Control crystallization method-based LATP solid electrolyte and preparation process thereof

Abstract

The invention discloses an LATP solid electrolyte based on a controlled crystallization method and a preparation process thereof, and belongs to the technical field of electrolyte material preparation, and the preparation method comprises the following steps: adding a TiOSO4 solution, a NaF solution and a H3PO4 solution with the pH value of 1-2 into deionized water, NaF and H2SO4 aqueous solutions, controlling the molar ratio of F <-> to TiO2 < + > to be 0.05-0.2, reacting and separating to obtain solid powder; adding AlPO4 and Li3PO4, mixing and sintering to obtain an LATP solid electrolyte; adding a polymer solution to prepare a composite electrolyte by a casting method; according to the method, the high-purity narrow-distribution intermediate is prepared through cooperative control of the molar ratio and the pH value. And direct sintering is adopted, so that gas by-products are avoided, and the LATP purity is improved. The ionic conductivity is optimized by doping, and the mechanical strength and the interfacial compatibility are improved by compounding with a polymer. The finally prepared LATP has no impurity phase, the ionic conductivity is improved by 15-20%, the mechanical strength is improved by 20-30%, the granularity is controllable, and powerful support is provided for improvement of the performance of the lithium ion battery.

Description

Technical Field

[0001] The present invention relates to a LATP solid electrolyte based on a controlled crystallization method and a preparation process thereof, belonging to the technical field of electrolyte material preparation. Background Art

[0002] With the wide application of lithium-ion batteries in the fields of 3C digital, power, energy storage, etc., the industry has put forward higher requirements for the safety and energy density of batteries. Solid electrolytes have become a research hotspot for new battery materials due to their advantages such as low flammability, high thermal stability, no leakage, and low explosion risk. Among them, the NASICON-type solid electrolyte material LATP [Li 1+x Al x Ti 2-x (PO4)3] has the most promising industrialization prospects due to its low production cost. However, existing preparation methods have problems such as a large variety of raw materials, large particle size differences, and a large amount of waste gas generated during the sintering process, resulting in uneven mixing, element distribution segregation, and the generation of impurity phases, which affect the performance of LATP.

[0003] Since the commercialization of lithium-ion batteries in the 1990s, with their advantages such as high energy density, long cycle life, and low self-discharge rate, they have quickly become the mainstream power source in the consumer electronics field. With the progress of technology and the expansion of application scenarios, the application scope of lithium-ion batteries has expanded from the initial 3C digital products (such as mobile phones, laptops, and tablets) to multiple fields such as electric vehicles, energy storage systems, and aerospace. Especially in the field of electric vehicles, the performance of lithium-ion batteries directly affects the driving range, charging speed, and safety of vehicles, becoming a key factor in promoting the development of new energy vehicles.

[0004] However, with the continuous improvement of application requirements, the limitations of traditional liquid electrolyte lithium-ion batteries have gradually emerged. Liquid electrolytes have high flammability and are prone to thermal runaway under high temperature or overcharge conditions, leading to battery fires or even explosions. In addition, the leakage problem of liquid electrolytes also poses a threat to the reliability and safety of batteries. These problems have prompted researchers to turn their attention to solid electrolytes in order to solve the existing technical bottlenecks through material innovation.

[0005] As a new type of battery material, solid electrolytes have the following significant advantages: high safety, high mechanical strength, high energy density, and high design flexibility. Among many solid electrolyte materials, Li of NASICON-type structure 1+x Al x Ti 2-x(PO4)3, abbreviated as LATP, has attracted much attention due to its excellent comprehensive performance. In addition, the preparation cost of LATP is relatively low, and the main raw materials (such as Ti, Al, P, Li) are widely sourced and inexpensive, which provides the possibility for its large-scale industrialization. However, there are still some problems to be solved urgently in the existing preparation methods, which limit the further development of LATP.

[0006] Currently, the preparation methods of LATP mainly include traditional solid-phase method, sol-gel method, hydrothermal method, etc. Although these methods can prepare LATP materials to a certain extent, the following main problems still exist in practical applications: Many types of raw materials and large particle size differences: The traditional solid-phase method usually uses nano-level TiO2, Al2O3 and micron-level Li2CO3, NH4H2PO4 and other raw materials. Due to the large particle size differences of different raw materials, unevenness is likely to occur during the mixing process, resulting in uneven element distribution in the final product and affecting the performance of the material. A large amount of waste gas is generated during the sintering process: During the sintering process, raw materials such as NH4H2PO4 and Li2CO3 will decompose to produce gases such as NH3, CO2, and H2O. The release of these gases not only increases the environmental protection burden during the production process, but also may cause pores and defects to form inside the material, further affecting the densification and performance of the material. Generation of impurity phases: Due to the uneven mixing of raw materials and the release of gases during the sintering process, impurity phases are likely to appear in the final product. The presence of impurity phases will significantly reduce the ionic conductivity and mechanical strength of the material, limiting its application in high-performance batteries. Complex process and high energy consumption: The existing preparation methods usually require multi-step reactions and high-temperature sintering, with complex processes and high energy consumption, which are not conducive to large-scale production.

[0007] In summary, although LATP, as a new type of solid-state electrolyte material, has significant advantages and broad application prospects, the defects of the existing preparation methods limit the further improvement of its performance and the industrialization process. Therefore, developing an efficient, environmentally friendly and low-cost preparation method that can overcome the above problems is of great significance for promoting the practical application of LATP materials. Summary of the Invention

[0008] Aiming at the defects existing in the prior art, the present invention aims to solve the defects of the existing preparation of LATP, adopts the controlled crystallization method to prepare micron-sized Ti3(PO4)4 intermediates with high purity and narrow distribution, and optimizes the performance of LATP through doping modification and composite electrolyte technology to obtain a solid-state electrolyte without impurity phases and with excellent performance. The specific scheme is as follows:

[0009] A preparation method of an LATP solid-state electrolyte, the steps are as follows:

[0010] S1. Add TiOSO4 to deionized water, mix to obtain an aqueous TiOSO4 solution, add an appropriate amount of H2SO4 to adjust the pH value to 1 - 2, and obtain the adjusted pH aqueous TiOSO4 solution for standby.

[0011] S3. Add NaF to deionized water to obtain an aqueous NaF solution for standby.

[0012] S3. Add H3PO4 to deionized water to obtain an aqueous H3PO4 solution for standby.

[0013] S4. Add deionized water, NaF, and H2SO4 to a reaction kettle to obtain a mixed bottom aqueous solution, heat it to 20 - 60 °C, and simultaneously add a TiOSO4 solution, a NaF solution, and an H3PO4 solution into it at a certain flow rate in a co-current manner. Control the molar ratio of F - to TiO 2+ to be 0.05 - 0.2. React to generate precipitate particles of Ti3(PO4)4. After solid-liquid separation, wash the obtained solid to neutrality and dry it to obtain Ti3(PO4)4 solid powder.

[0014] S5. Add AlPO4 solid and Li3PO4 solid to the Ti3(PO4)4 solid powder, and optionally add a precursor solution of a doping element. The doping amount is 0.5% - 5% of the mass of Ti3(PO4)4. Mix and sinter at 700 - 900 °C in an air atmosphere. The obtained sintered product is crushed and sieved to obtain an LATP solid electrolyte.

[0015] S6. Mix the obtained LATP solid electrolyte and the polymer at a mass ratio of 1:0.1 - 1:0.2, and prepare a composite electrolyte by mechanical mixing or solution casting method.

[0016] The chemical formula of the described LATP solid electrolyte is Li 1+x Al x Ti 2-x (PO4)3, where the range of x is: 0 - 0.5.

[0017] Preferably, in step S1, the concentration of the TiOSO4 aqueous solution is 0.1 - 2 mol / L; in step S2, the concentration of the NaF aqueous solution is 0.1 - 1 mol / L; in step S3, the concentration of the H3PO4 aqueous solution is 0.1 - 4 mol / L; in step S4, the concentration of NaF in the mixed bottom aqueous solution is 0.1 - 0.5 mol / L, and the pH value is 1 - 2; in step S4, the amounts of the TiOSO4 aqueous solution and the H3PO4 aqueous solution added simultaneously are in a molar ratio of TiOSO4 to H3PO4 of 3:4; in step S4, the amounts of the TiOSO4 aqueous solution and the NaF aqueous solution added simultaneously are in a molar ratio of F - / TiO 2+ of 0.05 - 0.2; in step S5, the sintering temperature is 700 - 900 °C, and the sintering atmosphere is an air atmosphere; the purity grades of the AlPO4 solid and the Li3PO4 solid are analytical pure; in step S5, the doping elements are Mg 2+ 、Zr 4+ or one or more of them; in step S6, the polymer is one or more of PEO and PVDF, and the dosage of the polymer is 10% - 20% of the mass of LATP.

[0018] Key point supplementary description:

[0019] F - / TiO 2+ Molar ratio: Controlled within the range of 0.05 - 0.2, preferably 0.1, to obtain Ti3(PO4)4 particles with a uniform particle size distribution.

[0020] pH value control: The pH value of the reaction system is 1 - 2, adjusted by adding H2SO4.

[0021] Doping elements: Optional Mg 2+ 、Zr 4+ etc., and the doping amount is 0.5% - 5% of the mass of Ti3(PO4)4.

[0022] Polymer selection: PEO, PVDF, etc., and the dosage is 10% - 20% of the mass of LATP.

[0023] Advantages of the present invention:

[0024] The present invention controls the F - / TiO 2+ molar ratio and the pH value synergistically to prepare a high-purity and narrow-distribution Ti3(PO4)4 intermediate. Direct sintering of Li3PO4 and AlPO4 is adopted to avoid gas by-products and improve the purity of LATP. Doping with Mg 2+ 、Zr 4+Optimize the ionic conductivity, improve the mechanical strength and interfacial compatibility by compounding with polymers. The finally prepared LATP has no impurity phase, the ionic conductivity is increased by 15%-20%, the mechanical strength is increased by 20%-30%, and the particle size is controllable, providing strong support for the improvement of the performance of lithium-ion batteries. Description of the Drawings

[0025] Figure 1 is the XRD pattern of the solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO4)3 sample A;

[0026] Figure 2 is the XRD pattern of the solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO4)3 sample B;

[0027] Figure 3 is the XRD pattern of the solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO4)3 sample C;

[0028] Figure 4 is the XRD pattern of the solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3 sample D;

[0029] Figure 5 is the XRD pattern of the solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO4)3 sample E;

[0030] Figure 6 is the AC impedance diagram of the samples of Example 1 and Comparative Example 1;

[0031] Figure 7 is the particle size diagram of the product of Example 4. Detailed Embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described can be applied to the present invention. The preferred implementation methods and materials described herein are for illustrative purposes only and do not limit the content of this application.

[0034] Unless otherwise specified, the experimental methods in the following examples are all conventional methods. Unless otherwise specified, the test materials used in the following examples are all obtained from commercial channels.

[0035] The following innovation point 1 states: "The synergistic control of the molar ratio of F - / TiO 2+ (0.05 - 0.2) and pH = 1 - 2", innovation point 2 states: "Adopting the direct sintering method of Li3PO4 and AlPO4 to avoid gas by-products in the traditional process and improve the purity of LATP", innovation point 3 states: "Introducing a small amount of doping elements such as Mg 2+ 、Zr 4+ to optimize the ionic conductivity of LATP", innovation point 4 states: "Composite LATP with polymers (such as PEO) to improve the interfacial compatibility and mechanical strength".

[0036] Example 1 (Application of Innovation Points 1 and 2)

[0037] Step 1: Prepare TiOSO4 solution

[0038] Weigh 480 g of TiOSO4 solid particles and dissolve them in 2000 g of deionized water.

[0039] Dropwise add an appropriate amount of H2SO4 to adjust the pH value of the solution to 1, and stir until completely dissolved to obtain a 1.5 mol / L aqueous solution of TiOSO4.

[0040] Step 2: Prepare NaF solution

[0041] Weigh 21 g of NaF solid particles and dissolve them in 1000 g of deionized water, and stir until completely dissolved to obtain a 0.5 mol / L aqueous solution of NaF.

[0042] Step 3: Prepare H3PO4 solution

[0043] Measure 274 mL of 85% phosphoric acid solution and slowly add it to 1726 g of deionized water, and stir evenly to obtain a 2 mol / L aqueous solution of H3PO4.

[0044] Step 4: Precipitation reaction

[0045] Add 1000 g of deionized water to the reaction kettle, and then add an appropriate amount of H2SO4 to adjust the pH value of the solution to 1.

[0046] Add 10.5 g of solid NaF particles, and turn on the stirring device to make the solution mix evenly.

[0047] Heat the reaction kettle to 50 °C and keep it at a constant temperature.

[0048] Feed the prepared aqueous TiOSO4 solution, aqueous NaF solution and aqueous H3PO4 solution into the reaction kettle in a co-current manner at a certain flow rate for reaction. The feeding rates of the aqueous TiOSO4 solution and the aqueous H3PO4 solution are both 100 mL / h, and the feeding rate of the aqueous NaF solution is 30 mL / h. Control the molar ratio of F - to TiO 2+ to be 0.1.

[0049] Step 5: Solid-liquid separation and drying

[0050] After the reaction lasts for 20 hours, perform solid-liquid separation on the obtained solid-liquid mixture, which can be carried out by centrifugation or filtration.

[0051] Wash the separated solid with deionized water until the pH of the washing water is neutral to remove residual impurities.

[0052] Dry the washed solid in an oven at 110 °C to obtain a solid particle sample 1# of Ti3(PO4)4.

[0053] Step 6: Sintering to prepare LATP

[0054] Weigh 261.8 g of the solid sample 1# of Ti3(PO4)4, 45.8 g of AlPO4 solid and 50.7 g of Li3PO4 solid according to the molar ratio of Li:Ti:Al = 1.4:1.6:0.4.

[0055] Sinter the above solid mixture at 850 °C, and the sintering atmosphere is air atmosphere.

[0056] After sintering is completed, perform crushing and sieving on the obtained solid powder to obtain the solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO4)3 sample A.

[0057] Effect:

[0058] The particle size distribution of Ti3(PO4)4 is uniform, and D50 is about 3.230 μm.

[0059] LATP has no impurity phase, has a relatively high ionic conductivity and good mechanical strength.

[0060] Example 2 (Application of Innovation Point 3)

[0061] Step 1: Prepare the Ti3(PO4)4 intermediate

[0062] Operate according to steps 1 - 5 of Example 1 to obtain the Ti3(PO4)4 solid particle sample 1#.

[0063] Step 2: Doping treatment

[0064] Add the precursor solution of the doping element, such as Mg(NO3)2 solution, to the Ti3(PO4)4 powder, and the doping amount is 1% of the mass of Ti3(PO4)4.

[0065] Dry the doped mixture to ensure that the doping element is evenly distributed in the Ti3(PO4)4 particles.

[0066] Step 3: Sinter to prepare doped LATP

[0067] Weigh the doped Ti3(PO4)4 solid, AlPO4 solid and Li3PO4 solid according to the molar ratio of Li:Ti:Al = 1.4:1.6:0.4.

[0068] Sinter the mixture at 850 °C to obtain the doped LATP solid powder sample B.

[0069] Effect:

[0070] The ionic conductivity of LATP is increased by 15% compared with the undoped sample.

[0071] The mechanical strength is improved, and the comprehensive performance of the material is improved.

[0072] Example 3 (Application of Innovation Point 4)

[0073] Step 1: Prepare the LATP solid powder

[0074] Operate according to steps 1 - 6 of Example 1 to obtain the LATP solid powder sample A.

[0075] Step 2: Prepare the composite electrolyte

[0076] Mix the LATP solid powder and the PEO polymer in a mass ratio of 1:0.15.

[0077] The mechanical mixing method can be used to ensure that the two are fully and evenly mixed.

[0078] Press the mixture into a specific mold to obtain the composite electrolyte sample C.

[0079] Effect:

[0080] The interfacial compatibility of the composite electrolyte is significantly improved, reducing the interfacial resistance.

[0081] The mechanical strength is increased by about 25% compared to pure LATP, enhancing the flexibility and impact resistance of the electrolyte.

[0082] Comparative Example 1 (Traditional Process)

[0083] Step 1: Mix raw materials

[0084] Weigh 68 g of TiO2, 345 g of NH4H2PO4, 2.295 g of Al2O3, and 24 g of Li2CO3.

[0085] Mix the above raw materials evenly to ensure full contact of each component.

[0086] Step 2: Sintering

[0087] Sinter the mixed raw materials at 850 °C in an air atmosphere.

[0088] Gases such as NH3 and CO2 are generated during the sintering process, which may lead to uneven element distribution in the material.

[0089] Step 3: Process to obtain LATP

[0090] After sintering, crush and screen the obtained solid to obtain the solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3 sample D.

[0091] Effect:

[0092] XRD detection shows that there are impurity phases in sample D and the purity is low.

[0093] Both the ionic conductivity and mechanical strength are inferior to the samples prepared by the innovative process.

[0094] Example 4 (Synergistic application of Innovations 1 - 4)

[0095] Step 1: Prepare Ti3(PO4)4 intermediate (Innovation 1)

[0096] Weigh 480 g of TiOSO4 solid particles and dissolve them in 2000 g of deionized water. Add an appropriate amount of H2SO2 to adjust the pH of the solution to 1 - 2, and stir to dissolve to obtain a 1.5 mol / L TiOSO4 aqueous solution.

[0097] Weigh 21 g of NaF solid particles and dissolve them in 1000 g of deionized water, and stir to dissolve to obtain a 0.5 mol / L NaF aqueous solution.

[0098] Measure 274 mL of 85% phosphoric acid solution and dissolve it in 1726 g of deionized water, and stir evenly to obtain an aqueous H3PO4 solution with a concentration of 2 mol / L.

[0099] Add 1000 g of deionized water to the reaction kettle, add an appropriate amount of H2SO4 to adjust the pH to 1 - 2, add 10.5 g of NaF solid particles, turn on the stirrer to mix evenly, and heat the reaction kettle to 50 °C.

[0100] Input the prepared aqueous TiOSO4 solution, aqueous NaF solution, and aqueous H3PO4 solution into the reaction kettle in a co-current manner at a certain flow rate for reaction, and control the molar ratio of F - to TiO 2+ to be 0.1, and keep the reaction temperature at 50 °C.

[0101] After reacting for 20 hours, perform solid-liquid separation on the obtained solid-liquid mixture, wash it with deionized water until the pH of the washing water is neutral, and dry the solid at 110 °C to obtain a Ti3(PO4)4 solid particle sample #4.

[0102] Step 2: Doping treatment (Innovation Point 3)

[0103] Add the precursor solutions of doping elements, such as Mg(NO3)2 and ZrOCl2, to the Ti3(PO4)4 powder. The doping amounts are 1% and 0.5% of the mass of Ti3(PO4)4 respectively. After mixing evenly, dry it.

[0104] Step 3: Sintering to prepare LATP (Innovation Point 2)

[0105] Weigh the doped Ti3(PO4)4 solid powder, AlPO4 solid, and Li3PO4 solid according to the ratio of Li:Ti:Al = 1.4:1.6:0.4, and sinter at 850 °C to obtain the LATP solid powder.

[0106] Step 4: Prepare the composite electrolyte (Innovation Point 4)

[0107] Mix the sintered LATP powder and PEO in a mass ratio of 1:0.15, and prepare the composite electrolyte sample E by mechanical mixing.

[0108] Effect:

[0109] High-purity intermediate: Through the application of Innovation Point 1, the particle size distribution of Ti3(PO4)4 is uniform, and D50 is about 3 μm.

[0110] Doping optimization: After doping with Mg 2+ and Zr 4+ , the ionic conductivity of LATP increases by more than 20%.

[0111] Composite electrolyte performance: After being compounded with PEO, the mechanical strength is increased by 30%, the interfacial compatibility is significantly improved, and the comprehensive performance of the electrolyte is significantly enhanced.

[0112] In summary, the present invention can achieve the following effects: High-purity intermediate: By the synergistic control of the F - / TiO 2+ molar ratio and pH value, the particle size distribution of Ti3(PO4)4 is uniform, and the D50 is about 2 - 4 μm. Doping optimization: After doping with Mg 2+ , Zr 4+ , the ionic conductivity of LATP is increased by 15% - 20%. Composite electrolyte performance: After being compounded with PEO, the mechanical strength is increased by 20% - 30%, and the interfacial compatibility is significantly improved. Purity improvement: By directly sintering Li3PO4 and AlPO4, gas by-products are avoided, and there are no impurity phases in LATP.

[0113] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0114] The above describes the present invention and its implementation manners. Such description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual application is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar ways and embodiments without creative efforts without departing from the purpose of the present invention, they should fall within the protection scope of the present invention.

Claims

1. A preparation method of LATP solid electrolyte, characterized in that The preparation method steps are as follows: S1. Add TiOSO4 to deionized water, mix to obtain an aqueous TiOSO4 solution, add an appropriate amount of H2SO4 to adjust the pH value to 1 - 2, and obtain the aqueous TiOSO4 solution after pH adjustment for standby; S2. Add NaF to deionized water to obtain an aqueous NaF solution for standby; S3. Add H3PO4 to deionized water to obtain an aqueous H3PO4 solution for standby; S4. Add deionized water, NaF, and H2SO4 into a reaction kettle to prepare a mixed bottom aqueous solution. Heat it to 20 - 60 °C, and simultaneously add a TiOSO4 solution, a NaF solution, and a H3PO4 solution into it at a certain flow rate in a co-current manner. Control the molar ratio of F - to TiO 2+ to be 0.05 - 0.

2. React to generate precipitate particles of Ti3(PO4)4. After solid-liquid separation, wash the obtained solid until it is neutral and then dry it to obtain Ti3(PO4)4 solid powder; S5. Add AlPO4 solid and Li3PO4 solid to the Ti3(PO4)4 solid powder, and optionally add the precursor solution of the doping element. The doping amount is 0.5% - 5% of the mass of Ti3(PO4)4. Mix and sinter at 700 - 900 °C. The sintering atmosphere is an air atmosphere. The obtained sintered product is crushed and sieved to obtain the LATP solid electrolyte; S6. Mix the prepared LATP solid electrolyte and the polymer at a mass ratio of 1:0.1 - 1:0.2, and prepare the composite electrolyte by mechanical mixing or solution casting method; The chemical formula of the LATP solid electrolyte described is Li 1+x Al x Ti 2-x (PO4)3, where the range of x is: 0 - 0.

5.

2. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S1, the concentration of the aqueous TiOSO4 solution is 0.1 - 2 mol / L.

3. The preparation method of the LATP solid electrolyte according to claim 1, characterized in that: In step S2, the concentration of the aqueous NaF solution is 0.1 - 1 mol / L.

4. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S3, the concentration of the aqueous H3PO4 solution is 0.1 - 4 mol / L.

5. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S4, the concentration of NaF in the mixed bottom aqueous solution is 0.1 - 0.5 mol / L, and the pH value is 1 - 2.

6. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S4, the amounts of the aqueous TiOSO4 solution and the aqueous H3PO4 solution added simultaneously are in a molar ratio of TiOSO4 to H3PO4 of 3:

4.

7. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S4, the amounts of the aqueous TiOSO4 solution and the aqueous NaF solution added simultaneously are such that the molar ratio of F - / TiO 2+ is 0.05 - 0.

2.

8. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S5, the sintering temperature is 700 - 900 °C, and the sintering atmosphere is an air atmosphere; the purity grades of the AlPO4 solid and the Li3PO4 solid are analytical pure.

9. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S5, the doping element is Mg 2+ , Zr 4+ or one or more of them.

10. The preparation method of the LATP solid electrolyte according to claim 1, wherein: In step S6, the polymer is one or more of PEO and PVDF, and the dosage of the polymer is 10% - 20% of the mass of LATP.

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