Solid-state battery cell and preparation method therefor, battery device, and electrical device

Abstract

The present application relates to a solid-state battery cell and a preparation method therefor, a battery device, and an electrical device. The preparation method for the solid-state battery cell provided by the present application comprises: coating a carbonate polymer on a surface of a positive electrode active material, to form a composite positive electrode material having a core-shell structure; forming, on at least one surface of a positive electrode current collector, a positive electrode active layer containing the composite positive electrode material and a sulfide electrolyte, and then performing a carbonate polymer removal treatment, or forming a positive electrode active layer containing the composite positive electrode material and a sulfide electrolyte, performing a carbonate polymer removal treatment, and then attaching same to at least one surface of a positive electrode current collector, so as to obtain a positive electrode sheet; and stacking and assembling the positive electrode sheet with a solid electrolyte layer and a negative electrode sheet, so as to obtain the solid-state battery cell. In the preparation process of the present application, the positive electrode active material is not prone to side reactions with the sulfide electrolyte, which can reduce the risk of impurities occurring in the positive electrode sheet, thereby improving the charging and discharging performance of the solid-state battery cell.

Description

Solid-state battery cells and their preparation methods, battery devices, and electrical devices.

[0001] This application claims priority to Chinese Patent Application No. 202411734361.9, filed on November 29, 2024, entitled "Solid-state battery cell and preparation method thereof, battery device, and power-consuming device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of battery technology, specifically relating to a solid-state battery cell and its preparation method, battery device, and power-consuming device. Background Technology

[0003] With the booming development of new energy vehicles, battery drive systems have become an important factor affecting the performance and cost of new energy vehicles. Due to their high energy density, low memory effect, and high operating voltage, batteries have become the preferred power source for battery drive systems.

[0004] Solid-state batteries, as a type of rechargeable battery, are characterized by high energy density. In the manufacturing process of the positive electrode of a solid-state battery cell, a solvent-free dry process is often used to improve the quality of the active material film. However, this process typically involves thorough and effective mixing of the positive electrode active material and the sulfide electrolyte. This can easily lead to chemical reactions between the positive electrode active material and the sulfide electrolyte, generating byproducts that can damage the ion and electron networks in the positive electrode, thus affecting the battery's charge and discharge performance. Summary of the Invention

[0005] The purpose of this application is to provide a solid-state battery cell and its preparation method, battery device, and power-consuming device, aiming to solve the technical problem of how to reduce the side reactions of the positive electrode active material and sulfide electrolyte in the positive electrode sheet to improve the charge and discharge performance of solid-state batteries.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a method for preparing a solid-state battery cell, comprising:

[0008] A core-shell structured composite cathode material is formed by coating carbonate polymers onto the surface of the cathode active material.

[0009] A positive electrode active layer containing the composite positive electrode material and sulfide electrolyte is formed on at least one surface of the positive electrode current collector, and then a carbonate polymer removal process is performed to obtain a positive electrode sheet; or, a positive electrode active layer containing the composite positive electrode material and sulfide electrolyte is formed, a carbonate polymer removal process is performed, and then it is bonded to at least one surface of the positive electrode current collector to obtain a positive electrode sheet.

[0010] The positive electrode is stacked and assembled with a solid electrolyte layer and a negative electrode to obtain a solid-state battery cell.

[0011] A core-shell composite cathode material is formed by coating the surface of the positive electrode active material with a carbonate polymer. This composite material is then mixed with a sulfide electrolyte to form the positive electrode active layer. During this process, the positive electrode active material in the core is less prone to side reactions with the sulfide electrolyte. Subsequently, the carbonate polymer is removed, and the resulting solid-state battery cell is assembled. This preparation method is not only simple and easy to scale up, but it also reduces the risk of impurities in the positive electrode, resulting in solid-state battery cells with excellent charge-discharge performance.

[0012] In some embodiments, the carbonate polymer includes at least one of polyethylene carbonate, polypropylene carbonate, and polyvinyl carbonate.

[0013] The above-mentioned types of carbonate polymers, when coated on the surface of the positive electrode active material, not only make the positive electrode active material located in the core less prone to side reactions with the sulfide electrolyte and easier to remove, but also have wide availability and are easy to prepare.

[0014] In some embodiments, the mass ratio of the positive electrode active material to the carbonate polymer is 1:(0.1 to 1.2).

[0015] When carbonate polymers are coated onto the surface of the positive electrode active material in the above mass ratio, they can effectively and completely coat the positive electrode active material particles.

[0016] In some embodiments, the step of coating the surface of the positive electrode active material with a carbonate polymer includes: dissolving the carbonate polymer in an organic solvent to obtain a colloid, mixing the colloid with the positive electrode active material, and then performing a solvent removal treatment.

[0017] Carbonate polymers are formulated into a liquid and then coated onto the positive electrode active material. This allows the carbonate polymers to be coated in a liquid form, thereby forming a uniform coating layer on the surface of the positive electrode active material.

[0018] In some embodiments, the weight ratio of the carbonate polymer to the organic solvent is 1:(0.1-9);

[0019] And / or, the organic solvent includes at least one of anisole, toluene, p-xylene, and heptane.

[0020] When carbonate polymers and organic solvents are mixed in the above proportions, a uniformly dispersed adhesive solution can be obtained. The above-mentioned types of organic solvents can effectively disperse carbonate polymers.

[0021] In some embodiments, the solvent removal process includes vacuum drying at 80–90°C for 20–24 hours.

[0022] The above-mentioned solvent removal process parameters can effectively remove organic solvents from the adhesive solution.

[0023] In some embodiments, the preparation step of the positive electrode active layer includes: dry mixing the composite positive electrode material, the sulfide electrolyte, a conductive agent, and a binder, followed by hot pressing to form a film.

[0024] Compared to wet processes, dry mixing does not require the use of solvents, avoiding the side effects of solvents. Moreover, the dry mixing process can fully mix the composite cathode material, sulfide electrolyte, conductive agent, and binder.

[0025] In some embodiments, the dry mixing process includes stirring and dispersing at a speed of 1500 rpm to 5000 rpm;

[0026] And / or, the hot pressing includes rolling at 60–80°C.

[0027] Stirring at the aforementioned speeds ensures thorough mixing of the dry-mixed materials. Furthermore, the coating effect of the carbonate polymers reduces the risk of damage to the positive electrode active material during stirring. Rolling at the aforementioned temperatures allows for effective hot-pressing of the dry-mixed materials into a film.

[0028] In some embodiments, the mass ratio of the composite cathode material, the sulfide electrolyte, the conductive agent, and the binder is (50-99):(0.1-50):(0.1-5):(0.1-5).

[0029] The positive electrode active material layer formed according to the above mass ratio can not only form a good ion-conducting network in the positive electrode active layer of the positive electrode sheet, but also has good stability and is not easy to fall off.

[0030] In some embodiments, the decarbonate polymer treatment step includes: heat-treating the positive electrode active layer under vacuum conditions at 200–230°C.

[0031] Vacuum heat treatment under the above conditions can fully volatilize and remove the carbonate polymers in the positive electrode sheet.

[0032] In some embodiments, the positive electrode active material includes a lithium-containing positive electrode active material or a sodium-containing positive electrode active material;

[0033] And / or, the sulfide electrolyte and the electrolyte in the solid electrolyte layer each independently include at least one of the following: silver-germanium sulfide type electrolyte, lithium-germanium-phosphorus-sulfur electrolyte, and lithium-phosphorus pentasulfide complex electrolyte.

[0034] Carbonate polymer coatings can be applied to solid-state lithium battery cells or solid-state sodium battery cells. The aforementioned sulfide electrolytes exhibit excellent ionic conductivity.

[0035] Secondly, embodiments of this application provide a solid-state battery cell, including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; the solid-state battery cell is prepared by the preparation method provided in the first aspect of this application.

[0036] Based on this application, the mixing process of the positive electrode active material and the sulfide electrolyte in the solid-state battery cell is isolated by a carbonate polymer, which reduces the risk of impurities. Such a solid-state battery cell has good discharge specific capacity and cycle stability, and has excellent charge and discharge performance.

[0037] Thirdly, embodiments of this application provide a battery device, including a solid-state battery cell provided in the second aspect of embodiments of this application.

[0038] By using the solid-state battery cells provided in the embodiments of this application, the solid-state battery cells can have excellent discharge specific capacity and cycle stability, and such battery devices have excellent charge and discharge performance.

[0039] Fourthly, embodiments of this application provide an electrical device, including a solid-state battery cell provided in the second aspect of embodiments of this application or a battery device provided in the third aspect of embodiments of this application, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

[0040] By employing solid-state battery cells or battery devices provided in the embodiments of this application, electrical devices exhibit good charging and discharging performance and can operate more effectively.

[0041] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0042] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0043] Figure 1 is a schematic diagram of a solid-state battery cell according to an embodiment of this application;

[0044] Figure 2 is an exploded view of the solid-state battery cell shown in Figure 1;

[0045] Figure 3 is a schematic diagram of one embodiment of the battery module of this application;

[0046] Figure 4 is a schematic diagram of one embodiment of the battery pack of this application;

[0047] Figure 5 is an exploded view of the battery pack shown in Figure 4.

[0048] Figure 6 is a schematic diagram of one embodiment of an electrical device that uses a solid-state battery as a power source according to an embodiment of this application.

[0049] Explanation of reference numerals in the attached drawings: 10-Solid-state battery cell; 11-Housing casing; 12-Top cover assembly; 13-Electrode assembly; 20-Battery module; 30-Battery pack; 31-Upper casing; 32-Lower casing. Detailed Implementation

[0050] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0052] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0053] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0054] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0055] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). "At least one" refers to one or more (including one, two, three, etc.).

[0056] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0057] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0058] With the dwindling availability of traditional energy resources, the development of new energy storage devices is receiving increasing attention. Among these, secondary batteries are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but are also widely applied in electric vehicles such as electric bicycles, electric motorcycles, and electric cars. As the application areas of secondary batteries as power batteries continue to expand, the market demand is also constantly increasing, while the performance requirements for these batteries are becoming increasingly stringent.

[0059] Solid-state batteries are batteries that use solid electrodes and solid electrolytes. Because solid-state battery technology uses a solid electrolyte as the conductive material instead of the traditional liquid electrolyte, it significantly improves the battery's energy density. For solid-state batteries containing sulfide electrolytes, when using wet processes to prepare battery electrodes, solvents need to be added during the mixing of active materials. However, in the electrode manufacturing process of sulfide-based solid-state batteries, commonly used solvents are highly polar solvents (such as N-methyl-2-pyrrolidone, water, etc.). These solvents may react with the sulfide electrolyte, leading to degradation or reduction in battery performance. Therefore, dry manufacturing processes that do not require solvents are generally preferred for electrode preparation.

[0060] In the dry process of solid-state battery electrodes, high-speed shearing and stirring are generally used to ensure that the positive electrode active material particles and sulfide electrolyte particles are fully and effectively mixed. However, during the stirring process, the increased collisions and friction between material particles or between material particles and the mechanical stirring device can cause the temperature to rise, leading to chemical reactions between the positive electrode active material and the sulfide electrolyte. These reactions result in the production of inactive byproducts, which can easily damage the ion and electron network in the positive electrode, thereby affecting the performance of the solid-state battery.

[0061] Based on this, in the embodiment of this application, a layer of carbonate polymer is coated on the surface of the positive electrode active material during the preparation of the solid-state battery. This coating reduces the risk of side reactions when the core positive electrode active material and the sulfide electrolyte are mixed, thereby improving the battery's charge and discharge performance. The specific technical solution is as follows.

[0062] Solid-state battery cells and their preparation methods

[0063] Firstly, embodiments of this application provide a method for preparing a solid-state battery cell. Specifically, the steps of the solid-state battery cell preparation method of this application embodiment include:

[0064] S01: A composite cathode material with a core-shell structure formed by coating a carbonate polymer onto the surface of the cathode active material;

[0065] S02: A positive electrode active layer containing composite positive electrode material and sulfide electrolyte is formed on at least one surface of the positive electrode current collector, and then the carbonate polymer is removed to obtain the positive electrode sheet.

[0066] Alternatively, a positive electrode active layer containing composite positive electrode material and sulfide electrolyte is first formed, and after removing carbonate polymers, it is bonded to at least one surface of the positive electrode current collector to obtain a positive electrode sheet.

[0067] S03: The positive electrode sheet is stacked and assembled with the solid electrolyte layer and the negative electrode sheet to obtain a solid-state battery cell.

[0068] Carbonate polymers are polymers formed by the polymerization of carbonate monomers. These polymers are stable and have a high melting point under normal temperature and pressure (generally around 25℃ and 1.01325Pa pressure). Coating the surface of the positive electrode active material with this carbonate polymer to form a core-shell structured composite positive electrode material can prevent direct contact between the positive electrode active material and the sulfide electrolyte during the mixing process, reducing the risk of side reactions and minimizing the formation of impurities. Subsequently, the carbonate polymer can be removed, reducing its impact on battery performance.

[0069] Therefore, the preparation method of this application embodiment is not only simple and easy to prepare on a large scale, but also the solid-state battery cell prepared has good discharge specific capacity and cycle stability, thereby improving the charge and discharge performance of the solid-state battery cell.

[0070] Step S01 is the preparation step of the composite cathode material, namely the carbonate polymer coating process.

[0071] In some embodiments, the carbonate polymer includes at least one of polyethylene carbonate, polypropylene carbonate, and polyvinyl carbonate. These carbonate polymers are widely available, easy to prepare, and easy to remove from the surface of the positive electrode active material.

[0072] Taking polypropylene carbonate (PPC) as an example, also known as polymethyl ethylene carbonate, it has a high melting point and a certain amount of binder. It coats the surface of the positive electrode active material particles, so that the core positive electrode active material can be physically isolated from the sulfide electrolyte during the mixing process. At the same time, the composite positive electrode material can be tightly bonded to the sulfide electrolyte to form a film.

[0073] In some embodiments, the mass ratio of the positive electrode active material to the carbonate polymer is 1:(0.1 to 1.2). Exemplarily, the mass ratio of the positive electrode active material to the carbonate polymer can be 1:0.125, 1:0.5, 1:1, 1:1.2, etc. When the carbonate polymer is coated on the surface of the positive electrode active material according to the above mass ratio, it can effectively and completely coat the positive electrode active material particles. Further, when the mass ratio of the positive electrode active material to the carbonate polymer is 1:(1 to 1.2), the more carbonate polymer coating there is, the less opportunity there is for direct contact between the positive electrode active material and the sulfide electrolyte during the mixing process, and the fewer side reaction impurities.

[0074] Among them, the particle size D of the positive electrode active material V 50 can typically range from 200 nm to 15 μm. For example, the particle size D of the positive electrode active material... V 50 can represent 200nm, 500nm, 1μm, 2μm, 5μm, 8μm, 10μm, 12μm, 15μm, etc.

[0075] In some embodiments, the step of coating the surface of the positive electrode active material with a carbonate polymer includes: dissolving the carbonate polymer in an organic solvent to obtain a gel, mixing the gel and the positive electrode active material, and then performing a solvent removal treatment. This process allows the carbonate polymer to be coated in a liquid form, completely coating the surface of the positive electrode active material particles with the carbonate polymer-containing gel, and then removing the solvent. In this way, the carbonate polymer can form a uniform coating layer on the surface of the positive electrode active material through solution impregnation, resulting in a core-shell structured composite positive electrode material.

[0076] In some embodiments, in the step of dissolving the carbonate polymer in an organic solvent to obtain a gel, the weight ratio of the carbonate polymer to the organic solvent is 1:(0.1 to 9). For example, the weight ratio of the carbonate polymer to the organic solvent is 1:0.1, 1:0.5, 1:1, 1:5, 1:8, etc. Mixing the carbonate polymer and the organic solvent according to the above mass ratio allows the carbonate polymer to be fully dispersed, resulting in a uniformly dispersed gel, which facilitates better subsequent coating of the positive electrode active material particles. Further, with a weight ratio of carbonate polymer to organic solvent of 1:(1 to 9), the more organic solvent added, the more uniformly the carbonate polymer is dispersed in the gel.

[0077] In some embodiments, a carbonate polymer and an organic solvent are thoroughly mixed at a weight ratio of 1:(1-9) to obtain a colloid. Then, the colloid and the positive electrode active material are mixed evenly at a mass ratio of 1:(1-1.2) between the positive electrode active material and the carbonate polymer in the colloid, so that the surface of the positive electrode active material can be fully coated with carbonate polymer.

[0078] In some embodiments, the organic solvent includes at least one of anisole, toluene, p-xylene, and heptane. These organic solvents can effectively disperse carbonate polymers, and subsequently, after the organic solvents evaporate, the carbonate polymers can be fully precipitated on the surface of the positive electrode active material particles, forming a uniform coating layer on the surface of the positive electrode active material particles.

[0079] In some embodiments, the step of solvent removal after mixing the adhesive and the positive electrode active material includes vacuum drying at 80–90°C for 20–24 hours. This vacuum drying process allows the organic solvent to fully evaporate, resulting in a dried core-shell composite positive electrode material.

[0080] Step S02 is the preparation of the positive electrode sheet.

[0081] In some embodiments, the preparation step of the positive electrode active layer includes: dry mixing the composite positive electrode material, sulfide electrolyte, conductive agent and binder, and then hot pressing them into a film.

[0082] If a positive electrode active layer containing a composite positive electrode material and a sulfide electrolyte is formed on at least one surface of the positive electrode current collector, the process involves dry-mixing the composite positive electrode material, the sulfide electrolyte, a conductive agent, and a binder, then hot-pressing the mixture onto the surface of the positive electrode current collector to form a film, followed by removing the carbonate polymer. If the positive electrode active layer is prepared first and then bonded to the positive electrode current collector, the process involves dry-mixing the composite positive electrode material, the sulfide electrolyte, a conductive agent, and a binder, then directly hot-pressing the mixture into a film, followed by removing the carbonate polymer, and finally bonding the carbonate polymer-treated positive electrode active film to at least one surface of the positive electrode current collector.

[0083] Dry mixing, compared to wet mixing, eliminates the need for solvents, avoiding the side effects of solvents in the wet process. Dry mixing allows for thorough mixing of the composite cathode material, sulfide electrolyte, conductive agent, and binder. This application's embodiment, based on a core-shell structured composite cathode material, reduces impurity formation during dry mixing, thereby improving the specific capacity of the composite cathode material. In the aforementioned dry mixing process, this application embodiment further adjusted the dry mixing parameters and tested the thermal stability and impurity composition of the mixed material. It was found that the prepared cathode sheet did not exhibit a significant reduction in thermal failure, and phase analysis of the mixed material also revealed very few obvious impurities.

[0084] In some embodiments, the dry mixing process includes stirring and dispersing at a rotation speed of 1500 rpm to 5000 rpm. Exemplarily, the dry mixing speed can be 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, or 5000 rpm. Dry mixing at these speeds allows the materials to be mixed uniformly. For example, the dry mixing process includes stirring and dispersing at a rotation speed of 1500 rpm to 5000 rpm for 05 to 1 hour.

[0085] Uniform mixing of materials is crucial to the performance of dry-process electrodes. To ensure the sulfide electrolyte is uniformly and effectively dispersed on the surface of the composite cathode material particles, the composite cathode material, sulfide electrolyte, conductive agent, and binder in this embodiment are stirred at the aforementioned speed. This ensures thorough mixing of the dry materials, and the coating effect of the carbonate polymer reduces the risk of damage to the cathode active material during stirring. While the high-speed stirring conditions allow for better uniform mixing, the increased collisions and friction between particles and between particles and the mechanical stirring device inevitably raise the temperature during stirring. Direct contact between the cathode active material and the sulfide electrolyte during high-speed dispersion and shearing can easily lead to a chemical reaction. However, because this embodiment uses a core-shell structured composite cathode material, the coating and isolation effect of the carbonate polymer on the surface of the cathode active material particles reduces the chance of contact with the sulfide electrolyte, thus minimizing the formation of byproducts.

[0086] For example, comparative verification experiments in this application revealed that without carbonate polymer coating, when the exposed positive electrode active material and sulfide electrolyte are mixed under the aforementioned high-speed dispersion conditions, a significant chemical reaction occurs between the positive electrode active material and the sulfide electrolyte particles in the air, generating inert impurities. Specifically, the reaction initiation temperature of the uncoated positive electrode active material and sulfide electrolyte material under different mixing times was tested using TG / DSC and other methods. The results showed that the reaction initiation temperature decreased significantly with increasing mixing time (from 245°C to 215°C). Furthermore, the impurity content was tested at different high-speed mixing stages. The impurity content increased with increasing mixing time. Through the selection of different types of positive electrode active materials and different types of sulfide electrolytes, the generated impurities mainly include NiO, NiS, Li3PO4, P4O8, Co3S4, S, and CoPS3. These impurities are inert substances that severely affect the capacity utilization of the positive electrode particles. Therefore, the embodiments of this application can effectively reduce the thermal runaway reaction between the sulfide electrolyte material and the positive electrode active material by coating with carbonate polymers.

[0087] In this embodiment, XRD testing is used to test side reaction impurities: the X-ray diffractometer is equipped with Cu Kα radiation. Operating at 36kV and 20mA voltage and current within the 2θ range of 10–80, it is primarily used for testing impurities in dry-process positive electrode sheets.

[0088] Further characterization of composite cathode materials can be achieved using SEM testing: Field emission scanning electron microscopy (SEM, HITACHI, SU8100) is used to characterize the surface morphology of composite cathode material particles.

[0089] Further analysis of the materials in the positive active layer of the positive electrode sheet can be performed using XPS: X-ray photoelectron spectroscopy (XPS, ULVAC-PHI, Inc., PHI 5000VersaProbe III) with monochromatic Al Kα radiation is used to analyze the composition of the positive active layer of the dry-process positive electrode sheet.

[0090] In some embodiments, the composite cathode material, sulfide electrolyte, conductive agent, and binder are dry-mixed and then rolled into a film at 60–80°C. Hot rolling at this temperature allows the dry-mixed material to be effectively hot-pressed into a film.

[0091] In some embodiments, the positive electrode active layer further contains a conductive agent and a binder, and the mass ratio of the composite positive electrode material, solid electrolyte, conductive agent, and binder is (50–99):(0.1–50):(0.1–5):(0.1–5). The positive electrode active material layer formed according to the above mass ratio not only enables the positive electrode active layer of the positive electrode sheet to form a good ion-conducting network, but also exhibits good stability and is not easily detached.

[0092] In some embodiments, the sulfide electrolyte includes at least one of a sulfide-germanium ore type electrolyte, a lithium germanium phosphorus sulfide electrolyte, and a lithium pentasulfide diphosphorus sulfide complex electrolyte. The electrolyte in the solid electrolyte layer includes at least one of a sulfide-germanium ore type electrolyte, a lithium germanium phosphorus sulfide electrolyte, and a lithium pentasulfide diphosphorus sulfide complex electrolyte. The sulfide electrolyte and the electrolyte in the solid electrolyte layer can be the same or different; to improve the performance stability of the solid-state battery cell and facilitate its fabrication, the same sulfide electrolyte is used. The aforementioned sulfide electrolyte has excellent ionic conductivity.

[0093] Among them, the silver-germanium sulfide type electrolyte includes the chemical formula Li 6±s P 1-j A j S 5±s-t B t X 1±sA sulfide electrolyte, where 0 ≤ j < 1, 0 ≤ t < 1, 0 ≤ s < 1, A is selected from one or more elements of Ge, Si, Sn, and Sb, B is one or more elements of O, Se, and Te, and X is selected from one or more elements of Cl, Br, I, and F; the lithium germanium phosphorus sulfur (LGPS) - type electrolyte includes a chemical formula of Li 10±δ5 Ge 1-g G g P 2-q Q q S 12-w W w A sulfide electrolyte, where 0 ≤ δ5 < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is selected from one or two elements of Si and Sn, Q is Sb, and W is selected from one or more elements of O, Se, Te, Cl, Br, I, and F; the lithium sulfide - diphosphorus pentasulfide complex - type sulfide electrolyte includes a chemical formula of (100 - u - v)Li2S·uP2S5·vM m N n A sulfide electrolyte, where 0 < u < 100, 0 ≤ v < 100, 0 ≤ u + v < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more elements of Li, B, Ge, Si, Sn, and Sb, and N is selected from one or more elements of S, Se, Te, O, Cl, Br, I, and F.

[0094] In some embodiments, the particle size D V 50 of the sulfide electrolyte in the positive electrode active layer is less than 1 μm. By adding the sulfide electrolyte with the above - mentioned particle size in the positive electrode active layer, it can better contact and mix with the composite positive electrode material, thereby improving the overall ionic conductivity of the positive electrode sheet. The particle size D V 50 of the positive electrode active material in the composite positive electrode material can generally be 200 nm to 15 μm; the particle size D V 50 of the solid electrolyte in the solid electrolyte layer can be 1 nm to 20 μm, for example, 50 nm to 1 μm.

[0095] The size of particulate materials is called particle size, the percentage of particles in different particle size intervals in the total amount is called particle size distribution, and the volume - distributed particle size is the particle size calculated cumulatively in terms of particle volume. For example, Dv50 represents the average particle size corresponding to when the cumulative volume particle size distribution percentage in a sample reaches 50%. In specific embodiments, a particle size tester can be used to test the average particle size. For the particle size test of the embodiments of this application: it can be carried out in accordance with GB / T 19077 - 2016 "Laser Diffraction Method for Particle Size Distribution", and a Mastersizer 2000E type laser particle size analyzer of Malvern Instruments Limited, UK, can be used for determination.

[0096] In some embodiments, the positive electrode active material of the positive electrode active layer can be a lithium positive electrode active material or a sodium positive electrode active material, i.e., carbonate polymer coating can be applied to solid-state lithium battery cells or solid-state sodium battery cells. As an example, the lithium positive electrode active material of a solid-state lithium metal battery may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. These positive electrode active materials may be used alone or in combination. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNiO2). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in batteries may also be used.

[0097] In some embodiments, the conductive agent in the positive electrode active layer can be a conductive material commonly used in the art, including but not limited to at least one of graphite, carbon nanotubes, nanofibers, carbon black, and graphene. Specifically, it can be selected from at least one of SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes CNTs, and graphene and their composite conductive agents. The binder can be a binder commonly used in the art, selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), and fluorinated acrylate resins.

[0098] In some embodiments, the positive current collector may be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc., may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector may include a polymeric material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0099] In some embodiments, after dry mixing and pressing the composite cathode material, sulfide electrolyte, conductive agent and binder to obtain the cathode active layer, the process further includes: removing carbonate polymers.

[0100] High-speed dispersion technology can uniformly mix and disperse powder materials. Because the surface of the composite cathode material is coated with carbonate polymers, even with increased rotation speed and extended time, the core-shell structure of the composite cathode material can better reduce the risk of side reactions during the mixing process. Furthermore, after forming the dry cathode sheet, the carbonate polymers can be removed through high-temperature treatment. This not only reduces the risk of direct contact between the sulfide electrolyte and the cathode active material during cathode sheet preparation by coating with carbonate polymers, thus reducing impurity formation, but also reduces the negative impact of carbonate polymers on the battery's internal structure by removing them from the final cathode sheet. This results in a dry cathode sheet with high ionic conductivity, further improving the charge-discharge performance of solid-state battery cells.

[0101] In some embodiments, the step of removing carbonate polymers includes heat-treating the positive electrode active layer under vacuum conditions at 200–230°C. Vacuum heat treatment under these conditions allows for better volatilization and removal of carbonate polymers from the positive electrode sheet. While a small amount of residual carbonate polymers may remain, this has a minimal impact on overall battery performance. For example, heat-treating the prepared positive electrode active layer under vacuum conditions at 200–230°C for 10–14 hours allows for maximum volatilization of the carbonate polymers.

[0102] Therefore, by subjecting the positive active film layer of the positive electrode sheet to the above-mentioned negative pressure and high temperature treatment, the carbonate polymers are removed as much as possible, which can ultimately significantly improve the charge and discharge performance of the solid-state battery cell.

[0103] Step S03 is the solid-state battery cell assembly process.

[0104] In some embodiments, the negative electrode sheet used may only contain a negative current collector, i.e., the corresponding solid-state battery cell is a solid-state metal battery cell without negative electrode active materials such as silicon carbide. Alternatively, the negative electrode sheet includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. As an example, the negative current collector has two surfaces opposite each other in its own thickness direction, and the negative active material is disposed on either or both of the two opposite surfaces of the negative current collector.

[0105] The negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, the metal foil can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, or foamed carbon, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). In some embodiments, the positive electrode current collector can be made of aluminum foil, and the negative electrode current collector can be made of copper foil.

[0106] The negative electrode active layer contains a negative electrode active material. As an example, the negative electrode active material can be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0107] The negative electrode active layer may optionally include a binder. The binder may be selected from 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 negative electrode active layer may also optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the negative electrode active layer may also optionally include other additives, such as dispersants, thickeners (e.g., sodium carboxymethyl cellulose), etc.

[0108] The electrolyte in the solid electrolyte layer and the sulfide electrolyte in the positive electrode can be the same or different; for example, the same sulfide electrolyte can be used.

[0109] Specifically, the above-mentioned positive electrode, solid electrolyte layer and negative electrode can be assembled by stacking or winding processes to obtain a solid-state battery cell.

[0110] Secondly, embodiments of this application also provide a solid-state battery cell. Specifically, the solid-state battery cell includes: (1) a positive electrode; (2) a negative electrode; and (3) a solid electrolyte layer located between the positive and negative electrode. This solid-state battery cell is prepared by the preparation method provided in the first aspect of embodiments of this application.

[0111] As can be seen from the above preparation method, in the solid-state battery cell of this application embodiment, the mixing process of the positive electrode active material of the positive electrode sheet and the sulfide electrolyte is physically isolated by carbonate polymers, which reduces the risk of impurities. Such solid-state battery cells have good discharge specific capacity and cycle stability, and have excellent charge and discharge performance.

[0112] In the solid-state battery cell provided in the second aspect of the present application, the positive electrode is the positive electrode formed in steps S01 and S02 of the preparation method provided in the first aspect of the present application; the solid electrolyte layer and the negative electrode are the solid electrolyte layer and the negative electrode used in step S03 of the preparation method provided in the first aspect of the present application.

[0113] In this embodiment, the solid-state battery cell is a rechargeable battery cell, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used. The solid-state battery cell can be a lithium-ion battery cell or a sodium-ion battery cell.

[0114] In this embodiment, the solid-state battery cell may include a battery casing and an electrode assembly encapsulated within the battery casing. The shape of the solid-state battery cell is not particularly limited; it can be cylindrical, square, or any other arbitrary shape. Figure 1 shows a square-structured solid-state battery cell 10.

[0115] In some embodiments, as shown in FIG2, the outer packaging of the solid-state battery cell 10 may include a housing 11 and a top cover assembly 12. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the top cover assembly 12 is used to cover the opening to close the receiving cavity. For embodiments of this application, the positive electrode sheet, solid electrolyte layer and negative electrode sheet contained in the solid-state battery cell 10 may be formed into an electrode assembly 13 by a lamination or winding process. The electrode assembly 13 is encapsulated in the receiving cavity.

[0116] [Battery Device]

[0117] A third aspect of this application provides a battery device. The battery device of this application includes a solid-state battery cell provided in the second aspect of this application, specifically a solid-state battery cell prepared by the preparation method provided in the first aspect of this application. By employing the solid-state battery cell provided in this application, the battery device exhibits excellent cycle performance, specific capacity, and initial coulombic efficiency, enabling it to perform charge and discharge effectively.

[0118] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0119] In some embodiments, the battery device of this application may include any one of a solid-state battery cell, a battery module, or a battery pack.

[0120] A battery module refers to a module assembled from the solid-state battery cells described in this application embodiment. In other words, it may contain multiple solid-state battery cells, and the specific number can be adjusted according to the application and capacity of the battery module.

[0121] In some embodiments, FIG3 is a schematic diagram of a battery module 20 as an example. In the battery module 20, a plurality of solid-state battery cells 10 may be arranged sequentially along the length direction of the battery module 20. Of course, they can also be arranged in any other manner. Furthermore, the plurality of solid-state battery cells 10 can be fixed by fasteners.

[0122] Optionally, the battery module 20 may also include a housing with a receiving space in which a plurality of solid-state battery cells 10 are received.

[0123] A battery pack refers to an assembly of solid-state battery cells 10, as described above. It can contain multiple solid-state battery cells 10, which can be assembled into a battery module 20. The specific number of solid-state battery cells 10 or battery modules 20 contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0124] As shown in the embodiment, Figures 4 and 5 are schematic diagrams of a battery pack 30 as an example. The battery pack 30 may include a battery compartment and multiple battery modules 20 disposed within the battery compartment. The battery compartment includes an upper compartment 31 and a lower compartment 32, the upper compartment 31 covering the lower compartment 32 and forming a closed space for accommodating the battery modules 20. The multiple battery modules 20 can be arranged in any manner within the battery compartment.

[0125] Electrical appliances

[0126] This application provides an electrical device. The electrical device includes a solid-state battery cell provided in the second aspect of this application or a battery device provided in the third aspect of this application. The solid-state battery cell or battery device is used to store or provide electrical energy. Based on the use of the solid-state battery cell or battery device of this application, the electrical device of this application can operate more effectively.

[0127] Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, portable devices, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric cars, electric toys, power tools, etc.), electric trains, ships, satellites and spacecraft, energy storage systems, etc. The electrical device can be configured with sub-solid-state battery cells, battery modules, or battery packs according to its usage requirements.

[0128] Figure 6 is a schematic diagram of an example electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0129] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use rechargeable batteries as their power source.

[0130] Example

[0131] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0132] Example 1

[0133] The composition and preparation method of a solid-state battery cell are as follows.

[0134] (1) Positive electrode plate

[0135] Preparation of composite cathode material: Polypropylene carbonate (PPC) material solvent was dissolved in anisole solvent (weight ratio 50:50) to obtain a gel solution; after the gel solution was stirred until it became translucent, the cathode active material NCM811 was added to the above gel solution, the weight ratio of gel solution to NCM811 was 7:3; then the mixed solution was stirred for 12 hours, and after the stirring and mixing was completed, it was ultrasonically dispersed for 10 minutes, and then placed in a vacuum oven at 80°C for evaporation of anisole solvent for 24 hours, finally obtaining a composite cathode material of NCM811 coated with PPC.

[0136] Preparation of the positive electrode sheet: The above-mentioned composite positive electrode material was mixed according to the following mass ratio: composite positive electrode material: sulfide electrolyte Li6PS5Cl: conductive agent nano-carbon fiber VGCF: binder polytetrafluoroethylene PTFE = 70:26:2:2. The mixture was stirred and dispersed at 4000 rpm for 0.5 h. Then, the dry-mixed powder was rolled into a film using a hot roller at a temperature of 80℃ to obtain the initial positive electrode active film material. The prepared initial positive electrode active film material was placed in a vacuum oven at 200℃ for 12 h. Finally, the positive electrode active film material was double-sided laminated with an aluminum foil current collector coated with a primer at a high temperature of 80℃ to obtain the positive electrode sheet. The electrode sheet was then die-cut using a custom die, with the size of the positive electrode active material corresponding to the die being 6*9.5 cm.

[0137] (2) Electrolyte tablets:

[0138] Li6PS5Cl and PTFE were mixed evenly at a weight ratio of 98:2 and heated on a heating stage at 80℃. The electrolyte membrane was prepared by dry rolling and layering. The dry electrolyte membrane was then die-cut using a custom-made die with dimensions of 6.5*9.8cm.

[0139] (3) Negative electrode plate

[0140] Nano-silicon, graphite, VGCF, and PVDF (mass ratio 62:35:1:2) were prepared. PVDF was then dissolved in NMP to obtain a binder solution. The binder solution was mixed with other components to form a homogenized slurry. NMP was added to the slurry to control the solid content to 30%, resulting in a negative electrode slurry. This negative electrode slurry was continuously coated onto both sides of a copper foil, with a coating width of 9.5 cm. After coating, the electrode was dried at 80°C and then rolled to obtain the negative electrode sheet. A custom die-cutting die was used to cut the electrode sheet, with the die corresponding to an active material size of 6.4 x 9.7 cm.

[0141] (4) Solid-state battery cell assembly

[0142] The positive electrode, electrolyte sheet, and negative electrode prepared above are assembled in an alternating stacked manner, and then hot-pressed and sealed with aluminum-plastic film under negative pressure to obtain a soft-pack all-solid-state battery cell.

[0143] Examples 2-8

[0144] See Table 1 for the differences from Example 1.

[0145] Comparative Example 1

[0146] The difference from Example 1 is that, during the preparation of the positive electrode sheet, the surface of the positive active material was not coated with PPC; that is, the positive active material layer of the positive electrode sheet was directly prepared according to the weight ratio of NCM811:LPSCl:VGCF:PTFE = 70:26:2:2. Everything else is the same as in Example 1.

[0147] Comparative Example 2

[0148] The difference from Example 1 is that, during the preparation of the positive electrode sheet, the surface of the positive active material is not coated with PPC; that is, the positive active material layer of the positive electrode sheet is directly prepared according to the weight ratio LFP:LPSCl:VGCF:PTFE = 70:26:2:2. Everything else is the same as in Example 1.

[0149] Performance testing

[0150] (1) Testing of impurities in the positive electrode sheet: XRD testing was used, and the X-ray diffractometer was equipped with Cu Kα radiation. Operating at 36kV and 20mA voltage and current within the 2θ range of 10–80, it is primarily used for testing impurities in dry-process positive electrode sheets.

[0151] (2) Initial discharge capacity test: The assembled solid-state battery cell was charged to 4.3V at a current density of 0.1C, left to stand for 10 minutes, and then discharged to 2.0V at a current density of 0.1C to obtain the initial discharge capacity of the battery. The battery was tested at 25℃, where 1C = 200mA / g.

[0152] (3) Initial Coulombic Efficiency: The initial coulombic efficiency of a solid-state battery cell can be obtained by dividing the initial discharge capacity obtained by testing at 0.1C by the initial charge capacity.

[0153] (4) Cycle capacity retention test: The assembled solid-state battery cells were first subjected to constant current charge-discharge for 3 cycles at a current density of 0.1C to obtain the initial discharge capacity and initial coulombic efficiency. Then, a long-cycle test was conducted at a current density of 0.33C for 50 cycles to calculate the battery's cycle capacity retention. The battery voltage test window was 2.0–4.8V vs. Li + / Li, the battery was tested at 25℃ and 50MPa pressure, where 1C=200mA / g.

[0154] The test results are shown in Table 2.

[0155] Table 1

[0156] Table 2

[0157] As shown in the table above, compared with Comparative Example 1, Examples 1-7 using ternary cathode materials, or Example 8 using lithium iron phosphate, compared with Comparative Example 2, significantly reduced the impurity content of the cathode sheets (all in the examples were below 2%, with the lowest being only 0.52%, while the comparative examples were all above 3.2%) due to the use of a unique intermediate transition coating material during the cathode sheet preparation process. This improved the specific capacity, initial coulombic efficiency, and capacity retention of the battery cells. Under the same conditions, the more coating material used and the higher the removal temperature during vacuum heat treatment, the better the effect.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a solid-state battery cell, characterized in that, include: A core-shell structured composite cathode material is formed by coating carbonate polymers onto the surface of the cathode active material. A positive electrode active layer containing the composite positive electrode material and sulfide electrolyte is formed on at least one surface of the positive electrode current collector, and then a carbonate polymer removal process is performed to obtain a positive electrode sheet; or, a positive electrode active layer containing the composite positive electrode material and sulfide electrolyte is formed, a carbonate polymer removal process is performed, and then it is bonded to at least one surface of the positive electrode current collector to obtain a positive electrode sheet. The positive electrode is stacked and assembled with a solid electrolyte layer and a negative electrode to obtain a solid-state battery cell.

2. The preparation method according to claim 1, characterized in that, The carbonate polymers include at least one of polyethylene carbonate, polypropylene carbonate, and polyvinyl carbonate.

3. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the positive electrode active material to the carbonate polymer is 1:(0.1 to 1.2).

4. The preparation method according to any one of claims 1-3, characterized in that, The step of coating the surface of the positive electrode active material with the carbonate polymer includes: dissolving the carbonate polymer in an organic solvent to obtain a glue solution, mixing the glue solution and the positive electrode active material, and then performing a solvent removal treatment.

5. The preparation method according to claim 4, characterized in that, The weight ratio of the carbonate polymer to the organic solvent is 1:(0.1-9); And / or, the organic solvent includes at least one of anisole, toluene, p-xylene, and heptane.

6. The preparation method according to claim 4 or 5, characterized in that, The solvent removal process includes vacuum drying at 80–90°C for 20–24 hours.

7. The preparation method according to any one of claims 1-6, characterized in that, The preparation steps of the positive electrode active layer include: dry mixing the composite positive electrode material, the sulfide electrolyte, the conductive agent and the binder, and then hot pressing them into a film.

8. The preparation method according to claim 7, characterized in that, The dry mixing process includes stirring and dispersing at a speed of 1500 rpm to 5000 rpm; And / or, the hot pressing includes rolling at 60–80°C.

9. The preparation method according to claim 7 or 8, characterized in that, The mass ratio of the composite cathode material, the sulfide electrolyte, the conductive agent, and the binder is (50-99):(0.1-50):(0.1-5):(0.1-5).

10. The preparation method according to any one of claims 1-9, characterized in that, The step of removing carbonate polymers includes: heat-treating the positive electrode active layer under vacuum conditions at 200-230°C.

11. The preparation method according to any one of claims 1-10, characterized in that, The positive electrode active material includes lithium-containing positive electrode active material or sodium-containing positive electrode active material; And / or, the sulfide electrolyte and the electrolyte in the solid electrolyte layer each independently include at least one of the following: silver-germanium sulfide type electrolyte, lithium-germanium-phosphorus-sulfur electrolyte, and lithium-phosphorus pentasulfide complex electrolyte.

12. A solid-state battery cell, characterized in that, It includes a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; the solid battery cell is prepared by the preparation method according to any one of claims 1-11.

13. A battery device, characterized in that, Includes the solid-state battery cell as described in claim 12.

14. An electrical appliance, characterized in that, Includes a solid-state battery cell as described in claim 12 or a battery device as described in claim 13, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

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