Manufacturing method for bipolar battery
Patent Information
- Application Number
- JP2023144326
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-09-06
- Publication Date
- 2025-03-18
Smart Images
Figure 2025037409000001_ABST
Abstract
Description
[Technical field]
[0001] This application relates to a method for manufacturing a bipolar battery. [Background technology]
[0002] Patent Documents 1 and 2 disclose a bipolar battery including a bipolar electrode stack in which a plurality of bipolar electrode bodies are stacked, and a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode stack. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2023-46589 A [Patent Document 2] JP 2020-177761 A Summary of the Invention [Problem to be solved by the invention]
[0004] In the bipolar batteries disclosed in Patent Documents 1 and 2, the current collector is made of a rectangular metal foil, and a frame-shaped member made of resin is provided on the periphery of this current collector. In such batteries, in the welding process for forming the frame-shaped member, sheet-shaped resin members arranged in the stacking direction are welded. Usually, the amount of resin member is set to a minimum from the viewpoint of increasing the battery capacity. Therefore, the region where the resin member is welded (welded region) is also set to a minimum. However, in the welding process, the welding of the resin member cannot be stably controlled, and the resin member may be welded beyond the range of the welded region. In a battery welded in this way, there is a risk that the electrodes will buckle when the battery contracts due to charging and discharging, which is undesirable.
[0005] In view of the above, a main object of the present disclosure is to provide a manufacturing method for a bipolar battery that can appropriately weld resin members. [Means for solving the problem]
[0006] The present disclosure provides at least the following aspects.
[0007] The first aspect is a manufacturing method for a bipolar battery including a bipolar electrode laminate in which a plurality of bipolar electrode bodies are stacked, and a frame-shaped member that seals the entire periphery of the side of the bipolar electrode laminate, the manufacturing method including: a manufacturing step of manufacturing a bipolar electrode body in which a sealing member is arranged around a rectangular current collector, and a positive electrode layer is arranged on a first surface of the current collector and a negative electrode layer is arranged on a second surface of the current collector; a stacking step of stacking a plurality of bipolar electrode bodies via separators and arranging spacers between the sealing members of adjacent bipolar electrode bodies in the stacking direction to obtain a bipolar electrode laminate; and a welding step of welding the sealing members and spacers aligned in the stacking direction to form a frame-shaped member that seals the entire periphery of the side of the bipolar electrode laminate, in which the spacer has a plurality of resin layers from its outer edge toward the inside when viewed in the stacking direction, and the plurality of resin layers have a welding layer arranged at the outermost side and a non-welding layer arranged adjacent to the inside of the welding layer, and the welding step is to weld the welding layers of the seal members and the spacers.
[0008] A second embodiment is the manufacturing method according to the first embodiment, in which the seal member and the welding layer of the spacer are made of the same resin.
[0009] A third aspect is the manufacturing method according to the first or second aspect, wherein in the spacer, the welding layer contains a polyolefin-based resin, and the non-welding layer contains a polyester-based resin.
[0010] A fourth embodiment is a manufacturing method according to any one of the first to third embodiments, in which the spacer has a third resin layer arranged adjacent to the inside of the non-weld layer, and the third resin layer is made of the same resin as the sealing member. Effect of the Invention
[0011] According to the manufacturing method of the bipolar battery disclosed herein, the sealing member and the spacer can be appropriately welded. [Brief description of the drawings]
[0012] [Figure 1] FIG. 2 is a plan view of the bipolar electrode body 10. [Diagram 2] FIG. 2 is a cross-sectional view of the bipolar electrode body 10. [Diagram 3] 1 is a cross-sectional view of a bipolar electrode laminate 50 obtained in a lamination step S2. [Figure 4] FIG. [Diagram 5] 1 is a cross-sectional view focusing on one side surface 51 of a bipolar electrode stack 50. FIG. [Figure 6] FIG. 2 is a plan view of a spacer 140. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] The manufacturing method of the bipolar battery of the present disclosure will be described using one embodiment.
[0014] One embodiment is a method for manufacturing a bipolar battery including a bipolar electrode laminate in which a plurality of bipolar electrode bodies are laminated, and a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode laminate. The method includes a fabrication step S1, a lamination step S2, and a welding step S3. Each step will be described below.
[0015] <Production process S1> The fabrication process S1 is a process for fabricating a bipolar electrode body 10 in which a sealing member 14 is disposed around a rectangular current collector 11, a positive electrode layer 12 is disposed on a first surface 11a of the current collector 11, and a negative electrode layer 13 is disposed on a second surface 11b of the current collector 11. A plan view of the bipolar electrode body 10 is shown in Fig. 1. A cross-sectional view of the bipolar electrode body 10 is shown in Fig. 2.
[0016] (Current collector 11) The current collector 11 is a rectangular sheet-like conductive member in a plan view. The current collector 11 has a first surface 11a and a second surface 11b located on the opposite side of the first surface 11a. The current collector 11 is made of, for example, a metal foil or an alloy foil. Examples of the metal foil include copper foil, aluminum foil, titanium foil, and nickel foil. Examples of the alloy foil include stainless steel foil, plated steel sheet, and plated stainless steel sheet. The alloy foil may be an alloy foil of the metals exemplified as the material of the metal foil. The current collector 11 may be formed by integrating or laminating a plurality of metal foils, or may be formed by plating the surface of a metal foil with another metal.
[0017] (Positive electrode layer 12) The positive electrode layer 12 is a rectangular sheet-like member in a plan view, and is disposed on the first surface 11a of the current collector 11. The positive electrode layer 12 includes a positive electrode active material. Examples of the positive electrode active material include a composite oxide, metallic lithium, and sulfur. The composition of the composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. Examples of the composite oxide include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, and LiNiMnCoO2.
[0018] The positive electrode layer 12 may contain a conductive additive. Examples of the conductive additive include acetylene black, carbon black, and graphite.
[0019] The positive electrode layer 12 may contain a binder. Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluorine rubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, acrylic resins containing monomer units such as acrylic acid and methacrylic acid, styrene-butadiene rubber (SBR), carboxymethyl cellulose, alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester crosslinked bodies, and starch-acrylic acid graft polymers.
[0020] The method of forming the positive electrode layer 12 on the first surface 11a of the current collector 11 is not particularly limited, and a known method may be appropriately adopted. For example, a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, a curtain coating method, etc. may be mentioned. Specifically, the material constituting the positive electrode layer 12 is mixed with a solvent to obtain a slurry, and then the slurry is applied to the first surface 11a of the current collector 11 and dried to obtain the positive electrode layer 12. The solvent is, for example, N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, or water. In order to increase the electrode density, the positive electrode layer 12 after drying may be compressed.
[0021] (Negative electrode layer 13) The negative electrode layer 13 is a rectangular sheet-like member in a plan view, and is disposed on the second surface 11b of the current collector 11. The negative electrode layer 13 includes a negative electrode active material. Examples of the negative electrode active material include carbon such as graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, metal compounds, elements capable of forming an alloy with lithium or compounds of such elements, and boron-added carbon. Examples of elements capable of forming an alloy with lithium include silicon and tin.
[0022] The negative electrode layer 13 may contain a conductive assistant. The conductive assistant may be selected from those used in the positive electrode layer 12. The negative electrode layer 13 may also contain a binder. The binder may be selected from those used in the positive electrode active material layer 12.
[0023] The method for forming the negative electrode layer 13 on the second surface 11b of the current collector 11 is not particularly limited, and any known method may be appropriately adopted. For example, the method may be selected from the methods for forming the positive electrode layer 12.
[0024] (Sealing member 14) The sealing member 14 is a rectangular frame-shaped member disposed around the current collector 11 in a plan view. As shown in Fig. 1 and Fig. 2, the sealing member 14 is disposed at a position spaced apart from the positive electrode layer 12 and the negative electrode layer 13. The sealing member 14 includes a first sealing member 14a disposed on the first surface 11a of the current collector 11 and a second sealing member 14b disposed on the second surface 11b of the current collector 11.
[0025] The first seal member 14a is a rectangular frame-shaped member that is disposed along the periphery of the first surface 11a of the current collector 11 and is joined to the first surface 11a. The outer edge of the first seal member 14a is larger than the outer edge of the current collector 11, and the inner edge of the first seal member 14a is smaller than the outer edge of the current collector 11. In addition, in a plan view, the inner edge of the first seal member 14a is separated from the positive electrode layer 12. The first seal member 14a and the current collector 11 are joined in a region where they overlap each other in a plan view.
[0026] The second seal member 14b is different from the first seal member 14a in that it is disposed on the second surface 11b of the current collector 11, but the other configurations are the same as those of the first seal member 14a. That is, the second seal member 14b is a rectangular frame-shaped member, and is disposed along the periphery of the second surface 11b of the current collector 11 and is bonded to the second surface 11b. As shown in FIG. 2, the outer edge of the second seal member 14b is larger than the outer edge of the current collector 11, and the inner edge of the second seal member 14b is smaller than the outer edge of the current collector 11. In addition, in a plan view, the inner edge of the second seal member 14b is separated from the negative electrode layer 13. The second seal member 14b and the current collector 11 are bonded in a region where they overlap each other in a plan view. The first seal member 14a and the second seal member 14b may be bonded in a region where they contact each other.
[0027] The first seal member 14a and the second seal member 14b are made of a polyolefin resin such as polyethylene, polypropylene, etc. The first seal member 14a and the second seal member 14b may be made of the same material or different materials.
[0028] The above describes the manufacturing process S1 of the bipolar electrode body 10. In the bipolar electrode stack 50 described below, a positive electrode terminal electrode body 21 and a negative electrode terminal electrode body 22 arranged at the ends in the stacking direction are used. Therefore, the positive electrode terminal electrode body 21 and the negative electrode terminal electrode body 22 may be manufactured in the manufacturing process. The positive electrode terminal electrode body 21 is the bipolar electrode body 10 without the negative electrode layer 13. The negative electrode terminal electrode body 22 is the bipolar electrode body 10 without the positive electrode layer 12.
[0029] <Lamination process S2> The lamination step S2 is a step of laminating a plurality of bipolar electrode bodies 10 with separators 30 interposed therebetween, and arranging spacers 40 between the sealing members 14 of the bipolar electrode bodies 10 adjacent in the lamination direction, to obtain a bipolar electrode laminate 50. Fig. 3 shows a cross-sectional view of the bipolar electrode laminate 50 obtained by the lamination step S2.
[0030] (Separator 30) The separators 30 are sheet-like members and are disposed between the bipolar electrode bodies 10. Specifically, they are disposed between the electrode layers (positive electrode layer 12 and negative electrode layer 13) of the bipolar electrode bodies 10 adjacent in the stacking direction. The separators 30 are, for example, porous sheets or nonwoven fabrics containing a polymer that absorbs and retains an electrolyte. Examples of materials constituting the separators 30 include polypropylene, polyethylene, polyolefin, and polyester. The separators 30 may have a single-layer structure or a multi-layer structure.
[0031] In a bipolar battery, the separator 30 is used in a state in which it is impregnated with an electrolyte. The electrolyte impregnated in the separator 30 may be, for example, an electrolyte containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The electrolyte salt may be, for example, a lithium salt such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, or LiN(CF3SO2)2. The non-aqueous solvent may be, for example, a cyclic carbonate, a cyclic ester, a chain carbonate, a chain ester, or an ether. The electrolyte is injected into the space S after the welding step S3. This will be described in detail later.
[0032] (Spacer 40) The spacers 40 are rectangular frame-shaped members disposed between the bipolar electrode bodies 10. Specifically, the spacers 40 are disposed between the seal members 14 of the bipolar electrode bodies 10 adjacent in the stacking direction. More specifically, the spacers 40 are disposed between the first seal member 14a of one bipolar electrode body 10 and the second seal member 14b of the other bipolar electrode body 10 in the bipolar electrode bodies 10 adjacent in the stacking direction.
[0033] The spacer 40 may be an integrally formed rectangular frame member, or may be a rectangular frame member formed by using strip-shaped members and arranging the ends of each member so as to overlap each other.
[0034] 3, when viewed in the stacking direction, the outer edge of the spacer 40 is located outside the outer edges of the seal members 14 (first seal member 14a and second seal member 14b), while the inner edge of the spacer 40 is located outside the inner edge of the seal member 14. For example, the distance between the inner edge of the spacer 40 and the inner edge of the seal member 14 may be 1 mm or more.
[0035] Fig. 4 shows a plan view of the spacer 40. Fig. 5 shows a cross-sectional view of one side surface 51 of the bipolar electrode laminate 50. As shown in Figs. 4 and 5, the spacer 40 has a plurality of resin layers extending from its outer edge toward the inside when viewed in the lamination direction. The plurality of resin layers include a welding layer 41 disposed on the outermost side, a non-welding layer 42 disposed adjacent to the inner side of the welding layer, and a third resin layer 43 disposed adjacent to the inner side of the non-welding layer 42.
[0036] The welding layer 41 is a resin layer disposed on the outermost side (outer edge) of the spacer 40 as viewed in the stacking direction, and has a rectangular frame shape. The welding layer 41 is used for welding to the seal member 14 in the welding step S3. The resin contained in the welding layer 41 is not particularly limited as long as it is a resin having electrolyte resistance and can be appropriately welded to the seal member 14 in the welding step S3. The melting point of the welding layer 41 may be 130°C or higher and 150°C or lower. Specific examples of the resin contained in the welding layer 41 include polyolefin resins such as polyethylene and polypropylene. The welding layer 41 may be made of a polyolefin resin. The welding layer 41 may be made of the same resin as the seal member 14. The length L1 from the outer edge to the inner edge of the welding layer 41 is not particularly limited, but may be 1 mm or more from the viewpoint of appropriately welding the welding layer 41 and the seal layer 14.
[0037] The non-welding layer 42 is a resin layer disposed adjacent to the inner side of the welding layer 41 when viewed in the stacking direction, and has a rectangular frame shape. The non-welding layer 42 is not used for welding to the seal member 14 in the welding step S3. That is, the non-welding layer 42 is not compatible with the welding layer 41 during welding, and is intended to control the range of the welding area between the spacer 40 and the seal member 14. The resin contained in the non-welding layer 42 is not particularly limited as long as it is a resin having electrolyte resistance and is not welded to the seal member 14 in the welding step S3. Therefore, the melting point of the non-welding layer 42 is set higher than the melting points of the welding layer 41 and the seal member 14. The melting point of the non-welding layer 42 may be 220° C. or higher. Specific examples of the resin contained in the non-welding layer 42 include polyester-based resins such as polyethylene terephthalate. The non-welding layer 42 may also be made of polyester-based resins. The length L2 from the outer edge to the inner edge of the non-weld layer 42 is not particularly limited, but may be 1 mm or more.
[0038] The third resin layer 43 is a resin layer disposed adjacent to the inner side of the non-welding layer 42 when viewed in the stacking direction, and has a rectangular frame shape. The third resin layer 43 is welded to the seal member 14 and is used to enhance the bonding with the seal member 14. This can suppress the lamination misalignment. The resin contained in the third resin layer 43 is not particularly limited as long as it is a resin having electrolyte resistance. The melting point of the third resin layer 43 is not particularly limited, but may be, for example, 130°C or more and 150°C or less. Specific examples of the resin contained in the third resin layer 43 include polyolefin resins such as polyethylene and polypropylene. The third resin layer 43 may be made of a polyolefin resin. The third resin layer 43 may be made of the same resin as the seal member 14. The length L3 from the outer edge to the inner edge of the third resin layer 43 is not particularly limited, but may be 1 mm or more.
[0039] (Layering method) The lamination method will be further described. First, a plurality of bipolar electrode bodies 10 are laminated via a separator. At this time, the bipolar electrode bodies 10 adjacent in the lamination direction are laminated so that the positive electrode layer 12 of one bipolar electrode body 10 faces the negative electrode layer 13 of the other bipolar electrode body 10. The separator 30 is disposed between these positive electrode layers 12 and negative electrode layers 13. In addition, a positive electrode terminal electrode body 21 is disposed at one end of the lamination direction of the bipolar electrode laminate 50, and a negative electrode terminal electrode body 22 is disposed at the other end. Furthermore, when laminating the bipolar electrode bodies 10, a spacer 40 is disposed between the sealing members 14 of the bipolar electrode bodies 10 adjacent in the lamination direction. As a result, the sealing members 14 and the spacers 40 are disposed alternately on each side of the bipolar electrode laminate 50.
[0040] <Welding process S3> The welding step S3 is a step of welding the sealing members 14 and the spacers 40 aligned in the stacking direction to form a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode stack 50. Specifically, the welding step S3 welds the welding layers 41 of the sealing members 14 and the spacers 40. The obtained frame-shaped member is a member in which the sealing members 14 and the spacers 40 are integrated by welding them together.
[0041] As described above, the spacer 40 has a plurality of resin layers (the welding layer 41, the non-welding layer 42, and the third resin layer). Then, in the welding step S3, the seal member 14 and the welding layer 41 are welded. On the other hand, the melting point of the non-welding layer 42 is set higher than that of the seal member 14 and the welding layer 41, and the non-welding layer 42 is not welded to the seal member 14 in the welding step S3. Therefore, in the welding step S3 of one embodiment, the welding layer 41 and the seal member 14 are welded, and the non-welding layer 42 and the seal member 14 are not welded, so that the range in which the seal member 14 and the spacer 40 are welded can be controlled. Therefore, according to one embodiment, even if the welding accuracy (heating accuracy) by the heat source is low, the welding area (range of the length L1) can be stably secured. That is, according to one embodiment, the welding area (range of the length L1) and the non-welding area (range other than the length L1) can be precisely controlled. In the welding step S3, the third resin layer 43 may be welded to the seal member 14. This can prevent the lamination from shifting.
[0042] The method of welding the seal member 14 and the spacer 40 is not particularly limited, and may be any method that heats each side surface of the bipolar electrode stack 50. The type of heat source for heating each side surface of the bipolar electrode stack 50 is not particularly limited, but may be, for example, an IR heater.
[0043] In the welding process S3, the seal members 14 and the spacers 40 on each side are welded, and a frame-shaped member is formed over the entire side of the bipolar electrode stack 50. By forming the frame-shaped member, a space S is formed inside the bipolar electrode stack 50. Specifically, a space S is formed between the bipolar electrodes 10, between the positive electrode terminal electrode body 21 and the bipolar electrode body 10, and between the negative electrode terminal electrode body 22 and the bipolar electrode body 10. Since the space S is for storing the electrolyte, the space S is sealed by the frame-shaped member so that the electrolyte does not leak from the space S.
[0044] The electrolyte is injected into the space S after the welding step S3. The method of injecting the electrolyte is not particularly limited, but for example, by sandwiching a predetermined insert between the seal member 14 and the spacer and performing the welding step S3, an inlet through which the electrolyte can be injected can be formed. Then, after the electrolyte is injected into the space S from the inlet, the inlet is blocked by heating, thereby preventing the electrolyte from leaking from the space S.
[0045] <Supplementary Information> In one embodiment, the spacer 40 having three resin layers is used, but the shape of the spacer is not limited to this. The spacer has a plurality of resin layers from its outer edge toward the inside when viewed in the stacking direction, and the plurality of resin layers may have at least a welding layer arranged on the outermost side and a non-welding layer arranged adjacent to the inside of the welding layer. For example, a spacer 140 having only a welding layer 141 and a non-welding layer 142 may be used. FIG. 6 shows a plan view of the spacer 140. Even if a spacer having such a shape is used, the above-mentioned effect can be obtained. In this case, the length from the outer edge to the inner edge of the non-welding layer 142 is within the range of the sum of the length L2 of the welding layer 42 in the bipolar electrode laminate 50 and the length L3 of the third resin layer.
[0046] The manufacturing method of the bipolar battery according to the present disclosure has been described above using one embodiment. According to the manufacturing method of the bipolar battery according to the present disclosure, the sealing member and the spacer can be appropriately welded. [Explanation of symbols]
[0047] 10 Bipolar electrode body 11 Current collector 12 Positive electrode layer 13 Negative electrode layer 14 Sealing material 14a First sealing member 14b Second seal member 21 Positive terminal electrode body 22 Negative terminal electrode body 30 Separator 40, 140 Spacer 50 Bipolar electrode stack
Claims
1. A method for manufacturing a bipolar battery comprising a bipolar electrode stack in which a plurality of bipolar electrode bodies are stacked, and a frame-shaped member that seals an entire periphery of a side surface of the bipolar electrode stack, comprising: a fabrication step of fabricating a bipolar electrode body in which a sealing member is disposed around a rectangular current collector, and a positive electrode layer is disposed on a first surface of the current collector and a negative electrode layer is disposed on a second surface of the current collector; a stacking step of stacking a plurality of the bipolar electrode bodies with separators interposed therebetween and disposing spacers between the sealing members of the bipolar electrode bodies adjacent in a stacking direction to obtain the bipolar electrode stack; a welding process of welding the sealing members and the spacers arranged in a stacking direction to form the frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode stack, the spacer has a plurality of resin layers extending from an outer edge toward an inside thereof as viewed in a stacking direction, the plurality of resin layers having an outermost welding layer and a non-welding layer disposed adjacent to the inner side of the welding layer; The welding step includes welding the welding layer of the seal member and the welding layer of the spacer. How to manufacture a bipolar battery.
2. The manufacturing method according to claim 1 , wherein the sealing member and the welding layer of the spacer are made of the same resin.
3. The method according to claim 1 or 2, wherein in the spacer, the welding layer contains a polyolefin resin, and the non-welding layer contains a polyester resin.
4. 3. The method according to claim 1, wherein the spacer has a third resin layer disposed adjacent to the inner side of the non-weld layer, the third resin layer being made of the same resin as the sealing member.
Citation Information
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