Composite positive electrode material layer, and preparation method therefor and use thereof

Abstract

The present application relates to the technical field of new energy materials, and discloses a composite positive electrode material layer, and a preparation method therefor and a use thereof. The composite positive electrode material layer disclosed in the present application comprises 70-90 parts by weight of a positive electrode active material and 8-30 parts by weight of a sulfide electrolyte. In the thickness direction of the composite positive electrode material layer, the content of the positive electrode active material and the content of the sulfide electrolyte are in gradient distribution. In the thickness direction of the composite positive electrode material layer, the mass fraction of the positive electrode active material decreases from 74%-95% to 60%-85% and the mass fraction of the sulfide electrolyte increases from 5%-24% to 10%-32%, or the increase and decrease directions of the two are reversed; and the difference between the maximum mass fraction and the minimum mass fraction of each of the positive electrode active material and the sulfide electrolyte is larger than 5% and smaller than 30%. The composite positive electrode material layer has high areal capacity, can improve the energy density of solid-state batteries, and can further improve the power density of solid-state batteries.

Description

Composite positive electrode material layer and preparation method and application thereof

[0001] This application claims priority to Chinese Patent Application No. 202410891481.3, filed on July 4, 2024. This application incorporates the entirety of the aforementioned Chinese Patent Application. TECHNICAL FIELD

[0002] The present application relates to the technical field of new energy materials, in particular to a composite positive electrode material layer and a preparation method and application thereof. BACKGROUND

[0003] To meet the demand of people for high energy density and high safety of energy storage system, solid-state batteries have shown great application potential to replace traditional liquid batteries. In solid-state batteries, solid electrolyte is used as a separator, and a silicon-based negative electrode or a metal lithium negative electrode with high energy density is used on the negative electrode side. Therefore, the capacity of the solid-state battery is high. In addition, the lack of flammable electrolyte components in the solid-state battery can improve the use safety of the battery system.

[0004] At present, the most promising solid electrolyte is mainly sulfide electrolyte, oxide electrolyte and halide electrolyte. Among them, sulfide electrolyte is a kind of electrolyte material with high ionic conductivity (1-25 mS·cm -1 Therefore, the development of sulfide-based solid-state batteries is the current mainstream development route. Compared with liquid batteries, solid-state batteries still have the problem of low power density, which can be attributed to the kinetic limitation of solid materials. Therefore, the electrochemical performance of solid-state batteries under high surface capacity / high current density conditions needs to be further improved.

[0005] In the composite electrode of the solid-state battery, the electrolyte and the active material respectively play the roles of transporting ions and electrons. However, in a thick electrode, the ion and electron transport has a large tortuosity, which limits the transmission rate of electrons and ions. The effective electron / ion conductivity is formula I:

[0006] wherein σ eff is the effective electron / ion conductivity, σ0 is the intrinsic electron / ion conductivity of the material, Φ is the volume fraction of the material in the electrode, and τ is the electron / ion transmission tortuosity. In addition to the intrinsic electron / ion conductivity of the material, the volume fraction of the material in the composite electrode and the electron / ion transmission tortuosity also affect the effective electron / ion conductivity in the composite electrode. The volume fraction of the material is usually determined by the feeding ratio, and the electron / ion transmission tortuosity is related to the uniformity of the distribution of the material in the composite electrode and the porosity.

[0007] To further improve the energy density of the solid-state battery, it is usually necessary to prepare an electrode with high surface capacity. However, under high current density (high rate), the electrochemical performance of the solid-state battery is often limited by the electron / ion kinetics, which cannot make the solid-state battery have both high energy density and high power density. SUMMARY

[0008] The main purpose of the present application is to provide a composite positive electrode material layer, a preparation method and application thereof, so as to solve the problem that the solid-state battery in the prior art cannot have both high energy density and high power density.

[0009] To achieve the above-mentioned purpose, according to the first aspect of the present application, a composite positive electrode material layer is provided, which comprises the following components by weight: 70-90 parts of a positive electrode active material and 8-30 parts of a sulfide electrolyte; along the thickness direction of the composite positive electrode material layer, the content of the positive electrode active material and the content of the sulfide electrolyte in the composite positive electrode material are gradiently distributed; along the same thickness direction of the composite positive electrode material layer, the mass fraction of the positive electrode active material decreases from 74%-95% to 60%-85%, and the mass fraction of the sulfide electrolyte increases from 5%-24% to 10%-32%, or, the mass fraction of the positive electrode active material increases from 60%-85% to 74%-95%, and the mass fraction of the sulfide electrolyte decreases from 10%-32% to 5%-24%, and the difference between the highest mass fraction and the lowest mass fraction of the positive electrode active material and the sulfide electrolyte is greater than 5% and less than 30%.

[0010] Further, the composite positive electrode material layer described above further comprises 0-3 parts of a conductive agent and 0.3-4 parts of a binder.

[0011] Further, the conductive agent described above comprises at least one of conductive carbon black, conductive graphite, acetylene black, ketjen black, carbon nanotube, vapor grown carbon fiber, graphene; and / or, the binder described above comprises at least one of styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, styrene-ethylene-butylene-styrene copolymer, fluorine glue.

[0012] Further, the weight of the positive electrode active material is 75-90 parts, and the weight of the sulfide electrolyte is 9-21 parts.

[0013] Further, the positive electrode active material comprises at least one of NCM positive electrode material, NCA positive electrode material, LFP positive electrode material, lithium nickel manganese oxide positive electrode material, lithium-rich manganese-based positive electrode material.

[0014] Further, the sulfide electrolyte comprises LPS, Li6PS5X, Li 5.5 PS 4.5 X 1.5LiPSX, Li 11-a M 2-a P 1+a S 12 X is at least one selected from F, Cl, Br, I, M is at least one selected from Ge, Si, Sn, and 0.01≤a≤1.

[0015] Further, the D50 particle size of the positive electrode active material is 0.5-15 μm, and the D50 particle size of the sulfide electrolyte is 0.1-15 μm.

[0016] Further, the positive electrode active material is NCM positive electrode material, and the sulfide electrolyte is Li 5.5 PS 4.5 X 1.5 .

[0017] According to a second aspect of the present application, a preparation method of the composite positive electrode material layer is provided, and the preparation method comprises the following steps:

[0018] S1, dispersing the components in the solvent according to the proportion to obtain a positive electrode slurry;

[0019] S2, coating the positive electrode slurry prepared in S1 to the surface of the current collector, drying to obtain a composite positive electrode material layer;

[0020] In S1, the solid content of the positive electrode slurry is 40%-75%; in S2, the drying condition is 40-75℃, 2-40h.

[0021] Further, the solvent is at least one of toluene, xylene, anisole, isobutyl isobutyrate, butyl butyrate; and / or, the coating method is one of doctor blade coating, micro-recess coating, slot extrusion coating, spraying, dip coating, electrospinning.

[0022] Further, the preparation process of the composite positive electrode material layer is carried out in a dry environment or inert atmosphere with a dew point lower than-50℃; and / or, the viscosity of the positive electrode slurry is 0.1-0.8 Pa·s.

[0023] In addition, according to a third aspect of the present application, the composite positive electrode material layer or the composite positive electrode material layer prepared by the above preparation method is applied in a solid-state battery, and the solid-state battery comprises a positive electrode current collector, a composite positive electrode material layer, a solid-state electrolyte layer and a negative electrode sheet layer which are sequentially stacked, one side of the composite positive electrode material layer rich in positive electrode active material is in contact with the positive electrode current collector, and the other side of the composite positive electrode material layer rich in sulfide electrolyte is in contact with the solid-state electrolyte layer.

[0024] By applying the technical solution of the present application, the composite positive electrode material layer is constructed by the positive electrode active material and the sulfide electrolyte, the amounts of the two and the distribution states of the two in the composite positive electrode material layer are limited, and the energy density and the power density of the solid-state battery can be simultaneously improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a schematic structural diagram of a solid-state battery prepared by a composite positive electrode material layer of the present application;

[0026] FIG. 2 is a cross-sectional SEM image of the composite positive electrode material layer of Example 1;

[0027] The above drawings include the following reference signs: 1, composite positive electrode material layer; 2, positive electrode current collector; 3, solid-state electrolyte layer; 4, negative electrode sheet layer; 1-1, positive electrode active material; 1-2, sulfide electrolyte. DETAILED DESCRIPTION

[0028] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0029] A solid-state battery is a battery that uses a solid-state electrolyte instead of a liquid or gel electrolyte. They do not leak or catch fire, and usually have a longer service life and higher safety. Solid-state batteries are currently being widely researched and developed, and are considered an important part of next-generation battery technology, which can be applied in electric vehicles, mobile devices and energy storage systems, etc. However, the capacity and power density of solid-state batteries still have some gap compared with liquid batteries.

[0030] In order to further improve the electrochemical performance of the solid-state battery, in one typical embodiment of the present application, a composite positive electrode material layer is provided, which comprises the following components by weight: 70-90 parts of positive electrode active material, 8-30 parts of sulfide electrolyte; along the thickness direction of the composite positive electrode material layer, the content of the positive electrode active material and the content of the sulfide electrolyte in the composite positive electrode material layer are gradiently distributed; along the same thickness direction of the composite positive electrode material layer, the mass fraction of the positive electrode active material decreases from 74%-95% to 60%-85%, and the mass fraction of the sulfide electrolyte increases from 5%-24% to 10%-32%, or, the mass fraction of the positive electrode active material increases from 60%-85% to 74%-95%, and the mass fraction of the sulfide electrolyte decreases from 10%-32% to 5%-24%; along the thickness direction of the composite positive electrode material layer, the difference between the highest mass fraction and the lowest mass fraction of the positive electrode active material and the sulfide electrolyte is greater than 5% and less than 30%.

[0031] The positive electrode active material can accept electrons and undergo chemical reactions, which plays a crucial role in the capacity of the battery, and the electrolyte is used for ion transmission and is a good conductor of ions, among which the sulfide electrolyte is a commonly used solid-state electrolyte material with high ionic conductivity and chemical stability. By selecting the positive electrode active material and the sulfide electrolyte to construct the composite positive electrode material layer, the amount of the two and their distribution state in the composite positive electrode material layer are selected as described above, which can make the ion and electron have good transmission efficiency in the positive electrode material, thereby improving the energy density of the battery while also increasing its power density. By limiting the content of the positive electrode active material, the content of the sulfide electrolyte, and the gradient of the two along the thickness direction of the composite positive electrode material layer, the transmission rate of lithium ions and electrons in the composite positive electrode material layer can be balanced, thereby further improving the electrochemical performance of the composite positive electrode material layer.

[0032] As a preferred embodiment of the present application, the composite positive electrode material layer further comprises 0-3 parts of a conductive agent and 0.3-4 parts of a binder. The conductive agent and the binder help to improve the conductivity and cycle stability of the battery.

[0033] Typically but not limitedly, the conductive agent includes at least one of conductive carbon black, conductive graphite, acetylene black, ketjen black, carbon nanotubes, vapor grown carbon fiber, graphene; and / or the binder includes at least one of styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, styrene-ethylene-butylene-styrene copolymer, fluorine glue.

[0034] As a preferred embodiment of the present application, the weight parts of the positive electrode active material is 75-90 parts, and the weight parts of the sulfide electrolyte is 9-21 parts.

[0035] The above limitation on the amount of positive electrode active material and sulfide electrolyte can make the components in the composite positive electrode material layer have a better gradient distribution state, thereby greatly improving the power density of the battery without losing its capacity.

[0036] Typically but not limitedly, the positive electrode active material includes at least one of NCM positive electrode material, NCA positive electrode material, LFP positive electrode material, lithium nickel manganese oxide positive electrode material, lithium-rich manganese-based positive electrode material.

[0037] Typically but not limitedly, the sulfide electrolyte includes LPS, Li6PS5X, Li 5.5 PS 4.5 X 1.5 , LiSiPSX, Li 11-a M 2-a P 1+a S 12at least one of F, Cl, Br, I, M is at least one of Ge, Si, Sn, and 0.01≤a≤1; and / or, the D50 particle size of the positive active material is 0.5-15 μm, and the D50 particle size of the sulfide electrolyte is 0.1-15 μm.

[0038] When the positive active material and the sulfide electrolyte are of the above-mentioned composition, the electrochemical performance of the battery is relatively good, and in addition, the particle size of the positive active material and the sulfide electrolyte is a conventional size, and it has good comprehensive performance within the above-mentioned range.

[0039] As a preferred embodiment of the present application, the above-mentioned positive active material is an NCM positive material, and further preferably, the NCM positive material is LiNi 0.9 Co 0.05 Mn 0.05 O2; and the above-mentioned sulfide electrolyte is Li 5.5 PS 4.5 X 1.5 The above-mentioned preferences for the types of the two materials can further improve the capacity of the battery.

[0040] In another typical embodiment of the present application, a preparation method of the above-mentioned composite positive material layer is provided, and the preparation method comprises the following steps:

[0041] S1, dispersing the components in a solvent according to the proportions to obtain a positive slurry;

[0042] S2, coating the positive slurry prepared in S1 to the surface of the current collector, drying to obtain a composite positive material layer;

[0043] In S1, the solid content of the positive slurry is 40%-75%; and in S2, the drying conditions are 40-75℃, 2-40h.

[0044] The above-mentioned limitations on the solid content of the positive slurry and the drying conditions can make the positive active material and the sulfide electrolyte migrate with the volatilization of the solvent. Since the positive active material and the sulfide electrolyte have different densities, the composite positive material layer is constructed with the gradient direction of the contents of the positive active material and the sulfide electrolyte being opposite, so that after being assembled into a battery, the end close to the positive current collector is rich in the positive active material, but also contains a certain amount of sulfide electrolyte, while the end close to the electrolyte is rich in the sulfide electrolyte, but also contains a certain amount of positive active material, thereby making the battery have good energy density and power density.

[0045] Typically but not limitedly, the solvent is at least one of toluene, xylene, anisole, isobutyl isobutyrate, butyl butyrate; and / or, the coating method is one of doctor blade coating, micro-recess coating, slot-die coating, spray coating, dip coating, electrospinning.

[0046] As a preferred embodiment of the present application, the preparation process of the composite cathode material layer is carried out in a dry environment or inert atmosphere with a dew point lower than -50℃. The preparation under the above conditions can avoid the introduction of other impurities.

[0047] As a preferred embodiment of the present application, the viscosity of the above-mentioned cathode slurry is 0.1-0.8 Pa·s. The above limitation on the viscosity of the cathode slurry can make the content of the cathode active material and the sulfide electrolyte form a good gradient in the composite cathode material layer, and further the transmission rate of ions and electrons in the composite cathode material layer. In the description of the present application, the viscosity is measured at 25℃ by using a rheometer.

[0048] In yet another typical embodiment of the present application, the use of the above-mentioned composite cathode material layer or the composite cathode material layer prepared by the above-mentioned preparation method in a solid-state battery is provided. The solid-state battery comprises a cathode current collector, a composite cathode material layer, a solid-state electrolyte layer and a negative electrode sheet layer which are sequentially stacked, the side of the composite cathode material layer rich in the cathode active material is in contact with the cathode current collector, and the side of the composite cathode material layer rich in the sulfide electrolyte is in contact with the solid-state electrolyte layer.

[0049] The "side rich in the cathode active material" mentioned in the present application represents the side with the highest content of the cathode active material along the thickness direction of the composite cathode material layer, and the "side rich in the sulfide electrolyte" represents the side with the highest content of the sulfide electrolyte along the thickness direction of the composite cathode material layer.

[0050] The present application will be further described in detail below in combination with specific examples, which cannot be understood as limiting the scope of the present application.

[0051] The materials used in the examples and comparative examples are as follows:

[0052] Cathode active material: LiNi 0.8 Co 0.1 Mn 0.1 O2, D50 particle size is 4 μm; LiNi 0.9 Co 0.05 Mn 0.05 O2, D50 particle size is 4 μm;

[0053] Sulfide electrolyte: Li6PS5Cl, D50 particle size is 3 μm; Li 5.5 PS 4.5 Cl 1.5D50 particle size is 3 pm;

[0054] Binder: styrene-butadiene-styrene triblock copolymer;

[0055] Solvent: isobutyl isobutyrate;

[0056] Foil: Al foil, 20 pm.

[0057] The composite positive electrode material layer in the examples and comparative examples was prepared in a dry room with a dew point lower than -50℃.

[0058] Examples 1-10

[0059] The preparation method of the composite positive electrode material layer in the examples of the present application is as follows:

[0060] S1, disperse the components in isobutyl isobutyrate according to the ratio to obtain a positive electrode slurry;

[0061] S2, coat the positive electrode slurry on the surface of the foil by scraping, dry in a blast oven to obtain a composite positive electrode material layer with a surface capacity of 5 mAh·cm -2 and a positive electrode sheet.

[0062] Comparative Example 1

[0063] A composite positive electrode material layer, which is different from Example 3 in that the contents of the sulfide electrolyte and the binder are different, as shown in Table 1.

[0064] Comparative Example 2

[0065] A composite positive electrode material layer, which is different from Example 1 in that the solid content of the positive electrode slurry and the drying conditions are different, as shown in Table 1.

[0066] The components of the composite positive electrode material layer, their amounts (parts by weight) and preparation conditions are shown in Table 1.

[0067] Table 1

[0068] Performance test:

[0069] 1. The mass fraction of the positive electrode active material (A1) and the mass fraction of the sulfide electrolyte (A2) in the side of the composite positive electrode material layer rich in the positive electrode active material, and the mass fraction of the positive electrode active material (E1) and the mass fraction of the sulfide electrolyte (E2) in the side rich in the sulfide electrolyte were tested and calculated by an energy-dispersive spectrometer, and the test results are shown in Table 2.

[0070] 2. The positive electrode sheets prepared from the composite positive electrode material layers of the examples and comparative examples were tested for the capacity, the capacity retention rate, the initial efficiency, the cycle life and the safety performance. 0.5The In negative electrode was assembled into a half battery for rate performance testing, wherein the side rich in sulfide electrolyte was connected to Li 0.5 The In negative electrode was connected to the positive electrode, and the test results are shown in Table 3.

[0071] Table 2

[0072] Table 3

[0073] As can be seen from Table 3, the discharge capacity of the composite positive electrode material layer prepared in Examples 1-10 can all reach 190 mAh·g -1 mAh·g -1 mAh·g 0.9 and the 1C / 0.05C capacity ratio can all reach more than 45%, having good energy density and certain power density. The results show that, compared to the positive electrode material layer with uniform distribution of components, the positive electrode material layer with gradient distribution of positive electrode active material and electrolyte has relatively better electrochemical performance, and the battery prepared therefrom has higher power density.

[0074] In addition, it can be found from the test results of Comparative Examples 3-7 that, when the weight part of the positive electrode active material is 75-90 parts and the weight part of the sulfide electrolyte is 9-21 parts, the 1C / 0.05C capacity ratio is all higher than 50%, having good energy density and power density.

[0075] It can be found from the test results of Comparative Examples 8-9 and Example 3 that, when the positive electrode active material is NCM positive electrode material, and is LiNi 0.9 Co 0.05 Mn 0.05 O2, the discharge capacity and rate performance of the battery are obviously better; in addition, when the sulfide electrolyte is Li 5.5 PS 4.5 X 1.5 , the electrochemical performance is better.

[0076] It can be found from the test results of Comparative Examples 3-5 and Example 10 that, when the amount of the binder is 0.3-4 parts, the rate performance is better.

[0077] Figure 1 is a structural schematic diagram of a solid-state battery prepared from the composite cathode material layer of the present application; wherein: 1, composite cathode material layer; 2, cathode current collector; 3, solid-state electrolyte layer; 4, anode sheet layer; 1-1, cathode active material; 1-2, sulfide electrolyte; Figure 2 is a cross-sectional SEM image of the composite cathode material layer of Example 1; wherein: 1-1, cathode active material; 1-2, sulfide electrolyte. As can be seen from the figure, the cathode active material and the sulfide electrolyte in the composite cathode material layer are gradiently distributed, and the gradient directions of the two are opposite. The above-mentioned solid-state battery has both high energy density (≥5 mAh·cm -2 ) and good power density.

[0078] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A composite cathode material layer, characterized by, The composite positive electrode material layer comprises the following components in parts by weight: positive electrode active material 70-90 parts, sulfide electrolyte 8-30 parts; the content of the positive electrode active material and the content of the sulfide electrolyte are gradiently distributed along the thickness direction of the composite positive electrode material layer; along the same thickness direction of the composite positive electrode material layer, the mass fraction of the positive electrode active material decreases from 74%-95% to 60%-85%, and the mass fraction of the sulfide electrolyte increases from 5%-24% to 10%-32%, or the mass fraction of the positive electrode active material increases from 60%-85% to 74%-95%, and the mass fraction of the sulfide electrolyte decreases from 10%-32% to 5%-24%, and the difference between the highest mass fraction and the lowest mass fraction of each of the positive electrode active material and the sulfide electrolyte is greater than 5% and less than 30%.

2. The composite cathode material layer of claim 1, wherein, It also comprises 0-3 parts of a conductive agent and 0.3-4 parts of a binder.

3. The composite cathode material layer of claim 2, wherein, The conductive agent comprises at least one of conductive carbon black, conductive graphite, acetylene black, ketjen black, carbon nanotube, vapor grown carbon fiber, graphene; and / or the binder comprises at least one of styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, styrene-ethylene-butylene-styrene copolymer, fluorine glue.

4. The composite cathode material layer of any one of claims 1 to 3, wherein, The weight parts of the positive electrode active material are 75-90 parts, and the weight parts of the sulfide electrolyte are 9-21 parts.

5. The composite positive electrode material layer according to any one of claims 1-3, wherein, The positive electrode active material comprises at least one of NCM positive electrode material, NCA positive electrode material, LFP positive electrode material, lithium nickel manganese oxide positive electrode material, and lithium-rich manganese-based positive electrode material; and / or, The sulfide electrolyte comprises at least one of LPS, Li6PS5X, Li 5.5 PS 4.5 X 1.5 , LiSiPSX, Li 11-a M 2-a P 1+a S 12 , X is selected from at least one of F, Cl, Br, I, M is selected from at least one of Ge, Si, Sn, and 0.01≤a≤1; and / or, The D50 particle size of the positive electrode active material is 0.5-15 μm, and the D50 particle size of the sulfide electrolyte is 0.1-15 μm.

6. The composite cathode material layer of claim 5, wherein, The positive electrode active material is an NCM positive electrode material, and the sulfide electrolyte is Li 5.5 PS 4.5 X 1.5 .

7. A method for producing the composite positive electrode material layer according to any one of claims 1 to 6, characterized by, The method comprises the following steps: S1, dispersing each component in a solvent according to the ratio to obtain a positive electrode slurry; S2, coating the positive electrode slurry to the surface of the current collector, drying to obtain the composite positive electrode material layer; In S1, the solid content of the positive electrode slurry is 40%-75%; in S2, the drying conditions are 40-75℃ and 2-40h.

8. The preparation method of the composite positive electrode material layer according to claim 7, wherein, The solvent is at least one of toluene, xylene, anisole, isobutyl isobutyrate, and butyl butyrate; and / or, The coating is one of doctor blade coating, micro-recess coating, slot extrusion coating, spraying, dip coating, and electrospinning.

9. The method for producing a composite positive electrode material layer according to claim 7 or 8, characterized by, The preparation process of the composite positive electrode material layer is carried out in a dry environment or inert atmosphere with a dew point lower than -50℃; and / or the viscosity of the positive electrode slurry is 0.1-0.8 Pa·s.

10. Use of a layer of a composite cathode material in a solid-state battery, characterized in that The solid-state battery comprises a positive electrode current collector, a composite positive electrode material layer, a solid-state electrolyte layer and a negative electrode sheet layer which are sequentially stacked, the composite positive electrode material layer is the composite positive electrode material layer according to any one of claims 1 to 6 or the composite positive electrode material layer prepared by the preparation method of the composite positive electrode material layer according to any one of claims 7 to 9; one side of the composite positive electrode material layer rich in positive electrode active material is in contact with the positive electrode current collector, and one side of the composite positive electrode material layer rich in sulfide electrolyte is in contact with the solid-state electrolyte layer.

Images