Composite cathode sheets and their preparation methods, quality control methods, batteries, battery packs, and electrical devices.

Abstract

This application belongs to the field of battery technology and discloses a composite positive electrode sheet and its preparation method, quality control method, battery, battery pack, and power device. The composite positive electrode sheet includes a positive current collector and a composite positive electrode layer located on at least one side of the positive current collector. The composite positive electrode layer includes positive electrode material particles and solid electrolyte particles, and the composite positive electrode layer satisfies: 0.6 ≤ R e ≤1.0, where is the effective contact ratio between the cathode material particles and the solid electrolyte particles in the composite cathode layer; N0 is the total number of cathode material particles; S0·(l1 / l2) is the effective contact factor of a single cathode material particle, S0 is the area of ​​a single cathode material particle, l1 is the effective contact perimeter between a single cathode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single cathode material particle. This composite cathode sheet has high uniformity, enabling solid-state batteries to possess both high specific capacity, excellent rate performance, and cycle life.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to composite cathode sheets and their preparation methods, quality control methods, batteries, battery packs, and electrical devices. Background Technology

[0002] With the rapid development of markets such as electronic devices, electric vehicles, smart homes, power tools, and intelligent transportation, the demand for batteries is constantly increasing. Currently, solid-state batteries have attracted significant attention from academia and industry due to their higher energy density and safety. However, solid-state batteries also face performance bottlenecks, primarily due to insufficient ion transport kinetics and solid-solid interface contact failure. As a core component of solid-state batteries, the microstructure uniformity of composite cathodes directly determines ion transport efficiency and interface contact. However, related technologies lack precise design and quantitative control of the microscopic parameters of composite cathodes, resulting in actual capacity and cycle life of solid-state batteries being far lower than theoretical values. Therefore, developing a highly uniform composite cathode would be of great significance. Summary of the Invention

[0003] This application aims to at least partially solve one of the technical problems in the related art. To this end, this application proposes a composite positive electrode sheet and its preparation method, quality control method, battery, battery pack, and power supply device. The composite positive electrode sheet has high uniformity, thereby helping the battery using the composite positive electrode sheet to have both high specific capacity, excellent rate performance, and cycle life.

[0004] In a first aspect of this application, a composite positive electrode is provided, comprising: a positive current collector and a composite positive electrode layer covering at least one side of the positive current collector, the composite positive electrode layer comprising positive electrode material particles and solid electrolyte particles, and the composite positive electrode layer satisfying the following: 0.6≤R e ≤1.0 in, , which is the effective contact ratio between the cathode material particles and the solid electrolyte particles in the composite cathode layer; N0 is the total number of the positive electrode material particles, and is an integer not less than 50; S0·(l1 / l2) is the effective contact factor of a single positive electrode material particle, S0 is the area of ​​a single positive electrode material particle, l1 is the effective contact perimeter between a single positive electrode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single positive electrode material particle. The composite positive electrode sheet in this application defines the effective contact ratio Re between the positive electrode material particles and the solid electrolyte particles in the composite positive electrode layer. Re is used as a quantitative standard for local uniformity in the composite positive electrode layer to reflect the utilization rate of the active material, where 0.6 ≤ R. eA value of ≤1.0 allows for sufficient and uniform effective contact between the cathode material particles and the solid electrolyte particles, essentially ensuring the high uniformity of the composite cathode layer and providing numerous and continuous ion transport paths, thereby effectively improving the specific capacity, rate performance, and cycle life of solid-state batteries.

[0005] In addition, the composite positive electrode sheet according to the above embodiments of this application may also have the following additional technical features: In some embodiments, the composite cathode layer satisfies: 0.9 ≤ R e ≤1.0. This helps to further improve the high uniformity of the composite cathode layer and further promote the transport of active ions, thereby effectively improving the specific capacity, rate performance, and cycle life of solid-state batteries.

[0006] In some embodiments, 0.6 ≤ l1 / l2 ≤ 1, specifically 0.9 ≤ l1 / l2 ≤ 1. The closer l1 / l2 is to 1, the more sufficient the contact between the cathode material particles and the solid electrolyte particles, resulting in a greater number of ion transport particle sizes and better continuity, which in turn helps to improve the rate performance and cycle life of the battery.

[0007] In some embodiments, the ratio λ of the particle size D50 of the positive electrode material particles to the particle size D50 of the solid electrolyte particles satisfies: 0.2 ≤ λ ≤ 40, specifically 4 ≤ λ ≤ 20. This helps to further optimize the microstructure of the composite positive electrode sheet, thereby improving the uniformity of the composite positive electrode layer.

[0008] In some embodiments, the mass ratio of the cathode material particles to the solid electrolyte particles in the composite cathode layer is (70:30) to (90:10). This ratio range can basically ensure that the composite cathode layer has a certain capacity while also ensuring the smooth transport of active ions within the composite cathode layer.

[0009] In some embodiments, the compaction density of the composite cathode layer is 3.0 g / cm³. 3 ~3.3 g / cm 3 This helps to improve the energy density of batteries using this composite cathode.

[0010] In some embodiments, the solid electrolyte particles include at least one of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes and their derivatives, or composite solid electrolytes, preferably the sulfide solid electrolyte particles include Li 7-m+a-c-d M m / n P 1-a A a S 5-b D b Cl c X dM includes at least one of Na, Mg, Ca, Zn, and Al; A includes at least one of S, Sn, and Ge; D includes at least one of O and Se; X includes at least one of Br and I, 0≤m≤1, 1≤n≤3, 0≤a≤1, 0≤b≤2, 0≤c<2, 0≤d<2, and 1≤c+d<2. In some embodiments, the cathode material particles include at least one of ternary cathode materials, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium cobalt oxide.

[0011] In some embodiments, the composite positive electrode layer further includes at least one of a binder and a conductive agent.

[0012] In some embodiments, the positive current collector includes at least one of aluminum foil current collector, stainless steel current collector, and composite current collector.

[0013] In a second aspect of this application, a method for preparing a composite positive electrode is provided, comprising: The cathode material particles and solid electrolyte particles are premixed to obtain a premixed product; The premixed product, the solid electrolyte particles, and the organic solvent are mixed under vacuum to obtain a slurry. The slurry is coated onto at least one surface of the positive current collector, and then dried and rolled to obtain the composite positive electrode sheet. Therefore, the preparation steps are simple, highly compatible with existing processes, and the resulting composite positive electrode sheet exhibits high uniformity.

[0014] In some embodiments, the solid electrolyte particles in the premixed product have a mass percentage content of 1% to 5%.

[0015] In some embodiments, the vacuum stirring mixture satisfies at least one of the following conditions: The vacuum level is -0.08 MPa to -0.095 MPa; The stirring speed is 2000 rpm to 6000 rpm, specifically 3000 rpm to 6000 rpm; The stirring time is 4 h to 10 h, specifically 8 h to 10 h.

[0016] This helps to fully mix the raw materials and organic solvents and ensures that the mixing is basically uniform, thereby increasing the effective contact ratio between the cathode material particles and the solid electrolyte particles.

[0017] In some embodiments, the solid content of the slurry is 50% to 70%. This facilitates thorough mixing of the cathode material particles and solid electrolyte particles, promotes an increase in the effective contact ratio between the cathode material particles and solid electrolyte particles, and simultaneously ensures the electrochemical performance of the composite cathode sheet while meeting the requirements for subsequent coating.

[0018] In some embodiments, the drying process includes sequentially performing a first-stage drying, a second-stage drying, and a third-stage drying, wherein the temperature of the first-stage drying is 40°C to 50°C; the temperature of the second-stage drying is 80°C to 90°C; and the temperature of the third-stage drying is 100°C to 110°C.

[0019] In a third aspect of this application, a quality control method for a composite positive electrode is proposed. The composite positive electrode includes a positive current collector and a composite positive electrode layer disposed on at least one side of the positive current collector. The composite positive electrode layer includes positive electrode material particles and solid electrolyte particles. The quality control method includes: Calculate the effective contact ratio R between the cathode material particles and the solid electrolyte particles in the composite cathode layer. e , ; Determine the effective contact ratio R between the cathode material particles and the solid electrolyte particles in the composite cathode layer. e Does it satisfy 0.6≤R? e ≤1.0, if 0.6≤R e If 0.6 ≤ R, then the composite positive electrode meets the requirements; if not, 0.6 ≤ R e If the R value is ≤1.0, the composite positive electrode does not meet the requirements. The preparation process of the composite positive electrode should be adjusted until the composite positive electrode layer satisfies 0.6≤R. e ≤1.0; Wherein, N0 is the total number of the positive electrode material particles; S0·(l1 / l2) is the effective contact factor of a single positive electrode material particle, S0 is the area of ​​a single positive electrode material particle, l1 is the effective contact perimeter between a single positive electrode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single positive electrode material particle.

[0020] According to an embodiment of this application, the quality control method includes: determining the effective contact ratio R between the positive electrode material particles and the solid electrolyte particles in the composite positive electrode layer. e Does it satisfy 0.9≤R? e ≤1.0, if 0.9≤R e If 0.9 ≤ R ≤ 1.0, then the composite positive electrode meets the requirements; if not, 0.9 ≤ R e If the R value is ≤1.0, the composite positive electrode does not meet the requirements. The preparation process of the composite positive electrode should be adjusted until the composite positive electrode layer satisfies 0.9≤R. e≤1.0.

[0021] In a fourth aspect of this application, a battery is proposed, comprising the aforementioned composite positive electrode or a composite positive electrode prepared by the aforementioned method. This battery possesses high specific capacity, excellent rate performance, and long cycle life.

[0022] In some embodiments, the battery comprises an all-solid-state battery. Thus, the solid-state battery combines high specific capacity, excellent rate performance, and cycle life.

[0023] In a fifth aspect of this application, a battery pack is proposed, comprising the aforementioned composite positive electrode, the composite positive electrode prepared by the aforementioned method, or the aforementioned battery. Therefore, the battery pack exhibits high specific capacity, excellent rate performance, and cycle life.

[0024] In a sixth aspect of this application, an electrical device is provided, comprising the aforementioned composite positive electrode, the composite positive electrode prepared by the aforementioned method, the aforementioned battery, or the aforementioned battery pack. Thus, the electrical device possesses high specific capacity, excellent rate performance, and cycle life. Attached Figure Description

[0025] Figure 1 This is a SEM image of a cross-section of the composite positive electrode sheet of Embodiment 8 of this application. Detailed Implementation

[0026] The embodiments of this application are described in detail below. The embodiments described below are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0027] This application is based on the inventor's following discoveries and understandings: As mentioned earlier, the composite cathode sheet, as a core component of the battery, directly determines the ion transport efficiency and interfacial contact due to the uniformity of its microstructure (e.g., the spatial distribution and contact degree of cathode material particles and solid electrolyte particles). Specifically, on the one hand, the effective contact ratio between cathode material particles and solid electrolyte particles is low, which makes it easy for cathode material particles and solid electrolyte particles to form "island" structures, thereby reducing the ion transport path and affecting the battery's capacity performance. On the other hand, the low contact uniformity between cathode material particles and solid electrolyte particles will cause localized enrichment of cathode material particles to generate stress concentration due to volume expansion during charging and discharging. This stress difference will cause interparticle crack propagation and cathode material particle peeling, resulting in irreversible capacity loss and reduced cycle capacity retention.

[0028] In view of this, this application proposes a highly uniform composite cathode sheet with high microstructure uniformity, which helps to enable the battery to have both high specific capacity, excellent rate performance and cycle life.

[0029] A first aspect of this application proposes a composite positive electrode sheet, comprising: a positive current collector and a composite positive electrode layer located on at least one side of the positive current collector, the composite positive electrode layer comprising positive electrode material particles and solid electrolyte particles, and the composite positive electrode layer satisfying: 0.6 ≤ R e ≤1.0, where, , is the effective contact ratio between the cathode material particles and the solid electrolyte particles in the composite cathode layer; N0 is the total number of cathode material particles, and is an integer not less than 50; S0·(l1 / l2) is the effective contact factor of a single cathode material particle, S0 is the area of ​​a single cathode material particle, l1 is the effective contact perimeter between a single cathode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single cathode material particle.

[0030] In this application, the inventor will use R e As a quantitative standard for the local uniformity of composite cathode sheets, R quantifies the effective contact ratio between cathode material particles and solid electrolyte particles, thereby reflecting the utilization rate of cathode material particles. e The closer the value is to 1, the higher the utilization rate of the cathode material particles, resulting in higher uniformity of the composite cathode layer, lower probability of agglomeration of cathode material particles and solid electrolyte particles, more ion transport paths, and lower possibility of stress concentration. This can effectively improve the specific capacity, rate performance, and cycle performance of batteries using this composite cathode sheet.

[0031] Specifically, a characterization and analysis method combining FIB-SEM and AI can be used. The composite cathode sheet can be cut using FIB (Focused Ion Beam) or CP (Ion Polishing) and SEM (Scanning Electron Microscopy) images of the cut surfaces can be captured. These SEM images are then imported into an AI model (i.e., the segment anything2 model). The AI ​​model directly reads the total number of cathode material particles N0, the area S0 of a single cathode particle, the effective contact perimeter l1 between a single cathode material particle and an electrolyte particle, and the total perimeter l2 of a single cathode material particle from the SEM images of the composite cathode sheet. This yields the effective contact factor S0·(l1 / l2) for each cathode material particle. Summing and normalizing the effective contact factors of each cathode material particle and electrolyte particle gives the overall effective contact ratio of the composite cathode sheet, thus providing a quantified result R of local uniformity. e .

[0032] For example, R eThe effective contact ratio between the cathode material particles and the solid electrolyte particles in the composite cathode layer can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, etc. Within this range, the effective contact ratio between the cathode material particles and the solid electrolyte particles in the composite cathode layer ensures uniform dispersion and a high effective contact ratio, resulting in good local uniformity of the composite cathode sheet. This provides more ion transport channels, thereby improving the battery's specific capacity, rate performance, and cycle performance. Specifically, a high effective contact ratio between the cathode material particles and the electrolyte particles reduces ion transport path obstruction, improves rate performance, and allows the cathode material particles to fully utilize their capacity. Simultaneously, it alleviates stress concentration caused by volume expansion during charging and discharging of non-uniformly contacted cathode material particles (agglomerated or containing many local pores), improves interparticle crack propagation and active material peeling, thus preventing irreversible capacity loss and improving the battery's cycle capacity retention rate.

[0033] For R e Composite cathode sheets with a diameter <0.6 can be improved by changing the materials (e.g., changing the cathode material and / or solid electrolyte) and adjusting the particle size D of the cathode material. 50 Adjusting the particle size D of the solid electrolyte 50 By altering the dispersion and stirring shear rates or extending the stirring time, the process can be effectively improved to ensure that the composite cathode layer satisfies: 0.6 ≤ R e ≤1.0.

[0034] In some embodiments, the composite cathode layer satisfies: 0.9 ≤ R e ≤1.0, specifically, R e The effective contact ratio between the cathode material particles and the solid electrolyte particles in the composite cathode layer is within the above range, which can further improve the utilization rate of the cathode material particles and the uniformity of the composite cathode layer, thereby further improving the specific capacity, rate performance and cycle life of the battery.

[0035] It is understandable that calculating R... e It is difficult to statistically analyze all cathode material particles in a composite cathode sheet. Typically, a subset of these particles is selected for analysis, and R is calculated. e In some embodiments, R e In the calculation formula, N0 represents the total number of cathode material particles actually counted. It can be understood that a sufficient number of cathode material particles participating in the count helps to increase R. eThe calculation more closely reflects the actual particle contact distribution in the composite cathode sheet, accurately reflecting the microstructural characteristics of the composite cathode layer. If N0 is too small, the number of particles counted is small, and the influence of random factors is large, resulting in a lower calculated R. e This may deviate from reality and fail to accurately reflect the microstructural characteristics of the composite cathode layer. Considering that in actual testing, cross-sectional SEM images of the composite cathode sheet are generally used for statistical analysis, one or more SEM images can be used to calculate R. e The number of cathode material particles in each SEM image should be as large as possible while ensuring clear particle boundaries. In some embodiments, the number of cathode material particles in each image can be 50-300, specifically 100-200. For example, R can be calculated by counting the number of cathode material particles in a single SEM image. e In this case, N0 can be between 50 and 300, specifically between 100 and 200. Therefore, the particle boundaries in the SEM image are clear, and the statistical count is sufficient to reflect the characteristics of the cathode material particles. It can be understood that in actual statistical analysis, N0 can be determined based on the total number of cathode material particles read from the SEM image of the cross-section of the composite cathode sheet, provided the determined value falls within the aforementioned range.

[0036] In some embodiments, 0.6 ≤ l1 / l2 ≤ 1, and more specifically, 0.9 ≤ l1 / l2 ≤ 1. For example, l1 / l2 can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, etc. When l1 / l2 is within the above range, it indicates sufficient contact between the cathode material particles and the solid electrolyte particles. The closer l1 / l2 is to 1, the more sufficient the contact between the cathode material particles and the solid electrolyte particles, thus helping to form a better "ion conduction network" between the cathode material particles and the electrolyte particles, reducing ion migration resistance in the composite cathode layer, and thereby improving the rate performance and cycle life of the battery.

[0037] It is understandable that there are no special restrictions on the units of l1 and l2. They can be flexibly chosen according to the actual testing process, as long as the units of the two are consistent, such as nanometers or micrometers.

[0038] In some embodiments, the particle size D of the cathode material particles 50 The particle size D of the solid electrolyte particles 50The ratio λ satisfies: 0.2 ≤ λ ≤ 40, more specifically: 4 ≤ λ ≤ 20. For example, λ can be 0.2, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, etc. A suitable particle size ratio allows for a more reasonable distribution of the two types of particles in the composite cathode layer. Within the above range, λ can adapt the particle size difference between the cathode material particles and electrolyte particles, increasing the effective contact ratio l1 / l2, thereby increasing the effective contact ratio between the cathode material particles and electrolyte particles, facilitating ion transport, improving the ionic conductivity of the composite cathode layer, and further ensuring battery performance. Simultaneously, within the above range, λ can effectively reduce problems such as stress concentration and interface detachment caused by excessive particle size differences. During battery charge-discharge cycles, the electrode material undergoes volume changes due to ion insertion / extraction. A suitable particle size ratio allows for more uniform interface stress, maintaining interface stability, reducing side reactions, and improving battery cycle life.

[0039] In some embodiments, in the composite cathode layer, the mass ratio of the cathode material particles to the solid electrolyte particles is 70:30 to 90:10. Specifically, the mass ratio of the cathode material particles to the solid electrolyte particles can be 70:30, 75:25, 80:20, 85:15, 90:10, etc. The cathode material particles are the main body for storing and deintercalating active ions, while the solid electrolyte particles provide pathways for the conduction of active ions. When the mass ratio of the cathode material particles to the solid electrolyte particles is within the above range, the battery can have both high energy density and a high ion transport rate during cycling. If the proportion of cathode material particles is too high, the ion transport pathway may be limited, and the battery capacity may be low.

[0040] In some embodiments, this application does not limit the shape of the cathode material particles, and the shape of the cathode material particles includes at least one of spherical and non-spherical shapes. Therefore, the composite cathode sheet has high material compatibility, allowing for the selection of different cathode material particles according to actual conditions; at the same time, it directly utilizes the intrinsic morphology of various materials without additional processing, saving process costs while preserving the original physicochemical properties of the materials.

[0041] In this paper, cathode material particles with a sphericity Φ satisfying the condition 0.7 < Φ ≤ 1 are called spherical particles, while those not satisfying this condition are called non-spherical particles. Specifically, the area and perimeter of the cathode material particles can be obtained from the SEM images using the same AI model described above. The sphericity Φ = (4π × particle area) / (particle perimeter) 2 .

[0042] In some embodiments, the compaction density of the composite cathode layer is 3.0 g / cm³. 3 ~3.3 g / cm 3Specifically, it can be 3.0 g / cm³. 3 3.05 g / cm 3 3.1 g / cm 3 3.15 g / cm 3 3.2 g / cm 3 3.25 g / cm 3 3.3 g / cm 3 The compaction density of the composite cathode layer is within the range of 1 / 2 or any two of the above ranges, which can effectively improve the structural stability and particle contact uniformity of the composite cathode layer, thereby improving the electrochemical performance of the battery using the composite cathode sheet.

[0043] In this paper, the compaction density of the composite cathode layer is defined as m / V, where m is the mass of the composite cathode layer and V is its volume. As specific examples, m can be obtained using an electronic balance with an accuracy of 0.01 g or higher. The volume V of the composite cathode layer is the product of its surface area and thickness, which can be measured using a micrometer with an accuracy of 0.5 μm. The surface area of ​​the composite cathode layer is defined as its length × its width, and the length and width can be measured separately using a ruler.

[0044] In some embodiments, the solid electrolyte particles include at least one of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes and their derivatives, or composite solid electrolytes.

[0045] In some embodiments, the sulfide solid electrolyte particles include Li 7-m+a-c-d M m / n P 1-a A a S 5-b D b Cl c X d Wherein, M includes at least one of Na, Mg, Ca, Zn, and Al; A includes at least one of S, Sn, and Ge; D includes at least one of O and Se; X includes at least one of Br and I, 0≤m≤1, 1≤n≤3, 0≤a≤1, 0≤b≤2, 0≤c<2, 0≤d<2, and 1≤c+d<2. Therefore, different solid electrolytes can be selected according to actual needs.

[0046] In some embodiments, the cathode material particles include ternary cathode materials (such as LiNi). x Co y Mn zO2, 0 < x < 1, 0 < y < 1, 0 < z < 1), lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium cobalt oxide are all selected. All of the above cathode materials can meet the requirements for high energy density and have low cost; any cathode material particle can be selected according to actual needs.

[0047] In some embodiments, the composite cathode layer further includes at least one of a binder and a conductive agent. The binder is used to bond cathode material particles, solid electrolyte particles, etc., together to maintain the structural stability of the composite cathode layer; common examples include polyvinylidene fluoride (PVDF) and polyacrylic acid (PAA). The conductive agent can improve the electronic conductivity of the composite cathode layer and promote electron transport; commonly used examples include carbon black (Super P), graphene, and carbon fiber. This helps to further optimize the physical structure and electrochemical performance of the composite cathode layer, ensuring the normal operation of the battery.

[0048] In some embodiments, the positive electrode current collector includes at least one of an aluminum foil current collector, a composite current collector, and a stainless steel current collector. The composite current collector includes current collectors with a conductive coating disposed on the aforementioned metal current collectors, and can be selected as needed. This helps to ensure the output current in the battery.

[0049] In a second aspect of this application, a method for preparing a composite positive electrode is proposed, comprising: S10: Premix the cathode material particles and solid electrolyte particles to obtain a premixed product.

[0050] In this step, the cathode material particles and solid electrolyte particles can be added to a mixer for premixing. Premixing allows the solid electrolyte particles to adhere to the cathode material particles through shear force, increasing the contact between the two.

[0051] In some implementations, the solid electrolyte particles in the premixed product constitute 1% to 5% by mass, specifically 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof. Within this range, it effectively improves interfacial contact without causing agglomeration of the solid electrolyte particles. The premixed coating thickness is suitable and has good uniformity, thus facilitating the acquisition of R... e A composite cathode sheet that meets the requirements.

[0052] S20: Vacuum mixing of premixed product, solid electrolyte particles and organic solvent to obtain slurry.

[0053] In this step, the premixed product, solid electrolyte particles, and organic solvent are placed in a vacuum container with a vacuum degree of -0.08 MPa to -0.095 MPa and stirred evenly to obtain a slurry. Specifically, the vacuum degree in the vacuum container can be -0.08 MPa, -0.082 MPa, -0.085 MPa, -0.088 MPa, -0.09 MPa, -0.092 MPa, or -0.095 MPa. A vacuum degree within this range can effectively remove air, moisture, and other substances mixed in during the mixing of the premixed product, solid electrolyte particles, and organic solvent, thereby promoting sufficient and effective contact between the cathode material particles and the solid electrolyte particles to obtain R. e The composite positive electrode sheet meets the requirements; if the vacuum degree is insufficient, it may lead to the generation of a large number of bubbles, forming micropores in the dried composite positive electrode sheet, thereby reducing the local effective contact ratio.

[0054] In some embodiments, the stirring speed can be between 2000 rpm and 6000 rpm, specifically 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm, etc. A stirring speed within the above range helps to ensure thorough and uniform mixing of the raw materials and organic solvent, resulting in better dispersion of the raw material particles, thereby improving the uniformity of the composite positive electrode and obtaining R... e The composite cathode sheet must meet the requirements; if the stirring speed is too low, it may lead to insufficient mixing, uneven dispersion of raw materials, and cause enrichment of cathode material particles or loss of ion channels; if the stirring speed is too high, it may cause problems such as damage to raw material particles.

[0055] In some embodiments, the stirring time can be 4 h to 10 h, more specifically 8 h to 10 h. For example, the stirring time can be 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc. The above stirring times can basically ensure uniform mixing between the raw materials and the organic solvent, thereby ensuring uniform particle dispersion and ultimately obtaining a composite positive electrode sheet with high uniformity. If the stirring time is too short, it may lead to insufficient mixing; if the stirring time is too long, it may lead to problems such as increased time costs.

[0056] In some embodiments, the solid content of the slurry is 50% to 70%, specifically, it can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, etc. A solid content within this range helps balance the slurry's flowability and particle dispersion, while also contributing to the uniformity of subsequent coating, thereby further improving the uniformity of the composite cathode sheet. If the solid content in the slurry is too high, it may lead to particle agglomeration; if the solid content is too low, it may lead to uneven coating and the formation of voids, among other problems.

[0057] S30: The slurry is coated on at least one side of the positive current collector, and then dried and rolled to obtain the composite positive electrode sheet.

[0058] In this step, the slurry obtained above is sieved and coated onto one side of the current collector. After drying, it is then rolled to obtain a composite positive electrode sheet of the target size. It is understood that there are no particular restrictions on the operations such as coating the slurry, drying, and rolling in this step, and they can be performed according to conventional techniques in the field. This application does not impose any particular restrictions.

[0059] In some embodiments, the drying process includes sequentially performing a first-stage drying, a second-stage drying, and a third-stage drying, and satisfies the following conditions: the temperature of the first-stage drying is 40℃~50℃ (specifically, such as 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, or any two of these ranges); the temperature of the second-stage drying is 80℃~90℃ (specifically, such as 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, or any two of these ranges); and the temperature of the third-stage drying is 100℃~110℃ (specifically, such as 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, or any two of these ranges). Specifically, the first stage of drying occurs at a lower temperature, allowing most of the solvent to evaporate gently and initially shaping the electrode structure. The second stage gradually increases the temperature to the solvent's boiling point, removing most of the residual solvent. The third stage raises the temperature slightly above the solvent's boiling point, deeply removing the solvent and promoting interfacial contact through gentle heat. This gradient drying effectively addresses the problem of uneven dispersion and limited effective contact caused by rapid drying at high temperatures, where the rapid evaporation of surface solvent creates capillary forces that pull smaller solid electrolyte particles and conductive agents in the slurry to the surface, separating them from larger, heavier positive electrode particles. Simultaneously, it improves electrode stress cracking, forming dense and continuous ion channels.

[0060] In a third aspect of this application, a quality control method for a composite positive electrode is proposed. The composite positive electrode includes a positive current collector and a composite positive electrode layer disposed on at least one side of the positive current collector. The composite positive electrode layer includes positive electrode material particles and solid electrolyte particles. The quality control method includes: Calculate the effective contact ratio R between the cathode material particles and the solid electrolyte particles in the composite cathode layer. e , ; Determine the effective contact ratio R between the cathode material particles and the solid electrolyte particles in the composite cathode layer. e Does it satisfy 0.6≤R? e ≤1.0, if 0.6≤R e If 0.6 ≤ R, then the composite positive electrode meets the requirements; if not, 0.6 ≤ R e If the R value is ≤1.0, the composite positive electrode does not meet the requirements. The preparation process of the composite positive electrode should be adjusted until the composite positive electrode layer satisfies 0.6≤R. e ≤1.0; Wherein, N0 is the total number of the positive electrode material particles; S0·(l1 / l2) is the effective contact factor of a single positive electrode material particle, S0 is the area of ​​a single positive electrode material particle, l1 is the effective contact perimeter between a single positive electrode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single positive electrode material particle.

[0061] According to an embodiment of this application, the quality control method includes: determining the effective contact ratio R between the positive electrode material particles and the solid electrolyte particles in the composite positive electrode layer. e Does it satisfy 0.9≤R? e ≤1.0, if 0.9≤R e If 0.9 ≤ R ≤ 1.0, then the composite positive electrode meets the requirements; if not, 0.9 ≤ R e If the R value is ≤1.0, the composite positive electrode does not meet the requirements. The preparation process of the composite positive electrode should be adjusted until the composite positive electrode layer satisfies 0.9≤R. e ≤1.0.

[0062] It's understandable, R e The specific calculation method is the same as described above, and will not be repeated here.

[0063] In a fourth aspect of this application, a battery is proposed, comprising the aforementioned composite positive electrode. Thus, the battery possesses both high specific capacity, excellent rate performance, and long cycle life.

[0064] It is understood that the battery can be cylindrical, square, or any other shape, and according to the outer packaging, the battery can be hard-shell battery, soft-pack battery, etc.

[0065] In some embodiments, the battery can be an all-solid-state battery, including the aforementioned composite positive electrode, negative electrode, and solid electrolyte layer, and may also include a separator as needed. The composite positive electrode and negative electrode are alternately stacked, the solid electrolyte layer is disposed between the composite positive electrode and negative electrode, and the separator may also be disposed between the composite positive electrode and negative electrode.

[0066] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. As an example, the negative electrode active material layer may include a negative electrode material, a conductive agent, and a binder.

[0067] Specifically, the negative electrode current collector can be a metal foil, for example, copper foil. The negative electrode material can include carbon-based materials, silicon-based materials, tin-based materials, etc. The binder in the negative electrode material layer can include, but is not limited to, at least one 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). The conductive agent in the negative electrode material layer can include, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0068] In some embodiments, the solid electrolyte may be a solid electrolyte known in the art that can be used in batteries. Examples of solid electrolytes include, but are not limited to, oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, and polymer solid electrolytes.

[0069] In some embodiments, the separator may be a separator known in the art that can be used in batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0070] In a fifth aspect of this application, a battery pack is proposed, comprising the aforementioned composite positive electrode or the aforementioned battery. Therefore, the battery pack exhibits high specific capacity, excellent rate performance, and cycle life.

[0071] It is understood that the battery pack can be a battery module, a battery pack, etc. Specifically, the specific structure of the battery module and the battery pack can be referred to conventional technology in this field, and will not be described in detail here.

[0072] In a sixth aspect of this application, an electrical device is proposed, comprising the aforementioned composite positive electrode, or the aforementioned battery, or the aforementioned battery pack. Therefore, the electrical device possesses high specific capacity, excellent rate performance, and cycle life.

[0073] In some embodiments, the specific type of electrical device is not particularly limited and can be any device that uses a battery as a power source or energy storage unit. Examples of electrical devices include, but are not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, and so on.

[0074] It is understood that, in addition to the battery mentioned above, the electrical device also includes other necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0075] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0076] Example 1 The composite cathode sheet was prepared according to the preparation method in this application, as follows: 1. Select spherical lithium nickel cobalt manganese oxide ternary active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) is used as the cathode material particle, and sulfide Li 5.5 PS 4.5 ClBr 0.5 As solid electrolyte particles, NCM811 and Li 5.5 PS 4.5 ClBr 0.5 The D50 particle size ratio of the particles is λ=8; in a -50℃ dew point environment, NCM811 and Li 5.5 PS 4.5 ClBr 0.5 Weigh the samples according to a 97:3 mass ratio, mix thoroughly, and then add them to a premixing machine. Maintain a rotation speed of 3000 r / min and a time of 4 min to ensure thorough mixing and homogeneity, thus obtaining Li. 5.5 PS 4.5 ClBr 0.5 Coated cathode material particles Li 5.5 PS 4.5 ClBr 0.5 @NCM811 refers to the premixed product.

[0077] In a -50°C dew point environment, the premixed cathode material particles Li 5.5 PS 4.5 ClBr 0.5 @NCM811, sulfide solid electrolyte Li 5.5 PS 4.5 ClBr 0.5 Styrene-butadiene rubber binder (SBR) with a solid content of 9%wt and conductive carbon black CB are mixed in a weight ratio of 154.64:45.36:10:1 (i.e., positive electrode material particles: sulfide solid electrolyte: conductive agent: binder = 150:50:10:1, at which point the ratio of positive electrode material particles to solid electrolyte particles is 75:25). The mixture was thoroughly stirred in xylene solvent at 6000 rpm for 10 h (vacuum stirring, vacuum degree -0.095 MPa) to maintain a solid content of 60%. The slurry was then sieved and coated onto both sides of the positive electrode current collector, followed by staged gradient drying: the first stage was drying at 50℃ for 30 s, the second stage at 80℃ for 1 min, and the third stage at 120℃ for 30 s. The mixture was then rolled and slit to obtain the composite positive electrode sheet of this application, with a compaction density of 3.3 g / cm³. 3 .

[0078] 2. Preparation of negative electrode sheet High-purity nano-silicon particles, conductive carbon (such as carbon nanotubes), and water-based binders (such as sodium carboxymethyl cellulose-polyacrylic acid CMC-PAA composite system) are dispersed in water at a weight ratio of 90:0.5:9.5 by high-speed shearing to form a uniform slurry. The slurry is then sieved and coated onto a copper foil substrate, and dried at 100°C to obtain a negative electrode sheet.

[0079] 3. Preparation of electrolyte membranes LPSCl type sulfide solid electrolyte Li 5.5 PS 4.5 ClBr 0.5 A styrene-butadiene rubber binder containing 13 wt% was thoroughly mixed in xylene solvent at a weight ratio of 9:2. The slurry was then sieved and coated onto an aluminum foil substrate, and dried at 100°C to obtain a 50 μm thick electrolyte membrane.

[0080] 4. Solid-state battery fabrication The electrolyte membrane is transferred to both sides of the negative electrode and then rolled together. The positive electrode and the transferred negative electrode are stacked in a layered manner to form a stacked cell. The cell is first packaged and subjected to isostatic pressing at 500 MPa to ensure tight interface contact. After unpacking, tabs are welded and the cell is repackaged. After standing, formation, and capacity testing at 20 MPa pressure and 45°C, a solid-state battery is obtained.

[0081] Examples 2-18 Similar to Example 1, the main differences are shown in Table 1. In Examples 4-6, 8, and 10-18, after the slurry was sieved and coated onto both sides of the positive electrode current collector, it was directly dried at 100°C for 2 minutes without segmented gradient drying. It should also be noted that the specific material ratios in the specific operation process were adjusted accordingly based on the data shown in Table 1.

[0082] Comparative Examples 1-7 Similar to Example 1, the main differences are shown in Table 1. In Comparative Examples 1-7, the slurry was sieved and coated on both sides of the positive electrode current collector, and then directly dried at 100°C for 2 minutes without segmented gradient drying. In Comparative Examples 1-7, the positive electrode material particles, solid electrolyte particles, and organic solvent were directly mixed without premixing. It should also be noted that the specific material ratios in the specific operation process were adjusted accordingly based on the data shown in Table 1.

[0083] Detection methods Local uniformity test: The composite positive electrode sheet was laser-cut at -50℃ for 3 hours using an ion milling machine. After cutting, the sample was taken and its SEM cross-sectional image was captured using an SU8600 device. The image was sent to the AI ​​image segmentation model (i.e., the segmentanything2 segmentation model). The parameters such as the total number of positive electrode material particles N0, the area S0 of a single positive electrode material particle, the effective contact perimeter l1 between a single positive electrode particle and a solid electrolyte particle, and the total perimeter l2 of a single positive electrode particle can be obtained by reading the SEM-AI.

[0084] The compaction density of the composite cathode layer is calculated as follows: Compaction density of the composite cathode layer = m / V, where m is the mass of the composite cathode layer and V is the volume of the composite cathode layer. m can be obtained using an electronic balance with an accuracy of 0.01 g or higher. The volume V of the composite cathode layer is the product of its surface area and thickness. The thickness of the composite cathode layer can be measured using a micrometer with an accuracy of 0.5 μm. The surface area of ​​the composite cathode layer = length × width. The length and width of the composite cathode layer can be measured separately using a ruler.

[0085] Battery rate performance test: Apply 20MPa pressure to the battery, charge the solid-state battery at 0.1C to 4.2V at 45℃, charge at a constant voltage of 4.2V until the charging current is less than or equal to 0.05C, let it stand for 10 minutes, then discharge at 0.1C to 2.5V, and record the discharge capacity as C0. Charge at 0.1C to 4.2V, charge at a constant voltage of 4.2V until the current is less than or equal to 0.05C, and then discharge at 0.5C to 2.5V, and record the 0.5C discharge capacity as C2. The 0.5C discharge capacity retention rate is C2 / C0.

[0086] Battery cycle performance test: Apply 20MPa pressure to the battery, charge the solid-state battery at 0.2C to 4.2V at 45℃, charge at a constant voltage of 4.2V until the charging current is less than or equal to 0.05C, let it stand for 10 minutes, discharge at 0.2C to 2.5V, cycle 200 times, record the discharge capacity of the first cycle as C1, and the capacity of 200 cycles as C200. The battery capacity retention rate after 200 cycles is C200 / C1.

[0087] Battery first charge capacity test: Apply 20MPa pressure to the battery, charge the solid battery at 0.1C to 4.2V at 45℃, and charge at a constant voltage of 4.2V until the charging current is less than or equal to 0.05C, and record its charging specific capacity C.

[0088] Test results As can be seen from Examples 1-5 and Comparative Examples 1-2, when R e When the R0.6 is less than 0.6, the local uniformity of the cathode material particles and solid electrolyte particles in the composite cathode layer is poor, and the particles are not well dispersed, leading to particle enrichment or loss of ion pathways, resulting in poor cycle and rate performance of the battery; however, this application controls R0.6 to achieve better performance. e In the case of 0.6≤R e Within the range of ≤1, the dispersion and contact between the cathode material particles and the solid electrolyte particles are better, resulting in better local uniformity of the composite cathode layer. This can reduce the phenomenon of ion transport path obstruction and improve rate performance. At the same time, it can avoid the stress concentration caused by the volume expansion of non-uniformly contacted cathode material particles (agglomeration or containing more local pores) during charging and discharging, which would lead to the peeling of active material and cause irreversible capacity loss. This improves the cycle capacity retention rate of the battery. In addition, the high effective contact ratio between cathode material particles and solid electrolyte particles allows the capacity of cathode material particles to be fully utilized.

[0089] A comparison of Examples 1 and 6 shows that, due to the sulfide solid electrolyte Li 5.5 PS 4.5 ClBr 0.5 Compared to Li 5.7 PS 4.7 Cl 1.3 It has better formability, can better disperse and adhere to cathode material particles, provides more ion pathways, and improves local uniformity (the overall effective contact ratio R of the cathode sheet). e (A larger value), thereby improving battery performance.

[0090] As can be seen from Examples 1, 7 and Comparative Example 3, the compaction density of the positive electrode sheet also affects the local uniformity of the composite positive electrode layer. A lower compaction density will reduce the local uniformity between particles to a certain extent because the porosity is higher under low compaction density and the contact uniformity between particles is lower. On the other hand, an excessively high compaction density will cause secondary fragmentation of the positive electrode particles, which will lead to a reduction in uniformity and a significant decrease in performance.

[0091] As can be seen from Examples 1 and 8, the shape of the cathode material particles also affects the local uniformity. Spherical cathode material particles have better fluidity and dispersion than non-spherical particles, which improves the local contact uniformity and thus enhances the performance of the battery.

[0092] As can be seen from Examples 1 and 9, the type of cathode material particles also affects local uniformity. The composite cathode sheets made of NCM811 and NCM622 have similar local uniformity and both exhibit good cycle stability. However, due to the limitations of energy density and specific capacity of NCM622, NCM811 is better able to meet actual production needs and has better application prospects.

[0093] As can be seen from Examples 1 and 10, the mass ratio of cathode material particles to solid electrolyte particles in the composite cathode layer affects the local uniformity of the material. The higher the proportion of solid electrolyte particles, the easier it is for electrolyte particles to be evenly distributed around the cathode material particles, i.e., R e A larger value can provide a more complete pathway and better capacity utilization.

[0094] As can be seen from Examples 1, 11, 15, 16 and Comparative Example 4, the particle size ratio of the cathode material particles to the solid electrolyte particles in the composite cathode layer affects the local uniformity of the material. The particle size ratio directly affects the packing density and contact uniformity. When 0.2≤λ≤40, the effective contact ratio between the cathode material particles and the solid electrolyte particles is higher.

[0095] As can be seen from Examples 1, 17, 18 and Comparative Examples 1-7, premixing can increase the effective contact ratio between solid electrolyte particles and cathode material particles, which is beneficial for R... e The requirements are met, and the mass percentage of solid electrolyte particles in the premixed product is in the range of 1% to 5%, which can effectively improve the interfacial contact. It will not cause phenomena such as electrolyte particle agglomeration or uneven coating, thus reducing the ion and electron conduction efficiency.

[0096] As can be seen from Examples 1, 12 and Comparative Example 5, the vacuum degree of the slurry preparation affects the local uniformity of the material. When the vacuum degree is -0.08MPa to -0.095MPa, the effective contact ratio between the cathode material particles and the solid electrolyte particles is higher.

[0097] As can be seen from Examples 1, 13-14 and Comparative Example 6, the solid content of the slurry affects the local uniformity of the material. Too high or too low solid content of the slurry will reduce the contact uniformity between the positive electrode particles and the electrolyte particles. The control of the solid content of the slurry needs to balance the fluidity and particle dispersibility. A high solid content may lead to particle agglomeration, while a low solid content will cause pores to form on the surface of the composite positive electrode sheet. When the solid content is 50% to 70%, the performance of the prepared composite positive electrode sheet is better.

[0098] Table 1

[0099] Note: The chemical formula of NCM622 in the table above is LiNi. 0.6 Co 0.2 Mn 0.2 O2.

[0100] Conclusion: Solid-state batteries prepared using the composite cathode sheet described in this application exhibit high specific capacity, excellent rate performance, and cycle life.

[0101] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0102] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0103] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A composite positive electrode sheet, characterized by, include: A positive current collector and a composite positive electrode layer located on at least one side of the positive current collector, the composite positive electrode layer comprising positive electrode material particles and solid electrolyte particles, and the composite positive electrode layer satisfying the following: 0.6≤R e ≤1.0 wherein, is an effective contact ratio of the positive electrode material particles to the solid-state electrolyte particles in the composite positive electrode layer; N0 is the total number of the positive electrode material particles, and is an integer not less than 50; S0·(l1 / l2) is the effective contact factor of a single positive electrode material particle, S0 is the area of ​​a single positive electrode material particle, l1 is the effective contact perimeter between a single positive electrode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single positive electrode material particle.

2. The composite cathode sheet according to claim 1, characterized by The composite positive electrode layer satisfies: 0.9 ≤ R e ≤ 1.

0.

3. The composite cathode sheet according to any one of claims 1 to 2, characterized by, 0.6≤l1 / l2≤1, preferably 0.9≤l1 / l2≤1.

4. The composite positive electrode sheet according to any one of claims 1 to 3, characterized by The ratio λ of the particle size D50 of the positive electrode material particles to the particle size D50 of the solid electrolyte particles satisfies: 0.2≤λ≤40, preferably 4≤λ≤20.

5. The composite positive electrode sheet according to any one of claims 1 to 4, characterized by At least one of the following conditions must be met: In the composite positive electrode layer, the mass ratio of the positive electrode material particles to the solid electrolyte particles is (70:30) to (90:10). The compacted density of the composite cathode layer is 3.0 g / cm 3 ~ 3.3 g / cm 3 .

6. The composite positive electrode sheet according to any one of claims 1 to 5, characterized by At least one of the following conditions must be met: The solid electrolyte particles include at least one of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes and their derivatives, or composite solid electrolytes. Preferably, the sulfide solid electrolyte particles include Li. 7-m+a-c-d M m / n P 1-a A a S 5-b D b Cl c X d M includes at least one of Na, Mg, Ca, Zn, and Al; A includes at least one of S, Sn, and Ge; D includes at least one of O and Se; X includes at least one of Br and I, 0≤m≤1, 1≤n≤3, 0≤a≤1, 0≤b≤2, 0≤c<2, 0≤d<2, and 1≤c+d<2. The cathode material particles include at least one of ternary cathode materials, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium cobalt oxide. The composite positive electrode layer further includes at least one of a binder and a conductive agent; The positive current collector includes at least one of aluminum foil current collector, stainless steel current collector, and composite current collector.

7. A method of producing the composite positive electrode sheet according to any one of claims 1 to 6, characterized by, include: The cathode material particles and solid electrolyte particles are premixed to obtain a premixed product; The premixed product, the solid electrolyte particles, and the organic solvent are mixed under vacuum to obtain a slurry. The slurry is coated on at least one side of the positive electrode current collector, and then dried and rolled to obtain the composite positive electrode sheet.

8. The method of claim 7, wherein, At least one of the following conditions must be met: The solid electrolyte particles in the premixed product have a mass percentage content of 1% to 5%; The vacuum degree of the vacuum stirring and mixing is -0.08MPa to -0.095MPa; The stirring speed of the vacuum mixing is 2000 rpm to 6000 rpm, preferably 3000 rpm to 6000 rpm; The stirring time for vacuum mixing is 4 h to 10 h, preferably 8 h to 10 h; The solid content of the slurry is 50% to 70%.

9. The method according to claim 7 or 8, characterized in that, The drying process includes sequentially performing a first-stage drying, a second-stage drying, and a third-stage drying, and satisfies the following conditions: The drying temperature of the first stage is 40℃~50℃; The temperature of the second-stage drying is 80℃~90℃; The temperature of the three-stage drying process is 100℃~110℃.

10. A quality control method of a composite positive electrode sheet including a positive electrode current collector and a composite positive electrode layer provided on at least one side of the positive electrode current collector, the composite positive electrode layer including positive electrode material particles and solid-state electrolyte particles, characterized by, The quality control method includes: calculating an effective contact ratio R of the positive electrode material particles and the solid-state electrolyte particles of the composite positive electrode layer e , ; Determine the effective contact ratio R between the cathode material particles and the solid electrolyte particles in the composite cathode layer. e Does it satisfy 0.6≤R? e ≤1.0, if 0.6≤R e If 0.6 ≤ R, then the composite positive electrode meets the requirements; if not, 0.6 ≤ R e If the R value is ≤1.0, the composite positive electrode does not meet the requirements. The preparation process of the composite positive electrode should be adjusted until the composite positive electrode layer satisfies 0.6≤R. e ≤1.0; Wherein, N0 is the total number of the positive electrode material particles; S0·(l1 / l2) is the effective contact factor of a single positive electrode material particle, S0 is the area of ​​a single positive electrode material particle, l1 is the effective contact perimeter between a single positive electrode material particle and the solid electrolyte particle, and l2 is the total perimeter of a single positive electrode material particle.

11. The quality control method according to claim 10, characterized in that, Determine the effective contact ratio R between the cathode material particles and the solid electrolyte particles in the composite cathode layer. e Does it satisfy 0.9≤R? e ≤1.0, if 0.9≤R e If 0.9 ≤ R ≤ 1.0, then the composite positive electrode meets the requirements; if not, 0.9 ≤ R e If the R value is ≤1.0, the composite positive electrode does not meet the requirements. The preparation process of the composite positive electrode should be adjusted until the composite positive electrode layer satisfies 0.9≤R. e ≤1.

0.

12. A battery, characterized in that, The composite positive electrode sheet includes any one of claims 1 to 6 or the composite positive electrode sheet prepared by any one of claims 7 to 9.

13. The battery according to claim 12, characterized in that, The battery includes an all-solid-state battery.

14. A battery pack, characterized by The battery of claim 12 or 13.

15. An electrical device, comprising: The battery of claim 12 or 13.

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