Electrode for battery and battery

Abstract

To provide an electrode for a battery capable of reducing resistance, and a battery.SOLUTION: In an electrode 50 for a battery, a collector layer, a carbon coat layer and an active material layer are laminated successively. The carbon coat layer contains a carbon material and a resin. On a surface of the active material layer on the side of the carbon coat layer, a ratio Ra / RSm of arithmetic average roughness Ra with respect to an average length RSm of elements is 0.10 or more to 1.70 or less. A battery 60 includes the electrode 50 for the battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a battery electrode and a battery. [Background technology]

[0002] Attempts have been made to improve the adhesion between a current collector layer and an active material layer in battery electrodes. For example, Patent Document 1 discloses an electrode for use in an all-solid-state battery, the electrode having a current collector layer, an adhesive carbon material layer, and an active material layer in this order in the thickness direction, and the carbon material layer contains a carbon material, a dispersant, and a binder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-109290 Summary of the Invention [Problem to be solved by the invention]

[0004] The battery electrode disclosed in Patent Document 1 has improved adhesion between the current collector and the active material layer, particularly at high temperatures (80°C), but has the problem of increased resistance.

[0005] Therefore, an object of the present disclosure is to provide a battery electrode and a battery that can reduce resistance. [Means for solving the problem]

[0006] The present disclosure achieves the above object by the following means. <Aspect 1> A current collector layer, a carbon coating layer, and an active material layer are laminated in this order, The carbon coating layer contains a carbon material and a resin, and The arithmetic mean roughness Ra The average length of the elements, RS m Ratio to R a / RS m is between 0.10 and 1.70, Electrodes for batteries. Aspect 2: The battery electrode according to Aspect 1, wherein the carbon coating layer contains 10% by mass or more and less than 15% by mass of a carbon material. Aspect 3: A battery comprising the battery electrode according to aspect 1 or 2. Aspect 4: The battery according to aspect 3, which is a solid-state battery. [Effects of the Invention]

[0007] According to the present disclosure, R a and RS m Ratio of a / RS m By setting the "sharpness" of the surface irregularities within a predetermined range, it is possible to provide a battery electrode and a battery that can reduce resistance. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of a battery electrode according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view of FIG. 1, showing the carbon coat layer and the active material layer separately for the purpose of explanation. [Figure 3] FIG. 3 is a cross-sectional view showing an example of a conventional battery electrode. [Figure 4] FIG. 4 is a schematic cross-sectional view of FIG. 3, showing the carbon coat layer and the active material layer separately for the purpose of explanation. [Figure 5] FIG. 5 is a cross-sectional view schematically illustrating an example of a battery including a battery electrode according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present disclosure. In addition, in the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions will be omitted.

[0010] In the present disclosure, the battery may be a liquid-based battery containing an electrolytic solution as the electrolyte, or a solid-state battery containing a solid electrolyte as the electrolyte. In the present disclosure, a "solid-state battery" refers to a battery that uses at least a solid electrolyte as the electrolyte, and therefore a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as the electrolyte. In the present disclosure, the battery may also be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as the electrolyte.

[0011] 《Battery electrode》 The battery electrode of the present disclosure comprises: a current collector layer, a carbon coating layer, and an active material layer laminated in this order; The carbon coating layer contains a carbon material and a resin, and The arithmetic mean roughness R a The average length of the elements, RS m Ratio to R a / RS m However, it is between 0.10 and 1.70.

[0012] Fig. 1 is a cross-sectional view showing an example of a battery electrode according to the present disclosure. Fig. 2 is a cross-sectional view showing the carbon coating layer and the active material layer separated from each other for the sake of explanation, as compared to Fig. 1. Fig. 3 is a cross-sectional view showing an example of a conventional battery electrode. Fig. 4 is a cross-sectional view showing the carbon coating layer and the active material layer separated from each other for the sake of explanation, as compared to Fig. 3.

[0013] In the battery electrode 50, a current collector layer 10, a carbon coating layer 20, and an active material layer 30 are laminated in this order.

[0014] Without being bound by theory, in the battery electrode 50 of the present disclosure, as shown in FIGS. 1 and 2, the surface 36 of the active material layer 30 on the carbon coating layer 20 side is a / RS m is within a predetermined range, that is, the "sharpness" of the surface irregularities is within a predetermined range, so that the number of contact points between the carbon material 22 dispersed in the resin in the carbon coating layer 20 and the active material layer 30 increases. Therefore, the battery electrode 50 of the present disclosure can reduce the resistance. In particular, the content of the resin 24 is increased to improve the peel strength between the carbon coating layer 20 and the active material layer 30, and even if the content of the carbon material is relatively reduced, the resistance can be advantageously reduced.

[0015] 3 and 4, in the conventional battery electrode 50, the "sharpness" of the irregularities on the surface 36 of the active material layer 30 on the carbon coating layer 20 side is not particularly specified, and the contact point between the carbon material 22 of the carbon coating layer 20 and the active material layer 30 is insufficient. Therefore, the resistance of the conventional battery electrode 50 is increased.

[0016] Hereinafter, each configuration of the battery electrode of the present disclosure will be described.

[0017] <Current collector layer> The current collector layer of the battery electrode of the present disclosure may be a negative electrode current collector layer or a positive electrode current collector layer, which will be described later.

[0018] <Carbon coating layer> The carbon coating layer contains a carbon material and a resin. The carbon material ensures electrical conductivity between the current collector layer and the active material layer, reducing the resistance of the battery electrode. The resin provides adhesiveness to the carbon coating layer, ensuring peel strength (hereinafter sometimes simply referred to as "peel strength") between the current collector layer and the active material layer.

[0019] From the viewpoint of reducing the resistance of the battery electrode, the content of the carbon material in the carbon coating layer is preferably 3% by mass or more, 5% by mass or more, 7% by mass or more, or 10% by mass or more. If the amount of carbon material is excessive, the amount of resin will relatively decrease, so from the viewpoint of ensuring peel strength, the content of the carbon material in the carbon coating layer is preferably 32% by mass or less, 30% by mass or less, 28% by mass or less, 26% by mass or less, 25% by mass or less, 23% by mass or less, 20% by mass or less, 17% by mass or less, 15% by mass or less, or less than 15% by mass.

[0020] From the viewpoint of ensuring peel strength, the resin content in the carbon coating layer is preferably 70% by mass or more, 72% by mass or more, 74% by mass or more, 75% by mass or more, 76% by mass or more, 77% by mass or more, 78% by mass or more, 80% by mass or more, 82% by mass or more, or 83% by mass or more. If the resin content is excessive, the amount of carbon material will relatively decrease, so from the viewpoint of reducing the resistance of the battery electrode, the resin content in the carbon coating layer is preferably 90% by mass or less, 89% by mass or less, 88% by mass or less, 87% by mass or less, 86% by mass or less, or 85% by mass or less.

[0021] The carbon material is not particularly limited, and examples thereof include carbon black, carbon fiber, carbon nanotube (CNT), and carbon nanofiber (CNF). Examples of carbon black include acetylene black (AB), furnace black (FB), and ketjen black (KB). The carbon material may be a particulate carbon material or a fibrous carbon material.

[0022] The resin is not particularly limited, and may be a thermoplastic resin or a curable resin. Examples include acrylic resins such as polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polybutyl acrylate, polyhexyl acrylate, poly2-ethylhexyl acrylate, polydecyl acrylate, and polyacrylic acid; methacrylic binders such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, poly2-ethylhexyl methacrylate, and polymethacrylic acid; fluoride resins such as polyvinylidene fluoride (PVdF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVdF-HFP), polytetrafluoroethylene, and fluororubber; and rubber resins such as butadiene rubber, hydrogenated butadiene rubber, styrene butadiene rubber (SBR), hydrogenated styrene butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, and ethylene propylene rubber.

[0023] <Active material layer> The active material layer of the battery electrode of the present disclosure may be either a negative electrode active material layer or a positive electrode active material layer, which will be described later.

[0024] The arithmetic mean roughness R on the surface of the active material layer on the carbon coating layer side a The average length of the elements, RS m Ratio to R a / RS m is between 0.10 and 1.70. a / RS m is an index showing the "sharpness" of the surface irregularities; a relatively large value means that the irregularities are relatively sharp, and conversely, a relatively small value means that the irregularities are relatively soft. a and the average length of the elements RS m Complies with JIS B 0601:2013 (ISO 4287:1997, Amd. 1:2009). a and RS mFor example, before laminating the carbon coating layer and the active material layer, the surface of the active material layer to be laminated with the carbon coating layer is observed by SEM, and the value can be calculated from the surface profile.

[0025] R a / RS m If R is 0.10 or more, the number of contact points between the carbon material of the carbon coating layer and the active material layer can be increased. a / RS m R may be 0.10 or greater, 0.30 or greater, 0.50 or greater, 0.70 or greater, 0.90 or greater, 1.00 or greater, 1.30 or greater, or 1.40 or greater. a / RS m If R is 1.70 or less, it is advantageous to avoid damage to the surface of the active material layer and / or the carbon coating layer during lamination. a / RS m may be 1.65 or less, 1.60 or less, 1.55 or less, or 1.50 or less.

[0026] The arithmetic mean roughness R on the surface of the active material layer on the carbon coating layer side a teeth 、 The thickness may be 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, and may be 10.0 μm or less, 8.0 μm or less, 6.0 μm or less, 5.0 μm or less, 4.0 μm or less, or 3.0 μm or less.

[0027] "battery" Fig. 5 is a cross-sectional schematic diagram showing an example of a battery including a battery electrode according to the present disclosure. The battery 60 includes a first electrode current collector layer 12, a carbon coating layer 20, a first electrode active material layer 32, an electrolyte layer 40, a second electrode active material layer 34, the carbon coating layer 20, and a second electrode current collector layer 14. The embodiment shown in Fig. 5 is a single cell, but is not limited to this.

[0028] In FIG. 5 , both the first electrode 52, which is composed of the first electrode current collector layer 12, the carbon coating layer 20, and the first electrode active material layer 32, and the second electrode 54, which is composed of the second electrode active material layer 34, the carbon coating layer 20, and the second electrode current collector layer 14, are battery electrodes 50 of the present disclosure. However, this is not limited thereto, and either the first electrode 52 or the second electrode 54 may be a battery electrode 50 of the present disclosure. The combination of the first electrode 52 and the second electrode 54 may be a combination of a positive electrode and a negative electrode, or a combination of a negative electrode and a positive electrode. The carbon material 22 and the resin 24 of the carbon coating layer 20 are not shown. Furthermore, the surface roughness of the carbon coating layer 20 side of the first electrode active material layer 32 and the second electrode active material layer 34 is not shown.

[0029] In FIG. 5, the battery 60 may be a liquid battery or a solid battery depending on the electrolyte of the electrolyte layer 40.

[0030] <Battery electrode and battery manufacturing method> The method for producing the battery electrode of the present disclosure is not particularly limited, but can be, for example, as follows.

[0031] The method for manufacturing a battery electrode according to the present disclosure includes: Providing a current collector layer, a carbon coating layer, and an active material layer; Arithmetic mean roughness R a The average length of the elements, RS m Ratio to R a / RS m a member having at least a part of a transfer surface having a surface roughness of 0.10 or more and 1.70 or less; before laminating the current collector layer, the carbon coating layer, and the active material layer in this order, pressing the transfer portion of the member against the surface of the active material layer on the side of the carbon coating layer in advance to transfer the surface roughness; Includes.

[0032] In the above example of the manufacturing method, the current collector layer, the carbon coating layer, and the active material layer can be referred to in the description of "<Electrode Battery>".

[0033] The transfer surface of the part is filed to the desired radius using a tool such as a file. a / RS m The surface roughness of the transfer surface of the member can be given a and RS m Measure R a / RS m By calculating the calculated value, the R a / RS m It can be used as the R of the transfer surface of the part. a and RS m may be measured using a normal roughness measuring device, for example, a laser surface roughness measuring device, or may be obtained from the surface profile of the transferred surface observed using an SEM.

[0034] A battery including the battery electrode of the present disclosure can be manufactured by a known method, such as stacking a first electrode 52 and a second electrode 54 with an electrolyte layer 40 interposed therebetween in the case of the battery 60 shown in FIG.

[0035] Hereinafter, the configurations of the negative electrode current collector layer, the negative electrode active material layer, the electrolyte layer, the positive electrode active material layer, and the positive electrode current collector layer will be described.

[0036] <Negative electrode current collector layer> The material used for the negative electrode current collector layer is not particularly limited, and any material commonly used for a negative electrode current collector in a battery can be appropriately used. Examples of materials used for the negative electrode current collector layer include, but are not limited to, Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, and a carbon sheet. The negative electrode current collector layer may have a coating layer on its surface for the purpose of adjusting resistance, etc.

[0037] <Negative electrode active material layer> The negative electrode active material layer contains at least a negative electrode active material, and may further contain, optionally, a solid electrolyte, a conductive additive, a binder, etc. The negative electrode active material layer may also contain various other additives. The contents of the negative electrode active material, solid electrolyte, conductive additive, binder, etc. in the negative electrode active material layer may be appropriately determined depending on the desired battery performance. For example, when the entire negative electrode active material layer (total solid content) is taken as 100 mass%, the content of the negative electrode active material may be 40 mass% or more, 50 mass% or more, or 60 mass% or more, or may be 100 mass% or less, or 90 mass% or less.

[0038] (Negative electrode active material) As the negative electrode active material, various materials can be used that have a potential (charge / discharge potential) at which they absorb and release lithium ions that is lower than that of the positive electrode active material described below. The material for the negative electrode active material is not particularly limited, and may be metallic lithium or a material capable of absorbing and releasing metal ions such as lithium ions. Examples of materials capable of absorbing and releasing metal ions such as lithium ions include alloy-based negative electrode active materials, carbon materials, and lithium titanate (Li4Ti5O 12 ) and the like can be mentioned, but are not limited to these.

[0039] The alloy-based negative electrode active material is not particularly limited, and examples thereof include Si alloy-based negative electrode active materials and Sn alloy-based negative electrode active materials. Examples of Si alloy-based negative electrode active materials include silicon, silicon oxide, silicon carbide, silicon nitride, and solid solutions thereof. The Si alloy-based negative electrode active material may contain metal elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, and Ti. Examples of Sn alloy-based negative electrode active materials include tin, tin oxide, tin nitride, and solid solutions thereof. The Sn alloy-based negative electrode active material may contain metal elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, and Si.

[0040] The carbon material is not particularly limited, and examples thereof include hard carbon, soft carbon, graphite, and the like.

[0041] (solid electrolyte) The material of the solid electrolyte is not particularly limited, and may be, for example, a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer electrolyte.

[0042] Examples of sulfide solid electrolytes include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, and argyrodite-type solid electrolytes. Specific examples of sulfide solid electrolytes include Li2S-P2S5-based (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2(Li 13 GeP3S 16 , Li 10 GeP2S 12 etc.), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x etc.; or combinations thereof, but are not limited to these.

[0043] An example of an oxide solid electrolyte is Li7La3Zr2O 12 , Li 7-x La3Zr 1-x Nb x O 12 , Li 7-3x La3Zr2Al x O 12 , Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, or Li 3+x PO 4-x N x (LiPON), etc.; or combinations thereof.

[0044] The sulfide solid electrolyte and the oxide solid electrolyte may be glass or crystallized glass (glass ceramics).

[0045] Examples of polymer electrolytes include, but are not limited to, polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

[0046] (Conductive additive) The conductive additive is not particularly limited. Examples of the conductive additive include, but are not limited to, vapor-grown carbon fiber (VGCF), acetylene black (AB), ketjen black (KB), carbon nanotubes (CNT), and carbon nanofibers (CNF). The conductive additive may be, for example, particulate or fibrous, and its size is not particularly limited. The conductive additive is not particularly limited, and one type may be used alone, or two or more types may be used in combination.

[0047] (binder) The binder is not particularly limited. The binder may be, for example, polyvinylidene fluoride (PVdF), butadiene rubber (BR), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), or other materials, but is not limited to these. The binder is not particularly limited, and one type may be used alone, or two or more types may be used in combination.

[0048] <Electrolyte layer - solid electrolyte layer> The battery of the present disclosure may be a solid-state battery, i.e., a battery having a solid electrolyte layer as an electrolyte layer. The solid electrolyte layer contains at least a solid electrolyte and may also contain a conductive additive, a binder, etc. as necessary.

[0049] For the solid electrolyte, the conductive additive, and the binder, reference can be made to the above description of "<Negative electrode active material layer>".

[0050] <Electrolyte layer-electrolyte> The battery of the present disclosure can be a liquid battery, i.e., have an electrolyte solution as the electrolyte layer, particularly an electrolyte solution held in a separator layer.

[0051] (electrolyte) The electrolyte is not particularly limited, but preferably contains a supporting salt and a solvent.

[0052] The supporting salt (lithium salt) of the electrolyte solution having lithium ion conductivity is not particularly limited, but examples thereof include inorganic lithium salts and organic lithium salts. Examples of inorganic lithium salts include, but are not limited to, LiPF, LiBF, LiClO, and LiAsF. Examples of organic lithium salts include, but are not limited to, LiCF, SO, LiN(CF, SO), LiN(CF, SO), LiN(FSO), LiC(CF, SO), and LiC(CF, SO).

[0053] The solvent used in the electrolyte is not particularly limited, but examples thereof include cyclic carbonates, chain carbonates, etc. Examples of cyclic carbonates include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Examples of chain carbonates include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc. The electrolyte is not particularly limited, but one type may be used alone, or two or more types may be used in combination.

[0054] (separator) The separator is not particularly limited, and any separator commonly used for batteries can be appropriately used, such as a polyolefin-based, polyamide-based, or polyimide-based nonwoven fabric.

[0055] <Cathode active material layer> The positive electrode active material layer contains at least a positive electrode active material, and may further contain, optionally, a solid electrolyte, a conductive additive, a binder, etc. The positive electrode active material layer may also contain various other additives. The contents of the positive electrode active material, solid electrolyte, conductive additive, binder, etc. in the positive electrode active material layer may be appropriately determined depending on the desired battery performance. For example, when the entire positive electrode active material layer (total solid content) is taken as 100 mass%, the content of the positive electrode active material may be 40 mass% or more, 50 mass% or more, 60 mass% or more, or 100 mass% or less, or 90 mass% or less.

[0056] (Cathode active material) The material of the positive electrode active material is not particularly limited as long as it can absorb and release lithium ions. Examples of the positive electrode active material include lithium cobalt oxide (LiCoO), lithium nickel oxide (LiNiO), lithium manganese oxide (LiMnO), and nickel-cobalt-manganese oxide (NCM:LiCO 1 / 3 Ni 1 / 3 Mn 1 / 3 O2), lithium nickel-cobalt-aluminate (LiNi 0.8 (CoAl) 0.2 O2), Li 1+x Mn 2-x-y M y The material may be, but is not limited to, a different element-substituted Li-Mn spinel having a composition represented by O4 (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn).

[0057] The positive electrode active material may have a coating layer, although it is not particularly limited. The coating layer is a layer containing a substance that has lithium ion conductivity, low reactivity with the positive electrode active material and the solid electrolyte, and can maintain the shape of the coating layer without flowing even when in contact with the active material and the solid electrolyte. Specific examples of materials that constitute the coating layer include LiNbO3 and Li4Ti5O 12 , Li3PO4, etc., but are not limited to these.

[0058] For the solid electrolyte, conductive additive, and binder that can be contained in the positive electrode active material layer, reference can be made to the above description of "<Negative electrode active material layer>".

[0059] <Positive electrode current collector layer> The material used for the positive electrode current collector layer is not particularly limited, and any material commonly used for a battery positive electrode current collector can be appropriately adopted. Examples of materials used for the positive electrode current collector layer include, but are not limited to, Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. The positive electrode current collector layer may have a coating layer on its surface for purposes such as adjusting resistance. The positive electrode current collector layer may also be a metal foil or a substrate on which the above metals are plated or vapor-deposited. [Example]

[0060] <Sample Preparation> Each sample was prepared as follows.

[0061] <Preparation of Positive Electrode Active Material Layer> In a polypropylene container, polyvinylidene fluoride (PVdF) and the above positive electrode active material particles (Li coated with lithium niobate) were placed. 1.15 Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O particles), sulfide solid electrolyte (LiS-P2S5-based glass ceramic), and vapor-grown carbon fiber (VGCF) (Showa Denko K.K.) were added and stirred for 30 seconds using an ultrasonic disperser (UH-50, SMT Corporation). Next, the container was shaken for 3 minutes using a shaker (TTM-1, Shibata Scientific Co., Ltd.), and further stirred for 30 seconds using the ultrasonic disperser. The container was further shaken for 3 minutes using the shaker to obtain a positive electrode mixture.

[0062] The obtained positive electrode mixture was applied to an aluminum foil by a blade method using an applicator, and then the applied positive electrode mixture was air-dried and then dried on a hot plate at 100°C for 30 minutes to form a positive electrode active material layer on the aluminum foil as a release substrate.

[0063] <Preparation of negative electrode active material layer> PVdF, negative electrode active material particles (LTO particles), and the same sulfide solid electrolyte as above were placed in a polypropylene container and stirred for 30 minutes with an ultrasonic disperser to obtain a negative electrode mixture.

[0064] The obtained negative electrode mixture was applied to a copper foil as a negative electrode current collector by a blade method using an applicator. The applied negative electrode mixture was then air-dried and then dried on a hot plate at 100°C for 30 minutes to form a negative electrode active material layer on the copper foil as a negative electrode current collector. The negative electrode mixture was then similarly applied to the back surface of the copper foil as a negative electrode current collector and dried to form a negative electrode laminate having negative electrode active material layers on both sides of the copper foil as a negative electrode current collector.

[0065] <Preparation of solid electrolyte layer> Heptane, butadiene rubber (BR), and sulfide solid electrolyte were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser. Next, the container was shaken for 30 minutes using a shaker (Shibata Scientific TTM-1) and then further stirred for 30 seconds using the ultrasonic disperser. After shaking for 3 minutes using the shaker, the mixture was applied to aluminum foil using an applicator by the blade method. The mixture was then air-dried and then dried on a hot plate at 100°C for 30 minutes to form a solid electrolyte layer on the aluminum foil substrate.

[0066] <Preparation of carbon-coated positive electrode current collector> Acetylene black as a conductive material and an acrylic binder were weighed out in the proportions shown in Table 1 to produce the examples and comparative examples. Then, ethyl acetate was added to the acetylene black as a conductive material and the acrylic binder to prepare a carbon coating composition. Next, the carbon coating composition was applied to one side of an aluminum foil to a film thickness of 2 μm and dried at 100° C. for 1 hour to prepare a positive electrode current collector with a carbon coating layer (aluminum foil with a carbon layer).

[0067] <Preparing the electrode body> The negative electrode laminate obtained above and the solid electrolyte layer laminated on the release substrate were bonded together so that the negative electrode active material layer and the solid electrolyte layer were in direct contact with each other, and the negative electrode laminate was subjected to a load of 14.2 kN / cm 2 (1.6tf / cm 2 ), and then the aluminum foil, which was the substrate for peeling the solid electrolyte layer, was peeled off.

[0068] Next, the positive electrode active material layer laminated on the release substrate was further bonded so that the positive electrode active material layer and the solid electrolyte layer were in direct contact with each other, and pressed at 14.2 N / cm (1.6 tf / cm). Thereafter, the aluminum foil was peeled off, and the positive electrode active material layer was densified by roll pressing at a linear pressure of 44.5 kN (5 tf / cm). At this time, a stainless steel foil having a predetermined surface roughness was sandwiched between the press roll and the positive electrode active material layer, and the surface roughness of the stainless steel foil was transferred to the surface of the positive electrode active material layer, and the surface of the positive electrode active material layer was measured. The Ra and RS values ​​of the examples and comparative examples shown in Table 1 were obtained. m It has been made to have.

[0069] Thereafter, the positive electrode active material layer was cut to have an area of ​​70 mm x 70 mm, and tape was attached to the side where the negative electrode current collecting layer was not exposed, to obtain an electrode laminate.

[0070] <Attaching current collecting foil> A positive electrode current collector with a carbon coating layer was attached to the entire surface of the electrode laminate at 140° C. and 5 MPa so as not to protrude from the positive electrode active material layer. Thereafter, a terminal was welded, and the laminate was vacuum sealed to obtain a battery for evaluation.

[0071] Evaluation method and results The evaluation battery was CCCV charged at 2.95 V 0.3 C and then discharged to 1.5 V. It was then charged to 2.17 V and CC discharged at 5 C, and the resistance was calculated from the voltage difference.

[0072] The peel strength between the positive electrode current collector (positive electrode current collector layer with a carbon coating layer) and the positive electrode active material layer was measured by a 90° peel test. Specifically, the electrode laminate was cut into a width of 10 mm, and the positive electrode current collector on one side was peeled off. The electrode surface was then attached to a stage with double-sided tape, the positive electrode current collector was clamped, and a 90° peel test was performed.

[0073] The surface of the positive electrode active material layer on the side of the carbon coating layer was subjected to the above-mentioned method. a and RS m Measure R a / RS m was calculated.

[0074] The results are shown in Table 1. From Table 1, it can be seen that if the content of the carbon material in the carbon coating layer is the same, R a / RS m The resistance of the test battery of the example in which R is within the specified range is a / RS m It can be seen that the resistance is reduced compared to the resistance of the comparative test battery, which is outside the specified range. Furthermore, it can be seen from Table 1 that the peel strength increases as the carbon material content in the carbon coating layer decreases, i.e., as the resin content in the carbon coating layer increases.

[0075] [Table 1] [Explanation of symbols]

[0076] 10 Current collector layer 12 First electrode current collector layer 14 Second electrode current collector layer 20 carbon coating layer 22 Carbon Materials 24 Resin 30 Active material layer 32 First electrode active material layer 34 Second electrode active material layer 40 Electrolyte layer 50 Battery electrodes 60 batteries

Claims

1. a current collector layer, a carbon coating layer, and an active material layer laminated in this order; The carbon coating layer contains a carbon material and a resin, and The arithmetic mean roughness R ａ The average length of the elements RS ｍ Ratio to ａ / RS ｍ is 0.10 or more and 1.70 or less, Electrodes for batteries.

2. 2. The battery electrode according to claim 1, wherein the carbon coating layer contains 10% by mass or more and less than 15% by mass of a carbon material.

3. A battery comprising the battery electrode according to claim 1 or 2.

4. The battery of claim 3 which is a solid-state battery.

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