LLZO-LIC-GMOF solid electrolyte membrane and preparation method thereof

Abstract

The invention belongs to the technical field of new energy materials, and particularly relates to an LLZO-LIC-GMOF solid electrolyte membrane and a preparation method thereof. The preparation method comprises the following steps: preparing a PEO-based MOF framework, preparing a GMOF reinforced framework, and carrying out ball milling and calendering to form the film. According to the invention, MOF is subjected to defect-free graphene modification to form a reinforced framework GMOF, a GMOF matrix is filled with LLZO and LIC at the same time, and the novel solid electrolyte membrane is prepared through melt film pressing. The solid-state electrolyte membrane has the advantages of high ionic conductivity, small shuttle effect, stable physical and chemical properties and good flexibility and ductility, is a solid-state electrolyte membrane with excellent comprehensive performance, constructs a stable ion transport network on an electrolyte / electrode interface, and has important significance for industrialization of all-solid-state batteries. The method provided by the invention has the advantages of simple equipment required for production, short production period, simple operation and mild process environment, and is suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy materials, and specifically relates to an LLZO-LIC-GMOF solid electrolyte membrane and a preparation method thereof. Background Art

[0002] At present, the energy density of traditional liquid lithium batteries is close to the theoretical limit of 350Wh / kg, but there are still safety hazards such as thermal runaway of batteries. For example, when liquid batteries work under high current, lithium dendrites may appear, which may puncture the diaphragm and cause a short circuit. At the same time, the electrolyte of liquid batteries is an organic liquid, which may cause side reactions, oxidative decomposition, gas generation, and combustion at high temperatures. With the rapid expansion of the new energy vehicle market capacity, the urgent demand for high energy density and high safety of power batteries has promoted the development of solid-state batteries. With the rapid expansion of the new energy vehicle market capacity, the urgent demand for high energy density and high safety of power batteries has promoted the development of solid-state batteries. People are constantly looking for different routes of battery technology. In theory, the future of lithium-ion batteries is all-solid-state lithium batteries.

[0003] The development of all-solid-state lithium batteries mainly depends on the development of solid electrolytes. Currently, the most promising electrolytes are oxides, sulfides, halides and polymers. However, the advantages and disadvantages of various electrolytes are obvious, such as: -Currently, only some sulfide and halide electrolytes have ion conductivity close to or exceeding that of organic liquid electrolytes, but due to problems such as interfaces, their electrochemical stability, especially air chemical stability, is very poor. In particular, sulfur cathodes are unstable in high temperature environments, so these two solid electrolytes are difficult to use alone in all-solid-state batteries; -Compared with sulfide and halide electrolytes, oxide electrolytes have better electrochemical stability, but due to their low mechanical fracture toughness, they will cause brittle material disintegration after multiple cycles, and their ionic conductivity is low, which is difficult to be satisfactory. Oxide solid electrolytes also have disadvantages such as high shuttle effect and low initial efficiency in batteries, and the production cost is also high.

[0004] -From the perspective of production process, oxide, sulfide, and halide solid electrolytes are all ceramic materials, which have high hardness but insufficient tensile ductility, so it is difficult to wind and form them during the preparation of the battery cell. Even if they are used in laminated batteries, due to their inherent defects, if there is impact or collision in the use environment, even after multiple cycles, the electrolyte will be brittle and eventually disintegrate, and their air chemical stability is also poor. In addition, due to the high hardness of ceramic materials, their contact with the electrode surface is poor, and it is difficult to increase the interface tolerance of the electrolyte / sulfur-based positive electrode material by simple cold pressing.

[0005] -Polymer solid electrolytes have good toughness. They can alleviate the volume change of active materials and prevent the electrode structure from breaking. They have excellent tensile and ductility and are easy to form films, but their ionic conductivity is very low.

[0006] Therefore, designing and synthesizing a solid electrolyte with excellent comprehensive performance and constructing a stable ion transport network at the electrolyte / electrode interface are of great significance to the industrialization of all-solid-state batteries. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a LLZO-LIC-GMOF solid electrolyte membrane and a preparation method thereof.

[0008] The object of the present invention is achieved by the following technical scheme: a method for preparing a LLZO-LIC-GMOF solid electrolyte membrane, which comprises the following steps: S1. Preparation of PEO-based MOF: PEO powder was dissolved in a dichloromethane solution, lithium perchlorate was added, and the mixture was stirred at 20-30°C for 80-100 minutes to obtain a PEO-based MOF slurry; S2: preparing GMOF powder: the defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 are stirred and reacted at 40-60° C. for 4-6 hours, and the product is dried and crushed to obtain GMOF powder; S3. Ball milling and calendering film formation: Take lithium lanthanum zirconium oxide, Li 3 InCl 6 The powder is mixed with the GMOF powder, ball-milled at a speed of 500-600 rpm for 9-11 hours to obtain a mixed powder, and the mixed powder is melted and rolled into a film at a temperature of 60-80° C., namely, the LLZO-LIC-GMOF solid electrolyte membrane.

[0009] As a preferred technical solution, in step S1, the mass volume ratio of the PEO powder to dichloromethane is 2-10 g:1 ml, and the weight ratio of the PEO powder to the lithium perchlorate powder is 0.5-3:1.

[0010] As a preferred technical solution, the stirring in step S1 is performed using a magnetic stirrer, and the speed of the magnetic stirrer is 600-800 rpm.

[0011] As a preferred technical solution, the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry in step S2 is 1:50-100.

[0012] More preferably, the defect-free graphene powder in step S2 is added to ultrapure water, the volume ratio of the mass of the graphene powder to the ultrapure water is 0.3-0.5 mg:1 ml, and dispersed in an ultrasonic disperser with a power of not less than 1500 W for 20-24 hours to obtain a defect-free graphene slurry.

[0013] As a preferred technical solution, the stirring rate in step S2 is 250-350 rpm; the drying is carried out in a vacuum dryer at a drying temperature of 70-90° C.; and the pulverization is carried out in an air flow pulverizer or a high-speed vortex pulverizer.

[0014] As a preferred technical solution, the lithium lanthanum zirconium oxide, Li 3 InCl 6 The mass percentages of the powder and the GMOF powder are 10-20%, 20-60% and 20-60%, respectively.

[0015] As a preferred technical solution, the preparation method of lithium lanthanum zirconium oxide in step S3 is: 15.4mmol lithium nitrate, 6mmol lanthanum nitrate, 4mmol zirconium nitrate, 0.48mmol aluminum nitrate and 12.94mmol glycine are dissolved in 1 liter of deionized water and mixed and stirred evenly, and the resulting mixture is heated to 600-800°C in a Ma Fuel Furnace to undergo a combustion synthesis reaction, and the reaction time is 50-80min to obtain a white fluffy powder; the white fluffy powder is cold pressed into shape, vacuum sintered at a temperature of 850-950°C for 3-5h and then crushed. It should be noted that the aluminum nitrate added in this step is not an effective component of LLZO. The addition of aluminum nitrate can reduce the sintering temperature of LLZO to obtain a better cubic phase of LLZO.

[0016] As a preferred technical solution, the Li in step S3 3 InCl 6 The preparation method of the powder is as follows: 4.95mmol lithium chloride powder and 0.34mol indium chloride powder are dissolved in 1 liter of deionized water and mixed for aqueous phase synthesis, and white powder is obtained by evaporation and crystallization. The white powder is cold pressed at 25-35MPa, and then sintered at 180-220℃ in a vacuum sintering furnace for 1-2h and then crushed to obtain Li 3 InCl 6 Powder.

[0017] The LLZO-LIC-GMOF solid electrolyte membrane prepared by the above method.

[0018] In the present invention: 1. The present invention adopts PEO-based MOF (Metal organic frameworks), wherein the purpose of the PEO matrix is ​​to ensure the tensile ductility and toughness of the composite solid electrolyte material, so that in the production of solid-state batteries, whether it is a wound cell or a laminated cell, it can maintain bendability, foldability, and impact resistance, ensuring that the processing technology is feasible and the processing process is smooth. The purpose of using MOF is to establish a lithium ion migration network to improve the ionic conductivity of the solid electrolyte.

[0019] 2. The present invention uses defect-free graphene slurry when preparing GMOF. The role of defect-free graphene is to modify and construct a MOF-enhanced architecture, improve the mechanical strength of MOF, especially the tensile strength, and improve the toughness and elongation of MOF; strengthen the ion migration network, reduce the interface resistance with the electrode and the internal resistance of the electrolyte, reduce the shuttle effect, and solve the problem of unstable ion transmission at the solid-solid interface inside the battery. At the same time, it reduces the microcracks inside the filled ceramic, eradicates the source of brittle disintegration of the electrolyte, increases the air chemical stability of the electrolyte, reduces the risk of thermal runaway, and greatly improves the first effect and cycle number of the material. The modification also greatly improves the weather resistance and antioxidant properties of the material.

[0020] It should be particularly pointed out that the present invention does not use graphene oxide (GO) or reduced graphene oxide (rGO) with severe defects to modify and prepare the MOF framework. Due to the severe distortion of the lattice and electron hole defects of GO and rGO, the van der Waals force between its molecules is greatly reduced and it is easier to be electrochemically wetted, which means that it is easier to disperse initially and the modification is easier to carry out. Although the electrical performance of lithium-ion batteries in the early stage of modification is still far behind that of defect-free graphene, the mechanical properties of MOF are improved after all. However, as the number of cycles increases, the nucleation overpotential of GO or rGO becomes gradually higher than that of defect-free graphene, indicating that the Coulomb efficiency (CE) of GO or rGO modified electrodes begins to decrease and accelerates, resulting in severe electrolyte interface (SEI) growth and related FEC consumption, which re-destroys the stability of the electrolyte-electrode contact interface, and causes brittle disintegration of the interface after multiple cycles. In addition, the structural defects of GO or rGO itself are integrated into the MOF material, causing a large number of structural defects. Highly defective GO or rGO will promote the growth of unstable SEI. Although the electrolyte itself will not form dendrites, it will form filamentous lithium dendrites at the positive electrode, which will bring thermal runaway and explosion safety hazards to the battery. Another serious defect of GO or rGO is the residual acid ion defect. No matter what method is used to wash GO and rGO, the acid ions in their molecules cannot be completely removed. Under certain environmental conditions, the acid ions will precipitate from the materials modified by GO and rGO, and then corrode or poison the MOF material, and also produce a harmful environment to the human body in contact.

[0021] 3. The present invention fills the garnet oxide material LLZO (lithium lanthanum zirconium oxide, Li 7 La 3 Zr 2 O 12 ), the purpose is to improve the electrolyte ion conductivity, improve the internal chemical stability of the electrolyte, optimize the lattice and chemical structure design of the material, and maximize the balance between the ionic conductivity and electrochemical stability of the material.

[0022] 4. The present invention fills the halide material LIC (Li 3 InCl 6 ), the purpose is to further improve the electrolyte ion conductivity so that it reaches or even exceeds the ion conductivity of the liquid electrolyte, balance the material properties of garnet-type materials with high thermal stability and poor conductivity, and at the same time increase the interface inclusiveness, which is beneficial to the processing technology of solid-state battery production.

[0023] 5. The melt hot pressing solid electrolyte membrane of the present invention greatly simplifies the future production of solid-state lithium batteries. It only needs to spray (or laminate) the positive and negative electrode materials on the front and back sides of the membrane to generate a completely solid-state lithium battery membrane, and then cut, wind (or laminate), package, age and first charge according to market requirements, making large-scale and automated production very easy.

[0024] 6. The purpose of the ball milling operation before calendering film formation in the present invention is to make LLZO and LIC evenly distributed in the material to achieve a balance in the performance of the electrolyte material.

[0025] The present invention has the following advantages: The present invention discloses a method for preparing a LLZO-LIC-GMOF solid electrolyte membrane, wherein MOF is modified with defect-free graphene to form a solid electrolyte matrix reinforced frame GMOF, LLZO and LIC are simultaneously filled into the GMOF matrix, and a new solid electrolyte membrane is prepared by melt pressing. The solid electrolyte membrane prepared by the method of the present invention has the advantages of high ion conductivity, small shuttle effect, stable physical and chemical properties, good flexibility and ductility. It is a solid electrolyte membrane with excellent comprehensive performance, and a stable ion migration network is constructed at the electrolyte / electrode interface, which is of great significance to the industrialization of all-solid-state batteries. The production method of the present invention requires simple equipment, short production cycle, simple operation and mild process environment, and is suitable for industrial large-scale production. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with embodiments, and the protection scope of the present invention is not limited to the following: Example 1: A method for preparing a LLZO-LIC-GMOF solid electrolyte membrane, comprising the following steps: S1. Preparation of PEO-based MOF: PEO powder was dissolved in a dichloromethane solution, lithium perchlorate was added, and the mixture was stirred for 100 min at 20°C with a magnetic stirrer at a speed of 600 rpm to obtain a PEO-based MOF slurry; The mass volume ratio of the PEO powder to dichloromethane is 2 g:1 ml, and the weight ratio of the PEO powder to lithium perchlorate powder is 0.5:1.

[0027] S2 Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 were stirred and reacted at 40° C. and 250 rpm for 6 h, and the product was dried at 70° C. in a vacuum dryer, and then pulverized in a jet mill to obtain GMOF powder; Wherein, the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry is 1:50; The preparation method of the defect-free graphene slurry is: Defect-free graphene powder is added into ultrapure water, and the volume ratio of graphene powder to ultrapure water is 0.3 mg:1 ml. It is dispersed for 24 hours in an ultrasonic disperser with a power of not less than 1500 W to obtain defect-free graphene slurry.

[0028] S3. Ball milling and calendering film formation: Take lithium lanthanum zirconium oxide, Li 3 InCl 6 The powder was mixed with GMOF powder and ball-milled at a speed of 500 rpm for 11 h to obtain a mixed powder. The mixed powder contained lithium lanthanum zirconium oxygen, Li 3 InCl 6 The mass percentages of the powder and the GMOF powder are 10%, 60% and 30% respectively. After the mixed powder is melted, it is rolled into a film at a temperature of 60°C, which is the LLZO-LIC-GMOF solid electrolyte membrane.

[0029] The preparation method of lithium lanthanum zirconium oxide is as follows: 15.4mmol lithium nitrate, 6mmol lanthanum nitrate, 4mmol zirconium nitrate, 0.48mmol aluminum nitrate and 12.94mmol glycine are dissolved in 1 liter of deionized water and stirred evenly; the obtained mixed solution is heated to 600°C in a Ma furnace to undergo a combustion synthesis reaction; the reaction time is 80min to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 850°C for 5h, and then crushed.

[0030] The Li 3 InCl 6 The preparation method of the powder is as follows: 4.95mmol lithium chloride powder and 0.34mol indium chloride powder are dissolved in 1 liter of deionized water and mixed for aqueous phase synthesis, and white powder is obtained by evaporation and crystallization. The white powder is cold pressed under 25MPa, and then sintered at 180℃ for 2h in a vacuum sintering furnace and crushed to obtain Li 3 InCl 6 Powder.

[0031] Example 2: A method for preparing a LLZO-LIC-GMOF solid electrolyte membrane, comprising the following steps: S1. Preparation of PEO-based MOF: PEO powder was dissolved in a dichloromethane solution, lithium perchlorate was added, and the mixture was stirred at 30°C for 80 min with a magnetic stirrer at a speed of 800 rpm to obtain a PEO-based MOF slurry; The mass volume ratio of the PEO powder to dichloromethane is 10 g:1 ml, and the weight ratio of the PEO powder to lithium perchlorate powder is 3:1.

[0032] S2 Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 were stirred and reacted at 60° C. and 350 rpm for 4 h, and the product was dried at 90° C. in a vacuum dryer, and then pulverized in a high-speed vortex pulverizer to obtain GMOF powder; Wherein, the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry is 1:100; The preparation method of the defect-free graphene slurry is: Defect-free graphene powder is added into ultrapure water, and the volume ratio of graphene powder to ultrapure water is 0.5 mg:1 ml. It is dispersed for 20 hours in an ultrasonic disperser with a power of not less than 1500 W to obtain defect-free graphene slurry.

[0033] S3. Ball milling and calendering film formation: Take lithium lanthanum zirconium oxide, Li 3 InCl 6 The powder was mixed with GMOF powder and ball-milled at a speed of 600 rpm for 9 h to obtain a mixed powder. The mixed powder contained lithium lanthanum zirconium oxygen, Li 3 InCl 6 The mass percentages of the powder and the GMOF powder are 20%, 20% and 60% respectively. After the mixed powder is melted, it is rolled into a film at a temperature of 80°C, which is the LLZO-LIC-GMOF solid electrolyte membrane.

[0034] The preparation method of lithium lanthanum zirconium oxide is as follows: 15.4mmol lithium nitrate, 6mmol lanthanum nitrate, 4mmol zirconium nitrate, 0.48mmol aluminum nitrate and 12.94mmol glycine are dissolved in 1 liter of deionized water and mixed and stirred evenly; the obtained mixed solution is heated to 800°C in a Ma furnace to undergo a combustion synthesis reaction; the reaction time is 50min to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 950°C for 3h, and then crushed.

[0035] The Li 3 InCl 6The preparation method of the powder is as follows: 4.95mmol lithium chloride powder and 0.34mol indium chloride powder are dissolved in 1 liter of deionized water and mixed for aqueous phase synthesis, and white powder is obtained by evaporation and crystallization. The white powder is cold pressed under 35MPa, and then sintered at 220℃ in a vacuum sintering furnace for 1h and then crushed to obtain Li 3 InCl 6 Powder.

[0036] Example 3: A method for preparing a LLZO-LIC-GMOF solid electrolyte membrane, comprising the following steps: S1. Preparation of PEO-based MOF: PEO powder was dissolved in a dichloromethane solution, lithium perchlorate was added, and the mixture was stirred in a magnetic stirrer at 26°C for 90 min at a rate of 700 rpm to obtain a PEO-based MOF slurry; The mass volume ratio of the PEO powder to dichloromethane is 6 g:1 ml, and the weight ratio of the PEO powder to lithium perchlorate powder is 1.5:1.

[0037] S2 Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 were stirred and reacted at 50° C. and 300 rpm for 5 h, and the product was dried at 80° C. in a vacuum dryer, and then pulverized in a jet mill to obtain GMOF powder; Wherein, the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry is 1:80; The preparation method of the defect-free graphene slurry is: Defect-free graphene powder is added into ultrapure water, and the volume ratio of graphene powder to ultrapure water is 0.4 mg:1 ml. It is dispersed for 22 hours in an ultrasonic disperser with a power of not less than 1500 W to obtain defect-free graphene slurry.

[0038] S3. Ball milling and calendering film formation: Take lithium lanthanum zirconium oxide, Li 3 InCl 6 The powder was mixed with GMOF powder and ball-milled at a speed of 560 rpm for 10 h to obtain a mixed powder. The mixed powder contained lithium lanthanum zirconium oxygen, Li 3 InCl 6 The mass percentages of the powder and the GMOF powder are 15%, 35% and 50% respectively. After the mixed powder is melted, it is rolled into a film at a temperature of 70°C, which is the LLZO-LIC-GMOF solid electrolyte membrane.

[0039] The preparation method of lithium lanthanum zirconium oxide is as follows: 15.4mmol lithium nitrate, 6mmol lanthanum nitrate, 4mmol zirconium nitrate, 0.48mmol aluminum nitrate and 12.94mmol glycine are dissolved in 1 liter of deionized water and stirred evenly; the obtained mixture is heated to 750°C in a Ma furnace to undergo a combustion synthesis reaction; the reaction time is 58min to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 900°C for 4h and then crushed.

[0040] The Li 3 InCl 6 The preparation method of the powder is as follows: 4.95mmol lithium chloride powder and 0.34mol indium chloride powder are dissolved in 1 liter of deionized water and mixed for aqueous phase synthesis, and white powder is obtained by evaporation and crystallization. The white powder is cold pressed under 30MPa, and then sintered at 200℃ in a vacuum sintering furnace for 1.5h and then crushed to obtain Li 3 InCl 6 Powder.

[0041] The beneficial effects of the present invention are described below by experiments: Example 1: S1. Preparation of PEO-based MOF slurry: Dissolve PEO (polyethylene oxide) powder in dichloromethane solution, stir and dissolve completely, seal and place in an iodine volumetric flask for 12 hours, then add lithium perchlorate powder and continue to stir evenly. Seal the iodine volumetric flask and place it in a magnetic stirrer rotor and stir at 700 rpm at 25°C for 90 minutes to obtain a PEO-based MOF slurry. The mass volume ratio of PEO powder (polyethylene oxide) to dichloromethane solution is 5g:1ml, and the weight ratio of PEO powder (polyethylene oxide) to lithium perchlorate powder is 3:1.

[0042] S2. Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 were stirred in a mixing reactor at 50° C. and 300 rpm for 5 h, and the product was dried and crushed at 80° C. to obtain GMOF powder; wherein the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry was 1:100; The preparation method of the defect-free graphene slurry is as follows: defect-free graphene powder is added into ultrapure water, the mass volume ratio of graphene powder to ultrapure water is 0.5 mg:1 ml, and dispersed in an ultrasonic disperser with a power of not less than 1500 W for 20 hours to obtain defect-free graphene slurry.

[0043] S3. Ball milling and calendering film: LLZO (lithium lanthanum zirconium oxide), LIC (Li 3 InCl 6) and GMOF powder, and ball-milled at a speed of 600 rpm for 10 h to obtain a mixed powder, wherein the mass percentages of LLZO, LIC and GMOF powder in the mixed powder are 10%, 35% and 55% respectively, and the mixed powder is melted and rolled into a film at a temperature of 70° C., namely, LLZO-LIC-GMOF solid electrolyte membrane; The preparation method of LLZO (lithium lanthanum zirconium oxide) is as follows: 15.4 mmol lithium nitrate, 6 mmol lanthanum nitrate, 4 mmol zirconium nitrate, 0.48 mmol aluminum nitrate and 12.94 mmol glycine are dissolved in 1 liter of deionized water in an open high-temperature container, and the obtained mixed solution is heated to above 600°C in a Ma furnace to undergo a combustion synthesis reaction to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 850°C for 5 hours, and then crushed.

[0044] The LIC (Li 3 InCl 6 ) is prepared by mixing 4.95 mmol lithium chloride (LiCl) powder and 0.34 mol indium chloride (InCl 3 ) The powder is placed in an evaporation crystallizer, stirred and dissolved in 1 liter of deionized water for aqueous phase synthesis, and evaporated and crystallized to obtain white powder. The white powder is cold-pressed at 30 MPa, and then sintered at 200°C in a vacuum sintering furnace for 1 hour to obtain block LIC, which is then placed in a pulverizer and crushed to obtain LIC powder.

[0045] Example 2: S1. Preparation of PEO-based MOF slurry: Dissolve PEO (polyethylene oxide) powder in dichloromethane solution, stir and dissolve completely, seal and place in an iodine volumetric flask for 12 hours, then add lithium perchlorate powder and continue to stir evenly, seal the iodine volumetric flask and place it in a magnetic stirrer rotor for stirring at 800 rpm at 30°C for 90 minutes to obtain a PEO-based MOF slurry. The mass volume ratio of PEO powder (polyethylene oxide) to dichloromethane solution is 10g:1ml, and the weight ratio of PEO powder (polyethylene oxide) to lithium perchlorate powder is 1:1; S2. Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 are stirred in a mixing reactor at 60° C. and 200 rpm for 4 h, and the product is dried and crushed at 90° C. to obtain GMOF powder; wherein the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry is 1:50; The preparation method of the defect-free graphene slurry is as follows: adding defect-free graphene powder into ultrapure water, wherein the mass volume ratio of graphene powder to ultrapure water is 1 mg:1 ml, and dispersing the mixture in an ultrasonic disperser with a power of not less than 1500 W for 20 hours to obtain the defect-free graphene slurry.

[0046] S3. Ball milling and calendering film: LLZO (lithium lanthanum zirconium oxide), LIC (Li 3 InCl 6 ) was mixed with GMOF powder, and ball-milled at a speed of 600 rpm for 9 hours to obtain a mixed powder, wherein the mass percentages of LLZO, LIC and GMOF powder in the mixed powder were 10%, 35% and 55% respectively, and the mixed powder was melted and rolled into a film at a temperature of 80° C., namely, LLZO-LIC-GMOF solid electrolyte membrane; The preparation method of LLZO (lithium lanthanum zirconium oxide) is as follows: 15.4 mmol lithium nitrate, 6 mmol lanthanum nitrate, 4 mmol zirconium nitrate, 0.48 mmol aluminum nitrate and 12.94 mmol glycine are dissolved in 1 liter of deionized water in an open high-temperature container, and the obtained mixed solution is heated to above 600°C in a Ma furnace to undergo a combustion synthesis reaction to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 950°C for 3 hours, and then crushed.

[0047] The LIC (Li 3 InCl 6 ) is prepared by mixing 4.95 mmol lithium chloride (LiCl) powder and 0.34 mol indium chloride (InCl 3 ) powder was placed in an evaporation crystallizer, stirred and dissolved in 1 liter of deionized water for aqueous phase synthesis, and evaporated and crystallized to obtain white powder. The white powder was cold-pressed at 35 MPa, and then sintered at 220°C in a vacuum sintering furnace for 1 h to obtain block LIC, which was then placed in a pulverizer and crushed to obtain LIC powder.

[0048] Compared with Example 1, the key differences of Example 2 are 1) the weight ratio of PEO powder to lithium perchlorate powder was increased by 2 times, so as to observe the effect of the ratio of PEO powder to lithium perchlorate powder on the mechanical properties, chemical properties, and electrical properties of the MOF framework. 2) the defect-free graphene in the GMOF material was increased by 1 times, so as to observe the effect of graphene content on the mechanical properties, chemical properties, and electrical properties of the MOF framework. At the same time, the temperature, time and other parameters were fine-tuned.

[0049] Example 3: S1. Preparation of PEO-based MOF slurry: PEO (polyethylene oxide) powder was dissolved in dichloromethane solution, and after stirring and dissolving completely, it was sealed and placed in an iodine volumetric flask for 12 hours, and then lithium perchlorate powder was added and continued to be stirred evenly. The iodine volumetric flask was sealed and placed in a magnetic stirrer rotor for stirring at 30°C and 800 rpm for 90 minutes to obtain PEO-based MOF slurry. Among them, the mass volume ratio of PEO powder (polyethylene oxide) to dichloromethane solution was 5g:1ml, and the weight ratio of PEO powder (polyethylene oxide) to lithium perchlorate powder was 3:1.

[0050] S2. Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 are stirred in a mixing reactor at 60° C. and 200 rpm for 4 h, and the product is dried and crushed at 90° C. to obtain GMOF powder; wherein the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry is 1:50; The preparation method of the defect-free graphene slurry is as follows: adding defect-free graphene powder into ultrapure water, wherein the mass volume ratio of graphene powder to ultrapure water is 1 mg:1 ml, and dispersing the mixture in an ultrasonic disperser with a power of not less than 1500 W for 20 hours to obtain the defect-free graphene slurry.

[0051] S3. Ball milling and calendering film: LLZO (lithium lanthanum zirconium oxide), LIC (Li 3 InCl 6 ) is mixed with GMOF powder, the mass ratio of LLZO, LIC and GMOF powder is, ball milled at a speed of 600rmp for 10h to obtain a mixed powder, the mass percentages of LLZO, LIC and GMOF powder in the mixed powder are 20%, 30% and 50% respectively, and the mixed powder is melted and rolled into a film at a temperature of 80°C, that is, LLZO-LIC-GMOF solid electrolyte membrane; The preparation method of LLZO (lithium lanthanum zirconium oxide) is as follows: 15.4 mmol lithium nitrate, 6 mmol lanthanum nitrate, 4 mmol zirconium nitrate, 0.48 mmol aluminum nitrate and 12.94 mmol glycine are dissolved in 1 liter of deionized water in an open high-temperature container, and the obtained mixed solution is heated to above 600°C in a Ma furnace to undergo a combustion synthesis reaction to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 950°C for 3 hours, and then crushed.

[0052] The LIC (Li 3 InCl 6 ) is prepared by mixing 4.95 mmol lithium chloride (LiCl) powder and 0.34 mol indium chloride (InCl 3) The powder is placed in an evaporation crystallizer, stirred and dissolved in 1 liter of deionized water for aqueous phase synthesis, and evaporated and crystallized to obtain white powder. The white powder is cold-pressed at 30 MPa, and then sintered at 200°C in a vacuum sintering furnace for 1 hour to obtain block LIC, which is then placed in a pulverizer and crushed to obtain LIC powder.

[0053] Compared with Example 1, the key difference of Example 3 is that the GMOF content in the LLZO-LIC-GMOF composite material is doubled, so as to observe the effect of the GMOF content on the mechanical properties, chemical properties, and electrical properties of the solid electrolyte. At the same time, the temperature, time and other parameters are fine-tuned.

[0054] Example 4: S1. Preparation of PEO-based MOF slurry: Dissolve PEO (polyethylene oxide) powder in dichloromethane solution, stir and dissolve completely, seal and place in an iodine volumetric flask for 12 hours, then add lithium perchlorate powder and continue to stir evenly, seal the iodine volumetric flask and place it in a magnetic stirrer rotor at 30°C and 800 rpm to stir and react for 80 minutes to obtain PEO-based MOF slurry. Among them, the mass volume ratio of PEO powder (polyethylene oxide) to dichloromethane solution is 5g:1ml, and the weight ratio of PEO powder (polyethylene oxide) to lithium perchlorate powder is 3:1.

[0055] S2. Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 were stirred in a mixing reactor at 60° C. and 200 rpm for 4 h, and the product was dried and crushed at 90° C. to obtain GMOF powder; wherein the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry was 1:75; The preparation method of the defect-free graphene slurry is as follows: adding defect-free graphene powder into ultrapure water, wherein the mass volume ratio of graphene powder to ultrapure water is 1 mg:1 ml, and dispersing the mixture in an ultrasonic disperser with a power of not less than 1500 W for 20 hours to obtain the defect-free graphene slurry.

[0056] S3. Ball milling and calendering film: LLZO (lithium lanthanum zirconium oxide), LIC (Li 3 InCl 6 ) and GMOF powder, and ball-milled at a speed of 600 rpm for 10 h to obtain a mixed powder, wherein the mass percentages of LLZO, LIC and GMOF powder in the mixed powder are 10%, 55% and 35% respectively, and the mixed powder is melted and rolled into a film at a temperature of 80° C., namely, LLZO-LIC-GMOF solid electrolyte membrane; The preparation method of LLZO (lithium lanthanum zirconium oxide) is as follows: 15.4 mmol lithium nitrate, 6 mmol lanthanum nitrate, 4 mmol zirconium nitrate, 0.48 mmol aluminum nitrate and 12.94 mmol glycine are dissolved in 1 liter of deionized water in an open high-temperature container, and the obtained mixed solution is heated to above 600°C in a Ma furnace to undergo a combustion synthesis reaction to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 850°C for 3 hours, and then crushed.

[0057] The LIC (Li 3 InCl 6 ) is prepared by mixing 4.95 mmol lithium chloride (LiCl) powder and 0.34 mol indium chloride (InCl 3 ) The powder is placed in an evaporation crystallizer, stirred and dissolved in 1 liter of deionized water for aqueous phase synthesis, and evaporated and crystallized to obtain white powder. The white powder is cold-pressed at 30 MPa, and then sintered at 200°C in a vacuum sintering furnace for 1 hour to obtain block LIC, which is then placed in a pulverizer and crushed to obtain LIC powder.

[0058] Compared with Example 1, the key differences of Example 4 are that 1) the ratio of LLZO material and LIC material in the formula of LLZO-LIC-GMOF composite material is adjusted from LIC to LLZO; 2) the volume ratio of defect-free graphene slurry to PEO-based MOF slurry is 1:75, so as to observe the effect of the adjustment of the ratio of LLZO material and LIC material, and the change of the volume ratio of defect-free graphene slurry to MOF slurry on the mechanical properties, chemical properties, and electrical properties of the solid electrolyte. At the same time, the temperature, time and other parameters were fine-tuned.

[0059] Example 5: S1. Preparation of PEO-based MOF slurry: Dissolve PEO (polyethylene oxide) powder in dichloromethane solution, stir and dissolve completely, seal and place in an iodine volumetric flask for 12 hours, then add lithium perchlorate powder and continue to stir evenly, seal the iodine volumetric flask and place it in a magnetic stirrer rotor for stirring at 800 rpm at 30°C for 80 minutes to obtain PEO-based MOF slurry. Among them, the mass volume ratio of PEO powder (polyethylene oxide) to dichloromethane solution is 5g:1ml, and the weight ratio of PEO powder (polyethylene oxide) to lithium perchlorate powder is 3:1; S2. Preparation of GMOF powder: The defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 are stirred in a mixing reactor at 60° C. and 200 rpm for 4 h, and the product is dried and crushed at 90° C. to obtain GMOF powder; wherein the volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry is 1:65; The preparation method of the defect-free graphene slurry is as follows: adding defect-free graphene powder into ultrapure water, wherein the mass volume ratio of graphene powder to ultrapure water is 1 mg:1 ml, and dispersing the mixture in an ultrasonic disperser with a power of not less than 1500 W for 20 hours to obtain the defect-free graphene slurry.

[0060] S3. Ball milling and calendering film: LLZO (lithium lanthanum zirconium oxide), LIC (Li 3 InCl 6 ) and GMOF powder, and ball-milled at a speed of 600 rpm for 10 hours to obtain a mixed powder, wherein the mass percentages of LLZO, LIC and GMOF powder in the mixed powder are 15%, 35% and 50% respectively, and the mixed powder is melted and rolled into a film at a temperature of 70° C., namely, LLZO-LIC-GMOF solid electrolyte membrane; The preparation method of LLZO (lithium lanthanum zirconium oxide) is as follows: 15.4 mmol lithium nitrate, 6 mmol lanthanum nitrate, 4 mmol zirconium nitrate, 0.48 mmol aluminum nitrate and 12.94 mmol glycine are dissolved in 1 liter of deionized water in an open high-temperature container, and the obtained mixed solution is heated to above 600°C in a Ma furnace to undergo a combustion synthesis reaction to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at 850°C for 3 hours, and then crushed.

[0061] The LIC (Li 3 InCl 6 ) is prepared by mixing 4.95 mmol lithium chloride (LiCl) powder and 0.34 mol indium chloride (InCl 3 ) The powder is placed in an evaporation crystallizer, stirred and dissolved in 1 liter of deionized water for aqueous phase synthesis, and evaporated and crystallized to obtain white powder. The white powder is cold-pressed at 30 MPa, and then sintered at 200°C in a vacuum sintering furnace for 1 hour to obtain block LIC, which is then placed in a pulverizer and crushed to obtain LIC powder.

[0062] The performance of the LLZO-LIC-GMOF solid electrolyte membranes prepared in Examples 1 to 5 was tested, and the experimental results are shown in Table 1: Table 1: Performance test results of LLZO-LIC-GMOF solid electrolyte membranes prepared in Examples 1 to 5 From Table 1, we can see that: (1) During the preparation of GMOF materials, the volume ratio of defect-free graphene slurry to PEO-based MOF slurry increased from 1:200. At the beginning, there was no obvious effect on the MOF structure. When the volume ratio exceeded 1:100, it was clearly measured that the mechanical and chemical properties of the GMOF structure continued to improve, the surface contact resistance also continued to decrease, and the internal ionic conductivity of the electrolyte was not greatly affected. However, when the volume ratio exceeded 1:50, although the mechanical and chemical properties of the GMOF structure continued to improve, the surface contact resistance also continued to decrease, and there was still no effect on the internal ionic conductivity of the electrolyte, the electronic conductivity inside the electrolyte increased significantly, which is not conducive to battery charging and discharging. After multiple adjustments to the formula, the optimal volume ratio of defect-free graphene slurry to PEO-based MOF slurry was selected to be 1:65.

[0063] (2) In the preparation of LLZO-LIC-GMOF materials, based on the same reasons as above, the total mass ratio of GMOF cannot exceed 20%, and the optimal solution is 15%.

[0064] (3) In the preparation of LLZO-LIC-GMOF materials, the change in the relative proportion of LLZO and LIC in the total mass ratio has a great influence on the comprehensive performance of the final solid electrolyte. If the LLZO ratio is high and the LIC ratio is low, the internal chemical stability of the electrolyte is strong and the air stability is relatively strong, but the internal ion conductivity is low and the interface tolerance is not high. If the LLZO ratio is low and the LIC ratio is high, the internal ion conductivity of the electrolyte is high and the interface tolerance with the positive and negative electrodes is high, but the internal chemical stability and air stability are not strong. After multiple adjustments to the formula, LLZO and LIC accounted for 35% and 50% of the total mass.

[0065] In summary, from Example 1 to Example 4, it was found that when GMOF accounted for more than 20% in the LLZO-LIC-GMOF composite material, although the mechanical and chemical properties of the GMOF framework continued to improve, the surface contact resistance continued to decrease, and the ionic conductivity inside the electrolyte was still not affected, the electronic conductivity inside the electrolyte increased significantly, which is not conducive to battery charging and discharging. After adjusting the formula many times, it was selected that GMOF accounted for 15% in the LLZO-LIC-GMOF composite material as the best. Therefore, the key difference between Example 5 and Example 1 is that 1) GMOF accounts for 15% in the LLZO-LIC-GMOF composite material. 2) The volume ratio of defect-free graphene slurry to PEO-based MOF slurry is 1:65, and the temperature, time and other parameters are fine-tuned at the same time.

[0066] Therefore, in Example 5, we adjusted the volume ratio of defect-free graphene slurry to PEO-based MOF slurry according to the optimal choice, and the formula ratio of GMOF, LLZO and LIC was the optimal solution.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which are all covered by the protection scope of the present invention.

Claims

1. A method for preparing a LLZO-LIC-GMOF solid electrolyte membrane, characterized in that: It includes the following steps: S1. Preparation of PEO-based MOF: PEO powder was dissolved in a dichloromethane solution, lithium perchlorate was added, and the mixture was stirred at 20-30°C for 80-100 minutes to obtain a PEO-based MOF slurry; S2: preparing GMOF powder: the defect-free graphene slurry and the PEO-based MOF slurry prepared in step S1 are stirred and reacted at 40-60° C. for 4-6 hours, and the product is dried and crushed to obtain GMOF powder; S3. Ball milling and calendering film formation: Lithium lanthanum zirconium oxide, Li3InCl6 powder and GMOF powder are mixed, and ball milled at a speed of 500-600 rpm for 9-11 hours to obtain a mixed powder. After the mixed powder is melted, it is rolled into a film at a temperature of 60-80°C, which is the LLZO-LIC-GMOF solid electrolyte membrane.

2. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: In step S1, the mass volume ratio of the PEO powder to dichloromethane is 2-10 g:1 ml, and the weight ratio of the PEO powder to the lithium perchlorate powder is 0.5-3:

1.

3. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: The stirring in step S1 is performed using a magnetic stirrer at a speed of 600-800 rpm.

4. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: The volume ratio of the defect-free graphene slurry to the PEO-based MOF slurry in step S2 is 1:50-100.

5. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 4, characterized in that: The preparation method of the defect-free graphene slurry in step S2 is: adding defect-free graphene powder into ultrapure water, with the volume ratio of the mass of graphene powder to ultrapure water being 0.3-0.5 mg:1 ml, and dispersing it in an ultrasonic disperser with a power of not less than 1500 W for 20-24 hours to obtain defect-free graphene slurry.

6. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: The stirring rate in step S2 is 250-350 rpm; the drying is carried out in a vacuum dryer at a drying temperature of 70-90° C.; the pulverization is carried out in an air flow pulverizer or a high-speed vortex pulverizer.

7. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: The mass percentages of lithium lanthanum zirconium oxide, Li3InCl6 powder and GMOF powder in the mixed powder in step S3 are 10-20%, 20-60% and 20-60% respectively.

8. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: The preparation method of lithium lanthanum zirconium oxide described in step S3 is: 15.4mmol lithium nitrate, 6mmol lanthanum nitrate, 4mmol zirconium nitrate, 0.48mmol aluminum nitrate and 12.94mmol glycine are dissolved in 1 liter of deionized water and mixed and stirred evenly, and the obtained mixed solution is heated to 600-800°C in a Ma furnace to undergo a combustion synthesis reaction, and the reaction time is 50-80min to obtain a white fluffy powder; the white fluffy powder is cold-pressed into a shape, vacuum-sintered at a temperature of 850-950°C for 3-5h, and then crushed.

9. The method for preparing a LLZO-LIC-GMOF solid electrolyte membrane according to claim 1, characterized in that: The preparation method of the Li3InCl6 powder described in step S3 is: dissolve 4.95mmol lithium chloride powder and 0.34mol indium trichloride powder in 1 liter of deionized water and mix them for aqueous phase synthesis, evaporate and crystallize to obtain white powder, cold-press the white powder at 25-35MPa, sinter at 180-220°C in a vacuum sintering furnace for 1-2h, and then crush to obtain Li3InCl6 powder.

10. A LLZO-LIC-GMOF solid electrolyte membrane prepared according to the method of any one of claims 1 to 9.

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