Manufacturing method of power storage device, and the power storage device

Abstract

To provide a manufacturing method of a power storage device capable of sealing a liquid injection port with high sealability, and the power storage device.SOLUTION: After an electrolytic solution is injected into an internal space 114 through a liquid injection port 102 of a liquid injection port member 110, a welding part 124 of a lid member 120 is inserted into a liquid injection port frame of the liquid injection port member and heated from a support substrate side of the lid member to weld the welding part of the lid member and an inner wall of the liquid injection port frame to seal the liquid injection port. The inner wall of the injection port frame is made of a resin L, a portion other than the inner wall of the injection port frame is made of a resin H, at least an outer peripheral surface of the welding part is made of a resin S, and the support substrate is made of a material M. The preset invention provides a manufacturing method of a power storage device, in which a melting point Tm or a glass transition temperature Tg and a heating temperature in a sealing step satisfy the following conditions a, b, and c. The condition is that a: Tm or Tg of the resin L is less than Tm or Tg of the resin H, b: Tm or Tg of the resin S is less than Tm or Tg of the resin H, c: the heating temperature in the sealing step is equal to or higher than the Tm or Tg of the resin L, equal to or higher than the Tm or Tg of the resin S, and lower than the Tm or Tg of the resin H.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electricity storage device, and to an electricity storage device. [Background technology]

[0002] There is known an electric storage module that includes an electrode stack in which multiple electrodes are stacked with separators interposed therebetween, a case that holds the electrode stack, and an electrolyte solution contained between adjacent electrodes of the electrode stack. In such an electric storage module, the electrolyte solution is injected into the storage space of the electrode stack through a liquid injection port provided in the case that houses the electrode stack, and then a sealing member is attached to the liquid injection port to seal the electric storage module (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-173921 Summary of the Invention [Problem to be solved by the invention]

[0004] As a sealing method after the electrolyte is poured through the pouring hole, there is a method of sealing by providing a pouring hole frame around the pouring hole and sealing the pouring hole frame with a laminate or the like. FIG. 6 shows an example of a method for sealing the liquid filling port 102. The liquid filling port frame 104 is made of resin. After pouring electrolyte through the liquid filling port 102, sealing the resin liquid filling port frame 104 with a laminate 140 can be achieved by pressing a hot plate 130 against the liquid filling port frame 104 while the laminate 140 is in contact with the liquid filling port frame 104, as shown in FIG. 6 . In this case, the edge of the liquid filling port frame 104 may melt and be pushed toward the electrode stack 118. This may reduce the volume of the region enclosed by the liquid filling port frame 104 and the laminate 140 by, for example, ΔV, and increase the internal pressure of the region. The increased internal pressure causes gas present in the region enclosed by the liquid filling port frame 104 and the laminate 140 to escape to the outside, potentially creating a hole in the welded portion and reducing the hermeticity of the energy storage module.

[0005] An object of the present disclosure is to provide a method for manufacturing an electricity storage device that can seal the filling port with high hermeticity after pouring electrolyte solution through the filling port, and to provide an electricity storage device with a highly hermetic filling port. [Means for solving the problem]

[0006] Means for solving the above problems include the following aspects. <1> A method for manufacturing an electricity storage device including an electrode stack in which a plurality of bipolar electrodes are stacked with separators interposed therebetween, a sealing member that seals a peripheral edge portion of the electrode stack, and an electrolyte solution accommodated between the bipolar electrodes adjacent to each other in a stacking direction in the electrode stack, the method comprising: a liquid injection step of injecting the electrolyte into the internal space between the adjacent bipolar electrodes through a liquid injection port of a liquid injection port member including a liquid injection port for injecting the electrolyte into the internal space between the adjacent bipolar electrodes and a liquid injection port frame surrounding the periphery of the liquid injection port; a sealing step of, after the liquid pouring step, inserting a welded portion of a lid member, the welded portion including a support substrate supporting the welded portion and having a shape that follows the inner wall of the liquid pouring port frame, into the liquid pouring port frame of the liquid pouring port member, and heating the lid member from the support substrate side to weld the welded portion of the lid member to the inner wall of the liquid pouring port frame, thereby sealing the liquid pouring port, The liquid inlet member has an inner wall of the liquid inlet frame made of resin L, and a portion of the liquid inlet frame other than the inner wall made of resin H, In the lid member, at least the outer peripheral surface of the welding portion is made of resin S, and the support substrate is made of material M, The method for manufacturing an electricity storage device, wherein the melting point Tm or glass transition temperature Tg of each of the resins L, H, and S, and the heating temperature in the sealing step satisfy the following conditions a, b, and c: a: The melting point Tm or the glass transition temperature Tg of the resin L is lower than the melting point Tm or the glass transition temperature Tg of the resin H. b: The melting point Tm or the glass transition temperature Tg of the resin S is lower than the melting point Tm or the glass transition temperature Tg of the resin H. c: The heating temperature in the sealing step is equal to or higher than the melting point Tm or glass transition temperature Tg of the resin L, equal to or higher than the melting point Tm or glass transition temperature Tg of the resin S, and lower than the melting point Tm or glass transition temperature Tg of the resin H. <2> The resin H is polypropylene, and the resin L and the resin S are polyethylene. <1> A method for manufacturing the electricity storage device according to claim 1. <3> The welding portion includes a welding portion substrate and a resin S layer made of the resin S that covers the welding portion substrate. <1> or <2> A method for manufacturing the electricity storage device according to claim 1. <4> The shape of the storage device when viewed in the thickness direction is rectangular, and the length of each side of the rectangle is 1000 mm or more vertically and 10000 mm or more horizontally. <1> ~ <3> 10. A method for manufacturing the electricity storage device according to any one of the above. <5> An electricity storage device including: an electrode stack in which a plurality of bipolar electrodes are stacked with separators interposed therebetween; a sealing member that seals a peripheral edge portion of the electrode stack; and an electrolyte solution accommodated between the bipolar electrodes adjacent to each other in a stacking direction in the electrode stack, a liquid injection port member including a liquid injection port for injecting the electrolyte into an internal space between the adjacent bipolar electrodes and a liquid injection port frame surrounding the periphery of the liquid injection port; a lid member including a welding portion having a shape that follows the inner wall of the liquid filling port frame and a support substrate that supports the welding portion, the welding portion being welded to the inner wall of the liquid filling port frame, The liquid inlet member has an inner wall of the liquid inlet frame made of resin L, and a portion of the liquid inlet frame other than the inner wall made of resin H, In the lid member, at least the outer peripheral surface of the welding portion is made of resin S, and the support substrate is made of material M, The melting point Tm or the glass transition temperature Tg of each of the resins L, H, and S satisfies the following conditions a and b: a: The melting point Tm or the glass transition temperature Tg of the resin L is lower than the melting point Tm or the glass transition temperature Tg of the resin H. b: The melting point Tm or the glass transition temperature Tg of the resin S is lower than the melting point Tm or the glass transition temperature Tg of the resin H. [Effects of the Invention]

[0007] According to the present disclosure, there are provided a method for manufacturing an electricity storage device that can seal the filling port with high hermeticity after pouring electrolyte through the filling port, and an electricity storage device that has a highly hermetic filling port. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view illustrating an example of a power storage device. [Figure 2] 4 is a schematic view showing a liquid inlet member and a lid member at one end of the electrode stack. FIG. [Figure 3] FIG. 2 is a schematic front view showing an example of a liquid filling port frame. [Figure 4] FIG. 2 is a schematic front view showing an example of a cover member. [Figure 5] 3 is a schematic diagram showing a part of the cover member, with the dotted line portion A in FIG. 2 enlarged. FIG. [Figure 6] FIG. 10 is a schematic diagram showing an example of a method for sealing the liquid filling port frame with a laminate. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a method for manufacturing a power storage device and a power storage device according to the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the reference numerals will be omitted as appropriate within the same drawings. In the present disclosure, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0010] The method for manufacturing an energy storage device according to the present disclosure is a method for manufacturing an energy storage device including an electrode stack in which a plurality of bipolar electrodes are stacked with separators interposed therebetween, a sealing member that seals the peripheral edge of the electrode stack, and an electrolyte solution contained between adjacent bipolar electrodes in the stacking direction in the electrode stack. The method for manufacturing an electricity storage device according to the present disclosure includes a liquid filling step of filling an electrolyte solution into an internal space through a liquid filling port, and a sealing step of sealing the liquid filling port after the liquid filling step. In the liquid injection process, the electrolyte is injected into the internal space between adjacent bipolar electrodes through a liquid injection port of a liquid injection port member that includes a liquid injection port for injecting the electrolyte into the internal space between adjacent bipolar electrodes and a liquid injection port frame that surrounds the periphery of the liquid injection port. In the sealing process, the welding portion of the lid member, which includes a welding portion shaped to fit the inner wall of the pouring port frame and a support substrate supporting the welding portion, is inserted into the pouring port frame of the pouring port member, and the lid member is heated from the support substrate side, thereby welding the welding portion of the lid member to the inner wall of the pouring port frame and sealing the pouring port. In the liquid inlet member, the inner wall of the liquid inlet frame is made of resin L, and the portion other than the inner wall of the liquid inlet frame is made of resin H. In the lid member, at least the outer peripheral surface of the welded portion is made of resin S, and the support substrate is made of material M. The melting point Tm or glass transition temperature Tg of each of the resins L, H, and S, and the heating temperature in the sealing step, satisfy the following conditions a, b, and c. a: The melting point Tm or glass transition temperature Tg of resin L is lower than the melting point Tm or glass transition temperature Tg of resin H. b: The melting point Tm or glass transition temperature Tg of resin S is lower than the melting point Tm or glass transition temperature Tg of resin H. c: The heating temperature in the sealing process is equal to or higher than the melting point Tm or glass transition temperature Tg of resin L, equal to or higher than the melting point Tm or glass transition temperature Tg of resin S, and lower than the melting point Tm or glass transition temperature Tg of resin H.

[0011] The energy storage device according to the present disclosure also includes an electrode stack in which a plurality of bipolar electrodes are stacked with separators interposed therebetween, a sealing member that seals the peripheral edge of the electrode stack, and an electrolyte solution contained between adjacent bipolar electrodes in the stacking direction in the electrode stack. The electricity storage device according to the present disclosure also includes a liquid inlet member including a liquid inlet for injecting an electrolyte into an internal space between adjacent bipolar electrodes and a liquid inlet frame surrounding the periphery of the liquid inlet; The cover member includes a welding portion having a shape that fits the inner wall of the filling port frame and a support substrate that supports the welding portion, the welding portion being welded to the inner wall of the filling port frame. In the liquid inlet member, the inner wall of the liquid inlet frame is made of resin L, and the portion other than the inner wall of the liquid inlet frame is made of resin H. In the lid member, at least the outer peripheral surface of the welded portion is made of resin S, and the support substrate is made of material M. The melting points Tm or glass transition temperatures Tg of the resins L, H, and S satisfy the conditions a and b above.

[0012] Hereinafter, an example of the configuration of an energy storage device according to an embodiment of the present disclosure and an energy storage device manufactured by a method for manufacturing an energy storage device according to an embodiment of the present disclosure will be described. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions will be omitted as appropriate.

[0013] 1 is a schematic perspective view showing an example of an electricity storage device. The device body 20 includes an electrode stack 11 and a resin sealing member 12 that seals the electrode stack 11.

[0014] 2 is a schematic diagram showing the liquid inlet member and the lid member at one end of the electrode stack 11. In FIG. 2, the electrode stack and the like are shown in a simplified manner.

[0015] The electrode stack 118 is formed by stacking a plurality of bipolar electrodes 112 (sometimes simply referred to as "electrodes" in this specification) with separators (not shown) interposed between them. The periphery of each bipolar electrode 112 is sealed with a sealing member 12. The electrode stack 118 may include, for example, a stack of a plurality of bipolar electrodes, a negative terminal electrode, and a positive terminal electrode. An internal space 114 that contains an electrolyte is provided between adjacent bipolar electrodes 112 in the stacking direction.

[0016] The electrode laminate 118 has a rectangular shape when viewed in the thickness direction of the battery (i.e., when viewed in the stacking direction of the electrode laminate 118). Note that the term "rectangular" here does not only include cases where the shape is an exact rectangle (e.g., a rectangle, a square, etc.), but also includes cases where the battery as a whole has a shape close to a rectangle. Therefore, the above-mentioned "rectangular" also includes, for example, a shape close to a rectangle with slightly rounded corners. The rectangular battery can have a length of 1000 mm or more and a width of 10000 mm or more.

[0017] The sealing member 12 is formed into a rectangular cylindrical shape overall. The sealing member 12 is disposed on the side of the electrode stack 118. The sealing member 12 has a primary sealant 21 welded to the top and bottom edges of a laminated foil made of Al-Cu adhered via an adhesive layer, and a secondary sealant 22 welded to the edges of the primary sealant 21 and to the edges of a spacer disposed between the primary sealants 21, thereby sealing the inside and outside of the battery cell. The primary sealing material 21 is, for example, a resin film having a predetermined thickness in the lamination direction.

[0018] The secondary sealant 22 is provided on the outside of the electrode stack 11 and the primary sealant 21, and constitutes the outer wall (housing) of the energy storage device 4. The secondary sealant 22 extends over the entire length of the electrode stack 118 in the stacking direction. The secondary sealant 22 has a rectangular frame shape. The secondary sealant 22 is welded to the outer surface of the primary sealant 21, for example.

[0019] The primary sealant 21 and the secondary sealant 22 form an internal space between adjacent electrodes in the electrode stack 11 and seal the internal space 114. This internal space 114 contains, for example, an electrolyte solution (not shown) containing a non-aqueous solvent (described below) and an electrolyte salt dissolved in the non-aqueous solvent. The electrolyte solution is impregnated, for example, in the separators, positive electrodes, and negative electrodes that constitute the electrode stack 11.

[0020] A liquid inlet member 110 including a liquid inlet 102 and a liquid inlet frame 104 surrounding the liquid inlet 102 is provided on one side wall 12a that constitutes sealing member 12. In other words, liquid inlet member 110 constitutes part of secondary sealing material 22. An electrolyte solution is poured into internal space 114 through liquid inlet 102.

[0021] (liquid inlet member) 3 is a schematic front view showing an example of a liquid filling port frame. Liquid filling port member 110 includes liquid filling port 102 for pouring electrolyte and liquid filling port frame 104 that surrounds the periphery of liquid filling port 102. The liquid inlet 102 is formed across the primary seal portion 21 and the secondary seal portion 22 (liquid inlet member 110), and communicates with the internal space 114. By injecting the electrolyte solution from the liquid inlet 102, the electrolyte solution is supplied to the internal space 114 between the bipolar electrodes 112 adjacent in the stacking direction. The liquid inlet frame 104 has an inner wall 105 made of resin L, and the portion of the liquid inlet frame 104 other than the inner wall 105 made of resin H.

[0022] 2 shows three liquid filling ports 102, but a liquid filling port 102 is provided for each internal space 114 of adjacent bipolar electrodes 112. Specifically, eight liquid filling ports (not shown) and liquid filling port frames corresponding to each liquid filling port are provided in positions different from the liquid filling ports 102 shown in the figure.

[0023] (Cover member) Fig. 4 is a schematic front view showing an example of the lid member 120. Fig. 5 is a schematic structural diagram showing a part of the lid member, enlarging the dotted line portion A in Fig. 2. The lid member 120 includes a welding part 124 having a shape that fits along the inner wall of the pouring port frame, and a support substrate 126 that supports the welding part 124. As shown in Fig. 5, the welding part 124 is made up of a welding part substrate 123 and a resin S layer 125 made of resin S that covers the welding part substrate 123. The length of the welded portion 124 may be equal to or less than the length of the insertion portion 106 of the liquid inlet frame 104 of the liquid inlet member 110 .

[0024] The support substrate 126 is made of a material M. In the sealing process, the support substrate 126 is heated from the side where it is made, and therefore the material M of the support substrate 126 is a material that has higher heat resistance than the resin S, such as metal, ceramic, or resin. It is preferable that the welding portion substrate 123 is also made of the same material M as the support substrate 126 and is integrally formed with the support substrate 126. It is preferable that the welding portion substrate 123 and the support substrate 126 of the lid member 120 are made of a resin having a melting point Tm or glass transition temperature Tg higher than that of the resin S in particular.

[0025] The manufacturing method of the energy storage device according to the present disclosure includes a liquid filling step in which the liquid filling port member 110 and the cover member 120 as described above are used to fill the electrolyte into the internal space of the electrode stack through the liquid filling port surrounded by the liquid filling port frame, and a sealing step in which the liquid filling port is sealed after the liquid filling step.

[0026] <Liquid injection process> In the liquid injection step, for example, a liquid injection connector (not shown) is connected to the liquid injection frame 104 of the liquid injection member 110. The liquid injection connector is connected to a tank (not shown) that contains the electrolyte, and the electrolyte can be delivered by a pump (not shown). The electrolyte is injected into the internal space 114 through the liquid injection port 102 via the liquid injection connector connected to the liquid injection frame 104.

[0027] <Sealing process> After the liquid pouring step, the welded portion 124 of the lid member 120 is inserted into the insertion portion 106 in the liquid pouring port frame 104 of the liquid pouring port member 110 in the x direction as shown in FIG. After insertion, a heating and pressing member is pressed against lid member 120 from the support substrate 126 side of lid member 120 to heat it, thereby welding weld portion 124 of lid member 120 to the inner wall of pouring port frame 104 to seal pouring port 102. For example, it is preferable to heat lid member 120 from the support substrate 126 side by heat pressing with a plate-shaped heating body (hot plate).

[0028] From the viewpoint of ensuring reliable welding of welded portion 124 of lid member 120 to the inner wall of pouring port frame 104, it is preferable that the gap between inner wall 105 of pouring port frame 104 of pouring port member 110 and the outer peripheral surface of the welded portion of lid member 120 (surface of resin S layer) be narrower than 20% of the thickness of resin S layer. Since the expansion coefficient of PE when heated is approximately 20%, it is preferable to set the gap within this range.

[0029] If the heating temperature during the heat press is too low, welding portion 124 of lid member 120 and inner wall 105 of liquid filling port frame 104 will not be welded together, and if the heating temperature is too high, there is a risk that portions of liquid filling port frame 104 other than inner wall 105 will melt. Therefore, in the manufacturing method for an electricity storage device according to the present disclosure, the melting points Tm or glass transition temperatures Tg of resins L, H, and S, respectively, and the heating temperature in the sealing step are set so as to satisfy the following conditions a, b, and c. a: The melting point Tm or glass transition temperature Tg of resin L is lower than the melting point Tm or glass transition temperature Tg of resin H. b: The melting point Tm or glass transition temperature Tg of resin S is lower than the melting point Tm or glass transition temperature Tg of resin H. c: The heating temperature in the sealing process is equal to or higher than the melting point Tm or glass transition temperature Tg of resin L, equal to or higher than the melting point Tm or glass transition temperature Tg of resin S, and lower than the melting point Tm or glass transition temperature Tg of resin H.

[0030] (Resin H, Resin L, Resin S, and substrate) Examples of materials used for the resin L that forms the inner wall of the inlet frame in the inlet member, the resin H that forms the part other than the inner wall of the inlet frame, the resin S that forms the outer surface of the welded part of the lid member, and the material M of the welded part substrate will be described below. Examples of combinations of resin H, resin L, resin S, and material M include the following combination patterns. Combination pattern 1 Resin L: Polyethylene (PE, Tm = 130°C) Resin S:PE (Tm=130℃) Resin H: Polypropylene (PP, Tm = 160°C) Substrate M: PP (Tm=160℃) In this case, in the manufacturing method of the energy storage device according to the embodiment of the present disclosure, the heat pressing in the sealing process is performed at a temperature of 130°C or higher and lower than 160°C, and is preferably set at a temperature 10 to 20°C higher than the melting point Tm of resins L and S and 20 to 30°C lower than the melting point Tm of resin H.

[0031] Furthermore, the following combination patterns of resin H, resin L, and resin S are also preferred. Combination pattern 2 Resin L:PE (Tm=130℃) Resin S:PE (Tm=130℃) Resin H: Modified polyphenylene ether resin (modified PPE resin, Tg = 210°C) Substrate M: Modified PPE resin (Tg = 210°C) Combination pattern 3 Resin L: PP (Tm=160℃) Resin S:PP (Tm=160℃) Resin H: Modified PPE resin (Tg = 210°C) Substrate M: Modified PPE resin (Tg = 210°C)

[0032] It is preferable that resins L and S have the same melting point Tm or glass transition temperature Tg, and that resins H and the substrate material have higher melting points Tm or glass transition temperatures Tg than resins L and S.

[0033] As described above, after the liquid pouring process, the sealing process is performed to weld the welding portion 124 of the lid member 120 to the inner wall of the liquid pouring port frame 104, thereby achieving high sealing of the space inside the liquid pouring port frame that leads to the liquid pouring port.

[0034] Next, materials other than the liquid injection port member and the lid member that constitute the power storage device according to the embodiment of the present disclosure and the power storage device manufactured by the manufacturing method of the power storage device according to the embodiment of the present disclosure will be described.

[0035] (Positive electrode composite material layer) The electrode has a positive electrode composite material layer. The positive electrode composite material layer contains a positive electrode active material and may further contain, for example, a binder. Examples of the positive electrode active material include lithium nickel cobalt manganese composite oxide (hereinafter sometimes simply referred to as "LNCM"). The simplest LNCM has the following general formula: LiNi x Co y Mn z O2 (where x, y, z in the formula satisfy 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). LNCM may contain other additive elements in addition to Li, Ni, Co, and Mn, such as transition metal elements other than Ni, Co, and Mn, and typical metal elements other than Li. LNCM has a layered crystal structure. LNCM should exceed 50% by mass of the entire positive electrode active material and may occupy, for example, 80 - 100% by mass. The positive electrode active material may be composed only of LNCM. Also, as the positive electrode active material layer, lithium iron phosphate (LiFePO4, LFP), lithium manganese iron phosphate (LMFP), etc. may be used. Examples of other positive electrode active materials include lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, etc.

[0036] Examples of the binder contained in the positive electrode composite material layer include vinyl halide resins such as polyvinylidene fluoride (PVdF). The positive electrode composite material layer may further contain other components, such as a conductive material. Examples of the conductive material include graphitized carbon such as hard carbon and carbon black, and graphite.

[0037] (Negative electrode composite material layer) The electrode has a negative electrode composite material layer. The negative electrode mixture layer contains a negative electrode active material and may further contain, for example, a binder. Examples of the negative electrode active material include graphite-based carbon such as natural graphite, artificial graphite, amorphous coated graphite, etc. In graphite-based carbon, the proportion of graphite is generally 50% by mass or more, preferably 80% by mass or more. Examples of the binder contained in the negative electrode active material include rubbers such as styrene butadiene copolymer (SBR) and vinyl halide resins such as polyvinylidene fluoride (PVdF). The negative electrode mixture layer may further contain other components, such as a thickener, etc. Examples of the thickener include celluloses such as carboxymethyl cellulose (CMC).

[0038] (Current collectors: positive electrode current collector and negative electrode current collector) In the power storage device according to the embodiment of the present disclosure, for example, a plurality of bipolar electrodes each having a negative electrode composite layer on one side of a current collector and a positive electrode composite layer on the other side of the current collector are stacked with a separator interposed therebetween. The current collector is preferably a conductive member made of a metal with good conductivity (e.g., aluminum, stainless steel (SUS), Ni, Cr, Au, Pt, Fe, Ti, Zn, etc.).

[0039] (separator) The separator is an electrically insulating porous film. The separator electrically isolates the positive electrode and the negative electrode. The separator may have a thickness of, for example, 5 to 30 μm. The separator may be made of, for example, a porous polyethylene (PE) film, a porous polypropylene (PP) film, or the like. The separator may have a multilayer structure. For example, the separator may be made by laminating a porous PP film, a porous PE film, and a porous PP film in this order. The separator may have a heat-resistant layer on its surface. The heat-resistant layer contains a heat-resistant material. Examples of the heat-resistant material include metal oxide particles such as alumina, and high-melting-point resins such as polyimide.

[0040] (electrolyte) The power storage device according to the embodiment of the present disclosure further includes an electrolyte. Examples of the electrolyte include an electrolytic solution, and non-aqueous electrolytic solutions are particularly preferred. Non-aqueous electrolytic solutions will be described below.

[0041] ·solvent The non-aqueous electrolytic solution contains a solvent (non-aqueous solvent) and an electrolyte. Examples of the solvent (non-aqueous solvent) include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI), and 1-ethyl-2,3-dimethylimidazolium bis(fluorosulfonyl)imide (DEMI-FSI).

[0042] ·Electrolytes The electrolyte in the electrolytic solution may be, for example, a Li salt, such as lithium bis(fluorosulfonyl)imide (LiFSI), LiPF6 (lithium hexafluorophosphate), lithium tetrafluoroborate (LiBF4), or Li[N(CF3SO2)2]. The amount of electrolyte may be, for example, 1.0 to 2.0 mol / L, and is preferably 1.0 to 1.5 mol / L.

[0043] In addition to the solvent and electrolyte, the electrolytic solution may contain various additives such as a thickener, a film-forming agent, a gas generating agent, etc. The electrolyte is typically a non-aqueous electrolytic solution that is liquid at room temperature (e.g., 25±10°C). The electrolytic solution typically remains liquid in the environment in which the battery is used (e.g., a temperature environment of -20 to +60°C).

[0044] (Application) Examples of applications of the power storage device according to the embodiment of the present disclosure include power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). [Explanation of symbols]

[0045] 4 Electricity storage device, 11 Electrode stack, 12 Sealing member, 12a Wall portion, 20 Device body, 21 Primary seal portion, 22 Secondary seal portion, 102 Inlet, 104 Inlet frame, 105 Inner wall, 106 Insertion portion, 110 Inlet member, 112 Bipolar electrode, 114 Internal space, 120 Lid member, 123 Welding portion substrate, 124 Welding portion, 125 Resin S layer, 126 Support substrate

Claims

1. A method for manufacturing an electricity storage device including an electrode stack in which a plurality of bipolar electrodes are stacked with separators interposed therebetween, a sealing member that seals a peripheral edge portion of the electrode stack, and an electrolyte solution accommodated between the bipolar electrodes adjacent to each other in a stacking direction in the electrode stack, the method comprising: a liquid injection step of injecting the electrolyte into the internal space between the adjacent bipolar electrodes through a liquid injection port of a liquid injection port member including a liquid injection port for injecting the electrolyte into the internal space between the adjacent bipolar electrodes and a liquid injection port frame surrounding the periphery of the liquid injection port; a sealing step of, after the liquid pouring step, inserting a welded portion of a lid member, the welded portion including a support substrate supporting the welded portion and having a shape that follows the inner wall of the liquid pouring port frame, into the liquid pouring port frame of the liquid pouring port member, and heating the lid member from the support substrate side to weld the welded portion of the lid member to the inner wall of the liquid pouring port frame, thereby sealing the liquid pouring port, The liquid inlet member has an inner wall of the liquid inlet frame made of resin L, and a portion of the liquid inlet frame other than the inner wall made of resin H, In the lid member, at least the outer peripheral surface of the welding portion is made of resin S, and the support substrate is made of material M, The method for manufacturing an electricity storage device, wherein the melting points Tm or glass transition temperatures Tg of the resins L, H, and S, and the heating temperatures in the sealing step satisfy the following conditions a, b, and c: a: The melting point Tm or the glass transition temperature Tg of the resin L is lower than the melting point Tm or the glass transition temperature Tg of the resin H. b: The melting point Tm or the glass transition temperature Tg of the resin S is lower than the melting point Tm or the glass transition temperature Tg of the resin H. c: The heating temperature in the sealing step is equal to or higher than the melting point Tm or glass transition temperature Tg of the resin L, equal to or higher than the melting point Tm or glass transition temperature Tg of the resin S, and lower than the melting point Tm or glass transition temperature Tg of the resin H.

2. The method for manufacturing an electricity storage device according to claim 1 , wherein the resin H is polypropylene, and the resin L and the resin S are polyethylene.

3. The method for manufacturing an electricity storage device according to claim 1 , wherein the welded portion includes a welded portion substrate and a resin S layer made of the resin S that covers the welded portion substrate.

4. The method for manufacturing a power storage device according to claim 1 , wherein the power storage device has a rectangular shape when viewed in the thickness direction, and the lengths of the sides of the rectangle are 1000 mm or more in length and 10000 mm or more in width.

5. An electricity storage device including: an electrode stack in which a plurality of bipolar electrodes are stacked with separators interposed therebetween; a sealing member that seals a peripheral edge portion of the electrode stack; and an electrolyte solution accommodated between the bipolar electrodes adjacent to each other in a stacking direction in the electrode stack, a liquid injection port member including a liquid injection port for injecting the electrolyte into an internal space between the adjacent bipolar electrodes and a liquid injection port frame surrounding the periphery of the liquid injection port; a lid member including a welding portion having a shape that follows the inner wall of the liquid filling port frame and a support substrate that supports the welding portion, the welding portion being welded to the inner wall of the liquid filling port frame, The liquid inlet member has an inner wall of the liquid inlet frame made of resin L, and a portion of the liquid inlet frame other than the inner wall made of resin H, In the lid member, at least the outer peripheral surface of the welding portion is made of resin S, and the support substrate is made of material M, The melting point Tm or the glass transition temperature Tg of each of the resins L, H, and S satisfies the following conditions a and b: a: The melting point Tm or the glass transition temperature Tg of the resin L is lower than the melting point Tm or the glass transition temperature Tg of the resin H. b: The melting point Tm or the glass transition temperature Tg of the resin S is lower than the melting point Tm or the glass transition temperature Tg of the resin H.

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