Solid electrolyte preparation method based on cold isostatic pressing assisted sintering

Abstract

The invention discloses a solid electrolyte preparation method based on cold isostatic pressing assisted sintering, and belongs to the technical field of solid electrolyte preparation, and the method comprises the following steps: precursor powder preparation, cold isostatic pressing molding treatment, and material presintering; according to the method, the isostatic cool pressing technology is adopted, isotropic pressure is applied to powder at the normal temperature, so that the material reaches higher relative density during preliminary forming, internal pores and defects of the material can be effectively reduced, and in the auxiliary sintering stage, bonding among particles is further promoted through the heat activation diffusion effect and the combination pressure; the high density can significantly reduce the grain boundary resistance of the solid electrolyte and improve the ionic conductivity, the microstructure after sintering is more uniform, the grain size distribution is narrower, the preparation quality of the final finished product is greatly improved, and the actual application effect of the whole method is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid electrolyte preparation, and in particular relates to a solid electrolyte preparation method based on cold isostatic pressing assisted sintering. Background Art

[0002] Solid-state electrolytes are all-solid-state ion conductor materials used to replace traditional liquid or gel electrolytes. They enable the transfer of charge carriers such as lithium and sodium ions between the positive and negative electrodes of a battery. As a core component of all-solid-state batteries, they are considered a breakthrough in next-generation battery technology due to their high safety and energy density. The preparation of solid-state electrolytes requires the application of specific preparation methods.

[0003] A Chinese patent (CN113948765B) discloses a method for preparing a solid electrolyte, a solid electrolyte, and a lithium battery. The solid electrolyte preparation method comprises: mixing Li2S, P2S5, and Bi2Se3 in a molar ratio of 80:(10-19):(1-10) to obtain a premix; processing the premix into a sheet; and heat-treating the sheet to obtain a solid electrolyte. By mixing Li2S, P2S5, and Bi2Se3 in a molar ratio of 80:(10-19):(1-10) and subjecting the sheet to a series of processing steps to obtain the solid electrolyte, the stability of the solid electrolyte is improved. Furthermore, the incorporation of Bi into the transition metal selenide Bi2Se3 increases the carrier concentration and further expands the crystal structure, thereby increasing the lithium ion transfer rate and, consequently, the electrical conductivity of the solid electrolyte. Although the current preparation method of solid electrolytes can also complete the preparation of materials, it does not adopt the cold isostatic pressing assisted sintering method, which cannot improve the density inside the material and thus cannot improve the overall quality of the material. The actual application effect is not good. There is an urgent need for a solid electrolyte preparation method based on cold isostatic pressing assisted sintering. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that although the current preparation method of solid electrolytes can also complete the preparation of materials, it does not adopt the cold isostatic pressing assisted sintering method, cannot improve the density inside the material, and thus cannot improve the overall quality of the material, and the actual application effect is poor. A solid electrolyte preparation method based on cold isostatic pressing assisted sintering is proposed.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering, comprising the following steps:

[0006] S1. Preparing precursor powder;

[0007] S2, performing cold isostatic pressing;

[0008] S3, pre-sintering the material;

[0009] S4, calcining the material at high temperature;

[0010] S5, perform material post-processing;

[0011] S6. Conduct material performance test.

[0012] As a further description of the above technical solution:

[0013] In S1, precursor powder is prepared and solid electrolyte precursor powder is synthesized. The synthesis method adopts one of a solid phase method and a liquid phase method. The prepared precursor powder includes LLZO, LATP, and LAGP.

[0014] As a further description of the above technical solution:

[0015] In S1, the prepared precursor powder is placed in a drying device and dried at 60-80° C. The dried powder is placed in a ball milling device, the speed is controlled to 400-500 r / min, and the ball milling is performed for 8-12 hours. The ball-milled material is taken out and passed through a 200-260 mesh sieve.

[0016] As a further description of the above technical solution:

[0017] In S2, a cold isostatic pressing process is performed, specifically comprising the following steps: taking the screened precursor powder material, filling it into an elastic mold, extracting the air in the mold, applying isotropic pressure through a cold isostatic press, and pressing it into a high-density green body.

[0018] As a further description of the above technical solution:

[0019] In S2, the elastic mold selected is a polyurethane mold, the applied pressure is 150-250 MPa, the holding time is 10-15 min, and the density of the pressed green body is 3.0-3.5 g / cm 3 .

[0020] As a further description of the above technical solution:

[0021] In S3, the material is pre-sintered, specifically by placing the material in a sintering device and performing a low-temperature pre-sintering treatment, maintaining the temperature at 400-600°C, a heating rate of 10-15°C / min, and a holding time of 2-4h. During the sintering process, argon gas is introduced into the device, and after pre-sintering, the material is placed at room temperature for cooling.

[0022] As a further description of the above technical solution:

[0023] In S4, the material is calcined at high temperature, specifically by placing the green body in a calcining furnace, controlling the calcination temperature to 1200-1300°C, keeping the temperature for 10-12 hours, and heating at a rate of 20-25°C / min. Argon is introduced into the equipment during the sintering process, and the temperature is rapidly lowered and cooled after pre-sintering.

[0024] As a further description of the above technical solution:

[0025] In S5, material post-processing is performed, specifically including surface polishing, machining and surface coating of the sintered sample.

[0026] As a further description of the above technical solution:

[0027] In the above S5, the surface coating material is selected from one of a carbon layer and a polymer layer, the polishing granularity is gradually polished to a surface roughness Ra≤0.1 μm, and the coating thickness is 80-120 nm.

[0028] As a further description of the above technical solution:

[0029] In S6, material performance testing is performed, and the test contents include testing the ionic conductivity of the material, testing the density of the material, testing the crystal structure of the material, and testing the microscopic morphology of the material.

[0030] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0031] In the present invention, the method adopts cold isostatic pressing technology. By applying isotropic pressure to the powder at room temperature, the material can achieve a higher relative density during initial molding, which can effectively reduce the internal pores and defects of the material. In the auxiliary sintering stage, the thermally activated diffusion effect is further combined with pressure to promote the bonding between particles, and finally a dense structure close to the theoretical density is obtained. The high density can significantly reduce the grain boundary resistance of the solid electrolyte and improve the ionic conductivity. In addition, the microstructure after sintering is more uniform and the grain size distribution is narrower, which greatly improves the preparation quality of the final product. The overall method has good practical application effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of a solid electrolyte preparation method based on cold isostatic pressing assisted sintering. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Example 1

[0035] See also Figure 1 The present invention provides a technical solution: a method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering, comprising the following steps:

[0036] S1. Preparing precursor powders and synthesizing solid electrolyte precursor powders by a solid-phase method. The prepared precursor powders include LLZO, LATP, and LAGP. The prepared precursor powders are placed in a drying device and dried at 60° C. The dried powders are placed in a ball mill and the speed is controlled to 400 r / min. The ball milling is performed for 8 hours. The ball-milled material is taken out and passed through a 200-mesh sieve.

[0037] S2, cold isostatic pressing treatment, the specific steps are: take the screened precursor powder material, fill it into an elastic mold, and extract the air in the mold, apply isotropic pressure through a cold isostatic press, and press it into a high-density green body. The elastic mold selected is a polyurethane mold, the applied pressure is 150 MPa, the holding time is 10 min, and the density of the pressed green body is 3.0 g / cm 3 ;

[0038] S3, pre-sintering the material, specifically the following steps: placing the material in a sintering device, performing a low-temperature pre-sintering treatment, maintaining the temperature at 400°C, a heating rate of 10°C / min, and a holding time of 2 hours, introducing argon gas into the device during the sintering process, and cooling at room temperature after pre-sintering;

[0039] S4, calcining the material at high temperature, specifically the following steps: placing the green body in a calcining furnace, controlling the calcination temperature to 1200°C, holding the temperature for 10 hours, and heating at a rate of 20°C / min, introducing argon gas into the equipment during the sintering process, and rapidly cooling the material after pre-sintering;

[0040] S5. Post-processing of the material, specifically including surface polishing, machining and surface coating of the sintered sample. The surface coating material is a carbon layer. The polishing granularity is step-by-step grinding to a surface roughness Ra ≤ 0.1 μm and a coating thickness of 80 nm.

[0041] S6. Conduct material performance tests, including testing the ionic conductivity, density, crystal structure and micromorphology of the materials.

[0042] In this embodiment, the method adopts cold isostatic pressing technology, which applies isotropic pressure to the powder at room temperature to achieve a higher relative density when the material is initially formed, and can effectively reduce the internal pores and defects of the material.

[0043] Example 2

[0044] See also Figure 1 The present invention provides a technical solution: a method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering, comprising the following steps:

[0045] S1. Preparing precursor powders and synthesizing solid electrolyte precursor powders by a solid-phase method or a liquid-phase method. The prepared precursor powders include LLZO, LATP, and LAGP. The prepared precursor powders are placed in a drying device and dried at 70° C. The dried powders are placed in a ball mill and the speed is controlled to 450 r / min. The ball milling is performed for 10 hours. The ball-milled material is taken out and passed through a 220-mesh sieve.

[0046] S2, cold isostatic pressing treatment, the specific steps are: take the screened precursor powder material, fill it into an elastic mold, and extract the air in the mold, apply isotropic pressure through a cold isostatic press, and press it into a high-density green body. The elastic mold selected is a polyurethane mold, the applied pressure is 200 MPa, the holding time is 12 minutes, and the density of the pressed green body is 3.2 g / cm 3 ;

[0047] S3, pre-sintering the material, specifically the following steps: placing the material in a sintering device, performing a low-temperature pre-sintering treatment, maintaining the temperature at 500°C, a heating rate of 12°C / min, and a holding time of 3 hours, introducing argon gas into the device during the sintering process, and cooling at room temperature after pre-sintering;

[0048] S4, calcining the material at high temperature, specifically the following steps: placing the green body in a calcining furnace, controlling the calcination temperature to 1250°C, holding the temperature for 11 hours, and heating at a rate of 23°C / min, introducing argon gas into the equipment during the sintering process, and rapidly cooling the material after pre-sintering;

[0049] S5. Post-processing of the materials, specifically including surface polishing, machining and surface coating of the sintered samples. The surface coating material is a polymer layer. The polishing granularity is step-by-step grinding to a surface roughness Ra ≤ 0.1 μm and a coating thickness of 100 nm.

[0050] S6. Conduct material performance tests, including testing the ionic conductivity, density, crystal structure and micromorphology of the materials.

[0051] In this embodiment, the auxiliary sintering stage further promotes the bonding between particles through heat-activated diffusion combined with pressure, and finally obtains a dense structure close to the theoretical density. The high density can significantly reduce the grain boundary resistance of the solid electrolyte and improve the ionic conductivity. In addition, the microstructure after sintering is more uniform and the grain size distribution is narrower, which greatly improves the preparation quality of the final product. The practical application effect of the overall method is good.

[0052] Example 3

[0053] See also Figure 1 The present invention provides a technical solution: a method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering, comprising the following steps:

[0054] S1. Preparing precursor powders and synthesizing solid electrolyte precursor powders by a liquid phase method. The prepared precursor powders include LLZO, LATP, and LAGP. The prepared precursor powders are placed in a drying device and dried at 80° C. The dried powders are placed in a ball mill and the speed is controlled to 500 r / min. The ball milling is performed for 12 hours. The ball-milled material is taken out and passed through a 260-mesh sieve.

[0055] S2, cold isostatic pressing treatment, the specific steps are: take the screened precursor powder material, fill it into the elastic mold, and extract the air in the mold, apply isotropic pressure through the cold isostatic press, and press it into a high-density green body. The elastic mold selected is a polyurethane mold, the applied pressure is 250 MPa, the pressure holding time is 15 minutes, and the density of the pressed green body is 3.5 g / cm 3 ;

[0056] S3, pre-sintering the material, specifically the following steps: placing the material in a sintering device, performing a low-temperature pre-sintering treatment, maintaining the temperature at 600°C, a heating rate of 15°C / min, and a holding time of 4 hours, introducing argon gas into the device during the sintering process, and cooling at room temperature after pre-sintering;

[0057] S4, calcining the material at high temperature, specifically the following steps: placing the green body in a calcining furnace, controlling the calcination temperature to 1300°C, holding the temperature for 12 hours, and heating at a rate of 25°C / min, introducing argon gas into the equipment during the sintering process, and rapidly cooling the material after pre-sintering;

[0058] S5. Post-processing of the material, specifically including surface polishing, machining and surface coating of the sintered sample. The surface coating material is a carbon layer. The polishing granularity is step-by-step grinding to a surface roughness Ra ≤ 0.1 μm and a coating thickness of 120 nm.

[0059] S6. Conduct material performance tests, including testing the ionic conductivity, density, crystal structure and micromorphology of the materials.

[0060] In this embodiment, the method adopts cold isostatic pressing technology. By applying isotropic pressure to the powder at room temperature, the material can achieve a higher relative density when it is initially formed, which can effectively reduce the internal pores and defects of the material. In the auxiliary sintering stage, the thermally activated diffusion effect and the pressure are combined to promote the bonding between particles, and finally obtain a dense structure close to the theoretical density. The high density can significantly reduce the grain boundary resistance of the solid electrolyte and improve the ionic conductivity. In addition, the microstructure after sintering is more uniform and the grain size distribution is narrower, which greatly improves the preparation quality of the final product. The practical application effect of the overall method is good.

[0061] Example 4

[0062] See also Figure 1 The present invention provides a technical solution: a method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering, comprising the following steps:

[0063] S1. Preparing precursor powders and synthesizing solid electrolyte precursor powders by a solid-phase method. The prepared precursor powders include LLZO, LATP, and LAGP. The prepared precursor powders are placed in a drying device and dried at 80° C. The dried powders are placed in a ball mill and the speed is controlled to 500 r / min. The ball milling is performed for 12 hours. The ball-milled material is taken out and passed through a 260-mesh sieve.

[0064] S2, cold isostatic pressing treatment, the specific steps are: take the screened precursor powder material, fill it into the elastic mold, and extract the air in the mold, apply isotropic pressure through the cold isostatic press, and press it into a high-density green body. The elastic mold selected is a polyurethane mold, the applied pressure is 250 MPa, the pressure holding time is 15 minutes, and the density of the pressed green body is 3.5 g / cm 3 ;

[0065] S3. Pre-sintering the material, specifically the following steps: placing the material in a sintering device and performing a low-temperature pre-sintering treatment, maintaining the temperature at 550°C, a heating rate of 15°C / min, and a holding time of 4 hours, introducing argon gas into the device during the sintering process, and cooling the material at room temperature after pre-sintering;

[0066] S4, calcining the material at high temperature, specifically the following steps: placing the green body in a calcining furnace, controlling the calcination temperature to 1200°C, holding the temperature for 11 hours, and heating at a rate of 22°C / min, introducing argon gas into the equipment during the sintering process, and rapidly cooling the material after pre-sintering;

[0067] S5. Post-processing of the material, specifically including surface polishing, machining and surface coating of the sintered sample. The surface coating material is a carbon layer. The polishing granularity is step-by-step grinding to a surface roughness Ra ≤ 0.1 μm and a coating thickness of 120 nm.

[0068] S6. Conduct material performance tests, including testing the ionic conductivity, density, crystal structure and micromorphology of the materials.

[0069] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering, characterized in that: The steps include: S1. Preparing precursor powder; S2, performing cold isostatic pressing; S3, pre-sintering the material; S4, calcining the material at high temperature; S5, perform material post-processing; S6. Conduct material performance test.

2. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S1, precursor powder is prepared and solid electrolyte precursor powder is synthesized. The synthesis method adopts one of a solid phase method and a liquid phase method. The prepared precursor powder includes LLZO, LATP, and LAGP.

3. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S1, the prepared precursor powder is placed in a drying device and dried at 60-80° C. The dried powder is placed in a ball milling device, the speed is controlled to 400-500 r / min, and the ball milling is performed for 8-12 hours. The ball-milled material is taken out and passed through a 200-260 mesh sieve.

4. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S2, a cold isostatic pressing process is performed, specifically comprising the following steps: taking the screened precursor powder material, filling it into an elastic mold, extracting the air in the mold, applying isotropic pressure through a cold isostatic press, and pressing it into a high-density green body.

5. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S2, the elastic mold selected is a polyurethane mold, the applied pressure is 150-250 MPa, the holding time is 10-15 min, and the density of the pressed green body is 3.0-3.5 g / cm 3 .

6. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S3, the material is pre-sintered, specifically by placing the material in a sintering device and performing a low-temperature pre-sintering treatment, maintaining the temperature at 400-600°C, a heating rate of 10-15°C / min, and a holding time of 2-4h. During the sintering process, argon gas is introduced into the device, and after pre-sintering, the material is placed at room temperature for cooling.

7. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S4, the material is calcined at high temperature, specifically by placing the green body in a calcining furnace, controlling the calcination temperature to 1200-1300°C, keeping the temperature for 10-12 hours, and heating at a rate of 20-25°C / min. Argon is introduced into the equipment during the sintering process, and the temperature is rapidly lowered and cooled after pre-sintering.

8. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S5, material post-processing is performed, specifically including surface polishing, machining and surface coating of the sintered sample.

9. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In the above S5, the surface coating material is selected from one of a carbon layer and a polymer layer, the polishing granularity is gradually polished to a surface roughness Ra≤0.1 μm, and the coating thickness is 80-120 nm.

10. The method for preparing a solid electrolyte based on cold isostatic pressing assisted sintering according to claim 1, characterized in that: In S6, material performance testing is performed, and the test contents include testing the ionic conductivity of the material, testing the density of the material, testing the crystal structure of the material, and testing the microscopic morphology of the material.

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