Anode and method for manufacturing anode

Abstract

To provide a negative electrode that can effectively suppress deterioration of a negative electrode current collector.SOLUTION: A negative electrode for use in a battery, includes, in this order, a negative electrode current collector that is an Al current collector, a resin layer formed on the surface of the Al current collector, and a negative electrode active material layer, the resin layer contains a resin and Ni particles as a conductive additive, and the negative electrode active material layer contains a negative electrode active material having a reaction potential of 0.3 V(Li+ / Li) or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, with the rapid spread of electronic devices such as personal computers and mobile phones, the development of batteries to be used as their power sources has progressed. In addition, the automotive industry is also developing batteries for use in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0003] For example, Patent Document 1 discloses a stacked battery including a power generating element formed by electrically stacking in series a plurality of unit cell layers, each of which is formed by sequentially stacking a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector, and an exterior body in which the power generating element is disposed, wherein at least one of the positive electrode current collector and the negative electrode current collector includes a conductive resin layer, and the power generating element further includes a resistance-reducing layer adjacent to the resin layer on the outer surface side of the unit cell layer including the resin layer. Patent Document 1 also discloses that the resistance-reducing layer may include a metal material.

[0004] Patent Document 2 discloses a method for manufacturing a current collector for a negative electrode of a lithium-ion secondary battery having a copper film. Patent Document 3 discloses that a negative electrode in a secondary battery includes a negative electrode current collector made of Al and a negative electrode active material layer formed on at least one surface of the negative electrode current collector, and a plating layer made of Ni and / or Cr is formed on the surface of the negative electrode current collector on which the negative electrode active material layer is formed. Patent Document 4 discloses a lithium-ion secondary battery having a substrate made of an alloy mainly composed of aluminum, a substrate having a plating layer containing nickel and phosphorus plated on the surface of the substrate, and a negative electrode layer containing a negative electrode active material that forms an intermetallic compound with lithium. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 031688 [Patent Document 2] Japanese Patent Publication No. 2020-187932 [Patent Document 3] Japanese Patent Publication No. 2020-119696 [Patent Document 4] Japanese Patent Publication No. 2020-091997 Summary of the Invention [Problem to be solved by the invention]

[0006] From the viewpoints of reducing the weight of the battery to improve the energy density and enhancing the heat dissipation of the battery to suppress battery degradation, it is expected that Al (aluminum) will be used as the material for the negative electrode current collector. However, because Al has a relatively high reaction potential, if a material with a lower reaction potential than Al is used as the negative electrode active material, the negative electrode current collector (Al current collector) may react with carrier ions before the negative electrode active material, resulting in degradation of the negative electrode current collector.

[0007] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a negative electrode that can effectively suppress deterioration of the negative electrode current collector. [Means for solving the problem]

[0008] [1] A negative electrode for use in a battery, the negative electrode has, in this order, a negative electrode current collector which is an Al current collector, a resin layer formed on the surface of the Al current collector, and a negative electrode active material layer; The resin layer contains a resin and Ni particles as a conductive additive, The negative electrode active material layer has a reaction potential of 0.3 V (Li + / Li) or less.

[0009] [2] The negative electrode according to [1], wherein in the resin layer, a weight ratio of the Ni particles to the resin is 4.3 or less.

[0010] [3] The average particle diameter of the Ni particles (D 50 ) is 500 nm or less.

[0011] [4] The negative electrode according to any one of [1] to [3], wherein the negative electrode active material contains a Si-based active material.

[0012] [5] A method for producing a negative electrode according to any one of [1] to [4], a slurry preparation step of preparing a resin slurry containing the resin, the Ni particles, and a solvent; a resin layer forming step of applying the resin slurry to a surface of the Al current collector and drying the applied resin slurry to form the resin layer; and forming the negative electrode active material layer on the surface of the resin layer. [Effects of the Invention]

[0013] The present disclosure provides an effect of effectively suppressing deterioration of the negative electrode current collector. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a negative electrode according to the present disclosure. [Figure 2] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. [Figure 3] FIG. 1 is a flow diagram illustrating a method for producing a negative electrode according to the present disclosure. [Figure 4] 10 is a graph showing the results of evaluation 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] The negative electrode and the method for manufacturing the negative electrode according to the present disclosure will be described in detail below. The drawings shown below are schematic diagrams, and the size and shape of each part are appropriately exaggerated for ease of understanding.

[0016] A. Negative electrode FIG. 1 is a schematic cross-sectional view illustrating an example of a negative electrode according to the present disclosure. The negative electrode AN shown in FIG. 1 includes a negative electrode current collector 1, which is an Al current collector, a resin layer 2 formed on the surface of the Al current collector 1, and a negative electrode active material layer 3, in this order. The resin layer 2 contains a resin and Ni particles as a conductive additive. The negative electrode active material layer 3 is formed of a material having a reaction potential of 0.3 V (Li + The negative electrode active material contains a negative electrode active material having a capacitance of 1 / Li or less.

[0017] According to the present disclosure, a resin layer containing resin and Ni particles is disposed on the surface of the Al current collector, so that the reaction (deterioration) of the Al current collector can be suppressed. For example, the reaction potential of Si-based active materials and C-based active materials is low (0.3 V (Li + When a material (such as ethylenediaminetetraacetic acid / Li) is used as the negative electrode active material, an ion conduction path is formed between the negative electrode current collector (Al current collector) and carrier ions (e.g., Li ions), which may result in deterioration of the negative electrode current collector due to a reaction between Al and Li. In this regard, in the negative electrode of the present disclosure, a resin layer is disposed between the negative electrode active material layer and the Al current collector. This prevents contact between the electrolyte in the negative electrode active material layer and the Al current collector, preventing the formation of a conduction path for carrier ions, thereby suppressing the reaction of the Al current collector. Furthermore, from the perspective of electrical conductivity, the resin layer is usually expected to contain a conductive additive such as acetylene black (AB). In this regard, as mentioned above, carbon (carbon-based conductive additive) may react with Al. In contrast, in the present disclosure, the resin layer contains Ni particles as a conductive additive. Ni is a material that is less reactive with Al than carbon-based conductive additives, and therefore can more effectively suppress deterioration of the Al current collector.

[0018] 1.Negative electrode current collector The negative electrode current collector in the present disclosure is an Al current collector. The Al current collector is a current collector made primarily of aluminum (Al). The Al current collector may be Al alone or an Al alloy. In the Al alloy, the ratio of Al element to all metal elements is 50 mol% or more, or may be 70 mol% or more, or even 90 mol% or more. On the other hand, in the Al alloy, the ratio of Al element to all metal elements is, for example, 99 mol% or less. The Al current collector may be in the form of, for example, a foil or a mesh. The thickness of the Al current collector is not particularly limited, but is, for example, 1 μm or more and 50 μm or less.

[0019] 2. Resin layer The resin layer is a layer disposed on the surface of the Al current collector. Specifically, it is a layer disposed between the Al current collector and the negative electrode active material layer in the thickness direction of the negative electrode. The resin layer contains a resin and Ni particles as a conductive additive.

[0020] Examples of the resin include thermoplastic resins, thermosetting resins, and conductive polymers. Among these, the resin layer preferably contains a thermoplastic resin. A thermoplastic resin is a resin that softens when heated. The softening temperature of a thermoplastic resin is, for example, 100°C or higher and 200°C or lower. Examples of the thermoplastic resin include poly(meth)acrylic acid, polymethyl(meth)acrylate, polyethylene, polypropylene, polyethylene terephthalate, polyethernitrile, polyimide, polyamide, polytetrafluoroethylene, polyacrylonitrile, poly(meth)acrylate, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, and vinyl halide resins. Note that "(meth)acrylic acid" is a concept that encompasses both acrylic acid and methacrylic acid, and "(meth)acrylate" is a concept that encompasses both acrylate and methacrylate.

[0021] Examples of thermosetting resins include epoxy resins and vinyl ester resins. The resin layer usually contains a cured product of the thermosetting resin. Examples of conductive polymers include polyaniline and polypyrrole. The resin layer may contain one type of resin or two or more types of resins.

[0022] Ni particles function as a conductive additive in the resin layer. In the present disclosure, Ni particles refer to particles containing Ni as the primary element, and may be particles of simple Ni or particles of an alloy containing Ni. The resin layer may contain only Ni particles as a conductive additive, or may contain other materials in addition to Ni particles, with the former being preferred. Even in the latter case, it is preferable that the resin layer contains Ni particles as the primary conductive additive. "Containing Ni particles as the primary conductive additive" means that the proportion of Ni particles relative to the total conductive additives in the resin layer is 50% by weight or more. The proportion of Ni particles may be 60% by weight or more, 80% by weight or more, 90% by weight or more, or even 95% by weight or more. On the other hand, the proportion of Ni particles (the proportion of Ni particles when the resin layer contains multiple conductive additives) is, for example, 99% by weight or less. It is preferable that the resin layer does not contain a carbon-based conductive additive as a conductive additive.

[0023] The average particle size of Ni particles (D 50 ) is not particularly limited, but is, for example, 500 nm or less. 50 may be 400 nm or less, or may be 300 nm or less. 50 is, for example, 10 nm or more, may be 50 nm or more, may be 100 nm or more, or may be 200 nm or more. 50 refers to the cumulative 50% particle size in the volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer.

[0024] In the resin layer, the weight ratio of Ni particles to resin is not particularly limited, but may be, for example, 4.3 or less, or may be 4.0 or less, or may be 3.0 or less, or may be 2.6 or less, or may be 1.5 or less. On the other hand, the weight ratio of Ni particles to resin is, for example, 0.5 or more, or may be 1.0 or more, or may be 1.5 or more, or may be 2.0 or more.

[0025] In addition, in the resin layer, the ratio (weight ratio) of Ni particles to the total of resin and Ni particles is not particularly limited, but may be, for example, 30% by weight, 40% by weight or more, or 50% by weight or more. On the other hand, the ratio of Ni particles to the total of resin and Ni particles is, for example, 90% by weight or less, 80% by weight or less, 70% by weight or less, or 60% by weight or less. In addition, the ratio of Ni particles to all components in the resin layer is, for example, 25% by weight or more.

[0026] The thickness of the resin layer is not particularly limited, but may be, for example, 0.5 μm or more, or 1 μm or more, while the thickness of the resin layer may be, for example, 10 μm or less, or 5 μm or less.

[0027] 3.Negative electrode active material layer The negative electrode active material layer has a reaction potential of 0.3 V (Li + The negative electrode active material contains a negative electrode active material having a capacitance of 1 / Li or less.

[0028] The reaction potential of the negative electrode active material is 0.2V (Li + / Li) or less, and + On the other hand, the reaction potential of the negative electrode active material may be, for example, −0.5 V(Li + / Li) or more. The reaction potential of the negative electrode active material can be determined by cyclic voltammetry (CV).

[0029] Examples of negative electrode active materials include Si-based active materials, carbon-based active materials, and Li-based active materials. Si-based active materials are active materials containing Si elements. Examples of Si-based active materials include simple Si, Si alloys, and Si oxides. Si alloys preferably contain Si elements as a main component. The proportion of Si elements in Si alloys is, for example, 50 mol % or more and 99 mol % or less.

[0030] Carbon-based active materials are inorganic active materials containing C element, such as graphite, hard carbon, and soft carbon. Li-based active materials are active materials containing Li element, such as simple Li and Li alloys.

[0031] The shape of the negative electrode active material may be, for example, particulate or layered. 50 ) is, for example, 10 nm or more, and may be 100 nm or more. On the other hand, the average particle diameter (D 50 ) is, for example, 50 μm or less, and may be 20 μm or less. The proportion of the negative electrode active material in the negative electrode active material layer is, for example, 50 wt % or more and 80 wt % or less.

[0032] The negative electrode active material layer may contain at least one of a conductive additive, a binder, and an electrolyte, as necessary. Examples of binders include rubber-based binders such as butadiene rubber (BR), acrylate butadiene rubber (ABR), and styrene butadiene rubber (SBR), as well as fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). The proportion of the binder in the negative electrode active material layer is, for example, 0.01% by weight or more and 5% by weight or less.

[0033] Examples of the conductive additive include carbon materials. Examples of the carbon material include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fiber, carbon nanotubes (CNT), and carbon nanofibers (CNF). The proportion of the conductive additive in the negative electrode active material layer is, for example, 0.01% by weight or more and 10% by weight or less.

[0034] Examples of the electrolyte include solid electrolytes. Examples of the solid electrolyte include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. The sulfide solid electrolyte preferably contains sulfur (S) as the main component of the anion element. The oxide solid electrolyte preferably contains oxygen (O) as the main component of the anion element. The halide solid electrolyte preferably contains halogen as the main component of the anion. Among these, sulfide solid electrolytes are preferred.

[0035] Other examples of solid electrolytes include organic solid electrolytes such as polymer electrolytes and gel electrolytes. Liquid electrolytes (electrolytic solutions) can also be used as the electrolyte. The proportion of the electrolyte in the negative electrode active material layer is, for example, 30% by weight or more and 80% by weight or less.

[0036] The thickness of the negative electrode active material layer is not particularly limited, but is, for example, 0.5 μm or more and 1000 μm or less.

[0037] 4.Battery The negative electrode of the present disclosure is used in a battery. Fig. 2 is a schematic cross-sectional view showing an example of a battery of the present disclosure. The battery 10 shown in Fig. 2 has a positive electrode CA having a positive electrode active material layer 5 and a positive electrode current collector 6, a negative electrode AN having a negative electrode current collector 1, a resin layer 2, and a negative electrode active material layer 3, and an electrolyte layer EL disposed between the positive electrode CA and the negative electrode AN. In particular, in the battery 10 of the present disclosure, the negative electrode AN is the above-mentioned negative electrode.

[0038] The positive electrode active material layer contains at least a positive electrode active material. The positive electrode active material can be a conventionally known material used in batteries. Examples of the positive electrode active material include oxide active materials. The positive electrode active material layer may further contain at least one of an electrolyte, a conductive material, and a binder. The electrolyte, the conductive material, and the binder are the same as those described above, and therefore will not be described here.

[0039] The electrolyte layer contains at least an electrolyte. The electrolyte layer preferably contains the above-mentioned solid electrolyte. The electrolyte layer may also contain an electrolytic solution as the electrolyte.

[0040] A battery typically has a positive electrode current collector and a negative electrode current collector, which may be made of conventionally known materials.

[0041] The battery in the present disclosure may be a liquid-based battery or a solid-state battery. The solid-state battery may be a semi-solid battery or an all-solid-state battery. The type of battery is not particularly limited, but is typically a lithium-ion secondary battery. The use of the battery is not particularly limited, but examples include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. It is particularly preferred that the battery be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery in the present disclosure may also be used as a power source for mobile objects other than vehicles (e.g., trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0042] B. Negative electrode manufacturing method Fig. 3 is a flow diagram illustrating a method for producing a negative electrode according to the present disclosure. As shown in Fig. 3, in the method for producing a negative electrode, first, a resin slurry containing the resin, the Ni particles, and a solvent is prepared (slurry preparation step). Next, the resin slurry is applied to the surface of the Al current collector and dried to form the resin layer (resin layer formation step). Then, the negative electrode active material layer is formed on the surface of the resin layer (negative electrode active material layer formation step).

[0043] In the method for producing a negative electrode according to the present disclosure, a resin slurry containing a resin, Ni particles, and a solvent is applied to the surface of an Al current collector and then dried to form a resin layer. That is, the resin layer is formed by a coating method. This allows for easy production of a negative electrode. Furthermore, the use of a resin slurry allows for the formation of a resin layer in which Ni particles are well dispersed, thereby further suppressing the reaction of the Al current collector.

[0044] 1. Slurry preparation process In the slurry preparation step, a resin slurry containing a resin, Ni particles, and a solvent is prepared. The resin, Ni particles, and negative electrode active material are the same as those described in "A. Negative electrode."

[0045] The solvent is not particularly limited as long as it can disperse the above-mentioned components. In this disclosure, the term "solvent" refers not only to a strict solvent but also to a dispersion medium. Examples of the solvent include organic solvents such as butyl butyrate, dibutyl ether, heptane, and tetrahydrofuran. The ratio of resin and Ni particles in the resin slurry is the same as that described in "A. Negative Electrode."

[0046] The method for producing the resin slurry is not particularly limited. For example, a method can be used in which the resin, Ni particles, and solvent are stirred and mixed using an ultrasonic disperser or the like. The stirring and mixing process can be performed only once or twice or more times. In the latter case, for example, a method can be used in which the resin and Ni particles are mixed in advance, and then the solvent is added and mixed.

[0047] 2.Resin layer formation process In the resin layer forming step, the resin slurry is applied to the surface of the Al current collector and dried to form the resin layer, which is the same as that described in "A. Negative electrode."

[0048] The amount of resin slurry to be applied is adjusted appropriately so that a desired resin layer is formed. The drying conditions (drying temperature and drying time) are not particularly limited as long as the solvent in the resin slurry can be removed, and are adjusted appropriately.

[0049] 3. Negative electrode active material layer formation process In the negative electrode active material layer forming step, a negative electrode active material layer is formed on the surface of the resin layer (the surface opposite to the Al current collector described above). The method for forming the negative electrode active material layer is not particularly limited, and examples thereof include a coating method using a negative electrode slurry.

[0050] The negative electrode slurry contains at least a negative electrode active material and a solvent, and may contain at least one of a conductive additive, a binder, and an electrolyte, as necessary. The negative electrode active material and the solvent are as described above. The solvent may be the same as or different from the solvent in the resin slurry. The proportions of the negative electrode active material, conductive additive, binder, and electrolyte in the negative electrode slurry are the same as those described in "A. Negative Electrode." The negative electrode slurry may be prepared before the resin layer formation step.

[0051] The coating method is the same as that described above, and the negative electrode active material layer is the same as that described in "A. Negative electrode."

[0052] 4. Other processes The production of the negative electrode may include a pressing step in which a laminate having the Al current collector, the resin layer, and the negative electrode active material layer is pressed for densification. The pressing may be a roll press or a uniaxial press. The pressure in the pressing step is, for example, 100 MPa or more and 800 MPa or less. The pressing step may be performed in a room temperature environment or a heated environment.

[0053] The negative electrode produced by the above-described process is the same as that described in "A. Negative electrode."

[0054] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0055] [Example 1] A half cell was fabricated as an evaluation battery in the following manner. Vinyl resin and Ni particles (particles of Ni alone, D 50 (=300 nm) were weighed and mixed at a weight ratio of 28:72. The weight ratio of Ni particles to vinyl resin was 2.6. A solvent was added to the resulting mixture, and the mixture was mixed six times for 30 seconds using an ultrasonic homogenizer. This yielded a resin slurry. The resin slurry was applied to a 15 μm-thick negative electrode current collector (Al foil) using a blade method and dried on a hot plate at 50°C for 20 minutes. This was then further dried on a hot plate at 150°C for 30 minutes. This yielded a negative electrode member having a negative electrode current collector and a resin layer.

[0056] 100 mg of sulfide solid electrolyte (SE: Li2S-P2S5-based sulfide solid electrolyte) was placed in a 10 mm diameter cylindrical container and pressed at 100 MPa using a SUS pin. This produced a solid electrolyte pellet. The above-mentioned negative electrode member and Li foil were punched out to a diameter of 11.28 mm. The Al foil, resin layer, pellet (solid electrolyte layer), and Li foil were placed in this order in a 11.28 mm diameter cylindrical container and sandwiched between SUS pins. The container was then restrained with a restraining jig so that the pressure at the pressurized portion was 2 MPa. This produced an evaluation battery (half cell).

[0057] [Examples 2 and 3] Except for changing the proportion of Ni particles in the resin layer as shown in Table 1, a test battery was fabricated in the same manner as in Example 1.

[0058] [Table 1]

[0059] [Comparative Example 1] A battery for evaluation was produced in the same manner as in Example 1, except that an Al foil with a thickness of 15 μm (a negative electrode member having no resin layer) was used as the negative electrode member.

[0060] Comparative Example 2 A vinyl resin and acetylene black were weighed and mixed in a weight ratio of 60:40. A negative electrode member and a test battery were produced in the same manner as in Example 1, except that the resin layer was formed using the resulting mixture.

[0061] Comparative Example 3 A vinyl resin and VGCF-H were weighed and mixed in a weight ratio of 60:40. A negative electrode member and a test battery were fabricated in the same manner as in Example 1, except that the resin layer was formed using the resulting mixture.

[0062] [Rating 1] Each half-cell was set to a constant voltage of 0.1 V using an electrochemical measurement device (VMP300), and the current value flowing after 100 hours was measured. The current value of Comparative Example 2 was set to 100, and the results were evaluated relatively. The results are shown in FIG.

[0063] As shown in Fig. 4, current values ​​could not be measured in Examples 1 to 3, confirming that no reaction occurred in the Al current collector. On the other hand, large current values ​​were measured in Comparative Examples 1 to 3, confirming that the Al current collector had reacted (degraded). Although the current values ​​in Comparative Examples 2 and 3, which have a resin layer, were smaller than those in Comparative Example 1, it is believed that the reaction of Al itself occurred because the carbon-based conductive additive was contained as the conductive additive.

[0064] [Example 4] A full cell (all-solid-state battery) was fabricated as an evaluation battery in the following manner.

[0065] (Fabrication of Positive Electrode Laminate) Cathode active material (NCA: LiNi 0.8 Co 0.15 Al 0.05 A positive electrode slurry was prepared by mixing NCA (Non-CuO), a sulfide solid electrolyte (SE: Li2S-P2S5-based sulfide solid electrolyte), vapor-grown carbon fiber (VGCF), a polyvinylidene fluoride (PVdF) binder, and butyl butyrate using an ultrasonic disperser. The weight ratio of NCA, SE, VGCF, and binder in the positive electrode slurry was 78.3:18.8:2.9:2.8. This positive electrode slurry was applied to a positive electrode current collector (on Al foil) using a blade method and dried on a hot plate at 50°C for 20 minutes. It was then further dried on a hot plate at 150°C for 30 minutes. This resulted in a positive electrode with a positive electrode current collector and a positive electrode active material layer.

[0066] An SE slurry was obtained by mixing a sulfide solid electrolyte (SE: Li2S-P2S5-based sulfide solid electrolyte), an acrylonitrile butadiene rubber (ABR)-based binder, heptane, and butyl butyrate using an ultrasonic disperser. The weight ratio of SE to binder in the SE slurry was 99.4:0.6. This SE slurry was applied to a stainless steel (SUS) foil using the blade method and dried on a hot plate at 50°C for 1 minute. It was then further dried on a hot plate at 150°C for 30 minutes. This resulted in a transfer member with an SE layer.

[0067] The positive electrode and the transfer member were laminated so that the positive electrode active material layer and the SE layer faced each other, and pressed using a roll press at a pressure of 50 kN / cm and a temperature of 160°C. After pressing, the SUS foil of the transfer member was peeled off, and the laminate was cut into 1 cm pieces. 2 This resulted in a positive electrode laminate.

[0068] (Fabrication of negative electrode laminate) Vinyl resin and Ni particles (Ni particles, D 50 The vinyl resin and Ni particles (300 nm) were weighed and mixed at a weight ratio of 28:72. The weight ratio of Ni particles to vinyl resin was 2.6. A solvent was further added to the mixture, and the mixture was mixed for 30 seconds six times using an ultrasonic homogenizer. This produced a resin slurry. The resin slurry was applied to a 15 μm-thick negative electrode current collector (Al foil) using a blade method and dried on a hot plate at 50°C for 20 minutes. This was then further dried on a hot plate at 150°C for 30 minutes. This produced a negative electrode current collector with a resin layer.

[0069] Anode slurry was prepared by mixing anode active material (silicon), sulfide solid electrolyte (SE: Li2S-P2S5-based sulfide solid electrolyte), vapor-grown carbon fiber (VGCF), polyvinylidene fluoride (PVdF) binder, and butyl butyrate using an ultrasonic disperser. The weight ratio of silicon, SE, VGCF, and binder was 49:41.2:7.5:6.6. The anode slurry was applied to a resin layer using a blade method and dried on a hot plate at 50°C for 20 minutes. The resulting layer was then further dried on a hot plate at 150°C for 30 minutes. This resulted in a cathode consisting of anode current collector, resin layer, and anode active material layer, in that order.

[0070] A transfer member was prepared in the same manner as above. The negative electrode and the transfer member were laminated so that the negative electrode active material layer and the SE layer faced each other, and pressed using a roll press at a pressure of 50 kN / cm and a temperature of 160°C. After pressing, the SUS foil of the transfer member was peeled off, and the laminate was cut into 1 cm pieces. 2 The transfer member was then placed on top of the pressed SE layer and pressed with a flat uniaxial press (pressing pressure 100 MPa, temperature 25°C). After that, the SUS foil on the transfer member was peeled off, and the resulting sheet was cut into 1.08 cm pieces. 2 This resulted in a negative electrode laminate in which two SE layers were laminated on the negative electrode active material layer.

[0071] (Fabrication of all-solid-state batteries) The positive electrode laminate and the negative electrode laminate were stacked so that the SE layers faced each other. This stack was pressed using a flat uniaxial press at a pressure of 500 MPa and a temperature of 160°C. This produced an all-solid-state battery.

[0072] [Reference example] A battery for evaluation was produced in the same manner as in Example 4, except that Ni foil without a resin layer was used as the negative electrode current collector.

[0073] [Rating 2] The resulting battery was sandwiched between two restraining plates, which were clamped at a restraining pressure of 10 MPa using fastening parts to fix the distance between the restraining plates. The restrained battery was charged at a constant current of 0.1 C to 4.05 V, and then charged at a low voltage of 0.01 C at 4.05 V. It was then discharged at a constant current of 0.1 C to 2.5 V, and then discharged at a low voltage of 0.01 C at 2.5 V. This charge-discharge cycle was repeated, and the discharge capacity of the second cycle was obtained. The discharge capacity of the reference example was evaluated relative to 100. The results are shown in Table 2.

[0074] [Table 2]

[0075] As shown in Table 2, there was no difference in the discharge capacity at the second cycle between Example 4 and the Reference Example. This confirmed that the degradation of the current collector is an issue specific to Al current collectors. [Explanation of symbols]

[0076] 1...Negative electrode current collector (Al current collector) 2...Resin layer 3...Negative electrode active material layer 5...Cathode active material layer 6...Positive electrode current collector CA…Positive electrode AN…Negative electrode EL…electrolyte layer 10...battery

Claims

1. A negative electrode for use in a battery, the negative electrode includes, in this order, a negative electrode current collector that is an Al current collector, a resin layer formed on a surface of the Al current collector, and a negative electrode active material layer; The resin layer contains a resin and Ni particles as a conductive additive, The negative electrode active material layer has a reaction potential of 0.3 V (Li ＋ / Li) or less.

2. The negative electrode according to claim 1 , wherein in the resin layer, a weight ratio of the Ni particles to the resin is 4.3 or less.

3. The average particle diameter (D ５０ 2. The negative electrode according to claim 1, wherein the thickness of the first and second electrodes is 500 nm or less.

4. The negative electrode according to claim 1 , wherein the negative electrode active material contains a Si-based active material.

5. A method for producing the negative electrode according to any one of claims 1 to 4, comprising: a slurry preparation step of preparing a resin slurry containing the resin, the Ni particles, and a solvent; a resin layer forming step of applying the resin slurry to a surface of the Al current collector and drying the applied resin slurry to form the resin layer; and forming the negative electrode active material layer on the surface of the resin layer.

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