Electrode, method for manufacturing electrode, and method for manufacturing battery

Abstract

Provided are a method for manufacturing a battery having a current collector in which wrinkles are suppressed, and the battery. A method for manufacturing a battery having a current collector and a resin layer, the method including a step of welding the current collector and the resin layer using a lattice-shaped heater.

Description

Technical Field

[0001] The present disclosure relates to an electrode, a method for manufacturing the electrode, and a method for manufacturing a battery. Background Art

[0002] Research has been conducted on a battery having an electrode in which a reinforcing member made of a resin is disposed on a surface of a current collector not coated with an active material to suppress wrinkling and deformation of the current collector.

[0003] Japanese Patent Gazette No. 2022-69042 discloses "a storage battery cell comprising: a positive electrode and a negative electrode, wherein an active material layer is provided on one side of a current collector formed of a metal foil, and the active material layers are arranged opposite to each other; a separator is arranged between the positive electrode and the negative electrode and is interposed between the active material layers; a baffle is arranged between the positive electrode and the negative electrode and seals between the edges of the current collector in a manner of surrounding the active material layer to form a storage space for storing an electrolyte; and a reinforcing component is provided to reinforce an uncoated portion of the current collector where the active material layer does not exist, wherein the current collector has the uncoated portion between the baffle and the active material layer when viewed from the relative direction of the active material layers of the positive electrode and the negative electrode, and the reinforcing component is arranged along the uncoated portion in a manner of straddling a boundary between the active material layer and the uncoated portion and a boundary between the baffle and the uncoated portion when viewed from the relative direction". Summary of the invention Problems to be solved by the invention

[0004] However, when the collector and the resin layer are welded together during battery assembly, the resin will expand or contract due to heat, so wrinkles may be generated on the collector. There is still room for improvement in this regard. Wrinkles on the collector may cause damage or rupture of the collector and reduce the sealing performance of the electrolyte in the battery.

[0005] An object of one embodiment of the present disclosure is to provide an electrode having a current collector with suppressed wrinkles and a method for producing the electrode. A problem to be solved by another embodiment of the present disclosure is to provide a method for manufacturing a battery including an electrode having a current collector with suppressed wrinkles. Technical solutions to solve problems

[0006] The present disclosure includes the following aspects. <1> A method for manufacturing an electrode, the electrode comprising a current collector and a resin layer, The manufacturing method includes the step of fusing the current collector and the resin layer using a heater having a lattice-shaped heat generating portion. <2> according to <1> The described method for producing an electrode further includes the step of forming a positive electrode active material layer or a negative electrode active material layer on the current collector. <3> An electrode comprises a current collector and a resin layer, wherein a lattice-shaped fused portion and an unfused portion surrounded by the lattice-shaped fused portion are provided in a fused region between the current collector and the resin layer. The lattice shape is preferably a checkerboard shape. <4> A battery having <3> Recorded electrodes. <5> A method for manufacturing a battery, comprising at least: utilizing <1> or <2> The method for producing an electrode includes a step of producing an electrode; a step of producing a laminate by laminating the electrodes with a separator interposed therebetween; and a step of sealing the laminate by fusing a resin layer included in the electrode. Effects of the Invention

[0007] According to one embodiment of the present disclosure, there is provided a method for manufacturing an electrode having a current collector with suppressed wrinkles and an electrode. According to another embodiment of the present disclosure, there is provided a method for manufacturing a battery including an electrode having a current collector with suppressed wrinkles. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A This is a schematic plan view showing an example of the structure of the electrode of the present disclosure. Figure 1B yes Figure 1A 1B-1B line cross-sectional view. Figure 2A This is a schematic plan view showing an example of a welding step involved in the method for producing an electrode of the present disclosure. Figure 2B This is a schematic plan view showing another example of the welding step involved in the electrode manufacturing method of the present disclosure. Figure 3A It is a schematic cross-sectional view showing an example of a layer structure after a welding step and a welding mark in a resin layer. Figure 3B This is a schematic cross-sectional view showing another example of the layer structure after the welding step and the welding mark in the resin layer. Figure 4 This is a schematic side view showing an example of the structure of the resin layer after the welding step. Figure 5 This is a schematic cross-sectional view showing an example of the structure of the battery of the present disclosure (the resin layer is not shown). DETAILED DESCRIPTION

[0009] Hereinafter, embodiments of the present disclosure will be described, but the description is only for exemplifying the embodiments and does not limit the scope of the present disclosure.

[0010] In the present specification, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively. In the numerical range of stepwise recording in the present embodiment, the upper limit or lower limit recorded in a numerical range can be replaced by the upper limit or lower limit of the numerical range of other stepwise recordings. In addition, in the numerical range of recording in the present embodiment, the upper limit or lower limit of the numerical range can be replaced by the value shown in the embodiment.

[0011] In this specification, the term "process" is not limited to an independent process, but is also included in this term even if it cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0012] In this specification, when an embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the sizes of components in each figure are conceptual, and the relative relationship between the sizes of the components is not limited to this.

[0013] In this specification, each component may include a plurality of corresponding substances. In the present embodiment, when the amount of each component in the composition is mentioned, if there are a plurality of substances corresponding to each component in the composition, it means the total amount of the plurality of substances present in the composition unless otherwise specified.

[0014] <Electrode and method for manufacturing the same> The manufacturing method of the electrode disclosed in the present invention is a manufacturing method of an electrode having a current collector and a resin layer, and the method includes a step of fusing the current collector and the resin layer using a heater having a grid-shaped heating portion (hereinafter also referred to as a "fusing step"). By including the above-mentioned step, an electrode having a current collector with suppressed wrinkles is provided.

[0015] Here, Figure 1A : is a schematic top view showing an example of the structure of the electrode disclosed in the present invention. Figure 1B yes Figure 1A 1B-1B line cross-sectional view. Figure 1A and Figure 1B In the embodiment, the electrode has a current collector 10 and a resin layer 20. The resin layer 20 is provided on the active material-uncoated surface of the current collector 10. In addition, the active material layer 30 is provided on the current collector 10.

[0016] Hereinafter, the method for producing the electrode of the present disclosure and the details of the electrode will be described.

[0017] -Current Collector- The current collector preferably includes a positive electrode current collector and a negative electrode current collector, and may be a current collector in which the positive electrode current collector and the negative electrode current collector are bonded together.

[0018] Examples of the positive electrode current collector include current collectors made of nickel, iron, stainless steel (SUS), titanium, and aluminum.

[0019] The shape of the positive electrode current collector is, for example, a foil shape or a mesh shape.

[0020] Among them, the positive electrode current collector is preferably aluminum foil from the viewpoint of excellent corrosion resistance and conductivity. The aluminum foil may be surface-processed or carbon-coated.

[0021] The thickness of the positive electrode current collector is, for example, 8 μm to 10 μm.

[0022] Examples of the negative electrode current collector include current collectors made of copper, stainless steel (SUS), and nickel.

[0023] The shape of the negative electrode current collector is, for example, a foil or a mesh.

[0024] Among them, copper foil is preferably used as the negative electrode current collector because of its excellent corrosion resistance and conductivity.

[0025] The thickness of the negative electrode current collector is, for example, 10 μm to 20 μm.

[0026] -Resin layer- The resin layer is preferably a plate-like body containing resin before the welding step. In the case where the battery is a laminated battery, the resin layer may also be a part of the laminated exterior member. After the welding step, the resin layer is provided on a part or all of the active material uncoated surface of the collector.

[0027] As the resin, polyolefin resins can be cited. As the polyolefin resins, for example, high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (L-LDPE), and polypropylene (PP) can be cited. Among them, polypropylene (PP) is particularly preferred from the perspective of excellent weldability and electrolyte resistance. Polypropylene (PP) may also be modified polypropylene.

[0028] The thickness of the resin layer is, for example, 40 μm to 100 μm.

[0029] (Welding process) In the method for producing an electrode of the present disclosure, the current collector and the resin layer are welded together using a heater having a lattice-shaped heating portion. Figure 2A and Figure 2B This is a schematic plan view showing an example of a welding step in the method for producing an electrode according to the present disclosure. exist Figure 2A and Figure 2BIn the embodiment, the resin layer 20 is disposed on the uncoated surface of the current collector 10 on which the active material layer 30 is not coated, and a heater H as an example of a heater having a grid-shaped heating portion is disposed in a thermally connected state at the lower portion of the current collector 10. By performing welding using the heater H having a grid-shaped heating portion that is in contact with at least the resin layer, a battery having a current collector with suppressed wrinkles can be obtained.

[0030] The heater refers to a heater including a heating element having a heating portion, and may be a contact heater or a non-contact heater, and examples thereof include electric heaters, radiant heat heaters, and the like.

[0031] Here, particularly in the case where the heater is in contact with the object, the transfer of heat from the heater to the object depends on the shape of the heater. In the case where the collector and the resin layer are brought into contact with the heater for welding, a distribution of molten resin corresponding to the shape of the heating portion of the heater is formed in the resin layer during the heating process during welding. At least a portion of the distribution of the molten resin will remain during the cooling and solidification process of the welded portion even after the cooling and solidification process. That is, in the case of welding the collector and the resin layer using a heater whose heating portion is shaped like a grid, a grid-shaped distribution of the molten resin will be formed in the resin layer during the heating process during welding, and at least a portion of it will maintain this shape, and the resin layer and the collector will be welded. Figure 3A and Figure 3B is a schematic cross-sectional view showing an example of a layer structure after a welding process and a welding mark in a resin layer. Figure 4 FIG. 1 is a schematic side view showing an example of the structure of the resin layer after the welding process. Figure 3A , Figure 3B and Figure 4 As shown, after the welding process, the resin layer 20 has a grid-shaped welded portion 22b and an unwelded portion 22a surrounded by the grid-shaped welded portion 22b. The unwelded portion 22a and the welded portion 22b are arranged in a grid shape in the resin layer 20.

[0032] In the manufacturing method of the electrode disclosed in the present invention, during the period until the resin layer and the current collector are welded, the resin layer has a resin structure formed in a grid shape, thereby, parts with weaker welding are intermittently provided within the welding range, so that the internal stress generated during the welding process, which is caused by the difference in thermal expansion coefficient between the resin and the current collector, and the internal stress generated by the difference in cooling shrinkage rate between the resin and the current collector, will be dispersed in the surface direction of the resin layer. In particular, by forming a grid-shaped welded portion and forming a plurality of unwelded portions surrounded by the welded portion, the deformation accompanying the expansion and contraction of the resin during welding is absorbed. As a result, it is possible to weld to the current collector while suppressing the wrinkles of the collector. Therefore, according to the manufacturing method of the electrode disclosed in the present invention, an electrode having a current collector with suppressed wrinkles can be obtained.

[0033] Examples of the lattice shape include a plane lattice shape, a horizontal lattice shape, and a checkerboard lattice shape. From the perspective of alleviating the internal stress caused by expansion or contraction, it is preferred that the number of lattice points per unit area is large. In the example, a checkerboard lattice shape is preferred. When the shape of the heating portion of the heater is a checkerboard lattice shape, it is preferred to perform welding in such a manner that the number of lattice points per unit area increases. For example, examples of the shape of the heating portion of the heater H include: Figure 2A or Figure 2B The shape shown. Figure 2A The heating mark of the resin layer after heating is shown in Figure 3A .exist Figure 3A In FIG. 1 , a lattice shape is shown in which rectangular lattices are arranged in a manner such that the lattice arrangement direction is along the thickness direction of the resin layer and the orthogonal direction thereof. Figure 2B The heating mark of the resin layer after heating is shown in Figure 3B . Figure 3B The lattice shape is shown in which the rectangular lattice is tilted at 45° and the tilted rectangular (diamond) lattice is arranged in such a manner that the lattice arrangement direction is along the thickness direction of the resin layer and in the direction of 45° or -45°. The shape of the heat generating portion of the heater H is such that stress is unlikely to be concentrated when subjected to pressure from the inside of the electrode and good sealing properties are maintained. Figure 2A Shape ( Figure 3A The weld line shown) is Figure 2B Shape ( Figure 3B The weld line shown) is preferred.

[0034] The welding temperature can be set in the range of the softening point or melting point of the resin of the resin layer, preferably the softening point or melting point to 200° C., more preferably 130° C. to 200° C., and can also be set to 130° C. to 150° C. By welding in the above range, the resin will not be excessively plasticized, and welding can be performed with high welding strength, so that an electrode having a current collector with suppressed wrinkles can be easily obtained.

[0035] The welding pressure is not particularly limited as long as the current collector and the resin layer can be welded together while wrinkles of the current collector are suppressed. The welding pressure can be appropriately determined.

[0036] The welding method is also not particularly limited as long as the collector and the resin layer can be welded while suppressing the wrinkles of the collector. The collector and the resin layer can be welded by heating from the top and / or bottom with a heater, or by heating from the sides of the collector and the resin layer with a heater. In addition, from the perspective of sealing the electrode, it is preferred that the welding is performed under reduced pressure.

[0037] According to the manufacturing method of the electrode of the present disclosure described above, the present disclosure can provide a manufacturing method of an electrode having a current collector with suppressed wrinkles. Preferably, the electrode of the present disclosure has a current collector and a resin layer, and in the fusion region of the current collector and the resin layer, there are grid-shaped fusion portions and unfused portions surrounded by the grid-shaped fusion portions. Preferably, the resin layer has a grid-shaped fusion portion and unfused portions surrounded by the grid-shaped fusion portions. According to the present disclosure, among the grid-shaped ones, a checkerboard shape is preferred.

[0038] In addition, the manufacturing method of the electrode disclosed in the present invention may include other processes for manufacturing a battery (for example, a series of processes including a kneading process, a coating process, a drying process, a pressing process, a slitting process, etc. (i.e., an active material layer forming process described later)) in addition to the above-mentioned welding process. The manufacturing method of the electrode disclosed in the present invention preferably includes a process of forming a positive electrode active material layer or a negative electrode active material layer on a current collector, respectively (hereinafter also referred to as an "active material layer forming process").

[0039] In the kneading step, the positive electrode active material or the negative electrode active material, the conductive material and the binder are kneaded to prepare a slurry of the positive electrode or the negative electrode. The kneading can be carried out by a known method, for example, a planetary mixer, a sand mill, a ball mill, a planetary mill, a roller mill, an extruder, etc.

[0040] In the coating step, the slurry for forming the positive electrode active material layer or the negative electrode active material layer is coated on the positive electrode collector or the negative electrode collector, respectively. The coating can also be performed by a known method, such as a slot die method or a doctor roll method.

[0041] In the drying step, the slurry applied to form the positive electrode active material layer or the negative electrode active material layer is dried. The drying is performed at, for example, 80°C to 135°C.

[0042] In the pressing step, the dried positive electrode or negative electrode is pressed and rolled. The pressing is performed, for example, by roll pressing, cold isostatic pressing (CIP), etc. The pressing pressure is, for example, 1.0 t / cm 2 ~3.0t / cm 2 .

[0043] In the slitting step, the rolled positive electrode or negative electrode is cut into a predetermined size. The slitting can be performed by a known method.

[0044] <Battery Manufacturing Method> The manufacturing method of the battery disclosed in the present invention at least includes: a process of manufacturing an electrode using the electrode manufacturing method disclosed in the present invention (hereinafter also referred to as the "electrode manufacturing process"); a process of stacking the electrodes with separators to manufacture a stack (hereinafter also referred to as the "stack manufacturing process"), and a process of sealing the stack by welding the resin layer of the electrode (hereinafter also referred to as the "sealing process"), and may also include a connecting process, a laminating process, etc. as needed.

[0045] In the lamination step, the electrodes are alternately laminated with separate solid electrolyte layers or separators interposed therebetween to produce a laminated body. The lamination can be performed using, for example, a known lamination apparatus.

[0046] In the sealing step, the resin layer of the electrode is welded to seal the laminate. The welding can be performed using an ultrasonic welding device or the like.

[0047] In addition, when a connection step is included, the side member (terminal, etc.) is connected to the current collector (positive electrode current collector and / or negative electrode current collector). The terminal connection can be performed using, for example, an ultrasonic welding device.

[0048] When a lamination step is included, an electrode body including the electrode and active material layer of the present disclosure may be covered with a laminate exterior member and heat-sealed to form a laminate. When the battery including the electrode of the present disclosure is, for example, a laminated battery, the battery can be manufactured through a lamination step using a laminated exterior member.

[0049] <Battery> The battery disclosed herein preferably includes, in addition to an electrode having a current collector and a resin layer, a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer or a separator. In addition, when the battery is not an all-solid battery, it is preferred that the battery has a separator and contains a liquid electrolyte.

[0050] Figure 5 1 is a schematic cross-sectional view showing an example of the structure of the battery disclosed in the present invention (the resin layer is not shown). Figure 5 In the embodiment, the battery comprises a negative electrode current collector 113, a negative electrode active material layer A, a solid electrolyte layer B or a separator B, a positive electrode active material layer C, and a positive electrode current collector 115. The negative electrode active material layer A comprises a negative electrode active material 101, a conductive material 105, and a binder 109. The positive electrode active material layer C comprises a positive electrode active material 103, a conductive material 107, and a binder 111. The solid electrolyte layer B or the separator B may be a single-layer structure or a multi-layer structure.

[0051] - Positive electrode active material layer - The positive electrode active material layer preferably contains a positive electrode active material. Examples of the positive electrode active material include lithium composite oxides. The lithium composite oxide may contain at least one selected from the group consisting of F, Cl, N, S, Br, and I. The shape of the positive electrode active material is not particularly limited, and may be, for example, spherical (for example, true spherical, ellipsoidal, etc.), fibrous, or the like. When the positive electrode active material is spherical, the particle size is, for example, 0.1 μm to 30 μm. The specific surface area of ​​the positive electrode active material is, for example, 0.1 m 2 / g~100m 2 / g.

[0052] -Negative electrode active material layer- The negative electrode active material layer preferably contains a negative electrode active material. Examples of the negative electrode active material include lithium-based active materials such as metallic lithium, carbon-based active materials such as graphite, lithium titanate (e.g., Li 4 Ti 5 O 12 ) and other oxide-based active materials, and Si-based active materials such as Si single substance. The shape of the negative electrode active material is not particularly limited, and may be, for example, spherical (eg, true spherical, ellipsoidal, etc.), fibrous, or the like. When the negative electrode active material is spherical, the particle size is, for example, 0.1 μm to 30 μm. The specific surface area of ​​the negative electrode active material is, for example, 0.1 m 2 / g~1500m 2 / g.

[0053] The positive electrode active material layer and the negative electrode active material layer preferably further include a conductive material and a binder. By including a conductive material, the conductivity between the active materials and between the active materials and the current collector can be improved. In addition, by including a binder, the active materials and between the active materials and the current collector can be bonded.

[0054] Examples of the conductive material include acetylene black, Ketjen black, vapor grown carbon fiber (VGCF (registered trademark)), and carbon nanotubes.

[0055] The content of the conductive material is, for example, 3% by mass to 5% by mass based on the active material.

[0056] Examples of the binder include polyvinylidene fluoride (PVDF) / NMP-based binders and styrene butadiene rubber (SBR) / water-based binders. The content of the binder is, for example, 3% by mass to 5% by mass based on the active material.

[0057] -Solid electrolyte layer- In the case where the battery of the present disclosure is a solid battery (eg, an all-solid battery), the battery preferably has a solid electrolyte layer. As the solid electrolyte, for example, at least one solid electrolyte selected from the solid electrolyte group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, and a halide solid electrolyte can be cited. The shape of the solid electrolyte is not particularly limited and may be, for example, spherical (for example, true spherical, ellipsoidal, etc.), fibrous, etc. When the solid electrolyte is spherical, the particle size is, for example, 0.01 μm to 1 μm. The specific surface area of ​​the solid electrolyte is, for example, 25 m 2 / g~30m 2 / g.

[0058] -Spacers- When the battery of the present disclosure has a liquid electrolyte (electrolyte), the battery preferably has a separator. Examples of the separator include resin sheets of polyethylene (PE) and polypropylene (PP).

[0059] -Liquid electrolyte- Examples of the liquid electrolyte include a liquid electrolyte containing LiPF at a concentration of 0.1 mol / L to 1 mol / L. 6 , LiBF 4 、LiAsF 6 Carbonate solvents such as ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC).

Claims

1. A method for producing an electrode comprising a current collector and a resin layer, The manufacturing method includes the step of fusing the current collector and the resin layer using a heater having a lattice-shaped heat generating portion.

2. The method for manufacturing an electrode according to claim 1, wherein: The method further includes forming a positive electrode active material layer or a negative electrode active material layer on the current collector.

3. An electrode comprising a current collector and a resin layer, wherein a lattice-shaped fused portion and an unfused portion surrounded by the lattice-shaped fused portion are provided in a fused region between the current collector and the resin layer. A battery comprising the electrode according to claim 3.

5. A method for manufacturing a battery, comprising at least: A process for manufacturing an electrode using the method for manufacturing an electrode according to claim 1 or 2; The step of laminating the electrodes with a separator interposed therebetween to produce a laminate; as well as A step of sealing the laminate by fusing the resin layer included in the electrode.

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