Battery and manufacturing method thereof

Abstract

To provide a battery in which the deterioration of discharge characteristics caused by a negative electrode current collector (Al current collector) is suppressed.SOLUTION: The present disclosure provides a battery having a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, the negative electrode includes a negative electrode current collector which is an Al current collector, and a negative electrode active material layer containing a negative electrode active material having a lower reaction potential than Al, the negative electrode current collector is coated with a resin coating layer containing a resin and a conductive material, and further, an intermediate layer containing the resin and the negative electrode active material is disposed between the resin coating layer and the negative electrode active material layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to batteries and methods for making batteries. [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 power sources for these devices is progressing. 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 an anode for an all-solid-state battery, which includes an anode current collector layer and an anode active material layer, and the anode current collector layer is an aluminum foil or an aluminum alloy foil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-0855323 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of reducing the weight of the battery to improve the energy density, and from the viewpoint of improving the heat dissipation of the battery to suppress battery deterioration, it is expected that Al (aluminum) will be used as the material for the negative electrode current collector. However, since 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) will react with Li ions before the negative electrode active material, and the discharge characteristics will tend to deteriorate.

[0006] The present disclosure has been made in consideration of the above circumstances, and has as its main object to provide a battery in which the deterioration of discharge characteristics caused by the negative electrode current collector (Al current collector) is suppressed. [Means for solving the problem]

[0007] [1] A battery having a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, wherein the negative electrode has a negative electrode current collector which is an Al current collector, and a negative electrode active material layer containing a negative electrode active material having a lower reaction potential than Al, the negative electrode current collector is coated with a resin coating layer containing a resin and a conductive material, and further, an intermediate layer containing the resin and the negative electrode active material is disposed between the resin coating layer and the negative electrode active material layer.

[0008] [2] A battery having a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, wherein the negative electrode has a negative electrode current collector which is an Al current collector, and a negative electrode active material layer containing a negative electrode active material having a lower reaction potential than Al, and the negative electrode active material layer is a layer containing a resin, and is a concentration gradient layer in which the concentration of the resin increases from the electrolyte layer toward the negative electrode current collector.

[0009] [3] The battery according to [1] or [2], wherein the resin is a thermoplastic resin.

[0010] [4] The reaction potential of the negative electrode active material is 0.3V (Li + / Li) or less.

[0011] [5] The battery according to any one of [1] to [4], wherein the negative electrode active material contains a Si-based active material or a carbon-based active material.

[0012] [6] The battery according to [5], comprising the Si-based active material as the negative electrode active material.

[0013] [7] The battery according to any one of [1] to [6], wherein the electrolyte layer is a solid electrolyte layer containing a solid electrolyte.

[0014] [8] The battery according to [1], wherein the resin coating layer does not contain the negative electrode active material.

[0015] [9] The battery according to [1], wherein a ratio of a thickness of the intermediate layer to a total thickness of the negative electrode active material layer, the intermediate layer, and the resin coat layer is 0.80% or more.

[0016]

[10] The battery according to [1] or [9], wherein a ratio of a thickness of the intermediate layer to a total thickness of the negative electrode active material layer, the intermediate layer, and the resin coating layer is 7.0% or less.

[0017]

[11] The battery according to [1], wherein the resin coating layer has a thickness of 10 μm or less.

[0018]

[12] A battery manufacturing method for manufacturing the battery according to [1], the battery manufacturing method comprising: a laminate forming step of obtaining a laminate having, in a thickness direction, the Al current collector, the resin coating layer, and the negative electrode active material layer in this order; and a pressing step of applying a press pressure to the laminate in the thickness direction to form the intermediate layer.

[0019]

[13] A battery manufacturing method for manufacturing the battery according to [2], comprising a concentration gradient layer forming step of forming the concentration gradient layer on one surface of the Al current collector in the thickness direction. Effect of the Invention

[0020] The present disclosure provides an advantage in that it is possible to suppress deterioration of discharge characteristics caused by the negative electrode current collector (Al current collector). [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. [Diagram 2] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The battery and the method for manufacturing the battery according to the present disclosure will be described in detail below. Each of the figures shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, in this specification, when expressing an aspect in which another member is arranged relative to a certain member, the term "above" or "below" simply refers to both a case in which another member is arranged directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is arranged above or below a certain member via another member, unless otherwise specified.

[0023] A.Battery Fig. 1(a) is a schematic cross-sectional view illustrating a battery according to the present disclosure, and Fig. 1(b) is an enlarged view of a part of Fig. 1(a). Fig. 2 is a schematic cross-sectional view illustrating a battery according to the present disclosure. As shown in Figs. 1 and 2, a battery 10 according to the present disclosure has a thickness direction D T has a positive electrode CA, a negative electrode AN, and an electrolyte layer EL disposed between the positive electrode CA and the negative electrode AN. As shown in Fig. 1 and Fig. 2, the positive electrode CA usually has a positive electrode current collector 1 and a positive electrode active material layer 2. The negative electrode AN has a negative electrode current collector 3 which is an Al current collector, and a negative electrode active material layer 4 which contains a negative electrode active material having a lower reaction potential than Al.

[0024] As shown in Fig. 1(b), the negative electrode current collector 3 may be coated with a resin coating layer 5 containing a resin and a conductive material. Furthermore, in the negative electrode AN, an intermediate layer 6 containing the resin and the negative electrode active material may be disposed between the resin coating layer 5 and the negative electrode active material layer 4. On the other hand, as shown in Fig. 2, the negative electrode active material layer 4 may be a layer containing a resin, and may be a concentration gradient layer 7 in which the concentration of the resin increases from the electrolyte layer EL toward the negative electrode current collector 3.

[0025] According to the present disclosure, since the negative electrode has a negative electrode active material layer, an intermediate layer, and a resin coating layer, or since the negative electrode active material layer in the negative electrode is a concentration gradient layer, the intermediate layer or the concentration gradient layer ensures physical adhesion and conductivity at the interface between the negative electrode active material layer and the resin coating layer, contributing to reducing the electrical resistance at the interface, resulting in a battery in which deterioration of discharge characteristics caused by the negative electrode current collector (Al current collector) is suppressed.

[0026] As mentioned above, it is expected that Al (aluminum) will be used as the material for the negative electrode current collector from the viewpoints of reducing the weight of the battery to improve the energy density, and of improving the heat dissipation of the battery to suppress battery deterioration. However, since 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) will react with Li ions and form an alloy before the negative electrode active material does. Damage to the current collector caused by alloying tends to deteriorate the discharge characteristics.

[0027] In contrast, as shown in FIG. 1, in a battery 10 in which the negative electrode AN has a negative electrode active material layer 4, an intermediate layer 6, and a resin coating layer 5, a structure is formed in which the electrolyte EL, which is a migration path of Li ions, does not come into direct contact with the negative electrode current collector 3 due to the resin contained in the intermediate layer 6 and the resin contained in the resin coating layer. Since the migration path of Li ions is blocked by the intermediate layer 6 and the resin coating layer 5, it is possible to suppress the migration of Li ions to the negative electrode current collector 3. Even in a potential range in which Li ions react with the negative electrode current collector 3 (Al current collector) to form an alloy with lithium, since there are no Li ions near the surface of the negative electrode current collector 3 (Al current collector), damage to the current collector foil due to alloying of the negative electrode current collector 3 (Al current collector) does not occur. As a result, it is possible to suppress the deterioration of discharge characteristics caused by the negative electrode current collector 3 (Al current collector). In addition, by providing the intermediate layer 6, the adhesion between the negative electrode active material layer 4 and the resin coating layer 5 is improved due to the anchor effect. This improves the discharge characteristics.

[0028] 2, in a battery 10 in which the negative electrode active material layer 4 is a concentration gradient layer 7, the ratio of resin in the concentration gradient layer 7 increases toward the negative electrode current collector 3, and thus, as in the above, a structure is formed in which the electrolyte EL, which serves as a migration path for Li ions, does not come into direct contact with the negative electrode current collector 3, thereby making it possible to suppress migration of Li ions to the negative electrode current collector 3. As a result, it is possible to suppress deterioration of discharge characteristics caused by the negative electrode current collector 3 (Al current collector).

[0029] In addition, when Li ions are present near the surface of Al, the potential is relatively high (+0.3V vs Li / Li + ) alloying reaction with lithium occurs. Materials with lower reaction potential than Al (<+0.3V vs Li / Li + ) is used as the negative electrode active material, there is a concern that the Al will be damaged due to an alloying reaction between Li and Al, and the interface with the negative electrode active material layer 4 will peel off, resulting in electrical insulation and a decline in discharge characteristics. In contrast, in the present disclosure, because the negative electrode has a negative electrode active material layer, an intermediate layer, and a resin coating layer, or because the negative electrode active material layer in the negative electrode is a concentration gradient layer, a structure is formed in which the electrolyte EL, which is a migration path for Li ions, does not come into direct contact with the negative electrode current collector 3, and Li ions are no longer present near the surface of the Al current collector, thereby suppressing the alloying reaction of Al.

[0030] 1.Negative electrode The negative electrode in the present disclosure has a negative electrode current collector that is an Al current collector, and a negative electrode active material layer that contains a negative electrode active material that has a lower reaction potential than Al.

[0031] (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 using aluminum (Al) as a material. The Al current collector preferably contains Al as a main material. The Al current collector may be Al alone or an Al alloy. In an Al alloy, the reaction potential of metal elements other than Al is preferably lower than that of Al. The ratio of the Al element to all metal elements is, for example, 50 mol% or more, may be 70 mol% or more, or may be 90 mol% or more. On the other hand, in an Al alloy, the ratio of the Al element to all metal elements is, for example, 99 mol% or less. The shape of the Al current collector is, for example, a foil shape or a mesh shape. The thickness of the Al current collector is not particularly limited, but is, for example, 1 μm or more and 50 μm or less.

[0032] As shown in FIG. 1, a negative electrode current collector 3, which is an Al current collector, may be covered with a resin coating layer 5 containing a resin and a conductive material.

[0033] The resin coating layer contains a resin. Examples of the resin include a thermoplastic resin, a thermosetting resin, and a conductive polymer. The thermoplastic resin is a resin that is softened by heat. The softening temperature of the thermoplastic resin is, for example, 100°C or more and 200°C or less, and may be 110°C or more and 190°C or less, or may be 130°C or more and 180°C or less. Examples of the thermoplastic resin include poly(meth)acrylic acid, polymethyl(meth)acrylate, polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamide, polytetrafluoroethylene, polyacrylonitrile, poly(meth)acrylate, and halogenated vinyl resin. Note that "(meth)acrylic acid" is a concept that includes both acrylic acid and methacrylic acid, and "(meth)acrylate" is a concept that includes both acrylate and methacrylate.

[0034] Examples of the thermosetting resin include epoxy resin, vinyl ester resin, unsaturated polyester resin, phenol resin, and melamine resin. The resin coating layer usually contains a cured product of the thermosetting resin. Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylenevinylene, polyacrylonitrile, and polyoxadiazole. The resin contained in the resin coating layer may be one type or two or more types.

[0035] Among them, the resin contained in the resin coating layer is preferably a thermoplastic resin. Since the thermoplastic resin is softened by heat, the intermediate layer can be easily formed, for example, by a pressing process described later. In particular, the resin coating layer preferably contains at least one of poly(methyl (meth)acrylate), poly(meth)acrylic acid, and polyacrylonitrile as the resin.

[0036] The resin may be a crystalline resin, an amorphous resin, or a mixture of both. From the viewpoint of adhesion, the resin is preferably an amorphous resin. The "crystalline" resin means that the resin has an endothermic peak with a half-width of 10°C or less when measured at a heating rate of 10 (°C / min) in differential scanning calorimetry (DSC measurement), while the "amorphous" resin means that the half-width exceeds 10°C or that no clear endothermic peak is observed.

[0037] The resin contained in the resin coating layer may be the same as or different from the binder contained in the negative electrode active material layer described later. In addition, the resin contained in the resin coating layer does not have to be a fluorine-containing resin such as PVdF.

[0038] The resin coat layer contains a conductive material. Examples of the conductive material 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 nanotube (CNT), and carbon nanofiber (CNF). The ratio of the conductive material in the resin coat layer is, for example, 1 part by weight or more and 50 parts by weight or less, or 5 parts by weight or more and 40 parts by weight or less, or 10 parts by weight or more and 30 parts by weight or less, relative to 100 parts by weight of the resin. In addition, it is preferable that the resin coat layer does not contain a negative electrode active material described later. Similarly, it is preferable that the resin coat layer does not contain an electrolyte, particularly a solid electrolyte, described later.

[0039] The resin coating layer usually covers at least the surface (first surface) of the Al current collector on the electrolyte layer side in the thickness direction. The resin coating layer may cover surfaces of the Al current collector other than the first surface. When viewed in a plan view from the thickness direction, the ratio of the portion of the first surface covered by the resin coating layer (coverage rate) is, for example, 50% or more, 70% or more, or 90% or more. Meanwhile, the coverage rate may be 100%, less than 100%, or 95% or less.

[0040] The linear expansion coefficient of the resin coating layer is not particularly limited, but is, for example, 100×10 -6 ppm / K or more, 500×10 -6 ppm / K or less, 200×10 -6 ppm / K or higher, 430×10 -6 ppm / K or less, and -6 ppm / K or higher, 350×10 -6 It may be less than or equal to ppm / K. The value of the linear expansion coefficient is a value measured by a method in accordance with JIS H7404-1993.

[0041] The thickness of the resin coating layer is not particularly limited, but may be, for example, 0.5 μm or more, 1.0 μm or more, 3 μm or more, or 4 μm or more, while the thickness of the resin coating layer may be, for example, 10 μm or less, 8 μm or less, or 6 μm or less.

[0042] (2) Negative electrode active material layer The negative electrode active material layer contains a negative electrode active material having a reaction potential lower than that of Al.

[0043] The reaction potential of the negative electrode active material is not particularly limited as long as it is lower than the reaction potential of Al. For example, it is 0.3 V (Li + / Li) or less, and + / Li) or less, and 0.1V(Li + 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).

[0044] Examples of the negative electrode active material include Si-based active materials, carbon-based active materials, and Li-based active materials. The Si-based active material is an active material containing Si element. Examples of the Si-based active material include simple Si, Si alloys, and Si oxides. The Si alloy preferably contains Si element as a main component. The ratio of Si element in the Si alloy is, for example, 50 mol% or more, may be 70 mol% or more, or may be 90 mol% or more. On the other hand, the ratio of Si element in the Si alloy is, for example, 99 mol% or less. Examples of the Si alloy include Si-Al-based alloys, Si-Sn-based alloys, Si-In-based alloys, Si-Ag-based alloys, Si-Pb-based alloys, Si-Sb-based alloys, Si-Bi-based alloys, Si-Mg-based alloys, Si-Ca-based alloys, Si-Ge-based alloys, and Si-Pb-based alloys. The Si alloy may be a two-component alloy, or a multi-component alloy of three or more components. Examples of the Si oxide include SiO.

[0045] The carbon-based active material is an inorganic active material containing C element, such as graphite, hard carbon, and soft carbon, while the Li-based active material is an active material containing Li element, such as simple Li and Li alloys.

[0046] 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. 50 ) refers to the cumulative 50% particle size in the volume-based particle size distribution measured with a laser diffraction particle size analyzer.

[0047] The negative electrode active material layer may contain at least one of a conductive material, a binder, and an electrolyte, if necessary. Examples of the binder 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 conductive material is the same as that described above in "(1) Negative electrode current collector". Meanwhile, the electrolyte is the same as that described later in "3. Electrolyte layer".

[0048] 2, the negative electrode active material layer 4 may be a layer containing a resin, and may be a concentration gradient layer 7 in which the concentration of the resin increases from the electrolyte layer EL toward the negative electrode current collector 3. The resin is the same as the resin described above.

[0049] 2, in the negative electrode active material layer 4 (concentration gradient layer 7), the surface opposite to the negative electrode current collector 3 side is the first surface S1, and the surface on the negative electrode current collector 3 side is the second surface S2. In this case, the resin concentration C1 on the first surface S1 is smaller than the resin concentration C2 on the second surface S2. The ratio of C1 to C2 (C1 / C2) is, for example, 0.1 or more, may be 0.3 or more, or may be 0.5 or more. Meanwhile, C1 / C2 is, for example, 0.9 or less, and may be 0.7 or less.

[0050] The concentration of the resin in the concentration gradient layer may increase continuously or stepwise from the first surface S1 to the second surface S2. The second surface may be in contact with the Al current collector, or may be in contact with a resin coating layer that covers the Al current collector. When the second surface is observed from the thickness direction, the proportion of the resin in the concentration gradient layer may be, for example, 80% or more and 100% or less, or 90% or more and 99% or less.

[0051] 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.

[0052] (3) Middle class The negative electrode in the present disclosure may have an intermediate layer between the resin coating layer and the negative electrode active material layer. By providing the intermediate layer, the adhesion between the resin coating layer and the negative electrode active material layer is improved. The intermediate layer contains the negative electrode active material contained in the negative electrode active material layer and the resin contained in the resin coating layer. The intermediate layer is typically a layer in which a part of the negative electrode active material (one particle) contained in the negative electrode active material layer penetrates into the resin coating layer, and a part of the negative electrode active material (one particle) and a component of the resin coating layer are mixed. Therefore, the intermediate layer may have a part of the conductive material (one particle) contained in the resin coating layer. The negative electrode active material, the resin, and the conductive material are as described in "(1) Negative electrode current collector" and "(2) Negative electrode active material layer", respectively.

[0053] In the cross section of the intermediate layer, the ratio of the resin to the total ratio of the negative electrode active material and the resin is, for example, 10% or more and 90% or less. In addition, in the intermediate layer, the above-mentioned ratio of the resin may be uniform in the thickness direction. On the other hand, the ratio of the resin may change from the surface of the intermediate layer on the negative electrode active material layer side to the surface of the resin coat layer side. The ratio of the resin may increase continuously or stepwise, or may decrease continuously or stepwise, but the former is preferred.

[0054] The ratio of the thickness of the intermediate layer to the total thickness of the negative electrode active material layer, the intermediate layer, and the resin coat layer is, for example, 0.30% or more, may be 0.40% or more, may be 0.50% or more, may be 0.60% or more, may be 0.70% or more, may be 0.80% or more, may be 0.85% or more, may be 1.0% or more, or may be 1.5% or more. On the other hand, the ratio is, for example, 7.0% or less, may be 6.6% or less, may be 6.0% or less, may be 5.0% or less, or may be 3.0% or less.

[0055] The thickness of the intermediate layer is, for example, 10 nm or more, may be 30 nm or more, or may be 50 nm or more. On the other hand, the thickness of the intermediate layer is, for example, 1000 nm (1 μm) or less, may be 800 nm or less, 600 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less. The thickness of the intermediate layer is an average value of thicknesses measured at any 10 points by observing a laminated cross section cut in the thickness direction of the intermediate layer using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX). In addition, the components contained in the intermediate layer can be confirmed by EDX analysis of the chemical composition of the laminated cross section cut in the thickness direction of the intermediate layer using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX).

[0056] The method for forming the intermediate layer is not particularly limited, but for example, when the resin in the resin coating layer is a thermoplastic resin, the resin coating layer and the negative electrode active material layer are placed opposite each other and pressed while being heated to a temperature equal to or higher than the softening temperature of the thermoplastic resin. On the other hand, when the resin in the resin coating layer is a thermosetting resin, the thermosetting resin and the negative electrode active material are filled in a mold and heated to form the mold.

[0057] 2. Positive electrode The positive electrode in the present disclosure usually has, from the electrolyte layer side, a positive electrode active material layer and a positive electrode current collector.

[0058] The positive electrode active material layer contains at least a positive electrode active material. The positive electrode active material layer may contain at least one of a conductive material, a binder, and an electrolyte, as necessary. The conductive material, the binder, and the electrolyte are the same as those described in "1. Negative electrode".

[0059] The positive electrode active material may be, for example, an oxide active material. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and LiNi 0.8 Co 0.15 Al 0.05 Examples of the positive electrode active material include rock salt layer type active materials such as O2, spinel type active materials such as LiMn2O4, and olivine type active materials such as LiFePO4. Sulfur (S) may also be used as the positive electrode active material. The positive electrode active material may be, for example, in the form of particles.

[0060] The thickness of the positive electrode active material layer is not particularly limited, but is, for example, 0.1 μm or more and 1000 μm or less.

[0061] The positive electrode current collector is a member that collects electrons from the positive electrode active material layer. The material of the positive electrode current collector is not particularly limited, but examples thereof include SUS, aluminum, nickel, iron, titanium, and carbon. The shape of the positive electrode current collector may be, for example, a foil shape or a mesh shape.

[0062] 3. Electrolyte layer The electrolyte layer is disposed between the positive electrode and the negative electrode, more specifically, between the positive electrode active material layer and the negative electrode active material layer.

[0063] The electrolyte layer contains at least an electrolyte. 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 a main component of the anion element. The oxide solid electrolyte preferably contains oxygen (O) as a main component of the anion element. The halide solid electrolyte preferably contains halogen (N) as a main component of the anion. Among these, the sulfide solid electrolyte is preferred.

[0064] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-GeS2, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-LiI-LiBr, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S n (where m and n are positive numbers. Z is Ge, Zn, or Ga.), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In.)

[0065] Other examples of the solid electrolyte include organic solid electrolytes such as polymer electrolytes and gel electrolytes. A liquid electrolyte (electrolytic solution) can also be used as the electrolyte. The electrolyte layer in the present disclosure may be a layer in which a separator is impregnated with an electrolytic solution. The separator may be a conventionally known member.

[0066] In the present disclosure, an electrolyte layer containing a solid electrolyte may be referred to as a solid electrolyte layer, and a battery having a solid electrolyte layer may be referred to as an all-solid-state battery. The electrolyte layer may also contain a binder as necessary. The binder is the same as that described in "1. Negative electrode". The thickness of the electrolyte layer is, for example, 1 μm or more and 500 μm or less.

[0067] 4.Battery The battery of the present disclosure may include an exterior body that houses the above-mentioned members. Examples of the exterior body include a laminate-type exterior body and a case-type exterior body. The battery of the present disclosure may also include a restraining jig that applies a restraining pressure in the thickness direction to the above-mentioned members. As the restraining jig, a known jig can be used. The restraining pressure may be, for example, 0.1 MPa or more and 50 MPa or less, and may be 1 MPa or more and 20 MPa or less.

[0068] The type of the battery in the present disclosure is not particularly limited, but is typically a lithium ion secondary battery. In addition, the battery is preferably an all-solid-state battery. The use of the battery is not particularly limited, but examples thereof 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. In particular, it is preferable to use the battery as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). In addition, the battery in the present disclosure may be used as a power source for moving bodies other than vehicles (for example, railways, ships, and aircraft), and may be used as a power source for electrical products such as information processing devices.

[0069] B. Battery manufacturing method The present disclosure can also provide a method for manufacturing the above-mentioned battery. Specifically, the method can provide a method for manufacturing a battery having the above-mentioned negative electrode current collector (Al current collector) coated with a negative electrode active material layer, an intermediate layer, and a resin coating layer, the method including a laminate forming step of obtaining a laminate having the Al current collector, the resin coating layer, and the negative electrode active material layer in this order in the thickness direction, and a pressing step of applying a pressing pressure to the laminate in the thickness direction to form the intermediate layer.

[0070] In the laminate forming step, the resin coat layer may be formed by applying a slurry containing a resin and a conductive material to an Al current collector and drying the slurry. The negative electrode active material layer may be formed by applying a negative electrode slurry containing at least the negative electrode active material to the resin coat layer and drying the slurry. The negative electrode active material layer may be formed by transferring the negative electrode active material layer and the negative electrode active material layer onto the resin coat layer using a transfer member having a base material.

[0071] The laminate may have only the negative electrode active material layer, the resin coating layer, and the Al current collector. Alternatively, the laminate may have an electrolyte layer on the surface of the negative electrode current collector opposite to the Al current collector, or may have an electrolyte layer and a positive electrode.

[0072] The pressing process is not particularly limited as long as the intermediate layer can be formed by applying a pressing pressure to the laminate. The pressing conditions can be, for example, the conditions described in the examples. The pressing pressure may be applied only once, or may be applied twice or more. Examples of the pressing method include roll pressing and cold isostatic pressing (CIP). The pressing pressure may be, for example, 1 kN / cm or more and 100 kN / cm or less, or 5 kN / cm or more and 80 kN / cm or less. In particular, when the resin is a thermoplastic resin, it is preferable to perform the pressing while heating the laminate. The heating temperature is preferably determined in consideration of the softening temperature of the thermoplastic resin, and may be, for example, a temperature not lower than the softening temperature and not higher than the softening temperature + 100°C, or not lower than the softening temperature and not higher than the softening temperature + 80°C. The heating and pressing may be performed simultaneously or separately.

[0073] The present disclosure also provides a method for producing a battery in which the negative electrode active material layer is a concentration gradient layer, the method including a concentration gradient layer forming step of forming the concentration gradient layer on one surface of the Al current collector in the thickness direction. The concentration gradient layer forming step is not particularly limited as long as it can form the concentration gradient layer.

[0074] The battery obtained by the above-mentioned steps is the same as that described in "A. Battery".

[0075] The present disclosure is not limited to the above-described embodiment. The above-described embodiment is merely an example, and any configuration that is substantially the same as the technical idea described in the claims of the present disclosure and that exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0076] [Example 1] (Preparation of positive electrode laminate) A slurry containing a sulfide solid electrolyte (SE: Li2S-P2S5), a binder (acrylonitrile butadiene rubber (ABR)-based binder), and a dispersion medium (heptane and butyl butyrate) was stirred with an ultrasonic dispersing device to obtain an SE slurry. The weight ratio of SE to ABR-based binder was adjusted to 99.4:0.6. This SE slurry was applied onto a substrate (Al foil) by 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 having a substrate (Al foil) and a solid electrolyte layer (SE layer).

[0077] Next, the positive electrode active material (NCA: LiNi 0.8 Co 0.15 Al 0.05A positive electrode slurry was obtained by stirring a slurry containing NCA, sulfide solid electrolyte (SE: Li2S-P2S5), conductive material (vapor grown carbon fiber: VGCF), binder (PVdF-based binder), and dispersion medium (butyl butyrate) with an ultrasonic dispersion device. Here, the weight ratio of NCA, SE, VGCF, and PVdF-based binder was adjusted to 78.3:18.8:2.9:2.8. This positive electrode slurry was applied to a positive electrode current collector (Al foil) by the blade method and dried on a hot plate at 50 ° C for 20 minutes. Then, it was further dried on a hot plate at 150 ° C for 30 minutes. As a result, a positive electrode having a positive electrode current collector and a positive electrode active material layer was obtained.

[0078] The positive electrode and the transfer member were laminated so that the positive electrode active material layer and the solid electrolyte layer faced each other. This was pressed with a roll press at a pressure of 50 kN / cm and a temperature of 160°C. Then, the Al foil of the transfer member was peeled off, and the transfer member was cut into 1 cm pieces. 2 This resulted in a positive electrode side laminate having a positive electrode current collector, a positive electrode active material layer, and a solid electrolyte layer.

[0079] (Preparation of negative electrode laminate) A slurry containing a sulfide solid electrolyte (SE: Li2S-P2S5), a binder (acrylonitrile butadiene rubber (ABR)-based binder), and a dispersion medium (heptane and butyl butyrate) was stirred with an ultrasonic dispersing device to obtain an SE slurry. The weight ratio of SE to ABR-based binder was adjusted to 99.4:0.6. This SE slurry was applied onto a substrate (Al foil) by 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 having a substrate (Al foil) and a solid electrolyte layer (SE layer).

[0080] A resin slurry containing a vinyl resin (polymethyl methacrylate), a conductive material (carbon) and a dispersion medium was prepared. In the resin slurry, the ratio of the vinyl resin and the carbon was 4:1 by weight. This resin slurry was applied onto an Al foil by a blade method and dried on a hot plate at 50°C for 20 minutes. Then, it was further dried on a hot plate at 150°C for 30 minutes. This resulted in a negative electrode member having a negative electrode current collector (Al foil) and a resin coating layer. In addition, the thickness of the negative electrode member was measured with a micrometer, and the thickness of the resin coating layer was calculated by subtracting the thickness of the Al foil from the thickness of the negative electrode member. The thickness of the resin coating layer was 2 μm.

[0081] Next, a slurry containing a negative electrode active material (silicon), a sulfide solid electrolyte (SE: Li2S-P2S5), a conductive material (vapor grown carbon fiber: VGCF), a binder (PVdF-based binder) and a dispersion medium (butyl butyrate) was stirred with an ultrasonic dispersing device to obtain a negative electrode slurry. Here, the weight ratio of silicon:SE:VGCF:PVdF-based binder was adjusted to 49:41.2:7.5:6.6. This negative electrode slurry was applied onto the resin coat layer by a blade method and dried on a hot plate at 50 ° C for 20 minutes. Then, it was further dried on a hot plate at 150 ° C for 30 minutes. As a result, a negative electrode having a negative electrode current collector, a resin coat layer and a negative electrode active material layer was obtained.

[0082] The negative electrode and the transfer member were laminated so that the negative electrode active material layer and the solid electrolyte layer faced each other. This was pressed with a roll press at a pressure of 50 kN / cm and a temperature of 160°C. The Al foil of the transfer member was then peeled off. This resulted in a laminate having a negative electrode current collector, a resin coating layer, a negative electrode active material layer, and a solid electrolyte layer. Next, the laminate and the transfer member were laminated so that the solid electrolyte layers faced each other. This was pre-pressed at 100 MPa and 25°C using a flat uniaxial press. The Al foil of the transfer member was then peeled off, and a 1.08 cm 2 This resulted in a negative electrode laminate.

[0083] (Production of all-solid-state batteries) The positive electrode side laminate and the negative electrode side laminate were stacked so that the solid electrolyte layers faced each other, and pressed at 200 MPa and 120° C. using a flat uniaxial press to produce a battery (all-solid-state battery).

[0084] [Examples 2 and 3] A battery was produced in the same manner as in Example 1, except that the thickness of the resin coating layer in the negative electrode member was changed as shown in Table 1. The thickness of the resin coating layer was adjusted by changing the GAP by the blade method.

[0085] [Example 4] First, a positive electrode was obtained in the same manner as in Example 1. The SE slurry prepared in Example 1 was applied twice by a blade method onto the positive electrode active material layer of the obtained positive electrode. This resulted in a positive electrode side laminate having a positive electrode current collector, a positive electrode active material layer, and a solid electrolyte layer.

[0086] Next, a negative electrode slurry was obtained in the same manner as in Example 1. The obtained negative electrode slurry was applied onto a substrate (SUS foil) and dried. As a result, a transfer member for a negative electrode having a SUS foil (substrate) and a negative electrode active material layer was obtained.

[0087] The positive electrode laminate and the transfer member for the negative electrode were stacked so that the solid electrolyte layer and the negative electrode active material layer faced each other. This was pressed at 50 kN / cm and 160°C using a roll press. The SUS foil was then peeled off to obtain a laminate. This laminate and the negative electrode member produced in Example 2 were stacked so that the negative electrode active material layer and the resin coat layer faced each other, and pressed at 500 MPa and 160°C using a flat uniaxial press. This produced a battery.

[0088] [Comparative Example 1] A battery was produced in the same manner as in Example 1, except that the resin coating layer was not provided.

[0089] [Rating 1] (Percentage of middle class) Cross-sectional SEM images of the batteries produced in Examples 1 to 4 were obtained. When the SEM images were observed, it was confirmed that an intermediate layer was formed in all of Examples 1 to 4. In the observed intermediate layer, the ratio of resin increased toward the Al foil. In addition, based on the SEM images, the film thickness of the negative electrode active material layer, the film thickness of the intermediate layer, and the film thickness of the resin coating layer were measured, and the ratio (%) of the intermediate layer was calculated when the thickness from the negative electrode mixture to the resin paste was taken as 100. As a representative result, the ratio of the intermediate layer in Example 2 was 6.6%, and the ratio of the intermediate layer in Example 4 was 0.85%.

[0090] (Cycle test) The batteries produced in Examples 1 to 4 and Comparative Example 1 were subjected to cycle tests as described below, and the capacity retention rates were compared.

[0091] First, the battery was sandwiched between two restraining plates, and these two restraining plates were fastened with a fastener. This fixed the distance between the two restraining plates. The restrained battery was initially charged and discharged as follows. First, it was charged at a constant current of 1 / 10C to 4.05V, then it was charged at a constant voltage of 4.05V to a cut-off current of 1 / 100C, then it was discharged at a constant current of 1 / 10C to 2.5V, and finally it was discharged at a constant voltage of 2.5V to a cut-off current of 1 / 100C.

[0092] A cycle test was carried out on the battery that had been initially charged and discharged under the conditions of a temperature of 60°C, an upper limit voltage of 3.96V, a lower limit voltage of 2.89V, and 1 / 3C. The capacity retention rate (%) was calculated by dividing the capacity at the 30th cycle by the capacity at the 1st cycle. The results were compared as relative values, with the result of Comparative Example 1 being set at 100. The results are shown in Table 1.

[0093] [Table 1]

[0094] As shown in Table 1, Examples 1 to 4 had better capacity retention rates than Comparative Example 1. Moreover, as shown in Examples 1 to 3, the thicker the resin coat layer, the better the capacity retention rate. Moreover, as shown in Examples 2 and 4, the higher the proportion of the intermediate layer, the better the capacity retention rate.

[0095] The reason why the ratio of the intermediate layer was larger in Example 4 than in Example 2 is due to the manufacturing method of the battery. Specifically, in Example 4, the press pressure was applied three times while the resin coating layer and the negative electrode active material layer were in contact with each other. On the other hand, in Example 2, the press pressure was applied once while the resin coating layer and the negative electrode active material layer were in contact with each other. Therefore, in Example 2, the resin coating layer was embedded in the negative electrode active material layer, and the ratio of the intermediate layer was larger than in Example 4.

[0096] [Reference example 1] A resin slurry containing a vinyl resin (polymethyl methacrylate), a conductive material (carbon) and a dispersion medium was prepared. In the resin slurry, the ratio of the vinyl resin and the carbon was 4:1 by weight. This resin slurry was applied onto an Al foil by a blade method and dried on a hot plate at 50°C for 20 minutes. Then, it was further dried on a hot plate at 150°C for 30 minutes. This resulted in a negative electrode member having a negative electrode current collector (Al foil) and a resin coating layer. In addition, the thickness of the negative electrode member was measured with a micrometer, and the thickness of the resin coating layer was calculated by subtracting the thickness of the Al foil from the thickness of the negative electrode member. The thickness of the resin coating layer was 3 μm.

[0097] 100 mg of sulfide solid electrolyte (SE: Li2S-P2S5) was placed in a cylindrical container with a hole of φ11.28. Then, a SUS pin of φ11.28 was placed and pressed at 100 MPa. Then, a 1 cm 2 The punched negative electrode was placed on the plate and pressed at 600 MPa. 2 A punched Li foil was placed in the cell, and a SUS pin and a restraining jig were placed on the Al foil side and the Li foil side, in that order, and the cell was restrained at 15 MPa to obtain a half cell.

[0098] [Reference Example 2 and Reference Example 3] Half cells were produced in the same manner as in Reference Example 1, except that the thickness of the resin coating layer in the negative electrode member was changed as shown in Table 2. The thickness of the resin coating layer was adjusted by changing the GAP by the blade method.

[0099] [Comparative Example 1] A half cell was produced in the same manner as in Reference Example 1, except that no resin coating layer was provided.

[0100] [Rating 2] (Cyclic voltammetry measurement) Cyclic voltammetry (CV) measurements were performed on the half cells of Reference Examples 1 to 3 and Comparative Reference Example 1 using an electrochemical measurement device. The CV measurements were performed at a sweep rate of 0.5 mV / sec. The voltage was changed in the following order: from the initial voltage to 0 V, from 0 V to 2 V, and from 2 V to 0 V. In the second cycle, the maximum current value (maximum current value on the reduction side) that flowed up to 0 V was obtained. The maximum current value of Comparative Reference Example 1 was set to 100, and the results were evaluated relatively. The results are shown in Table 2. The current observed in the CV measurements using the above half cells is a current resulting from the reaction of Al and Li.

[0101] [Table 2]

[0102] As shown in Table 2, it was confirmed that the maximum current values ​​of Reference Examples 1 to 3 were significantly lower than that of Comparative Reference Example 1, and the reaction between the Al current collector and Li was significantly suppressed. Furthermore, the results of Tables 1 and 2 suggest that the same effect can be obtained even when the negative electrode active material layer is a layer containing a resin and is a concentration gradient layer in which the concentration of the resin increases from the electrolyte layer toward the negative electrode current collector. [Explanation of symbols]

[0103] 1...Positive current collector 2...Cathode active material layer 3...Negative electrode current collector (Al current collector) 4...Negative electrode active material layer 5 ... Resin coating layer 6. Middle class 7...Concentration gradient layer CA…Positive electrode AN…Negative electrode EL…electrolyte layer 10...battery

Claims

1. A battery having a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The negative electrode has a negative electrode current collector which is an Al current collector, and a negative electrode active material layer containing a negative electrode active material having a reaction potential lower than that of Al, the negative electrode current collector is coated with a resin coating layer containing a resin and a conductive material, and an intermediate layer containing the resin and the negative electrode active material is disposed between the resin coating layer and the negative electrode active material layer.

2. A battery having a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The negative electrode has a negative electrode current collector which is an Al current collector, and a negative electrode active material layer containing a negative electrode active material having a reaction potential lower than that of Al, the negative electrode active material layer is a layer containing a resin, and is a concentration gradient layer in which the concentration of the resin increases from the electrolyte layer toward the negative electrode current collector.

3. The battery according to claim 1 or 2, wherein the resin is a thermoplastic resin.

4. The reaction potential of the negative electrode active material is 0.3 V (Li ＋ 3. The battery according to claim 1 or claim 2, wherein the Li is less than or equal to 1. / Li.

5. 3. The battery according to claim 1, wherein the negative electrode active material contains a Si-based active material or a carbon-based active material.

6. The battery according to claim 5 , wherein the negative electrode active material contains the Si-based active material.

7. 3. The battery according to claim 1, wherein the electrolyte layer is a solid electrolyte layer containing a solid electrolyte.

8. The battery according to claim 1 , wherein the resin coating layer does not contain the negative electrode active material.

9. 2. The battery according to claim 1, wherein a ratio of a thickness of the intermediate layer to a total thickness of the negative electrode active material layer, the intermediate layer, and the resin coat layer is 0.80% or more.

10. 2. The battery according to claim 1, wherein a ratio of a thickness of the intermediate layer to a total thickness of the negative electrode active material layer, the intermediate layer, and the resin coat layer is 7.0% or less.

11. The battery according to claim 1 , wherein the resin coating layer has a thickness of 10 μm or less.

12. A method for producing the battery according to claim 1, comprising the steps of: a laminate forming step of obtaining a laminate having the Al current collector, the resin coating layer, and the negative electrode active material layer in this order in a thickness direction; and a pressing step of applying a pressing pressure to the laminate in the thickness direction to form the intermediate layer.

13. A method for producing the battery according to claim 2, comprising the steps of: forming the concentration gradient layer on one surface of the Al current collector in a thickness direction.

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