Solid-phase synthesis preparation method of sulfide solid-state battery electrolyte

Abstract

The invention provides a solid-phase synthesis preparation method of a sulfide solid-state battery electrolyte. The sulfide solid-state electrolyte is subjected to solid-phase synthesis through a method of combining high-energy ball milling with heat treatment. Researches find that the prolonging of the ball milling time is beneficial to crushing, mixing and grain refinement of raw material powder particles and the proceeding of an amorphization reaction. The rising of the sintering temperature is beneficial to generating a single pure phase, but the overhigh sintering temperature can melt and decompose the electrolyte and destroy the crystal structure. Meanwhile, the grinding aid plays a key role in improving the processability of the sulfide solid-state battery precursor and the final battery performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of sulfide solid electrolyte preparation, and in particular relates to a solid-phase synthesis preparation method of a sulfide solid-state battery electrolyte. Background Art

[0002] With the increasing demand for energy storage and the pursuit of environmentally friendly energy technologies, improving the storage and utilization of renewable energy such as wind and solar energy has become a key issue facing mankind.

[0003] Liquid electrolytes suffer from issues such as evaporation, combustion, and chemical instability, limiting their potential for further improvements in safety and energy density. In recent years, solid-state electrolytes have garnered widespread attention as a potential solution. Compared to traditional liquid electrolytes, solid-state electrolytes offer advantages such as greater chemical stability, lower combustion risk, and a wider operating temperature range. Sulfides, a typical solid-state electrolyte material, offer broad potential for solid-state battery applications due to their excellent ion transport properties, chemical stability, and mechanical properties.

[0004] For example, patent CN119009087A discloses a sulfide solid electrolyte membrane, a preparation method thereof, and a solid-state battery. The process is as follows: a certain mass of coarse sulfide solid electrolyte powder and fine powder are respectively placed in a mixer and mixed evenly with a binder that is easily fiberized; the mixer speed is increased to 4000 rpm to fiberize the powder, and the powder is placed in a glove box for standby use after standing; a certain amount of powder is placed in a mortar and continuously ground until it is kneaded into a ball, and the ball kneaded in the mortar is placed in a roller press and rolled. The coarse sulfide solid electrolyte powder mixture and the fine powder mixture are respectively rolled to a certain thickness, and the two are cut into the same size, stacked up and down, and rolled again to obtain a thin sulfide solid electrolyte membrane.

[0005] However, existing sulfide solid electrolytes still have problems such as poor cycle stability and low ionic conductivity, so further optimization and improvement of the materials are needed. Summary of the Invention

[0006] The purpose of the present invention is to provide a solid-phase synthesis method for preparing a sulfide solid-state battery electrolyte. The technical solution of the present invention is: a solid-phase synthesis method for preparing a sulfide solid-state battery electrolyte, characterized by comprising the following steps:

[0007] A. Material synthesis: Lithium sulfide, phosphorus pentasulfide, lithium chloride and ball milling dispersant were weighed in a certain mass ratio and placed in a ball mill for high-energy ball milling. The ball mill speed and ball milling time were set. Since the sulfide material is relatively "soft", the ball mill was opened every 2 hours to scrape the material to prevent the raw material from sticking to the wall and affecting the ball effect. After the ball milling was completed, it was transferred to a mortar and ground manually to obtain a sulfide solid electrolyte material precursor.

[0008] B. Place the sulfide solid electrolyte material precursor in a stainless steel mold and press it into a circular sheet of a certain thickness using a powder tablet press under a certain pressure. Place it in a quartz tube, seal it, and then perform heat treatment. After sintering, the sintered sheet is naturally cooled to room temperature along with the furnace body, and then manually ground in a mortar to obtain sulfide solid electrolyte material powder.

[0009] C. Assemble into Li / / LFP batteries and test their discharge specific capacity, cycle performance and ionic conductivity at a current density of 0.2C.

[0010] As a preferred technical solution of the present invention, in step A, the mass ratio of the lithium sulfide, phosphorus pentasulfide, and lithium chloride raw materials is 114-160:55-166:21-63:10-30.

[0011] As a preferred technical solution of the present invention, in step A, the method for preparing the grinding aid comprises the following steps:

[0012] a) mixing 0.5-3 parts of allyl(cyclopentadienyl)nickel (CAS No. 12107-46-9), 9-18 parts of ethanolamine thioglycolate, 0.05-0.6 parts of dimethylallyl diphosphate monoammonium salt (CAS No. 1186-30-7) and 1-4 parts of sodium tert-butoxide with 100-200 parts of ethylene dichloride;

[0013] b) heating the mixture to 60-70° C. while stirring and maintaining the temperature with stirring for 100-150 minutes to complete the reaction; c) after the reaction is completed, turning off the heating and stirring equipment, and removing the dichloroethane by reduced pressure distillation to obtain a grinding aid.

[0014] As a preferred technical solution of the present invention, in step A, the mass ratio of the zirconium beads to the raw materials is 30-50 to 1.

[0015] As a preferred technical solution of the present invention, in step A, the rotation speed of the ball mill is 500-800 rpm / min.

[0016] As a preferred technical solution of the present invention, in step A, the ball milling time is 4-12 hours.

[0017] As a preferred technical solution of the present invention, in step A, after the ball milling is completed, the ball mill is transferred to a mortar and manually ground for 10-20 minutes.

[0018] As a preferred technical solution of the present invention, in step B, the sulfide solid electrolyte precursor is placed in a stainless steel mold and pressed into a circular sheet with a thickness of 100-300 μm using a powder tablet press at 300-500 MPa.

[0019] As a preferred technical solution of the present invention, in step B, the sintering temperature is set to 350-650°C.

[0020] As a preferred technical solution of the present invention, in step B, the heating rate of the sintering furnace is 1-3°C / min.

[0021] As a preferred technical solution of the present invention, in step B, the sintering time is 5-10 hours.

[0022] As a preferred technical solution of the present invention, in step B, the sintered sample is further manually ground for 10-20 minutes.

[0023] 1. Reaction Mechanism

[0024] Allyl(cyclopentadienyl)nickel reacts with ethanolamine thioglycolate to form a thiol-allyl addition reaction. Similarly, dimethylallyl diphosphate triammonium salt reacts with ethanolamine thioglycolate to form a similar thiol-allyl addition reaction. Although the reaction pathway may be more complex due to the presence of more functional groups in its structure, the basic principle remains the same.

[0025] 2. Technical Effect

[0026] This grinding aid exhibits the following technical advantages in the grinding process of sulfide solid-state battery precursors:

[0027] 1. Improved dispersibility: Grinding aids improve the interaction between particles and reduce agglomeration, thereby improving the dispersion and uniformity of the material. This is crucial for the performance of solid-state batteries because good dispersion helps uniform distribution of electrolytes and ion transport.

[0028] 2. Reduce viscosity: During the grinding process, additives can reduce the viscosity of the slurry, making it easier to handle and apply. This helps improve production efficiency and reduce energy consumption.

[0029] 3. Enhanced interface stability: Additives can stabilize the interface between the electrode material and the electrolyte, preventing interfacial reactions and side reactions. This is very important for extending the cycle life of the battery and improving safety.

[0030] Overall, this grinding aid plays a key role in improving the processing performance of sulfide solid-state battery precursors and the final battery performance. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to specific embodiments.

[0032] Example 1

[0033] A solid-phase synthesis method for preparing a sulfide solid-state battery electrolyte, characterized by comprising the following steps:

[0034] A. Material synthesis: 114.8 g lithium sulfide, 55.5 g phosphorus pentasulfide, 21.2 g lithium chloride raw materials, and 10 g grinding aid were weighed and placed in a ball mill for high-energy ball milling. The mass ratio of grinding balls, zirconia beads, to raw materials was 20:1, the ball mill speed was 500 / min, and the ball milling time was 4 h. Since the sulfide material was relatively "soft", the ball mill was opened every 2 h for scraping to prevent the raw materials from sticking to the wall and affecting the ball effect. After the ball milling was completed, it was transferred to a mortar and manually ground for 10 min to obtain a sulfide solid electrolyte material precursor.

[0035] The preparation method of the grinding aid comprises the following steps:

[0036] a) 0.5 g of allyl(cyclopentadienyl)nickel (CAS No. 12107-46-9), 9 g of ethanolamine thioglycolate, 0.05 g of dimethylallyl diphosphate triammonium salt (CAS No. 1186-30-7) and 1 g of sodium tert-butoxide were mixed with 100 g of ethylene dichloride;

[0037] b) heating the mixture to 60° C. with stirring and maintaining the temperature with stirring for 100 minutes to complete the reaction;

[0038] c) After the reaction is completed, the heating and stirring equipment are turned off, and the dichloroethane is removed by reduced pressure distillation to obtain a grinding aid.

[0039] B. The sulfide solid electrolyte material precursor was placed in a stainless steel mold and pressed into a 100-μm-thick circular sheet using a powder tablet press at 300 MPa. The sheet was then sealed in a quartz tube and heat treated at a sintering temperature of 350°C, a heating rate of 1°C / min, and a holding time of 5 h. The sintered sheet was naturally cooled to room temperature along with the furnace body and then manually ground in a mortar for 10 min to obtain the LPSC electrolyte material powder.

[0040] C. The assembled Li / / LFP battery was tested to have a discharge capacity of 152.7 mAh / g at a current density of 0.2C, a capacity retention rate of 87.9% after 100 cycles, and an ionic conductivity of 0.0012 S / cm.

[0041] Example 2

[0042] A solid-phase synthesis method for preparing a sulfide solid-state battery electrolyte, characterized by comprising the following steps:

[0043] A. Material synthesis: 137.8 g of lithium sulfide, 111.1 g of phosphorus pentasulfide, and 42 g of lithium chloride raw materials were weighed, and 20 g of grinding aid was placed in a ball mill for high-energy ball milling. The mass ratio of grinding balls, zirconia beads, to raw materials was 30:1, the ball mill speed was 650 / min, and the ball milling time was 8 h. Since the sulfide material is relatively "soft", the ball mill was opened every 2 h for scraping to prevent the raw materials from sticking to the wall and affecting the ball effect. After the ball milling was completed, it was transferred to a mortar and manually ground for 15 min to obtain a sulfide solid electrolyte material precursor.

[0044] The preparation method of the grinding aid comprises the following steps:

[0045] a) 1.5 g of allyl(cyclopentadienyl)nickel (CAS No. 12107-46-9), 13.5 g of ethanolamine thioglycolate, 0.3 g of dimethylallyldiphosphate triammonium salt (CAS No. 1186-30-7) and 2 g of sodium tert-butoxide were mixed with 150 g of ethylene dichloride;

[0046] b) heating the mixture to 65° C. with stirring and maintaining the temperature with stirring for 125 minutes to complete the reaction;

[0047] c) After the reaction is completed, the heating and stirring equipment are turned off, and the dichloroethane is removed by reduced pressure distillation to obtain a grinding aid.

[0048] B. The sulfide solid electrolyte material precursor was placed in a stainless steel mold and pressed into a 150 μm thick circular sheet using a powder tablet press at 400 MPa. The sheet was then placed in a sealed quartz tube and heat treated. The sintering temperature was set to 500°C, the heating rate was 2°C / min, and the holding time was 8 hours. The sintered sheet was naturally cooled to room temperature along with the furnace body and then manually ground in a mortar for 15 minutes to obtain the LPSC electrolyte material powder.

[0049] C. The assembled Li / / LFP battery was tested to have a discharge capacity of 155.5 mAh / g at a current density of 0.2 C, a capacity retention rate of 90.1% after 100 cycles, and an ionic conductivity of 0.0024 S / cm.

[0050] Example 3

[0051] A solid-phase synthesis method for preparing a sulfide solid-state battery electrolyte, characterized by comprising the following steps:

[0052] A. Material synthesis: 160.8 g of lithium sulfide, 166.7 g of phosphorus pentasulfide, 63.6 g of lithium chloride raw materials, and 30 g of grinding aid were weighed and placed in a ball mill for high-energy ball milling. The mass ratio of grinding balls, zirconia beads, to raw materials was 40:1, the ball machine speed was 800 / min, and the ball milling time was 12 h. Since the sulfide material was relatively "soft", the ball mill was opened every 2 h for scraping to prevent the raw materials from sticking to the wall and affecting the ball effect. After the ball milling was completed, it was transferred to a mortar and manually ground for 20 min to obtain a sulfide solid electrolyte material precursor.

[0053] The preparation method of the grinding aid comprises the following steps:

[0054] a) 3 g of allyl(cyclopentadienyl)nickel (CAS No. 12107-46-9), 18 g of ethanolamine thioglycolate, 0.6 g of dimethylallyl diphosphate triammonium salt (CAS No. 1186-30-7) and 4 g of sodium tert-butoxide were mixed with 200 g of ethylene dichloride;

[0055] b) heating the mixture to 70° C. with stirring and maintaining the temperature with stirring for 150 minutes to complete the reaction;

[0056] c) After the reaction is completed, the heating and stirring equipment are turned off, and the dichloroethane is removed by reduced pressure distillation to obtain a grinding aid.

[0057] B. The sulfide solid electrolyte material precursor was placed in a stainless steel mold and pressed into a 200 μm thick circular sheet using a powder tablet press at 500 MPa. The sheet was then placed in a sealed quartz tube and heat treated at a sintering temperature of 350°C, a heating rate of 3°C / min, and a holding time of 10 h. The sintered sheet was naturally cooled to room temperature along with the furnace body and then manually ground in a mortar for 20 min to obtain the LPSC electrolyte material powder.

[0058] C. The assembled Li / / LFP battery was tested to have a discharge capacity of 160.2 mAh / g at a current density of 0.2 C, a capacity retention rate of 94.9% after 100 cycles, and an ionic conductivity of 0.0056 S / cm.

[0059] Comparative Example 1

[0060] A solid-phase synthesis method for preparing a sulfide solid-state battery electrolyte, characterized by comprising the following steps:

[0061] A. Material synthesis: 137.8 g of lithium sulfide, 111.1 g of phosphorus pentasulfide, and 42 g of lithium chloride were weighed and placed in a ball mill for high-energy ball milling. The mass ratio of zirconia beads to raw materials was 30:1, the ball mill speed was 650 / min, and the ball milling time was 8 h. Since the sulfide material is relatively "soft", the ball mill was opened every 2 h to scrape the material to prevent the raw material from sticking to the wall and affecting the ball effect. After the ball milling was completed, it was transferred to a mortar and manually ground for 15 min to obtain a sulfide solid electrolyte material precursor.

[0062] B. The sulfide solid electrolyte material precursor was placed in a stainless steel mold and pressed into a 150 μm thick circular sheet using a powder tablet press at 400 MPa. The sheet was then placed in a sealed quartz tube and heat treated. The sintering temperature was set to 500°C, the heating rate was 2°C / min, and the holding time was 8 hours. The sintered sheet was naturally cooled to room temperature along with the furnace body and then manually ground in a mortar for 15 minutes to obtain the LPSC electrolyte material powder.

[0063] C. The assembled Li / / LFP battery was tested to have a discharge capacity of 142.5 mAh / g at a current density of 0.2C, a capacity retention rate of 80.2% after 100 cycles, and an ionic conductivity of 0.0009 S / cm.

Claims

1. A solid phase synthesis method for preparing a sulfide solid-state battery electrolyte, characterized in that The following steps are involved: A. Material synthesis: Lithium sulfide, phosphorus pentasulfide, lithium chloride, and grinding aids were weighed in a certain mass ratio and placed in a ball mill for high-energy ball milling. The ball mill speed and ball milling time were set. Since sulfide is relatively "soft", the ball mill was opened every 2 hours to scrape the material to prevent the raw materials from sticking to the wall and affecting the ball effect. After the ball milling was completed, the raw materials were transferred to a mortar and ground manually to obtain a sulfide solid electrolyte material precursor. B. Place the sulfide solid electrolyte material precursor in a stainless steel mold and press it into a circular sheet of a certain thickness using a powder tablet press under a certain pressure. Place it in a quartz tube, seal it, and then perform heat treatment. After sintering, the sintered sheet is naturally cooled to room temperature along with the furnace body, and then manually ground in a mortar to obtain sulfide solid electrolyte material powder. C. Assemble into Li / / LFP batteries and test their discharge specific capacity, cycle performance and ionic conductivity at a current density of 0.2C.

2. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step A, the mass ratio of the lithium sulfide, phosphorus pentasulfide, lithium chloride raw materials and grinding aid is 114-160:55-166:21-63:10-30.

3. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step A, the method for preparing the grinding aid comprises the following steps: a) mixing 0.5-3 parts of allyl(cyclopentadienyl)nickel (CAS No. 12107-46-9), 9-18 parts of ethanolamine thioglycolate, 0.05-0.6 parts of dimethylallyl diphosphate monoammonium salt (CAS No. 1186-30-7) and 1-4 parts of sodium tert-butoxide with 100-200 parts of ethylene dichloride; b) heating the mixture to 60-70° C. while stirring and maintaining the temperature with stirring for 100-150 minutes to complete the reaction; c) After the reaction is completed, the heating and stirring equipment are turned off, and the dichloroethane is removed by reduced pressure distillation to obtain a grinding aid.

4. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step A, the mass ratio of the zirconium beads to the raw materials is 30-50 to 1.

5. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step A, the ball mill rotates at a speed of 500-800 rpm.

6. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step A, the ball milling time is 4-12 hours.

7. The solid phase synthesis method for preparing a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step A, after the ball milling is completed, the mixture is transferred to a mortar and ground manually for 10-20 min.

8. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step B, the sulfide solid electrolyte precursor is placed in a stainless steel mold and pressed into a circular sheet with a thickness of 100-300 μm using a powder tablet press at 300-500 MPa.

9. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step B, the sintering temperature is set to 350-650°C.

10. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step B, the heating rate of the sintering furnace is 1-3°C / min.

11. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step B, the sintering time is 5-10 hours.

12. The solid phase synthesis preparation method of a sulfide solid-state battery electrolyte according to claim 1, characterized in that: In step B, the sintered sample was further manually ground for 10-20 min.