Preparation method of positive electrode sheet with potential regulation function and solid-state battery

Abstract

The application discloses a preparation method of a positive plate with a potential regulation function, and comprises the following steps: configuring a boosting section slurry, configuring a voltage reducing section slurry, and gradient film forming, so that the positive plate with the potential regulation function is obtained. Through the gradient function layered structure of the boosting section and the voltage reducing section, the doping amount of LLZO gradually increases from the high-voltage positive plate to the solid-state electrolyte, a continuous and functionally oriented integrated interface layer is formed, so that the ions can form ohmic contact with the positive plate through the boosting section to maintain a high voltage of greater than or equal to 4.5V, and the potential gradient can be constructed through the voltage reducing section to reduce the potential on the electrolyte side to within the stable window, so that the positive plate side can maintain high-voltage work while ensuring high ion transmission efficiency.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a positive electrode with potential regulation function and a method for preparing a solid-state battery. Background Technology

[0002] To overcome the energy density bottlenecks and safety hazards of traditional liquid batteries, all-solid-state batteries have become a core research and development direction in the energy storage field. Achieving high energy density relies on the application of high-voltage cathode materials such as 5V-level high-nickel ternary and lithium-rich manganese-based materials, and typically requires matching with high-rate charge-discharge modes. However, high-voltage operating conditions significantly exacerbate the interfacial electrochemical instability between the electrodes and the solid electrolyte, a problem that has become a core bottleneck restricting the industrialization of high-voltage solid-state batteries. Specifically, when the battery operating voltage exceeds 4.5V (vs Li / Li...),... + When the high-voltage cathode is subjected to oxidation potential exceeding the electrochemical stability threshold of most solid electrolytes, an oxidative decomposition reaction occurs at the interface. Taking PEO electrolyte, commonly used in polymer systems, as an example, its electrochemical stability window only covers 0–4.2V. If directly matched with a high-voltage cathode above 4.5V, an oxidative breakage reaction of PEO segments will occur at the interface, generating inert byproducts such as CO2 and Li2CO3. These byproducts significantly increase interfacial impedance and damage the Li... + The continuous transmission channel leads to a significant degradation in battery cycle stability and rate performance; at the same time, such side reactions may also cause irreversible collapse of the interface structure, further aggravating battery performance degradation and even posing safety risks.

[0003] In existing technologies, solutions to the aforementioned interface problems mainly include optimizing the chemical composition of the solid electrolyte to broaden its electrochemical stability window and constructing passivation films at the interface. However, designs that broaden the electrolyte's electrochemical stability window often come at the cost of sacrificing its ionic conductivity; and traditional passivation films can only achieve interface isolation, making it difficult to achieve precise potential control. Consequently, they cannot simultaneously meet the dual technical requirements of "maintaining high voltage operation on the positive electrode side and avoiding oxidative decomposition on the electrolyte side," resulting in significant limitations in their control effect. Therefore, it is necessary to propose a new solution to address these issues. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a positive electrode sheet with potential regulation function and a method for preparing a solid-state battery. This method can effectively solve the problem that existing positive electrode sheets cannot maintain high voltage operation on the positive electrode side while avoiding oxidation decomposition on the electrolyte side.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a positive electrode with potential regulation function includes the following steps: (1) Preparation of pressurization section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of (75-85):(10-20):5, added to an organic solvent, and stirred evenly to obtain pressurization section slurry; (2) Preparation of pressure-reducing slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of (55-75):(25-40):5, added to an organic solvent, and stirred evenly to obtain pressure-reducing slurry; (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 30-100nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 80-200nm, thus obtaining a positive electrode sheet with potential regulation function.

[0006] As a preferred embodiment, the organic solvent in steps (1) and (2) is acetonitrile.

[0007] As a preferred embodiment, the high-voltage positive electrode body in step (3) is made of lithium-rich manganese-based positive electrode material.

[0008] A method for preparing a solid-state battery involves taking a positive electrode, a solid electrolyte, a negative electrode, and a current collector, and assembling them in an argon glove box by sequentially stacking them to obtain a solid-state battery; wherein the positive electrode is prepared by the aforementioned method for preparing a positive electrode with potential regulation function.

[0009] As a preferred embodiment, the solid electrolyte is PEO-LiTFSI, the negative electrode is lithium metal, and the current collector is copper foil.

[0010] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution: By adopting a gradient functional layered structure with a boost section and a buck section, the doping amount of LLZO gradually increases from the high-voltage positive electrode to the solid electrolyte, forming a continuous and functionally oriented integrated interface layer. This allows ions to maintain a high voltage of ≥4.5V by forming an ohmic contact with the positive electrode through the boost section, and to build a potential gradient through the buck section to reduce the electrolyte potential to within a stable window. This ensures high ion transport efficiency while maintaining high voltage operation on the positive electrode side.

[0011] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to several specific embodiments. Detailed Implementation

[0012] This invention discloses a method for preparing a positive electrode with potential regulation function, which includes the following steps: (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of (75-85): (10-20): 5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0013] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of (55-75):(25-40):5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0014] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 30-100nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 80-200nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0015] This invention discloses a method for preparing a solid-state battery, wherein a positive electrode, a solid electrolyte, a negative electrode, and a current collector are assembled in an argon glove box by sequentially stacking them to obtain a solid-state battery; wherein the positive electrode is prepared by the aforementioned method for preparing a positive electrode with potential regulation function, the solid electrolyte is PEO-LiTFSI, the negative electrode is lithium metal, and the current collector is copper foil.

[0016] The following detailed description is based on several specific embodiments.

[0017] Example 1 (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 85:10:5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0018] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 55:25:5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0019] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 100 nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 200 nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0020] (4) Assembly of solid-state battery: Take the positive electrode sheet, solid electrolyte, negative electrode sheet and current collector prepared by the above-mentioned positive electrode sheet preparation method with potential regulation function, and assemble them in an argon glove box by stacking them in sequence to obtain a solid-state battery; wherein, the solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0021] Example 2 (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 75:20:5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0022] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 55:25:5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0023] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 100 nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 200 nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0024] (4) Assembly of solid-state battery: Take the positive electrode sheet, solid electrolyte, negative electrode sheet and current collector prepared by the above-mentioned positive electrode sheet preparation method with potential regulation function, and assemble them in an argon glove box by stacking them in sequence to obtain a solid-state battery; wherein, the solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0025] Example 3 (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 85:10:5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0026] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 70:25:5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0027] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 100 nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 200 nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0028] (4) Assembly of solid-state battery: Take the positive electrode sheet, solid electrolyte, negative electrode sheet and current collector prepared by the above-mentioned positive electrode sheet preparation method with potential regulation function, and assemble them in an argon glove box by stacking them in sequence to obtain a solid-state battery; wherein, the solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0029] Example 4 (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 85:10:5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0030] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 55:25:5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0031] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 30nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 80nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0032] (4) Assembly of solid-state battery: Take the positive electrode sheet, solid electrolyte, negative electrode sheet and current collector prepared by the above-mentioned positive electrode sheet preparation method with potential regulation function, and assemble them in an argon glove box by stacking them in sequence to obtain a solid-state battery; wherein, the solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0033] Example 5 (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 80:15:5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0034] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 65:30:5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0035] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 80nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 100nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0036] (4) Assembly of solid-state battery: Take the positive electrode sheet, solid electrolyte, negative electrode sheet and current collector prepared by the above-mentioned positive electrode sheet preparation method with potential regulation function, and assemble them in an argon glove box by stacking them in sequence to obtain a solid-state battery; wherein, the solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0037] Example 6 (1) Preparation of booster section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 80:15:5, added to an organic solvent, and stirred evenly to obtain booster section slurry. The aforementioned organic solvent is acetonitrile.

[0038] (2) Preparation of pressure reduction section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of 70:35:5, added to an organic solvent, and stirred evenly to obtain pressure reduction section slurry; the aforementioned organic solvent is acetonitrile.

[0039] (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 80nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 150nm, thus obtaining a positive electrode sheet with potential regulation function; wherein, the high voltage positive electrode body is made of lithium-rich manganese-based positive electrode material.

[0040] (4) Assembly of solid-state battery: Take the positive electrode sheet, solid electrolyte, negative electrode sheet and current collector prepared by the above-mentioned positive electrode sheet preparation method with potential regulation function, and assemble them in an argon glove box by stacking them in sequence to obtain a solid-state battery; wherein, the solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0041] Comparative Example 1 A solid-state battery is assembled in an argon glove box by sequentially stacking a positive electrode sheet made of lithium-rich manganese-based positive electrode material, a solid electrolyte, a negative electrode sheet, and a current collector. The solid electrolyte is PEO-LiTFSI, the negative electrode sheet is lithium metal, and the current collector is copper foil.

[0042] The performance of the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0043]

[0044] Table 1 Analysis of the above data shows that the positive electrode prepared by the method of the present invention can work stably under high voltage and effectively suppress the occurrence of side reactions. No byproducts were detected in Examples 1, 2, 5 and 6 after 1000 cycles. Moreover, compared with Comparative Example 1, the interfacial impedance of Example 1 is very small, only one-quarter of that of Comparative Example 1, which has achieved significant progress and unexpected technical effects.

[0045] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a positive electrode with potential regulation function, characterized in that: It includes the following steps: (1) Preparation of pressurization section slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of (75-85):(10-20):5, added to an organic solvent, and stirred evenly to obtain pressurization section slurry; (2) Preparation of pressure-reducing slurry: PEO, LLZO and LiTFSI are mixed in a mass ratio of (55-75):(25-40):5, added to an organic solvent, and stirred evenly to obtain pressure-reducing slurry; (3) Gradient film formation: First, the boost section slurry obtained in step (1) is coated on the surface of the high voltage positive electrode body and dried in a vacuum environment at 60°C for 12 hours to form a boost section with a thickness of 30-100nm; then, the de-voltage section slurry obtained in step (2) is coated on the surface of the boost section and dried in a vacuum environment at 60°C for 12 hours to form a de-voltage section with a thickness of 80-200nm, thus obtaining a positive electrode sheet with potential regulation function.

2. The method for preparing a positive electrode with potential regulation function according to claim 1, characterized in that: The organic solvent in steps (1) and (2) is acetonitrile.

3. The method for preparing a positive electrode with potential regulation function according to claim 1, characterized in that: The high-voltage positive electrode body in step (3) is made of lithium-rich manganese-based positive electrode material.

4. A method for preparing a solid-state battery, characterized in that: A solid-state battery is obtained by sequentially stacking a positive electrode, a solid electrolyte, a negative electrode, and a current collector in an argon glove box; wherein the positive electrode is prepared by the method for preparing a positive electrode with potential regulation function as described in any one of claims 1-3.

5. The method for preparing a solid-state battery according to claim 4, characterized in that: The solid electrolyte is PEO-LiTFSI, the negative electrode is lithium metal, and the current collector is copper foil.

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