Electrode manufacturing method

Abstract

An electrode (11) manufacturing method comprises a placing step for placing a seal member (140) on an uncoated portion of a current collector (12), and a welding step for performing pressurized heating in which the seal member is heated while being pressed onto the uncoated portion using a jig (60), to thereby weld the seal member onto the current collector. The jig is provided with a heater portion (61) which is deformable and configured to heat the seal member, and a pressing portion (64) configured to press the heater portion onto the seal member. The placing step comprises placing the seal member on the uncoated portion in such a way that an exposed portion in which the seal member is not placed is formed in the uncoated portion. The welding step comprises performing heating in a state in which the heater portion is being pressed against the seal member and the exposed portion, while deforming the heater portion so as to follow compressive deformation of the pressing portion.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrode. [Background technology]

[0002] In an electricity storage device in which multiple electrodes are stacked, a sealing member may be welded to the current collector when manufacturing the electrode, for the purpose of insulating the current collectors from each other. For example, in the electrode manufacturing method described in Patent Document 1, the sealing member placed on the current collector is welded to the current collector by applying pressure and heat while a heater is pressed against the sealing member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-106963 Summary of the Invention [Problem to be solved by the invention]

[0004] When the seal member is welded to the current collector by applying pressure and heat to the seal member, the seal member expands as it is heated. When the heater is turned off during welding of the seal member to the current collector, the expanded seal member cools and contracts as it cools. If there is a large difference in the amount of contraction between the seal member and the current collector, the current collector may be compressed as the seal member contracts, which may cause wrinkles in the current collector. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided a method for manufacturing an electrode. The electrode includes a current collector having a first surface and a second surface opposite the first surface, active material layers provided on the first surface and the second surface, and a sealing member welded to the current collector. Each of the first surface and the second surface has a portion where the active material layer is provided and an uncoated portion where the active material layer is not provided. The manufacturing method includes a placement step of placing the sealing member on the uncoated portion of at least one of the first surface and the second surface, and a welding step of welding the sealing member to the current collector by applying pressure and heat to the sealing member while pressing the sealing member against the uncoated portion using a jig. The jig includes a deformable heater configured to heat the sealing member and a pressing portion configured to press the heater portion against the sealing member. The direction in which the pressing portion presses the sealing member is the pressing direction. The pressing portion is positioned alongside the heater portion and the sealing member in the pressing direction, and is configured to undergo compressive deformation in the pressing direction as the heater portion is pressed. The arranging step includes arranging the sealing member on the uncoated portion so that an exposed portion is formed in the uncoated portion, the exposed portion being a portion where the sealing member is not arranged and located between the active material layer and the sealing member. The welding step includes heating the heater portion while pressing it against the sealing member arranged in the uncoated portion and the exposed portion, while deforming the heater portion so as to follow the compressive deformation of the pressing portion.

[0006] According to the above method, the heater is deformed to follow the compressive deformation of the pressing portion, and the heater is pressed against the sealing member and the exposed portion while heating, thereby welding the sealing member to the current collector. Compared to applying pressure and heat only to the sealing member without applying pressure and heat to the exposed portion, the above method increases the amount of thermal expansion of the current collector due to heat transfer from the heater. This reduces the difference in the amount of thermal expansion between the sealing member and the current collector, thereby reducing the difference in the amount of contraction between the sealing member and the current collector due to cooling of the current collector and the sealing member. This reduces the occurrence of wrinkles in the current collector due to the difference in the amount of contraction between the sealing member and the current collector when the sealing member is welded to the current collector.

[0007] In the electrode manufacturing method, the jigs may be a pair of jigs located on both sides of the current collector in the pressing direction, and each of the pair of jigs may include the heater unit and the pressing unit. The placing step may include placing the sealing members on the uncoated portions of the first surface and the second surface. The welding step may include applying pressure and heat to the sealing members placed on the uncoated portions of the first surface and the second surface and the exposed portions of the first surface and the second surface using the pair of jigs.

[0008] According to the above method, the heater parts can be deformed to follow the compressive deformation of the pressing parts on both the first and second surfaces of the current collector, and the heater parts can be pressed against the sealing members and exposed parts while heating. As a result, the sealing members can be welded to the uncoated parts on both surfaces of the current collector by the heater parts and pressing parts.

[0009] In the method for manufacturing an electrode, the sealing member may include a main body portion disposed on the uncoated portion and a protrusion portion extending from the main body portion and protruding from an outer edge of the current collector. The welding step may include heating the sealing member while pressing the heater portion against the sealing member, except for at least a part of the protrusion portion.

[0010] According to the above method, the heater is pressed against the sealing member, except for at least a portion of the protrusion, and the sealing member is heated. Therefore, by heating the sealing member while the heater is pressed against the main body, the sealing member can be welded to the current collector. In this way, the sealing member can be welded to the current collector without applying pressure and heat to the entire protrusion with the heater. Therefore, the amount of thermal expansion of the sealing member can be reduced compared to when the entire sealing member is applied pressure and heat with the heater. As a result, the amount of contraction of the sealing member due to cooling can be reduced. Therefore, the difference in the amount of contraction between the sealing member and the current collector can be further reduced, further suppressing the occurrence of wrinkles in the current collector. [Effects of the Invention]

[0011] According to this invention, when the seal member is welded to the current collector, it is possible to suppress the occurrence of wrinkles in the current collector that would otherwise occur due to the difference in the amount of shrinkage between the seal member and the current collector. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of an electricity storage device according to an embodiment; [Figure 2] 2 is an enlarged cross-sectional view showing a part of the electricity storage device of FIG. 1. FIG. [Figure 3] 1. FIG. 3 is a diagram for explaining a method for manufacturing an electrode according to one embodiment, and is a top view showing a state in which a seal member is disposed on a current collector of an electrode that constitutes the electricity storage device of FIG. [Figure 4] FIG. 4 is a cross-sectional view illustrating a state before pressure and heat are applied to the current collector on which the sealing member of FIG. 3 is disposed, for explaining a method for manufacturing an electrode according to one embodiment. [Figure 5] 4 is a cross-sectional view illustrating a state in which pressure and heat are being applied to the current collector on which the sealing member of FIG. 3 is disposed, for explaining a method for manufacturing an electrode according to one embodiment. FIG. [Figure 6] 4 is a diagram for explaining a method for manufacturing an electrode according to one embodiment, and is a cross-sectional view showing the electrode in a state in which the sealing member of FIG. 3 has been integrated by applying pressure and heat. FIG. [Figure 7]7 is a cross-sectional view illustrating a laminate in a state in which the electrodes, separators, and spacers of FIG. 6 are stacked, illustrating a method for manufacturing an electricity storage device according to one embodiment. FIG. [Figure 8] FIG. 4 is a cross-sectional view illustrating a state before pressure and heat are applied to the current collector on which the sealing member of FIG. 3 is disposed, for explaining a method for manufacturing an electrode according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the electrode manufacturing method will be described below with reference to Figures 1 to 7. For convenience of explanation, the electricity storage device and the electrode will be described first before the electrode manufacturing method.

[0014] <Electricity storage device> As shown in Fig. 1, the energy storage device 10 includes a laminate 10a and a sealing body 15. The laminate 10a is configured by stacking a plurality of electrodes 11 between a positive terminal electrode 36 and a negative terminal electrode 37. The energy storage device 10 in this embodiment is a lithium ion secondary battery. Hereinafter, the direction in which the plurality of electrodes 11 are stacked will be simply referred to as the stacking direction X.

[0015] <Electrode> As shown in FIGS. 1 and 2 , each of the multiple electrodes 11 includes a current collector 12, a positive electrode active material layer 23 as an active material layer, and a negative electrode active material layer 33 as an active material layer. The current collector 12 is sheet-shaped. Active material layers are provided on both sides of the current collector 12. The current collector 12 has a first surface 12a and a second surface 12b that face opposite to each other in the stacking direction X. The first surface 12a of the current collector 12 is provided with a positive electrode active material layer 23, and the second surface 12b is provided with a negative electrode active material layer 33. Each of the multiple electrodes 11 is a bipolar electrode formed by such a current collector 12. In the stack 10a, the multiple electrodes 11 are stacked such that the first surface 12a of the current collector 12 of one of two electrodes 11 adjacent to each other in the stacking direction X faces the second surface 12b of the current collector 12 of the other electrode 11.

[0016] In a plan view seen from the stacking direction X (hereinafter simply referred to as a plan view), the positive electrode active material layer 23 is formed in the central portion of the first surface 12a of the current collector 12. In the plan view, the peripheral portion of the first surface 12a of the current collector 12 is a positive electrode uncoated portion 12c that is an uncoated portion where the positive electrode active material layer 23 is not provided. The positive electrode uncoated portion 12c is arranged so as to surround the periphery of the positive electrode active material layer 23 in the plan view. In the plan view, the negative electrode active material layer 33 is formed in the central portion of the second surface 12b of the current collector 12. In the plan view, the peripheral portion of the second surface 12b of the current collector 12 is a negative electrode uncoated portion 12d that is an uncoated portion where the negative electrode active material layer 33 is not provided. The negative electrode uncoated portion 12d is arranged so as to surround the periphery of the negative electrode active material layer 33 in the plan view.

[0017] The positive electrode active material layer 23 and the negative electrode active material layer 33 are disposed so as to face each other in the stacking direction X. The negative electrode active material layer 33 is formed, for example, to be slightly larger than the positive electrode active material layer 23. In a plan view, the entire region where the positive electrode active material layer 23 is formed is located within the region where the negative electrode active material layer 33 is formed.

[0018] <Current collector details> In this embodiment, the current collector 12 is formed by integrating a sheet-shaped positive electrode current collector 22 and a sheet-shaped negative electrode current collector 32. The first surface 12a of the current collector 12 is formed by one surface of the positive electrode current collector 22, and the second surface 12b is formed by one surface of the negative electrode current collector 32. The positive electrode current collector 22 and the negative electrode current collector 32 may be integrated by bonding the surface of the positive electrode current collector 22 opposite the first surface 12a to the surface of the negative electrode current collector 32 opposite the second surface 12b. The positive electrode current collector 22 and the negative electrode current collector 32 have the same shape in a plan view.

[0019] 3, current collector 12 has four sides 12f and is rectangular in plan view. Outer edge 12e of current collector 12 is formed by the four sides 12f. Two of sides 12f are also referred to as short sides 12g, and the two sides 12f longer than short sides 12g are also referred to as long sides 12h.

[0020] 1, the positive electrode current collector 22 and the negative electrode current collector 32 are chemically inactive electrical conductors that allow current to continue to flow through the positive electrode active material layer 23 and the negative electrode active material layer 33 during charging or discharging of the lithium-ion secondary battery. The positive electrode current collector 22 and the negative electrode current collector 32 may be made of a material such as a metal material, a conductive resin material, or a conductive inorganic material.

[0021] The conductive resin material may be, for example, a resin obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as needed. The positive electrode current collector 22 and the negative electrode current collector 32 may have multiple layers, including one or more layers containing a metal material or a conductive resin material. The surfaces of the positive electrode current collector 22 and the negative electrode current collector 32 may be coated with a known protective layer. The surfaces of the positive electrode current collector 22 and the negative electrode current collector 32 may be metal-plated by a known method such as plating.

[0022] The positive electrode current collector 22 and the negative electrode current collector 32 may have the form of, for example, a foil, a sheet, a film, a wire, a rod, a mesh, or a clad material. When the positive electrode current collector 22 and the negative electrode current collector 32 are metal foils, the positive electrode current collector 22 and the negative electrode current collector 32 may be, for example, aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The positive electrode current collector 22 and the negative electrode current collector 32 may be alloy foils of the above metals. When the positive electrode current collector 22 and the negative electrode current collector 32 are metal foils, the thickness of the positive electrode current collector 22 and the negative electrode current collector 32 is, for example, 1 to 100 μm. The positive electrode current collector 22 of this embodiment is aluminum foil. The negative electrode current collector 32 of this embodiment is copper foil. In order to improve the structural stability of the laminate 10a, for example, the current collectors 12 of the positive terminal electrode 36 and the negative terminal electrode 37, and some of the current collectors 12 of the multiple electrodes 11 consisting of bipolar electrodes, may have a thickness of 100 μm or more.

[0023] The current collector 12 is not limited to a configuration in which the positive electrode current collector 22 and the negative electrode current collector 32 are integrated, and may be a single sheet-like current collector made of a metal material, a conductive resin material, a conductive inorganic material, or the like. The current collector 12 may also be a single sheet-like current collector in which a coating layer is formed on one surface by plating or the like. In these cases, the single current collector 12 functions as both the positive electrode current collector 22 and the negative electrode current collector 32.

[0024] <Details of the positive electrode active material layer and the negative electrode active material layer> The positive electrode active material layer 23 includes a positive electrode active material capable of absorbing and releasing lithium ions as a charge carrier. The positive electrode active material may be, for example, a polyanion compound such as olivine-type lithium iron phosphate (LiFePO4), a lithium composite metal oxide having a layered rock salt structure, or a metal oxide having a spinel structure. The positive electrode active material used is one that can be used as a positive electrode active material for the power storage device 10, such as a lithium-ion secondary battery.

[0025] The negative electrode active material layer 33 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be any element, alloy, or compound capable of absorbing and releasing charge carriers such as lithium ions, without any particular limitations. For example, the negative electrode active material may be Li, carbon, a metal compound, an element capable of alloying with lithium, or a compound thereof. The carbon may be, for example, natural graphite, artificial graphite, hard carbon (non-graphitizable carbon), or soft carbon (easily graphitizable carbon). The artificial graphite may be, for example, highly oriented graphite or mesocarbon microbeads. The element capable of alloying with lithium may be, for example, silicon or tin.

[0026] The positive electrode active material layer 23 and the negative electrode active material layer 33 may contain other components, such as a conductive additive for improving electrical conductivity, a binder, an electrolyte (polymer matrix, ion-conductive polymer, liquid electrolyte, etc.), an electrolyte supporting salt (lithium salt) for improving ion conductivity, etc. The types and blending ratios of other components contained in the positive electrode active material layer 23 and the negative electrode active material layer 33 are not particularly limited.

[0027] The conductive additive may be, for example, acetylene black, carbon black, or graphite. The binder may be, for example, a fluorine-containing resin such as polyvinylidene fluoride, polytetrafluoroethylene, or fluorine rubber; a thermoplastic resin such as polypropylene or polyethylene; an imide resin such as polyimide or polyamideimide; an alkoxysilyl group-containing resin; an acrylic resin such as poly(meth)acrylic acid; styrene-butadiene rubber; carboxymethyl cellulose; an alginate such as sodium alginate or ammonium alginate; a water-soluble cellulose ester crosslinked product; or a starch-acrylic acid graft polymer. These binders may be used alone or in combination. The solvent or dispersion medium may be, for example, water, N-methyl-2-pyrrolidone, or the like.

[0028] <Separator> The electricity storage device 10 includes a separator 35. The separator 35 is disposed between the positive electrode active material layer 23 and the negative electrode active material layer 33. The separator 35 is a member that separates the positive electrode active material layer 23 and the negative electrode active material layer 33 to prevent a short circuit due to contact between the two electrodes, while allowing charge carriers such as lithium ions to pass through.

[0029] The separator 35 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains an electrolyte. The electrolyte impregnated in the separator 35 may be, for example, a liquid electrolyte containing a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent, or a polymer gel electrolyte containing an electrolyte retained in a polymer matrix. In this embodiment, a liquid electrolyte is used as the electrolyte. The electrolyte salt of the liquid electrolyte may be a known lithium salt such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, or LiN(CF3SO2)2. The nonaqueous solvent may be a known solvent such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, or ethers. Two or more of these known solvent materials may be used in combination. The material constituting the separator 35 may be, for example, polypropylene, polyethylene, polyolefin, or polyester. The separator 35 may have a single-layer structure or a multi-layer structure. The multi-layer structure may include, for example, an adhesive layer and a ceramic layer that is a heat-resistant layer.

[0030] <Positive and negative terminal electrodes> In the stacking direction X, the multiple electrodes 11 are located between a positive terminal electrode 36 and a negative terminal electrode 37. The positive terminal electrode 36 has a current collector 12 and a positive electrode active material layer 23 provided on a first surface 12a of the current collector 12, and is configured similarly to the electrode 11 except that it does not have the negative electrode active material layer 33. The negative terminal electrode 37 has a current collector 12 and a negative electrode active material layer 33 provided on a second surface 12b of the current collector 12, and is configured similarly to the electrode 11 except that it does not have the positive electrode active material layer 23. The current collector 12 of the positive terminal electrode 36 is located at one end of the stack 10a in the stacking direction X. The current collector 12 of the negative terminal electrode 37 is located at the other end of the stack 10a in the stacking direction X.

[0031] The second surface 12b of the current collector 12 of the positive terminal electrode 36 constitutes a first outer surface 32a, which is an outer surface located at one end of the stacking direction X of the laminate 10a. The first surface 12a of the current collector 12 of the negative terminal electrode 37 constitutes a second outer surface 22a, which is an outer surface located at the other end of the stacking direction X of the laminate 10a. The first outer surface 32a and the second outer surface 22a are flat surfaces extending perpendicular to the stacking direction X.

[0032] <Interior space> An internal space S is located between two current collectors 12 adjacent to each other in the stacking direction X. The internal space S is defined by the positive electrode current collector 22 and the negative electrode current collector 32 adjacent to each other in the stacking direction X, and the sealing body 15. One internal space S is defined for each pair of the positive electrode current collector 22 and the negative electrode current collector 32 adjacent to each other in the stacking direction X. In the internal space S, a positive electrode active material layer 23, a negative electrode active material layer 33, a separator 35, and a liquid electrolyte (not shown) are arranged. The liquid electrolyte is, for example, a so-called electrolytic solution containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0033] <Positive and negative conductive plates> The energy storage device 10 includes a positive electrode current-carrying plate 38 and a negative electrode current-carrying plate 39. The positive electrode current-carrying plate 38 and the negative electrode current-carrying plate 39 are made of a material with excellent conductivity. The material making up the positive electrode current-carrying plate 38 and the negative electrode current-carrying plate 39 may be a metal material such as aluminum, copper, or stainless steel. The stack 10a is disposed between the positive electrode current-carrying plate 38 and the negative electrode current-carrying plate 39 in the stacking direction X.

[0034] The positive electrode current-carrying plate 38 is electrically connected to the first outer surface 32a of the laminate 10a. The negative electrode current-carrying plate 39 is electrically connected to the second outer surface 22a of the laminate 10a. Terminals (not shown) are provided on each of the positive electrode current-carrying plate 38 and the negative electrode current-carrying plate 39. The energy storage device 10 is charged and discharged via the terminals provided on the positive electrode current-carrying plate 38 and the negative electrode current-carrying plate 39.

[0035] <Sealing body> The sealing body 15 is disposed so as to surround the periphery of the positive electrode active material layers 23 and negative electrode active material layers 33 of the multiple electrodes 11, the positive electrode terminal electrode 36, and the negative electrode terminal electrode 37, as viewed from the stacking direction X. Hereinafter, the electrodes 11, the positive electrode terminal electrode 36, and the negative electrode terminal electrode 37 may be simply referred to as electrodes 11a. The sealing body 15 seals the gap between adjacent current collectors 12 in the stacking direction X.

[0036] As shown in FIG. 2, the sealing body 15 has a plurality of seal portions 40 welded to the current collectors 12 of the plurality of electrodes 11a. That is, each of the plurality of electrodes 11a has a seal portion 40. The seal portions 40 are made of resin. Each of the seal portions 40 has two first seal portions 41 and a second seal portion 42. The first seal portion 41 is a portion disposed between the first surface 12a of the current collector 12 of one of the electrodes 11a adjacent to each other in the stacking direction X and the second surface 12b of the current collector 12 of the other electrode 11a. That is, the first seal portion 41 is disposed inside the outer edge 12e of the current collector 12 as viewed from the stacking direction X. The two first seal portions 41 are disposed on both sides of each current collector 12 in the stacking direction X. The two first seal portions 41 are welded to the first surface 12a and the second surface 12b of the current collector 12. The two first seal portions 41 are welded to the first surface 12a and the second surface 12b via weld portions 41a. The two first seal portions 41 are welded to the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d. In other words, the seal portions 40 are welded to the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, which are uncoated portions.

[0037] The first sealing portion 41 located on the positive electrode uncoated portion 12c is arranged so as to surround the periphery of the positive electrode active material layer 23. The first sealing portion 41 located on the negative electrode uncoated portion 12d is arranged so as to surround the periphery of the negative electrode active material layer 33. The first sealing portion 41 has a rectangular frame shape.

[0038] The first seal portion 41 located on the positive electrode uncoated portion 12c is spaced apart from the positive electrode active material layer 23. As a result, a portion of the positive electrode uncoated portion 12c becomes a positive electrode exposed portion 17 where the positive electrode active material layer 23 and the first seal portion 41 are not disposed. The positive electrode exposed portion 17, which is an exposed portion, is a portion of the positive electrode uncoated portion 12c, which is an uncoated portion, where the positive electrode active material layer 23, which is an active material layer, and the seal portion 40 are not disposed. The positive electrode exposed portion 17 is located between the positive electrode active material layer 23 and the seal portion 40. The positive electrode exposed portion 17 has a rectangular frame shape in a plan view. The positive electrode exposed portion 17 is located so as to surround the positive electrode active material layer 23 from the outside, and is located more inward than the first seal portion 41 located on the positive electrode uncoated portion 12c.

[0039] The first seal portion 41 located on the negative electrode uncoated portion 12d is spaced apart from the negative electrode active material layer 33. As a result, a part of the negative electrode uncoated portion 12d becomes a negative electrode exposed portion 18 where the negative electrode active material layer 33 and the first seal portion 41 are not located. The negative electrode exposed portion 18, which is an exposed portion, is a portion of the negative electrode uncoated portion 12d, which is an uncoated portion, where the negative electrode active material layer 33, which is an active material layer, and the seal portion 40 are not located. The negative electrode exposed portion 18 is located between the negative electrode active material layer 33 and the seal portion 40. The negative electrode exposed portion 18 has a rectangular frame shape in a plan view. The negative electrode exposed portion 18 is located so as to surround the negative electrode active material layer 33 from the outside, and is located more inward than the first seal portion 41 located on the negative electrode uncoated portion 12d.

[0040] The second seal portion 42 is a portion that extends from the first seal portion 41 outward beyond the outer edge 12e of the current collector 12. More specifically, the second seal portion 42 is a portion that is located outside the outer edge 12e of the current collector 12 when viewed from the stacking direction X. The second seal portion 42 is arranged so as to surround the periphery of the current collector 12 when viewed from the stacking direction X. The second seal portion 42 has a rectangular frame shape. The second seal portion 42 covers the end face that connects the first surface 12a and the second surface 12b of the current collector 12. The second seal portion 42 connects the outer periphery of the first seal portion 41 located on the positive electrode uncoated portion 12c to the outer periphery of the first seal portion 41 located on the negative electrode uncoated portion 12d.

[0041] The sealing body 15 has a plurality of spacer portions 50. The plurality of spacer portions 50 are made of resin. Each spacer portion 50 is sandwiched between adjacent current collectors 12 in the stacking direction X, between a first seal portion 41 located on the positive electrode uncoated portion 12c and a first seal portion 41 located on the negative electrode uncoated portion 12d. As a result, the spacer portion 50 is sandwiched between the first seal portions 41 between adjacent current collectors 12 in the stacking direction X. The spacer portion 50 is arranged so as to surround the periphery of the positive electrode active material layer 23 and the negative electrode active material layer 33 when viewed from the stacking direction X. The spacer portion 50 has a rectangular frame shape.

[0042] In the embodiment, both surfaces of the spacer portion 50 in the stacking direction X are not welded to the first seal portion 41. Both surfaces of the spacer portion 50 in the stacking direction X may be in contact with the first seal portion 41 or may be separated from the first seal portion 41.

[0043] The first seal portion 41 and the spacer portion 50 are positioned between adjacent current collectors 12 in the stacking direction X. As a result, the first seal portion 41 and the spacer portion 50 maintain a gap between the positive electrode current collector 22 of one of the two current collectors 12 adjacent to each other in the stacking direction X and the negative electrode current collector 32 of the other current collector 12, thereby providing insulation. In this way, the seal portion 40 and the spacer portion 50 prevent a short circuit between the positive electrode current collector 22 and the negative electrode current collector 32.

[0044] The sealing body 15 has a sealing portion 16. The sealing portion 16 is made of resin. The sealing portion 16 has a cylindrical shape extending in the stacking direction X. The sealing portion 16 is positioned so as to surround the seal portion 40, the spacer portion 50, and the plurality of current collectors 12 from the outside of the stack 10a.

[0045] The sealing portion 16 seals the internal space S between the current collectors 12 adjacent to each other in the stacking direction X. The sealing portion 16 can prevent moisture from entering the internal space S from the outside of the electricity storage device 10. The sealing portion 16 can prevent the liquid electrolyte accommodated in the internal space S from leaking out of the electricity storage device 10.

[0046] <Method of manufacturing electrode and electricity storage device> Next, a description will be given of a method for manufacturing the electrode 11 and the electricity storage device 10. Note that although the following description will be given using the electrode 11, the positive terminal electrode 36 and the negative terminal electrode 37 are also manufactured in the same manner.

[0047] As shown in FIG. 4 , when manufacturing the electrode 11, a sealing member 140 is placed on a current collector 12 having a positive electrode active material layer 23 and a negative electrode active material layer 33. Next, in the method of manufacturing the electrode 11, a pair of jigs 60 is used to weld the sealing member 140 to the current collector 12 having the positive electrode active material layer 23 and the negative electrode active material layer 33, which are active material layers, provided on both sides. The sealing member 140 is welded to the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, which are uncoated portions, using the jigs 60. The manufactured electrode 11 has the current collector 12 having active material layers provided on both sides thereof, and the sealing member 140 welded to the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, which are uncoated portions of the current collector 12.

[0048] The sealing member 140 is a precursor of the sealing portion 40 and the sealing portion 16. The sealing member 140 is disposed on each of the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d of the current collector 12. The current collector 12 is sandwiched between the two sealing members 140 from both sides in the thickness direction of the current collector 12. The sealing member 140 protrudes outward from the current collector 12 beyond the outer edge 12e of the current collector 12. In other words, when viewed from the direction in which the current collector 12 and the sealing members 140 are stacked, each sealing member 140 is disposed on the current collector 12 so as to have both a portion that overlaps with the current collector 12 and a portion that does not overlap with the current collector 12.

[0049] The sealing member 140 disposed on the positive electrode uncoated portion 12c is also referred to as a first sealing member 141. The first sealing member 141 is positioned so as to surround the periphery of the positive electrode active material layer 23. The sealing member 140 disposed on the negative electrode uncoated portion 12d is also referred to as a second sealing member 142. The second sealing member 142 is positioned so as to surround the periphery of the negative electrode active material layer 33. In other words, the sealing members 140 are disposed on both sides of the current collector 12 so as to surround the positive electrode active material layer 23 and the negative electrode active material layer 33.

[0050] The seal member 140 has a protruding portion 140b that protrudes from the outer edge 12e of the current collector 12. The protruding portion 140b of the first seal member 141 and the protruding portion 140b of the second seal member 142 are separated from each other. The portion of the seal member 140 that is disposed on the uncoated portion of the current collector 12 is referred to as a main body portion 140a. The first seal member 141 and the second seal member 142 each have a main body portion 140a and a protruding portion 140b. The main body portion 140a of the first seal member 141 is the portion of the first seal member 141 that is disposed on the positive electrode uncoated portion 12c. The main body portion 140a of the second seal member 142 is the portion of the second seal member 142 that is disposed on the negative electrode uncoated portion 12d. In the first seal member 141 and the second seal member 142, the protruding portion 140b extends from the main body portion 140a. The protruding portion 140b of the first seal member 141 is a portion of the first seal member 141 that is not located on the positive electrode uncoated portion 12c. The protruding portion 140b of the second seal member 142 is a portion of the second seal member 142 that is not located on the negative electrode uncoated portion 12d.

[0051] The main body portion 140a of the first seal member 141 is separated from the positive electrode active material layer 23. As a result, a part of the positive electrode uncoated portion 12c becomes a positive electrode exposed portion 17 where the positive electrode active material layer 23 and the first seal member 141 are not disposed. The positive electrode exposed portion 17 has a frame shape in a plan view. In a plan view, the positive electrode exposed portion 17 is located outside the positive electrode active material layer 23 and inside the first seal member 141.

[0052] The main body portion 140a of the second seal member 142 is separated from the negative electrode active material layer 33. As a result, part of the negative electrode uncoated portion 12d becomes the negative electrode exposed portion 18 where the negative electrode active material layer 33 and the second seal member 142 are not disposed. The negative electrode exposed portion 18 has a frame shape in plan view. In plan view, the negative electrode exposed portion 18 is located on the outer side of the negative electrode active material layer 33 and on the inner side of the second seal member 142.

[0053] In the present embodiment, the positive electrode exposed portion 17 and the negative electrode exposed portion 18 are portions of the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, which are uncoated portions, where the active material layer and the sealing member 140 are not disposed, and are portions located between the active material layer and the sealing member 140. The positive electrode exposed portion 17 and the negative electrode exposed portion 18 in the present embodiment correspond to exposed portions.

[0054] The portion of the positive electrode uncoated portion 12c where the sealing member 140 is disposed is referred to as the positive electrode covering portion 19. In a plan view, the positive electrode covering portion 19 is frame-shaped and is located outside the positive electrode exposed portion 17. The positive electrode uncoated portion 12c is composed of the positive electrode exposed portion 17 and the positive electrode covering portion 19. The positive electrode exposed portion 17 and the positive electrode covering portion 19 are adjacent to each other.

[0055] The portion of the negative electrode uncoated portion 12d where the sealing member 140 is disposed is referred to as the negative electrode covering portion 20. In a plan view, the negative electrode covering portion 20 is frame-shaped and is located outside the negative electrode exposed portion 18. The negative electrode uncoated portion 12d is composed of the negative electrode exposed portion 18 and the negative electrode covering portion 20. The negative electrode exposed portion 18 and the negative electrode covering portion 20 are adjacent to each other.

[0056] As shown in FIG. 3, the seal member 140 is arranged to extend along the side 12f of the current collector 12. More specifically, the seal member 140 is arranged to extend along each of the two long sides 12h and the two short sides 12g of the current collector 12. The seal member 140 includes four seal member pieces that are separate from one another and are arranged along the four sides 12f. Each seal member piece has a longitudinal direction along the corresponding side 12f and a transverse direction intersecting the corresponding side 12f. One seal member piece in the first seal member 141 and one seal member piece in the second seal member 142 are arranged along one side 12f.

[0057] The sealing member pieces may be arranged so that their longitudinal ends overlap each other, or may not overlap. In this embodiment, the longitudinal ends of the sealing member pieces arranged along the long sides 12h and the longitudinal ends of the sealing member pieces arranged along the short sides 12g overlap each other. In the sealing members 140 arranged on each of the first surface 12a and the second surface 12b, the sealing member pieces arranged along the long sides 12h and the short sides 12g are arranged to form a frame. The negative electrode active material layer 33 is surrounded by a second sealing member 142 including sealing member pieces arranged along the long sides 12h and short sides 12g. Although not shown in FIG. 3, the positive electrode active material layer 23 is surrounded by a first sealing member 141 including sealing member pieces arranged along the long sides 12h and short sides 12g.

[0058] In this embodiment, a pair of jigs 60 is used to weld the sealing member pieces arranged along the two long sides 12h of the current collector 12 to both sides of the current collector 12. Then, a pair of jigs 60 is used to weld the sealing member pieces arranged along the two short sides 12g of the current collector 12 to both sides of the current collector 12. The long side welding process, in which the sealing member pieces arranged along the two long sides 12h of the current collector 12 are welded to both sides of the current collector 12, may be performed on both sides simultaneously or one side at a time. The short side welding process, in which the sealing member pieces arranged along the two short sides 12g of the current collector 12 are welded to both sides of the current collector 12, may be performed on both sides simultaneously or one side at a time. The long side welding process and the short side welding process may be performed in either order.

[0059] As shown in FIG. 4 , each of the pair of jigs 60 includes a heater portion 61 and a pressing portion 64. The heater portion 61 is, for example, a metal plate with a built-in heating wire (not shown). The heater portion 61 can be switched on and off by adjusting the amount of current flowing through the heating wire. The heater portion 61 heats the sealing member 140 and is deformable. The pressing portion 64 presses the heater portion 61 against the sealing member 140 so that the sealing member 140 is pressed against the current collector 12. Hereinafter, the direction in which the pressing portion 64 presses the sealing member 140 is referred to as the pressing direction D. In other words, the pressing direction D is a direction perpendicular to the first surface 12a and the second surface 12b and extends from the jig 60 toward the sealing member 140. The pressing portion 64 includes a rubber portion 62 and a base portion 63. The rubber portion 62 is made of, for example, silicone rubber. The rubber portion 62 is positioned so as to overlap the heater portion 61 in the pressing direction D. That is, the pressing portion 64 is positioned so as to overlap the heater portion 61 in the pressing direction D. As a result, the pressing portion 64 is positioned side by side with the heater portion 61 and the sealing member 140 in the pressing direction D. The heater portion 61 is fixed to the rubber portion 62. The rubber portion 62 is compressively deformable.

[0060] The base portion 63 is made of, for example, metal. The rubber portion 62 is located between the base portion 63 and the heater portion 61. As a result, the rubber portion 62 insulates the base portion 63 from the heater portion 61. The rubber portion 62 suppresses heat transfer from the heater portion 61 to the base portion 63. The rubber portion 62 is fixed to the base portion 63. As a result, the heater portion 61 and the pressing portion 64 are integrated together. An operator operates an operating device (not shown) to change the position of the base portion 63 relative to the sealing member and current collecting foil, which are the objects to be welded. In other words, the base portion 63 is configured to be displaceable relative to the objects to be welded. When the position of the base portion 63 relative to the objects to be welded is changed, the heater portion 61 and the rubber portion 62, which are integrated with the base portion 63, are displaced together with the base portion 63.

[0061] When welding the seal member 140 to the current collector 12, a pair of jigs 60 are provided on both sides of the current collector 12 in the thickness direction so as to face the seal member 140. The thickness direction of the current collector 12 coincides with the pressing direction D. Hereinafter, the heater portion 61 disposed on the side of the current collector 12 facing the first surface 12a will also be referred to as the first heater portion 61a, and the heater portion 61 disposed on the side of the current collector 12 facing the second surface 12b will also be referred to as the second heater portion 61b. The heater portion 61 is provided at a position spaced apart from the positive electrode active material layer 23 and the negative electrode active material layer 33 in a direction perpendicular to the pressing direction D. The first heater portion 61a faces the positive electrode exposed portion 17 and the first seal member 141, and the second heater portion 61b faces the negative electrode exposed portion 18 and the second seal member 142. The pair of jigs 60 are displaced so that their respective base portions 63 approach the opposing sealing members 140, and as a result, the jigs 60 are displaced so that they approach each other with the sealing members 140 and the current collector 12 sandwiched therebetween.

[0062] 5, when the heater portion 61 moves to a predetermined position, the displacement of the base portion 63 stops, and the displacement of the pair of jigs 60 also stops. At this time, the first heater portion 61a abuts against the positive electrode exposed portion 17 and the first seal member 141. The second heater portion 61b abuts against the negative electrode exposed portion 18 and the second seal member 142.

[0063] The first heater portion 61a is pressed against the main body portion 140a of the first seal member 141 and the positive electrode exposed portion 17. The second heater portion 61b is pressed against the main body portion 140a of the second seal member 142 and the negative electrode exposed portion 18. The first heater portion 61a is pressed against a portion of the protruding portion 140b of the first seal member 141 that is connected to the main body portion 140a. The second heater portion 61b is pressed against a portion of the protruding portion 140b of the second seal member 142 that is connected to the main body portion 140a. Portions of the protruding portions 140b of the first seal member 141 and the second seal member 142 that are distant from the main body portion 140a are not pressed by the heater portion 61. That is, in this embodiment, the heater portion 61 is pressed against the seal member 140 except for a portion of the protruding portion 140b. In this embodiment, the pair of jigs 60 are displaced toward each other to sandwich the sealing member 140 and the current collector 12, and in this state, the heater portion of each jig is pressed against the sealing member 140 and the exposed portion. Therefore, one of the pair of jigs 60 also functions as a support member that receives the pressing force of the other jig.

[0064] The first heater portion 61a deforms from the first seal member 141 to the positive electrode exposed portion 17 and comes into contact therewith. The second heater portion 61b deforms from the second seal member 142 to the negative electrode exposed portion 18 and comes into contact therewith. The pressing portion 64 presses the heater portion 61 against the seal member 140. As the heater portion 61 is pressed against the seal member 140, the rubber portion 62 is compressively deformed in the pressing direction D. In detail, the portion of the rubber portion 62 that overlaps with the portion of the heater portion 61 that contacts the seal member 140 is compressively deformed to a greater extent than the portions of the rubber portion 62 that overlap with the portions of the heater portion 61 that contact the positive electrode exposed portion 17 and the negative electrode exposed portion 18. The rubber portion 62 is compressively deformed while the base portion 63 suppresses displacement of the rubber portion 62. In this way, as the heater portion 61 presses against the seal member 140, the pressing portion 64 is compressively deformed in the pressing direction D. The pressing portion 64 pressing the first heater portion 61a can apply uniform surface pressure to the first seal member 141 and the positive electrode exposed portion 17, and the pressing portion 64 pressing the second heater portion 61b can apply uniform surface pressure to the second seal member 142 and the negative electrode exposed portion 18.

[0065] 5 and 6 , the heater section 61 is heated in a state in which the heater section 61 is in contact with the sealing member 140, the positive electrode exposed portion 17, and the negative electrode exposed portion 18. Heating of the heater section 61 may start before or after the heater section 61 is in contact with the sealing member 140, the positive electrode exposed portion 17, and the negative electrode exposed portion 18. Pressurized heating is performed in which the heater section 61 is pressed against the first sealing member 141 and the second sealing member 142, which are the sealing member 140 arranged in the uncoated portion, and the positive electrode exposed portion 17 and the negative electrode exposed portion 18, which are the exposed portions, while deforming the heater section 61 so as to follow the compressive deformation of the pressing section 64. The sealing member 140 disposed on the uncoated portions on both sides of the current collector 12 and the positive electrode exposed portion 17 and the negative electrode exposed portion 18, which are exposed portions on both sides of the current collector 12, are pressurized and heated using a pair of jigs 60, thereby welding the sealing member 140 to both sides of the current collector 12. The heating and pressurization of the positive electrode exposed portion 17 and the negative electrode exposed portion 18 by the heater unit 61 and the heating and pressurization of the sealing member 140 by the heater unit 61 are started at the same time. This causes the sealing member 140 to be welded to the current collector 12. As a result, a first seal portion 41 welded to the current collector 12 is formed.

[0066] The pair of jigs 60 heats the main body 140a of each of the first seal member 141 and the second seal member 142 with the heater portion 61 pressed against the main body 140a. As a result, the main body 140a of the first seal member 141 is welded to the positive electrode cover portion 19. Furthermore, the main body 140a of the second seal member 142 is welded to the negative electrode cover portion 20. Welded portions 41a are formed at the boundary between the main body 140a of the first seal member 141 and the positive electrode cover portion 19, and at the boundary between the main body 140a of the second seal member 142 and the negative electrode cover portion 20. By welding the seal member 140 to the current collector 12 in this way, an electrode 11 is formed in which the current collector 12 and the seal member 140 are integrated.

[0067] Furthermore, the jig 60 also heats the portions of the protruding portions 140b of the first seal member 141 and the second seal member 142 that are connected to the main body portion 140a while pressing the heater portion 61 against them. As a result, the portions of the protruding portions 140b of the first seal member 141 and the second seal member 142 that have been pressurized and heated by the heater portion 61 melt and connect to each other, thereby forming the second seal portion 42. After the second seal portion 42 is formed, the first seal member 141 and the second seal member 142 are integrated into a single seal member 140.

[0068] The portion of the protruding portion 140b that is separated from the main body portion 140a does not melt because it is not subjected to pressure heating by the heater portion 61. That is, in this embodiment, the heater portion 61 is pressed against the sealing member 140 and heated, except for a portion of the protruding portion 140b.

[0069] Once the welded portion 41a is formed, the welding process of the seal member 140 to the current collector 12 by the pair of jigs 60 is completed. The welding process of the seal member 140 to the current collector 12 by the pair of jigs 60 is completed by stopping the heating of the heater unit 61. The heating and pressurization of the positive electrode exposed portion 17 and the negative electrode exposed portion 18 by the heater unit 61 and the heating and pressurization of the seal member 140 by the heater unit 61 are completed at the same time. It is preferable to maintain the sandwiched state of the seal member 140 and the current collector 12 by the pair of jigs 60 until the welded portion 41a is completely cooled, but the pair of jigs 60 may be displaced so that the heater unit 61 moves away from the seal member 140 when the heating of the heater unit 61 is stopped.

[0070] As the welding process of the sealing member 140 to the current collector 12 using the pair of jigs 60 is completed, the welded portion 41a is cooled, thereby completing the welding of the sealing member 140 to the current collector 12. This welding of the sealing members 140 to the current collector 12 is performed on the sealing members 140 arranged on all sides 12f of the current collector 12. By repeatedly welding the sealing members 140 to the current collector 12 using the pair of jigs 60, electrodes 11 in which the current collector 12 and the sealing members 140 are integrated are sequentially formed.

[0071] As shown in FIG. 7, an electrode 11a integrated with a sealing member 140, a separator 35, and a spacer portion 50 are sequentially stacked in the stacking direction X. Of two electrodes 11a adjacent to each other in the stacking direction X, the separator 35 is interposed between the positive electrode active material layer 23 of one electrode 11a and the negative electrode active material layer 33 of the other electrode 11a. This forms a stacked body 10a. Of two electrodes 11a adjacent to each other in the stacking direction X, a spacer portion 50 is interposed between the sealing member 140 integrated with one electrode 11a and the sealing member 140 integrated with the other electrode 11a.

[0072] Next, the sealing member 140 and the spacer portion 50 are welded together. The welding of the sealing member 140 and the spacer portion 50 may be performed without contact using, for example, a welding jig 70. The welding jig 70 is, for example, an infrared heater. In this case, the welding jig 70 is placed facing the sealing member 140 and the spacer portion 50 from the outside of the laminate 10a while being spaced apart in a direction intersecting with the stacking direction X. The protruding portion 140b of the sealing member 140 and a part of the spacer portion 50 are heated and melted by the infrared rays irradiated from the welding jig 70.

[0073] 2 and 7, when the spacer portion 50 and the protruding portion 140b are melted by the welding jig 70, the portion of the spacer portion 50 that overlaps with the protruding portion 140b in the stacking direction X and the protruding portion 140b are welded to each other, thereby forming the sealing portion 16. The portion of the seal member 140 that does not form the sealing portion 16 corresponds to the sealing portion 40 of the energy storage device 10.

[0074] [Action and effect] According to the above embodiment, the following actions and effects can be obtained. (1) In the manufacturing method of the electrode 11 of this embodiment, the sealing member 140 disposed in the positive electrode uncoated portion 12c of the current collector 12 and the positive electrode exposed portion 17, which is a portion of the positive electrode uncoated portion 12c of the current collector 12 where the positive electrode active material layer 23 and the sealing member 140 are not disposed, are pressurized and heated. The sealing member 140 disposed in the negative electrode uncoated portion 12d of the current collector 12 and the negative electrode exposed portion 18, which is a portion of the negative electrode uncoated portion 12d of the current collector 12 where the negative electrode active material layer 33 and the sealing member 140 are not disposed, are also pressurized and heated. Specifically, the heater portion 61 is deformed to follow the compressive deformation of the pressing portion 64, and the heater portion 61 is pressed against the sealing member 140, the positive electrode uncoated portion 12c, and the negative electrode uncoated portion 12d, while heating is performed. This causes the sealing member 140 to be welded to the current collector 12. Compared to when pressurizing and heating only the sealing member 140 without pressurizing and heating the positive electrode exposed portion 17 and the negative electrode exposed portion 18, the amount of thermal expansion of the current collector 12 due to heat transfer from the heater unit 61 is greater. Therefore, the difference in the amount of thermal expansion between the sealing member 140 and the current collector 12 is reduced, which can reduce the difference in the amount of contraction between the sealing member 140 and the current collector 12 due to cooling of the current collector 12 and the sealing member 140. Therefore, when the sealing member 140 is welded to the current collector 12, the occurrence of wrinkles in the current collector 12 due to the difference in the amount of contraction between the sealing member 140 and the current collector 12 can be suppressed.

[0075] (2) Each of the pair of jigs 60 includes a heater 61 and a pressing portion 64. The pair of jigs 60 is used to apply pressure and heat to the sealing member 140 disposed in the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, which are uncoated portions on both sides of the current collector 12, and to the positive electrode exposed portion 17 and the negative electrode exposed portion 18, which are exposed portions on both sides of the current collector 12. This causes the sealing member 140 to be welded to both sides of the current collector 12. Therefore, on both the first surface 12a and the second surface 12b of the current collector 12, the heater portion 61 can be deformed to follow the compressive deformation of the pressing portion 64, and heating can be performed while the heater portion 61 is pressed against the sealing member 140 and the exposed portions. As a result, the heater portion 61 and the pressing portion 64 can weld the seal member 140 to the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, which are uncoated portions on both sides of the current collector 12.

[0076] (3) The sealing member 140 includes a main body portion 140a disposed on the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d of the current collector 12, and a protruding portion 140b extending from the main body portion 140a and protruding from the outer edge 12e of the current collector 12. The heater portion 61 is pressed against the sealing member 140, except for a portion of the protruding portion 140b, when the sealing member 140 is heated. Therefore, by heating the main body portion 140a while the heater portion 61 is pressed against the sealing member 140, the sealing member 140 can be welded to the current collector 12. Thus, the sealing member 140 can be welded to the current collector 12 without applying pressure and heat to the entire protruding portion 140b with the heater portion 61. Therefore, the amount of thermal expansion of the sealing member 140 can be reduced compared to when the entire sealing member 140 is applied pressure and heat with the heater portion 61. As a result, the amount of contraction of the sealing member 140 due to cooling can be reduced. Therefore, the difference in the amount of shrinkage between the sealing member 140 and the current collector 12 can be made smaller, and the occurrence of wrinkles in the current collector 12 can be further suppressed.

[0077] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0078] As shown in FIG. 8 , a sheet material 65 may be disposed between the heater section 61 and the current collector 12 and the sealing member 140. Before the pair of jigs 60 sandwich the sealing member 140 and the current collector 12, the sheet material 65 may be disposed so as to leave a gap between the heater section 61 and the current collector 12 and between the current collector 12 and the sealing member 140. The sheet material 65 is, for example, a strip-shaped member extending in the longitudinal direction of the sealing member piece. The sheet material 65 may be held in a state in which a predetermined tension is applied in the longitudinal direction by a holding mechanism (not shown). When welding the sealing member 140 to the current collector 12, the sealing member 140 may be heated while the heater section 61 is pressed against the current collector 12 and the sealing member 140 via the sheet material 65. This prevents the molten sealing member 140 from adhering to the heated surface of the heater section 61. Furthermore, by displacing the pair of jigs 60 so that the heater portion 61 moves away from the seal member 140, the sheet material 65 moves away from the seal member 140 due to the applied tension.

[0079] The sheet material 65 may be, for example, a base sheet coated with a heat-resistant, non-adhesive, and slippery fluororesin. Alternatively, the sheet material 65 may be, for example, a heat-resistant base sheet impregnated with a fluorine-based compound such as polytetrafluoroethylene. The illustrated sheet material 65 is, for example, glass cloth impregnated with a fluorine-based compound. Glass cloth is made of glass fiber, which has a higher thermal conductivity than fluorine-based compounds. Therefore, using the sheet material 65 with a glass cloth base sheet can efficiently transfer heat from the heater unit 61 to the seal member 140. The sheet material 65 may also be, for example, a resin sheet formed by molding a resin containing the fluorine-based compound into a sheet.

[0080] After the sealing member 140 is disposed so as to extend along the side 12f of the current collector 12, the sealing member 140 may be temporarily fixed (temporarily welded) to the current collector 12 by spot welding using ultrasonic waves or heat. This prevents the sealing member 140 from shifting from its predetermined position until welding using the heater unit 61 is performed.

[0081] The seal member 140 may be made of a sealing material cut from a long strip of seal substrate. In such a long strip of seal substrate, the linear expansion coefficient of the seal substrate in the TD direction, which is the short direction of the seal substrate, is smaller than the linear expansion coefficient of the seal substrate in the MD direction, which is the longitudinal direction of the seal substrate. In light of this, the seal member pieces of the seal member 140 are cut out from the seal substrate so that the TD direction of the seal substrate and the longitudinal direction of the seal member pieces coincide with each other. The seal member pieces may then be placed on the current collector 12 so that the longitudinal direction of the seal member pieces aligns with the side 12f of the current collector 12. In this case, the amount of thermal shrinkage of the seal member 140 when welded to the current collector 12 can be reduced compared to, for example, when the seal member pieces are cut out from the seal substrate so that the MD direction of the seal substrate and the longitudinal direction of the seal member pieces coincide with each other.

[0082] After the sealing member pieces arranged along the two short sides 12g are welded to the current collector 12, the sealing member pieces arranged along the two long sides 12h may be welded to the current collector 12. The sealing member pieces arranged along the four sides 12f of the current collector 12 may be welded to the current collector 12 in order, or may be welded to the current collector 12 at the same time.

[0083] The sealing member pieces arranged along the four sides 12f of the current collector 12 may be integral with one another. In this case, the sealing member 140 is a frame-shaped body made up of four integrated sealing member pieces.

[0084] The pressing portion 64 may have a resin portion instead of the rubber portion 62. In this case, the resin portion is formed of, for example, a fluororesin such as polytetrafluoroethylene. The resin portion may be located between the heater portion 61 and the sealing member 140 in the pressing direction D. The resin portion that is the pressing portion 64 is located alongside the heater portion 61 and the sealing member 140 in the pressing direction D. In this case, too, the heater portion 61 can be pressed against the sealing members 140 arranged in the positive electrode uncoated portion 12c and the negative electrode uncoated portion 12d, and the positive electrode exposed portion 17 and the negative electrode exposed portion 18 while being deformed so as to follow the compressive deformation of the resin portion, thereby heating the heater portion 61.

[0085] The sealing portion 40 may be provided on only one of the first surface 12a and the second surface 12b of the current collector 12. Alternatively, the sealing member 140 may be welded while being disposed on only one of the first surface 12a and the second surface 12b of the current collector 12. In this case, instead of the pair of jigs 60, a jig may be configured with a first jig including a heater portion 61 and a second jig including a pressing portion 64. For example, when the sealing portion 40 is provided on the first surface 12a, the first jig is disposed so as to face the sealing member 140 disposed on the positive electrode uncoated portion 12c and the positive electrode exposed portion 17. The second jig is disposed so as to face a portion of the negative electrode uncoated portion 12d that overlaps with the sealing member 140 disposed on the positive electrode uncoated portion 12c and the positive electrode exposed portion 17 in the pressing direction D. In this case, the pressing portion 64 is positioned alongside the heater portion 61 and the sealing member 140 in the pressing direction D. In this case as well, the heater portion 61 can be heated while being pressed against the sealing member 140 and the positive electrode exposed portion 17 arranged in the positive electrode uncoated portion 12c while being deformed so as to follow the compressive deformation of the pressing portion 64.

[0086] The sealing member 140 arranged on the positive electrode uncoated portion 12c of the current collector 12 and the sealing member 140 arranged on the negative electrode uncoated portion 12d may be integral with each other. In this case, the sealing member 140 has, for example, a portion located along the outer edge 12e of the current collector 12. This portion located along the outer edge 12e connects the portion of the sealing member 140 located on the positive electrode uncoated portion 12c and the portion of the sealing member 140 located on the negative electrode uncoated portion 12d, thereby integrating the sealing members 140.

[0087] The timing at which the heater unit 61 starts applying pressure and heat to the positive electrode exposed portion 17 and the negative electrode exposed portion 18 and the timing at which the heater unit 61 starts applying pressure and heat to the sealing member 140 may be shifted. In this case, the same effect as in the above embodiment can be obtained by performing both the applying pressure and heat to the positive electrode exposed portion 17 and the negative electrode exposed portion 18 by the heater unit 61 and the applying pressure and heat to the sealing member 140 by the heater unit 61 in parallel. Note that it is preferable that the applying pressure and heat to the positive electrode exposed portion 17 and the negative electrode exposed portion 18 by the heater unit 61 and the applying pressure and heat to the sealing member 140 by the heater unit 61 finish at the same time.

[0088] The portion of the seal member 140 that is heated with the heater portion 61 pressed against it may be at least a part of the seal member 140, and the range of heating may be changed as appropriate. For example, when welding the seal member 140 to the current collector 12, the heater portion 61 may be pressed against the seal member 140, excluding the entire protrusion 140b. In this case, after welding the seal member 140 to the current collector 12, the second seal portion 42 may not be formed.

[0089] The protruding portion 140b may be omitted from the seal member 140. In this case, the seal member 140 is composed of only the main body portion 140a. The sealing portion 16 may be formed using a resin material different from that of the seal member 140.

[0090] Next, the technical ideas that can be understood from the above-described embodiment and modified examples will be described below. (Note 1) The current collector is configured by integrating a positive electrode current collector and a negative electrode current collector. [Explanation of symbols]

[0091] D...pressing direction, 11, 11a...electrode, 12...current collector, 12a...first surface, 12b...second surface, 12e...outer edge, 23...positive electrode active material layer, 33...negative electrode active material layer, 60...jig, 61...heater portion, 64...pressing portion, 140...sealing member, 140a...main body portion, 140b...protruding portion.

Claims

1. A method for manufacturing an electrode, comprising: the electrode includes a current collector having a first surface and a second surface opposite to the first surface, active material layers provided on the first surface and the second surface, and a seal member welded to the current collector; Each of the first surface and the second surface has a portion on which the active material layer is provided and an uncoated portion which is a portion on which the active material layer is not provided, and the manufacturing method includes: a disposing step of disposing the seal member on the uncoated portion of at least one of the first surface and the second surface; a welding step of welding the sealing member to the current collector by applying pressure and heat to the sealing member while pressing the sealing member against the uncoated portion using a jig, The jig is a deformable heater portion configured to heat the seal member; a pressing portion configured to press the heater portion against the sealing member, a pressing direction in which the pressing portion presses the sealing member; the pressing portion is positioned alongside the heater portion and the sealing member in the pressing direction, and is configured to be compressively deformed in the pressing direction as the heater portion is pressed, the disposing step includes disposing the sealing member on the uncoated portion such that an exposed portion is formed in the uncoated portion, the exposed portion being a portion where the sealing member is not disposed and located between the active material layer and the sealing member; The welding step includes heating the heater portion while pressing it against the sealing member placed on the uncoated portion and the exposed portion, while deforming the heater portion so as to follow the compressive deformation of the pressing portion.

2. the jigs are a pair of jigs located on both sides of the current collector in the pressing direction, each of the pair of jigs includes the heater portion and the pressing portion; the placing step includes placing the seal member on the uncoated portions of the first surface and the second surface; 2. The electrode manufacturing method according to claim 1, wherein the welding step includes applying pressure and heat to the sealing member disposed on the uncoated portion of the first surface and the second surface and the exposed portion of the first surface and the second surface using the pair of jigs.

3. the sealing member includes a main body portion disposed on the uncoated portion, and a protrusion portion extending from the main body portion and protruding from an outer edge of the current collector, The method for manufacturing an electrode according to claim 1 or 2, wherein the welding step includes heating the heater portion while pressing the heater portion against the sealing member, excluding at least a part of the protruding portion.

4. 3. The electrode manufacturing method according to claim 1, wherein the welding step includes starting pressurizing and heating the exposed portion by the heater unit and pressurizing and heating the sealing member by the heater unit at the same time, and ending pressurizing and heating the exposed portion by the heater unit and pressurizing and heating the sealing member by the heater unit at the same time.

Images