Solid-state battery and electric device

Abstract

A solid-state battery and an electric device. The solid-state battery comprises a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector, a first positive electrode active layer and a second positive electrode active layer, where the first positive electrode active layer is located on one side of the positive electrode current collector, the second positive electrode active layer is located on the side of the first positive electrode active layer away from the positive electrode current collector, the first positive electrode active layer comprises a first binder, the second positive electrode active layer comprises a second binder, the ionic conductivity of the second binder is greater than that of the first binder, and the sum of the thickness d1 of the first positive electrode active layer and the thickness d2 of the second positive electrode active layer is greater than or equal to 100 μm. The solid-state battery has high energy density and good cycle performance.

Description

Solid-state batteries and electrical devices Cross-references to related applications This application claims priority to Chinese patent application 202510486657.1, filed on April 17, 2025, entitled "Solid-state battery and power supply device", the entire contents of which are incorporated herein by reference. Technical Field This application relates to the field of solid-state battery technology, and more particularly to a solid-state battery and an electrical device. Background Technology Solid-state batteries are secondary batteries that use solid materials as electrolytes. Because they use solid electrolytes, solid-state batteries offer advantages such as high energy density and safety. Currently, consumers have increasingly higher demands for battery range and lifespan, but current battery energy density and cycle performance cannot meet these requirements. Therefore, there is an urgent need to improve battery energy density and cycle performance. Summary of the Invention This application provides a solid-state battery and an electrical device, the solid-state battery having high energy density and good cycle performance. A first aspect of this application provides a solid-state battery, including a positive electrode sheet. The positive electrode sheet includes a positive current collector, a first positive active layer, and a second positive active layer. The first positive active layer includes a first binder. The first positive active layer is located on at least one side of the positive current collector, and the second positive active layer is located on the side of the first positive active layer away from the positive current collector. The first positive active layer includes the first binder, and the second positive active layer includes a second binder. The ionic conductivity of the second binder is greater than that of the first binder. The sum of the thicknesses d1 and d2 of the first and second positive active layers is greater than or equal to 100 μm. In the solid-state battery provided in this application embodiment, the second positive electrode active layer is located on the side of the first positive electrode active layer away from the positive electrode current collector, and the ionic conductivity of the second binder is greater than that of the first binder. In this way, even when the total thickness of the active layers is greater than or equal to 100 μm, the ion concentration in the second active layer can still be increased, and the ion concentration difference between the first and second positive electrode active layers can be reduced, thereby achieving high energy density and good cycle performance in the solid-state battery. In some embodiments of this application, the mass percentage of the second binder is 1% to 3% based on the total mass of the second positive electrode active layer. In some embodiments of this application, the mass percentage of the second adhesive is 1% to 1.5%. In the above technical solution, based on the total mass of the second positive electrode active layer, the mass ratio of the second binder is within the above range, which can further help reduce the difference in ion concentration between the first positive electrode active layer and the second positive electrode active layer. In some embodiments of this application, the second binder includes an alkali metal and a polymer binder that forms coordination bonds with the alkali metal. In the above technical solution, the binder helps to improve the ionic conductivity of the second positive electrode active layer. In some embodiments of this application, the alkali metal includes one or more of lithium, sodium, and potassium. In some embodiments of this application, the polymer binder includes one or more of polyvinylidene fluoride, polyacrylate, and polytetrafluoroethylene. In some embodiments of this application, the first adhesive includes a styrene-ethylene-butene copolymer and / or synthetic rubber. In some embodiments of this application, the synthetic rubber includes one or more of butadiene rubber, silicone rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, nitrile rubber, and hydrogenated nitrile rubber. In some embodiments of this application, the second positive electrode active layer comprises a sulfide solid electrolyte. In some embodiments of this application, the mass percentage of the sulfide solid electrolyte is 5% to 30% based on the total mass of the second positive electrode active layer. In some embodiments of this application, the sulfide solid electrolyte includes Li6PS5Cl, Li6PS5Br, Li2S-P2S5, Li4GeS4, and Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li3PS4 and Li7P3S 11 One or more of them. In some embodiments of this application, the thickness d1 of the first positive electrode active layer and the thickness d2 of the second positive electrode active layer satisfy at least one of the following conditions: Ⅰ) 100μm≤d1+d2≤400μm; Ⅱ) 0.25≤d1 / d2≤1. In the above technical solution, by satisfying the above relationship through the thickness d1 of the first positive electrode active layer and the thickness d2 of the second positive electrode active layer, ions can have a suitable transport path in the first and second positive electrode active layers, which is conducive to the extraction and insertion of ions. This can help ions reach the extraction and insertion reaction equilibrium in the first and second positive electrode active layers, thereby helping to further improve the cycle performance of the secondary battery. In some embodiments of this application, 50μm≤d1≤200μm. In some embodiments of this application, 50μm≤d2≤200μm. In some embodiments of this application, the first positive electrode active layer includes a first positive electrode active material, and the second positive electrode active layer includes a second positive electrode active material, wherein the Dv50 of the first positive electrode active material and the Dv′50 of the second positive electrode active material satisfy: 0≤Dv50-Dv′50≤20μm. In the above technical solution, the Dv50 of the first positive electrode active material and the Dv′50 of the second positive electrode active material satisfy the above relationship, which can reduce the porosity in the active layer and the contact area between the second positive electrode active material and other particles, thereby reducing the occurrence of side reactions and improving the cycle performance of solid-state batteries. In some embodiments of this application, the positive electrode sheet further includes a toughening layer having a porous structure, and the toughening layer is located between the first positive electrode active layer and the second positive electrode active layer. In some embodiments of this application, the toughening layer comprises a nonwoven fabric. In some embodiments of this application, the thickness of the nonwoven fabric is 5μm to 100μm. In some embodiments of this application, the nonwoven fabric is made of one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyvinylidene fluoride, polyacrylonitrile, and cellulose. In some embodiments of this application, the porosity of the nonwoven fabric is 40% to 90%. In some embodiments of this application, the pore size of the nonwoven fabric is 1μm to 100μm. The second aspect of this application provides an electrical device, including a solid-state battery according to the first aspect of this application. Attached Figure Description Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the embodiments described below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application; Figure 2 is an exploded structural diagram of a battery device provided in some embodiments of this application; Figure 3 is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application. Explanation of reference numerals in the attached figures: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 51. First housing section; 52. Second housing section; 53. Reception space; 7. Solid-state battery; 10. Electrode assembly; 101. Electrode plate; 102. Hot melt adhesive frame. Embodiments of the present invention Hereinafter, embodiments of the solid-state battery and power-consuming device of this application are disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims. The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions. Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. As described in the background section, the energy density requirements for solid-state batteries are becoming increasingly stringent. To improve the energy density of solid-state batteries, the thickness of the electrode sheets is typically increased. However, the electron concentration in the active layer near the current collector is generally higher. This causes most ions to concentrate in the active layer near the current collector, resulting in a higher ion concentration in the active layer near the current collector compared to the side farther away from it. As the electrode sheet thickness increases, the difference in ion concentration between different regions of the active layer also increases, making it impossible for solid-state batteries to meet the requirements of high energy density and good cycle performance. In view of this, embodiments of this application provide a solid-state battery and an electrical device, the solid-state battery having high energy density and good cycle performance. The first aspect of this application provides a solid-state battery, including a positive electrode sheet, which includes a positive current collector, a first positive active layer, and a second positive active layer. The first positive active layer includes a first binder and is located on at least one side of the positive current collector. The second positive active layer is located on the side of the first positive active layer away from the positive current collector. The first positive active layer includes the first binder, and the second positive active layer includes a second binder. The ionic conductivity of the second binder is greater than that of the first binder. The sum of the thicknesses d1 and d2 of the first and second positive active layers is greater than or equal to 100 μm. In this paper, the thickness of the positive electrode active layer has a meaning well-known in the art and can be measured using methods and equipment known in the art. For example, the cross-section of the positive electrode sheet can be observed for microscopic morphology to observe the boundaries between different positive electrode active layers and determine the thickness of different positive electrode active layers, thereby obtaining the total thickness of the active layers. The cross-section of the positive electrode sheet refers to the section perpendicular to the thickness direction of the positive electrode sheet. In the solid-state battery provided in this application embodiment, the second positive electrode active layer is located on the side of the first positive electrode active layer away from the positive electrode current collector, and the ionic conductivity of the second binder is greater than that of the first binder. In this way, even when the total thickness of the active layers is greater than or equal to 100 μm, the ion concentration in the second active layer can still be increased, and the ion concentration difference between the first and second positive electrode active layers can be reduced, thereby achieving high energy density and good cycle performance in the solid-state battery. In embodiments of this application, the difference in ion concentration between the first positive electrode active layer and the second positive electrode active layer can be further reduced by adjusting the mass ratio of the second binder in the second positive electrode active layer. In some implementations, the second binder accounts for 1% to 3% of the total mass of the second positive electrode active layer. In some implementations, the second adhesive accounts for 1% to 1.5% of the total mass. For example, based on the total mass of the second positive electrode active layer, the mass percentage of the second binder may be, but is not limited to, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, or any combination of two of the above values. In the above embodiments, the mass percentage of the second binder can be measured using methods and equipment well known in the art, such as solvent extraction, which utilizes the solubility of the polymer in a specific solvent for separation. The specific method is as follows: Scrape off the powder of the second positive electrode active layer and collect the sample, recording its weight as M1. Immerse the weighed sample in an organic solvent (such as p-xylene, PX) and use ultrasound to dissolve the binder. Centrifuge to separate the insoluble matter (active material, conductive agent). After evaporating the solvent, weigh the remaining polymer mass M2. The mass percentage of the second binder is then W2 = M2 / M1. In the embodiments of this application, the rate at which ions migrate from the second positive electrode active layer to the first positive electrode active layer can be increased by selecting appropriate materials, thereby further reducing the occurrence of ion concentration gradients in the positive electrode sheet. In some embodiments, the second binder includes an alkali metal and a polymer binder that forms coordination bonds with the alkali metal. In this application, the aforementioned adhesive can be tested using methods and equipment known in the art. For example, infrared spectroscopy, nuclear magnetic resonance, etc., wherein FTIR is used to detect characteristic peaks (such as the CF2 stretching vibration peak of PVDF, ~1400 cm⁻¹). -1 The presence of the polymer was confirmed. Qualitative analysis can be achieved by combining the standard curve. In the above embodiments, the binder helps to improve the ionic conductivity of the second positive electrode active layer. In some embodiments, the alkali metal includes one or more of lithium, sodium, and potassium. In some embodiments, the polymer binder includes one or more of polyvinylidene fluoride, polyacrylate, and polytetrafluoroethylene. These polymer binders not only possess good adhesion but also exhibit good stability, reducing the occurrence of side reactions with the solid electrolyte. In some embodiments, the first binder includes a styrene-ethylene-butene copolymer and / or synthetic rubber. In some embodiments, the synthetic rubber includes one or more of butadiene rubber (BR), silicone rubber (SR), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), nitrile rubber (NBR), and hydrogenated nitrile rubber (HNBR). In some embodiments, the first positive electrode active layer and the second positive electrode active layer each independently include a solid electrolyte, which may include any one of lithium-ion solid electrolyte, sodium-ion solid electrolyte and potassium-ion solid electrolyte. The aforementioned lithium-ion solid electrolyte, sodium-ion solid electrolyte, and potassium-ion solid electrolyte can be any of the commonly used lithium-ion solid electrolyte, sodium-ion solid electrolyte, and potassium-ion solid electrolyte in this field. In some implementations, the solid electrolyte can be a lithium-ion solid electrolyte. The following are examples of lithium-containing solid electrolytes, including but not limited to: LISICON type: such as γ-Li3PO4, etc.; NASICON type; for example, Li (1+x1) Q x M (2-x1) (PO4)3, 0≤x1<1, Q includes one or more of Al, Cr, Ba, Fe, Sc, In, Lu, Y, and La; Garnet type; for example, Li (7-x2) La3Zr (2-x2) M x2 O 12 Etc., 0≤x2<1, M includes one or more of Sb, Nb, Ta, Te, and W; LIPON type: e.g., Lix3PO y1 N z1 ; 0 < x3 ≤ 1, 0 < y1 ≤ 1, 0 < z1 ≤ 1; Perovskite type: for example, Li 3x4 Q (2 / 3-x4)MO3, etc., 0.04 < x4 < 0.17, Q includes one or more of La, Sr, Ba, and Nd, and M includes one or more of Al, Ti, and Ge; Anti-Perovskite type: such as Li3OCl; Thio-LiSICON type: such as Li (3+x5) M y2 A (1-y2) Q (4-z2) T z2 Where -1 < x5 < 2, 0 ≤ y2 ≤ 1, 0 ≤ z2 ≤ 2, M includes one or more of B, Al, In, Si, Ge, Sn, Ti, W, and Mo, A includes one or more of P, As, Sb, and Bi, Q includes one or more of S and Se, and T includes one or more of F, Cl, Br, and I. In some embodiments, the second positive electrode active layer includes a sulfide solid electrolyte. The sulfide solid electrolyte can further improve the ionic conductivity of the second positive electrode active layer, thereby reducing the interfacial impedance. In some embodiments, the sulfide solid electrolyte accounts for 5% to 30% of the total mass of the second positive electrode active layer. Within this range, the sulfide solid electrolyte can improve the ionic conductivity of the second positive electrode active layer to reduce interfacial impedance, and also allow the second positive electrode active layer to have a higher mass proportion of positive electrode active material, thereby increasing the energy density of the solid-state battery. In other embodiments, the sulfide solid electrolyte particles include: thiophosphate type: Li3PS4, Li7P3S 11 etc.; Argyrodite type: Li6PS5Cl, Li6PS5Br; Halide type: Li3InCl6; Hydride type: 0.7Li(CB9H) 10 )-0.3Li(CB 11 H 12 One or more of the following; for example, Li (10+x6) M (1+y3) A (2-y3) Q (12-z3) H z3 Type: where -2 < x6 < 2, 0 ≤ y3 ≤ 2, 0 ≤ z3 ≤ 2, M includes one or more of B, Al, In, Si, Ge, Sn, Ti, W, and Mo; A includes one or more of P, As, Sb, and Bi; Q includes one or more of S and Se; H includes one or more of F, Cl, Br, and I: (100-x7)Li2S x7 M y4Q type: where 20≤x7≤30, 0≤y4≤50, M includes one or more of B2S3, Al2S3, In2S3, SiS2, GeS2, SnS2, P2S5, As2S3, Sb2S5, Bi2S3, WS2, and MoS2, and Q includes one or more of B2O3, Al2O3, In2O3, SiO2, GeO2, SnO2, P2O5, Sb2O5, Bi2O3, WO2, WO3, MoO2, MoO3, Fe2O3, ZnO, MgO, CuO, CaO, LiN, Li2O, LiF, LiCl, LiBr, and LiI; Argyrodite type: Li (6+x8) M y5 A (1-y5) Q (5-z5) T (1+z5) Where -1≤x8≤1, 0≤y5≤1, -1<z5≤1, M includes one or more of B, Al, In, Si, Ge, Sn, Ti, W, and Mo, A includes one or more of P, As, Sb, and Bi, Q includes one or more of S and Se, and T includes one or more of F, Cl, Br, and I; Halide type: Li3MJ or Li2Sc 2 / 3 J;M includes one or more of Y, Er, In, Sc, and Ga, and J includes one or more of F, Cl, Br, and I. When the aforementioned sulfide solid electrolyte particles are sulfide-type solid electrolyte particles, they include, but are not limited to: Li6PS5Cl, Li6PS5Br, Li2S-P2S5, Li4GeS4, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 Li3PS4 and Li7P3S 11 One or more of them. In other embodiments, the solid electrolyte may be a sodium ion solid electrolyte, including but not limited to: NASICON type: Na(1+x9+2y5)Zr (2-y5) M y5 P (3-x9) Si x9 O 12 0≤x9≤3, 0≤y5≤1, M includes one or more of Zn, Mg, and Ca; Na-β-Alumina type: Na2O·2Al2O3 or Na2O·3Al2O3, etc.; Na (3+x10) M y6 A (1-y6) Q (4-z6)T z6 Type, where -1 < x10 < 2, 0 ≤ y6 ≤ 1, 0 ≤ z6 ≤ 2, M includes one or more of B, Al, In, Si, Ge, Sn, Ti, W, and Mo, A includes one or more of P, As, Sb, and Bi, Q includes one or more of S and Se, and T includes one or more of F, Cl, Br, and I; Na (11+x11) M (2-y7) A (1+y7) Q (12-z7) T z7 Type, wherein -1 < x11 < 1, 0 ≤ y7 ≤ 2, 0 ≤ z7 ≤ 2, M includes one or more of B, Al, In, Si, Ge, Sn, Ti, W, and Mo, A includes P, As, Sb, and Bi; Q includes one or more of S and Se, and T includes one or more of F, Cl, Br, and I; anti-perovskite type Na3OX, where X includes one or more of Cl, Br, I, and BH4. In some embodiments, the solid electrolyte may also be a potassium-ion solid electrolyte, including but not limited to β-Alumina type such as K₂O. x13 Al2O3, etc., x13 takes any number from 8 to 11, Anti-Perovskite type such as K3O I It can be one or more of the following: K2Fe4O7 type and KSi2P3 type. In the above embodiments, the particle size of the solid electrolyte is less than or equal to 1 μm. For example, the particle size of the solid electrolyte may be, but is not limited to, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, or a range of any two of the above values. In some embodiments, the thickness d1 of the first positive electrode active layer and the thickness d2 of the second positive electrode active layer satisfy at least one of the following conditions: Ⅰ) 100μm≤d1+d2≤400μm; Ⅱ) 0.25≤d1 / d2≤1. In the above embodiments, by satisfying the above relationship between the thickness d1 of the first positive electrode active layer and the thickness d2 of the second positive electrode active layer, ions can have a suitable transport path in the first and second positive electrode active layers, which is conducive to the extraction and insertion of ions. This can help ions reach the extraction and insertion reaction equilibrium in the first and second positive electrode active layers, thereby helping to further improve the cycle performance of the secondary battery. In the embodiments of this application, by reasonably controlling the range of values ​​for d1 and d2, the difference between the migration rates of ions in the first positive electrode active layer and the second positive electrode active layer can be further reduced. In some implementations, 50μm≤d1≤200μm. In some implementations, 50μm≤d2≤200μm. In some embodiments, the positive electrode sheet further includes a toughening layer having a porous structure, the toughening layer being located between the first positive electrode active layer and the second positive electrode active layer. In the above embodiments, by placing the toughening layer between the first positive electrode active layer and the second positive electrode active layer, the toughness of the positive electrode sheet can be increased and the cracking of the first positive electrode active layer and the second positive electrode active layer can be reduced. In some implementations, the toughening layer comprises a nonwoven fabric. In the above embodiments, the nonwoven fabric can give the toughening layer high strength and toughness, which is beneficial to enhance the toughness of the positive electrode sheet and further reduce the cracking phenomenon of the first positive electrode active layer and the second positive electrode active layer. In some implementations, the thickness of the nonwoven fabric is 5 μm to 100 μm. In this document, the thickness of the nonwoven fabric has a meaning known in the art and can be measured using methods and equipment known in the art. For example, when observing the microstructure of the cross-section of the positive electrode sheet, the boundaries between different positive electrode active layers in the positive electrode sheet can be observed and the thicknesses of different positive electrode active layers and toughening layers can be determined. The specific methods can refer to the testing methods for the thickness of the positive electrode active layer, which will not be described in detail here. In the above embodiments, the thickness of the nonwoven fabric within the above-mentioned suitable range can help improve the toughness of the positive electrode sheet, while also enabling the secondary battery to have a high volumetric energy density. As an example, the thickness of the nonwoven fabric can be, but is not limited to, 5 μm. In some embodiments, the nonwoven fabric is made of one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyvinylidene fluoride, polyacrylonitrile, and cellulose. In the above embodiments, the nonwoven fabric is selected from the above materials, which can enhance the adhesion between the first positive electrode active layer and the second positive electrode active layer while improving the toughness of the positive electrode sheet. This further reduces the cracking of the positive electrode active layer and the separation between the first positive electrode active layer and the second positive electrode active layer. In some implementations, the porosity of the nonwoven fabric is 40% to 90%. In some implementations, the pore size of the nonwoven fabric is 1μm to 100μm. In the above embodiments, the porosity and pore size of the nonwoven fabric are within the above ranges, which can help reduce the resistance to ion migration. As an example, the porosity of the nonwoven fabric can be, but is not limited to, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, or any combination of two of the above values. The pore size of the nonwoven fabric can be, but is not limited to, 1μm, 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, 26μm, 28μm, 30μm, 32μm, 34μm, 36μm, 38μm, 40μm, 42μm, 44μm, 46μm, 48μm, 50μm, 52 ... The range of values ​​is 54μm, 56μm, 58μm, 60μm, 62μm, 64μm, 66μm, 68μm, 70μm, 72μm, 74μm, 76μm, 78μm, 80μm, 82μm, 84μm, 86μm, 88μm, 90μm, 92μm, 94μm, 96μm, 98μm, 100μm, or any two of the above values. In embodiments of this application, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active layer is disposed on either or both of the two opposite surfaces of the positive current collector. In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.). In some embodiments, the first positive electrode active layer includes a first positive electrode active material, and the second positive electrode active layer includes a second positive electrode active material, wherein the Dv50 of the first positive electrode active material and the Dv′50 of the second positive electrode active material satisfy: 0≤Dv50-Dv′50≤20μm. In this paper, Dv50 refers to the particle size of the first positive electrode active material when the particle sizes are accumulated from smallest to largest, reaching 50% of the total volume. Dv′50 refers to the particle size of the second positive electrode active material when the particle sizes are accumulated from smallest to largest, reaching 50% of the total volume. Dv50 and Dv′50 can be measured using instruments well-known in the art, such as a laser particle size analyzer. In the above embodiments, the Dv50 of the first positive electrode active material and the Dv′50 of the second positive electrode active material satisfy the above relationship, which can reduce the porosity in the active layer and the contact area between the second positive electrode active material and other particles, thereby reducing the occurrence of side reactions and improving the cycle performance of solid-state batteries. In the above embodiments, the Dv50 of the first positive electrode active material and the Dv′50 of the second positive electrode active material can be 1μm~20μm independently. In some embodiments, when the solid-state battery is a lithium-ion solid-state battery, the first and second positive electrode active materials can be positive electrode active materials known in the art for lithium-ion solid-state batteries. As an example, the positive electrode active material may include one or more of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2) and lithium nickel oxides (such as Li...). 1+a NiO2 (-0.3≤a≤0.3), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides (such as Li 1+a Ni b Co 1-b O2, -0.3≤a≤0.3, 0.3≤b≤0.8), lithium manganese cobalt oxide, lithium nickel manganese oxide (Li 1+a Ni 1-b Mn b O2, -0.3≤a≤0.3, 0.3≤b≤0.8), lithium nickel cobalt manganese oxides (such as LiNi) 1-a-b Co a Mn b O2, -0.3≤a≤0.3, 0.02≤b≤0.3, specifically, such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co0.2 Mn 0.3 O2 (may also be abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (may also be abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (may also be abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (may also be abbreviated as NCM811), LiNi 0.83 Mn 0.1 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2,) and modified compounds thereof, and the like, one or more of the above. Examples of the lithium-containing phosphate with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate (such as LiFePO4 (may also be abbreviated as LFP)), composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and composite material of lithium manganese iron phosphate and carbon. In some embodiments, to further improve the energy density of the solid-state battery, the positive active material for the lithium-ion solid-state battery may include a lithium transition metal oxide with the general formula Li a Ni b Co c M d O e A f and modified compounds thereof, one or more of the above. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M is selected from one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A is selected from one or more of N, F, S and Cl. In some embodiments, as an example, the positive electrode active material for lithium-ion solid-state batteries may include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 One or more of O2, LiFePO4 and LiMnPO4. In this application, the modified compounds of the above-mentioned positive electrode active materials can be those that have undergone doping modification and / or surface coating modification of the positive electrode active materials. As an optional technical approach in this application, the polyanionic compound can be Li 1+x Mn 1-y A y P 1-z R z O4; where x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, A includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and R includes one or more elements selected from B, S, Si and N; As an optional technical approach in this application, the polyanionic compound can be Li a A e Mn 1-f B f P 1-g C g O 4-n D nWherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from B, S, Si, and N; D includes one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1, e is selected from the range of 0.001 to 0.1, f is selected from the range of 0.001 to 0.5, g is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, and the positive electrode active material is electrically neutral. During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of cathode materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. When the cathode material is applied to the battery system, the molar Li content changes after charge-discharge cycles. In the examples of positive electrode active materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate. The positive electrode active material may also be a known positive electrode active material for sodium-ion solid-state batteries. As an example, the positive electrode active material may include one or more of the following materials: polyanionic compounds, sodium transition metal oxides, Prussian blue compounds, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, the polyanionic compound can be Li 1+x Mn 1-y A y P 1-z R z O4; where x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, A includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and R includes one or more elements selected from B, S, Si and N. As an optional technical approach in this application, the polyanionic compound can be Na... 4+x R 3-y P 4-m O 15 / C; where 0<x<0.5, 0<y≤0.5, 0<m≤0.2, R comprises one or more of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Cr, Nb, Mo, In, Ga, Sn, Hf, Ta, W and Pb. As an optional technical solution of the present application, the polyanionic compound may be Na x-a A a V y-b M b (PO4) 2-2c (DO4) 2c F z-d Q d , where element A represents an alkali metal element that dopes and substitutes for the Na element, element M represents a metal element that substitutes for the V element, element D represents a doping element that substitutes for the P element, element Q represents a doping element that substitutes for the F element, element D comprises one or more of Si and S, and the element Q comprises one or more of Cl and O; 3.5≤x≤4.5, 0≤a≤0.15x, 0.8≤y≤1.1, 0≤b≤0.3y, 0≤c≤0.15, 0.8≤z≤1.1, 0≤d≤0.2z. Optionally, element A comprises one or more of K and Li; element M comprises one or more of Fe, Cr, Al, Sc, Ga, In, Ti, Zr, Mn, Zn, Ni, Cu and Co. In the sodium transition metal compound, the transition metal may be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The sodium transition metal oxide is, for example, Na x MO2, where M is one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti and V, and 0<x≤1. The Prussian blue-type compound may be a class of compounds having sodium ions, transition metal ions and cyanide ions (CN - ). The transition metal may be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The Prussian blue-type compound is, for example, Na a Me b Me' c (CN)6, where Me and Me' are each independently one or more of Mn, Fe, Ni, Co, Cu and Zn, 0<a≤2, 0<b<1, 0<c<1. In some embodiments, the positive electrode active layer may optionally further comprise a conductive agent. As an example, the conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and vapor grown carbon fiber (VGCF). In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, solid electrolyte, conductive agent, first binder and any other components, in a solvent (e.g., p-xylene) to form a first positive active slurry; dispersing the positive active material, solid electrolyte, conductive agent, second binder and any other components in a solvent to form a second positive active slurry; coating the first positive active slurry and the second positive active slurry sequentially onto a positive current collector, and obtaining the positive electrode sheet after drying, cold pressing and other processes. In some embodiments, the negative electrode sheet includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. In some embodiments, the negative electrode current collector may include a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, aluminum mesh, copper foam, nickel foam, and aluminum foam. A composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). In some embodiments, the negative electrode active layer includes a negative electrode active material. The negative electrode active material may be any negative electrode active material known in the art for use in batteries. As examples, the negative electrode active material may include one or more of the following: artificial graphite, natural graphite, graphene, carbon nanotubes, mesophase microcarbon spheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, metal oxides, lithium metal, lithium alloys, and lithium composite materials. Silicon-based materials may be selected from one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin compounds, and tin alloys. Metal oxides include one or more of TiO2, MoO2, In2O3, Al2O3, Cu2O, VO2, Ga2O3, Sb2O5, and Bi2O5. Other elements in lithium alloys may include one or more of In, Mg, Al, Zn, Sn, Ag, Au, Ga, Pt, and Fe, such as Li-In alloys, Li-Mg alloys, Li-Al alloys, Li-Zn alloys, Li-Fe alloys, etc. In some embodiments, the negative electrode active layer may optionally include a binder. The binder may be selected from one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). In some embodiments, the negative electrode active layer may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Specifically, it may be selected from one or more of SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes (CNTs), and graphene and their composite conductive agents. In some embodiments, the negative electrode active layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)). In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as negative electrode active material, solid electrolyte, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes. The battery device of this application will now be described in detail. The solid-state batteries mentioned in the embodiments of this application can form battery cell assemblies, and battery devices can include multiple battery cell assemblies. A battery device is used to provide voltage and capacity. A battery cell assembly can include multiple solid-state batteries, which are connected in series, parallel, or mixed connections via busbars. In some embodiments, a battery cell assembly is typically formed by arranging multiple solid-state batteries; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple solid-state batteries into a single module. As an example, a battery module can be formed by bundling multiple solid-state batteries together with cable ties. In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing. As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing. As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple solid-state batteries to the housing. In this embodiment of the application, the battery cell can be a secondary battery cell, which refers to a battery cell that can be used again after being discharged by recharging to activate the active materials. In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams. In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc. The battery device disclosed in this application can be used in electrical devices that use the battery device as a power source or in various energy storage systems that use the battery device as an energy storage element. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc. For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device. Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. As shown in Figure 1, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1. The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving. In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1. Figure 2 is an exploded view of the battery device provided in some embodiments of this application. The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 51 and a second housing portion 52, which overlap each other, and together define a housing space 53 for housing the individual battery cells. The second housing portion 52 may be a hollow structure with one end open, and the first housing portion 51 may be a plate-like structure, with the first housing portion 51 covering the open side of the second housing portion 52 to form a housing 5 with the housing space 53; alternatively, both the first housing portion 51 and the second housing portion 52 may be hollow structures with one side open, with the open side of the first housing portion 51 covering the open side of the second housing portion 52 to form a housing 5 with the housing space 53. Of course, the first housing portion 51 and the second housing portion 52 can have various shapes, such as cylinders, cuboids, etc. To improve the sealing performance after the first housing part 51 and the second housing part 52 are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 51 and the second housing part 52. Assuming that the first box part 51 covers the top of the second box part 52, the first box part 51 can also be called the upper box cover, and the second box part 52 can also be called the lower box. In battery device 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel. Multiple battery cells can be directly connected in series, parallel, or in a mixed configuration and then housed in housing 5. Alternatively, multiple battery cells can first be connected in series, parallel, or in a mixed configuration to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed configuration to form a whole and housed in housing 5. In some embodiments, individual battery cells may be directly housed within the housing 5 to reduce the number of connecting or supporting components required to assemble the battery module and improve the energy density of the battery device 2. For example, a single battery cell may be the smallest unit constituting the battery device 2. The single battery cell may be a solid-state battery 7. As shown in Figure 3, a solid-state battery 7 typically includes a casing and an electrode assembly 10. The casing has an inner cavity in which the electrode assembly is disposed. The electrode assembly 10 includes a positive electrode, a negative electrode, and a solid electrolyte membrane located between the positive and negative electrode layers. The electrode layers have a solid electrolyte layer disposed on them. A hot-melt adhesive frame 102 is provided around the outer periphery of the electrode layers 101, and insulating adhesive frames between adjacent electrode layers are interconnected. The insulating adhesive frames insulate and support the electrode layers. In some embodiments, the packaging shell can be a flexible package, such as a pouch. The flexible package can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate. This application does not impose any particular restrictions on the shape of the solid-state battery; it can be cylindrical, square, or any other arbitrary shape. In some alternative embodiments, hot melt adhesive can be used to manufacture the insulating frame, forming a hot melt adhesive frame. I. Implementation Examples The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially. Example 1 (1) Preparation of positive electrode sheet The preparation method of the first positive electrode active slurry is as follows: sulfide solid electrolyte (Li6PS5Cl), ternary positive electrode material NCM811, conductive carbon black and first binder NBR are added to p-xylene in a mass ratio of 20:75:2:3 and mixed to obtain the first positive electrode active slurry, wherein the Dv50 of the ternary positive electrode material NCM811 is 5μm. The preparation method of the second positive electrode active slurry is as follows: sulfide solid electrolyte (Li6PS5Cl), ternary positive electrode active material NCM811, conductive carbon black and second binder PVDF-Li are added to p-xylene in a mass ratio of 20:75:2:3 and mixed to obtain the second positive electrode active slurry, wherein the Dv′50 of the ternary positive electrode material NCM811 is 5μm; The first positive electrode active slurry was coated onto the surface of aluminum foil to form an areal density of 15 mg / cm³.2 The first positive electrode active slurry layer, in a wet film state, is covered with polymer nonwoven fabric so that the nonwoven fabric is completely immersed in the wet film, and the electrode is kept in a semi-dry state by low temperature drying. The second positive electrode active slurry is coated onto the surface of the polymer nonwoven fabric layer to form an areal density of 15 mg / cm³. 2 The second positive electrode active slurry layer is dried, rolled and die-cut to obtain the positive electrode sheet. (2) Preparation of negative electrode sheet Silicon carbon, sulfide electrolyte (Li6PS5Cl), and styrene-butadiene rubber (SBR) binder were added to xylene solvent at a mass ratio of 75:22:3 and stirred evenly to obtain a negative electrode slurry with a solid content of 50%. The negative electrode slurry was coated on the surface of the negative electrode current collector copper foil, and after drying and cutting, the negative electrode sheet was obtained. (3) Preparation of solid electrolyte membranes In an argon-atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), a solid sulfide electrolyte (Li6PS5Cl) and styrene-butadiene rubber (NBR) were first dry-mixed at a mass ratio of 98:2, then dispersed and dissolved in p-xylene solvent to obtain a slurry with a solid content of 50%. The mixing speed was 1000 rpm for 3 hours to allow for complete dissolution. A solid electrolyte membrane with a thickness of 180 μm was prepared using conventional solution casting technology and drying. (4) Assembly of solid-state batteries The positive electrode, solid electrolyte membrane, and negative electrode are cut to the appropriate sizes, ensuring that the ratio of negative electrode capacity to positive electrode capacity is 1.1. The positive electrode, solid electrolyte membrane, and negative electrode are stacked in that order. The solid electrolyte membrane serves as both an ion conductor and a separator to fabricate a bare stacked battery. Then, tabs are welded to the bare cells, and a pouch battery is prepared using an encapsulation process. A temperature isostatic pressing process is then performed with controlled parameters of 500 MPa, 90°C, and 10 min to obtain the lithium-ion stacked battery product of Example 1. Example 2-20 The differences between Examples 2-20 and Example 1 are shown in Table 1. Comparative Examples 1-4 The differences between Comparative Examples 1 to 4 and Example 1 are shown in Table 1. II. Testing Section (1) Electrode bending test 1. Select shafts with different radii of curvature: 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 2mm, 2.5mm, 3mm, 5mm, and 7.5mm, with each shaft being 80mm long; 2. Press the positive electrode sheet prepared in the above embodiment onto shafts of different diameters in sequence, with the pressing order arranged from largest to smallest diameter. Bend the rods within 2s to 3s, and after bending, make the two thumbs symmetrical about the center line of the shafts. 3. Visually inspect the electrode sheet for any signs of damage such as mesh patterns, cracks, powdering, or peeling, or use a 4x magnifying glass. 4. Record the minimum radius of curvature of the shaft when the electrode is bent on shafts of different diameters without the electrode breaking. Use the minimum radius of curvature of the shaft to represent the flexibility of the electrode. (2) Ionic conductivity test At 25℃, the positive electrode active layer was scraped off from the current collector and collected to assemble a symmetrical cell with the following structure: Li-In / / SE / / positive electrode active layer powder / / SE / / Li-In. A pressure of 380 MPa was applied, and the assembled test cell was subjected to AC impedance testing at room temperature with a frequency range of 1MHz to 10Hz and a voltage amplitude of 10mV using an electrochemical workstation. The ionic conductivity was calculated using the following formula: σ = L / RA, where σ is the ionic conductivity (S / cm), R is the resistance (Ω), L is the thickness (cm), and A is the area (cm²). 2 The ionic conductivity is calculated based on the impedance value. (3) Battery cycle capacity retention test At 25°C, the battery is charged at a constant current of 1 / 3C to 4.25V, then charged at a constant voltage of 4.25V to a current of 0.05C, left to rest for 5 minutes, and then discharged at 1 / 3C to 2.5V. The resulting capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle is recorded. The battery capacity retention rate after each cycle is Pn = Cn / C0 × 100%. The battery cycle capacity retention rate is recorded after 1000 cycles. III. Analysis of Test Results for Each Embodiment and Comparative Example Battery cells for each embodiment and comparative example were prepared according to the above method, and various performance parameters were measured. The results are shown in Table 1 below.

[0001] Table 1. Experimental results of Examples 1-13 and Comparative Examples 1-4 Note: In Table 1, λ1 represents the ionic conductivity of the first positive electrode active layer, λ2 represents the ionic conductivity of the second positive electrode active layer, and the unit is mS / cm. A represents the mass percentage of the first binder in the first positive electrode active layer, and B represents the mass percentage of the second binder in the second positive electrode active layer. According to Table 1, a comparison of the test results in Examples 1-13 and Comparative Examples 1-4 shows that the ionic conductivity of the second binder in the second positive electrode active layer is greater than that of the first binder in the first positive electrode active layer. This enables the solid-state battery to have high energy density and good cycle performance when the total thickness of the active layers is greater than or equal to 100 μm. A comparison of the test results of Examples 4-10 and Comparative Examples 3-4 shows that adding a binder with high ionic conductivity to the second positive electrode active layer can maintain good cycle performance even as the thickness of the active layer gradually increases. A comparison of the test results from Examples 4 to 10 shows that when d1 / d2 is in the range of 0.25 to 1, the solid-state battery can maintain a high capacity retention rate after 1000 cycles. A comparison of the test results from Examples 1 and 11-13 shows that when the mass percentage B of the second binder is in the range of 1% to 5%, the capacity of the solid-state battery after 1000 cycles increases first and then decreases as B increases. Table 2 Experimental results of Examples 14-20 According to Table 2, a comparison of the test results of Examples 1 and 14-20 shows that the addition of the toughening layer can improve the toughness of the positive electrode sheet and reduce the occurrence of damage to the positive electrode active layer, thereby helping to improve the cycle performance of the battery. It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A solid-state battery, characterized in that, Includes a positive electrode plate, wherein the positive electrode plate comprises: Positive current collector; A first positive electrode active layer is located on at least one side of the positive electrode current collector, and the first positive electrode active layer includes a first binder; and The second positive electrode active layer is located on the side of the first positive electrode active layer away from the positive electrode current collector. The second positive electrode active layer includes a second binder, and the ionic conductivity of the second binder is greater than that of the first binder. The sum of the thicknesses of the first positive electrode active layer (d1) and the second positive electrode active layer (d2) is greater than or equal to 100 μm.

2. The solid-state battery according to claim 1, characterized in that, Based on the total mass of the second positive electrode active layer, the mass percentage of the second binder is 1% to 3%; Optionally, the second adhesive accounts for 1% to 1.5% of the total mass.

3. The solid-state battery according to claim 1 or 2, characterized in that, The second binder comprises an alkali metal and a polymer binder that forms coordination bonds with the alkali metal; Optionally, the alkali metal includes one or more of lithium, sodium, and potassium; Optionally, the polymer binder includes one or more of polyvinylidene fluoride, polyacrylate, and polytetrafluoroethylene.

4. The solid-state battery according to claim 3, characterized in that, The first adhesive comprises styrene-ethylene-butene copolymer and / or synthetic rubber; Optionally, the synthetic rubber includes one or more of butadiene rubber, silicone rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, nitrile rubber, and hydrogenated nitrile rubber.

5. The solid-state battery according to claim 1, characterized in that, The thicknesses d1 of the first positive electrode active layer and d2 of the second positive electrode active layer satisfy at least one of the following conditions: Ⅰ) 100μm≤d1+d2≤400μm; Ⅱ) 0.25≤d1 / d2≤1.

6. The solid-state battery according to claim 5, characterized in that, 50μm≤d1≤200μm; And / or, 50μm≤d2≤200μm.

7. The solid-state battery according to claim 1, characterized in that, The first positive electrode active layer includes a first positive electrode active material, and the second positive electrode active layer includes a second positive electrode active material, wherein the Dv50 of the first positive electrode active material and the Dv′50 of the second positive electrode active material satisfy: 0≤Dv50-Dv′50≤20μm.

8. The solid-state battery according to claim 1, characterized in that, The positive electrode sheet also includes: A toughening layer having a porous structure is located between the first positive electrode active layer and the second positive electrode active layer; Optionally, the toughening layer comprises a nonwoven fabric.

9. The solid-state battery according to claim 8, characterized in that, The nonwoven fabric satisfies one or more of the following conditions: (I) The thickness of the nonwoven fabric is 5μm~100μm; (II) The material of the nonwoven fabric includes one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyvinylidene fluoride, polyacrylonitrile and cellulose; (III) The porosity of the nonwoven fabric is 40%~90%; (IV) The pore size of the nonwoven fabric is 1μm~100μm.

10. The solid-state battery according to claim 1, characterized in that, The second positive electrode active layer includes a sulfide solid electrolyte; Optionally, based on the total mass of the second positive electrode active layer, the mass percentage of the sulfide solid electrolyte is 5% to 30%. Optionally, the sulfide solid electrolyte includes Li6PS5Cl, Li6PS5Br, Li2S-P2S5, Li4GeS4, and Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 Li3PS4 and Li7P3S 11 One or more of them.

11. An electrical appliance, characterized in that, Includes the solid-state battery according to any one of claims 1 to 10.

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