welding the sealing materials and the spacers to each other, wherein each of the plurality of sealing materials is welded to the current collector and the detection wire joined to the current collector, and the detection wire extends from the current collector and is drawn out from the outer surface along a second direction intersecting the first direction.

[0072] The energy storage module may also be [2] "the energy storage module according to [1] above, wherein the outer surface includes a protrusion that protrudes in the second direction at the portion of the detection line that extends from the outer surface."

[0073] The energy storage module may also be [3] "the energy storage module according to [2] above, wherein the lead portions of the plurality of detection lines are distributed to a plurality of positions in the third direction, such that adjacent lead portions in the first direction are provided at different positions in the third direction where they intersect the first and second directions, and the protrusions are formed with a width that spans the plurality of positions in the third direction."

[0074] The energy storage module may be [4] "the energy storage module according to [2] or [3] above, wherein at least two of the plurality of detection lines are arranged to overlap each other when viewed from the first direction, and the protrusions at each of the lead-out portions of the detection lines that overlap each other when viewed from the first direction are spaced apart from each other in the first direction."

[0075] The energy storage module may also be [5] "the energy storage module according to any of [1] to [4] above, wherein the current collector and the detection wire are made of different metals, and the thermal conductivity of the metal constituting the detection wire is lower than the thermal conductivity of the metal constituting the current collector."

[0076] The energy storage module may also be [6] "the energy storage module according to any of [1] to [5] above, wherein the current collector and the detection wire are made of metal, and the sealing material is made of an acid-modified resin."

[0077] The energy storage module may be [7] "the energy storage module according to [6] above, wherein the detection line is embedded in the sealing material in the portion where the sealing material and the spacer overlap along the first direction."

[0078] The energy storage module may also be [8] "an energy storage module according to any one of [1] to [7] above, wherein a notch is provided in the portion sandwiched between the current collector and the sealing material along the first direction in the detection line." [Explanation of symbols]

[0079] 1...Energy storage module, 10...Electrode stack, 15...Current collector, 20...Sealing body, 20s...Outer surface, 20p...Outlet portion, 21...Sealing material, 21s...First end face, 21k...Protrusion, 22...Spacer, 22s...Second end face, 22k...Recess, 30...Detection line, 34...Notch.

Claims

1. An electrode laminate is constructed by stacking a plurality of electrodes along a first direction, each having a current collector with an active material layer and a detection line joined to the current collector. A sealing body is provided on the electrode stack so as to surround the electrode stack, and is used to seal the internal space between adjacent current collectors in the first direction. Equipped with, The aforementioned encapsulant is Multiple resin sealing materials welded to each of the aforementioned multiple electrodes, A plurality of resin spacers are arranged between adjacent sealing materials in the first direction and together with the sealing materials form the internal space, The sealing material and the spacer are welded to each other, and the outer surface formed by the first end face of the sealing material opposite to the internal space and the second end face of the spacer opposite to the internal space, It has, Each of the aforementioned multiple sealing materials is welded to the current collector and the detection wire joined to the current collector. The detection line extends from the current collector and is drawn out from the outer surface along a second direction that intersects the first direction. The outer surface includes a projection that protrudes in the second direction at the portion of the detection line that extends from the outer surface, Energy storage module.

2. The lead portions of the multiple detection lines are distributed to multiple positions in the third direction, such that adjacent lead portions in the first direction are provided at different positions in the third direction where the first and second directions intersect. The protrusion is formed with a width that spans the plurality of positions in the third direction. The energy storage module according to claim 1.

3. At least two of the plurality of detection lines are arranged to overlap each other when viewed from the first direction. The protrusions at each of the lead-out portions of the detection lines that overlap each other when viewed from the first direction are spaced apart from each other in the first direction. The energy storage module according to claim 1.

4. The current collector and the detection wire are made of different metals. The thermal conductivity of the metal constituting the detection line is lower than that of the metal constituting the current collector. The energy storage module according to claim 1.

5. The current collector and the detection wire are made of metal. The sealing material is composed of an acid-modified resin. The energy storage module according to claim 1.

6. In the portion where the sealing material and the spacer overlap along the first direction, the detection line is embedded in the sealing material. The energy storage module according to claim 5.

7. A notch is provided in the portion of the detection line sandwiched between the current collector and the sealing material along the first direction. A storage module according to any one of claims 1 to 6.

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