A Lithium-Ion Solid-State Electrolyte and a Lithium-Ion Ternary Cathode Material and Their Preparation Methods

Abstract

The present invention relates to a lithium-ion solid electrolyte and a preparation method thereof. The preparation method includes the following steps: dissolving an aqueous thickener in pure water to obtain a colloid and dividing it into two parts; adding a lithium salt, an aluminum salt, and a titanium salt to a part of the colloid, adding an organic chelating agent under a water bath; adding a phosphate solution formed by neutralizing a basic substance A with purified phosphoric acid to the other part of the colloid; then mixing the two parts, and adding a basic substance B to react under stirring in a water bath to obtain a mixed colloidal solution; then raising the temperature and increasing the stirring speed to obtain a suspension; filtering the suspension, washing and drying to obtain an LATP precursor, and calcining and ball-milling the LATP precursor to obtain an LATP powder material. The present invention first uses an aqueous thickener to prepare a colloid and uses the colloid to dissolve soluble salts, and then uses the co-precipitation method to obtain a precipitate in the colloidal liquid phase. The precipitate is finally dried and calcined to obtain LATP, which has the advantages of both the sol-gel method and the co-precipitation method.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a lithium-ion solid electrolyte, a lithium-ion ternary cathode material, and a preparation method thereof. Background Art

[0002] Lithium aluminum titanium phosphate (Li 1+x Al x Ti 2-x (PO4)3, LATP) is a lithium-ion solid electrolyte material with high ionic conductivity (~10 -3 S / cm), excellent chemical and thermodynamic stability, good cathode compatibility, and a wide electrochemical window. At the same time, it has attracted extensive attention due to its extremely low raw material cost and preparation cost, and is considered to be one of the most promising solid electrolytes.

[0003] LATP can be used as a coating agent to coat the surface of the particles of a lithium-ion high-nickel ternary cathode material (NCM, where N, C, and M in NCM respectively refer to three elements of Ni, Co, and Mn. A ternary cathode material in which the Ni element accounts for more than 80% among the three elements of Ni, Co, and Mn is called a ternary high-nickel material). After high-temperature treatment, an LATP-NCM interface layer can be formed. This interface layer can effectively resist the erosion and damage of the electrolyte during the charge and discharge process of the ternary material, and at the same time improve the insertion and extraction rate of lithium ions, thereby improving the cycle performance of the ternary cathode material and the capacity utilization of the material.

[0004] Currently, the synthesis methods of LATP solid electrolytes mainly include the following several types:

[0005] (1) High-temperature solid-phase method. As a typical solid-phase synthesis method for synthesizing inorganic solid electrolytes, this method usually crushes, activates, and homogenizes the required raw materials by ball milling or other mechanical grinding methods, and then performs high-temperature calcination to obtain LATP solid electrolytes. It has the advantages of simple process and large output, but also has the disadvantages of many impurity phases, low degree of nanocrystallization, and low conductivity in the prepared materials.

[0006] (2) Sol-gel method. In the sol-gel method, these raw materials are uniformly mixed in a liquid phase and undergo hydrolysis and condensation chemical reactions to form a stable transparent sol system in the solution. Subsequently, the sol undergoes aging, and the colloidal particles slowly polymerize to form a gel with a three-dimensional network structure that loses fluidity. The gel network is filled with a solvent that has lost fluidity, forming a gel. Finally, the gel is dried, sintered, and solidified to prepare a material with a molecular or even nano-substructure, and the microstructure of LATP can be precisely reconstructed from the atomic / molecular scale. Compared with the high-temperature solid-phase method, LATP solid electrolytes with high nanocrystallinity can be synthesized at a lower sintering temperature. Although the solid-phase synthesis method can prepare materials on a large scale, the LATP solid electrolytes prepared usually have defects and heterophases, greatly reducing their electrochemical performance.

[0007] (3) Co-precipitation method. In addition to the sol-gel method, the co-precipitation method is also often used to precisely control the composition and morphology of the prepared materials. The salts of the required elements are dissolved in pure water to form a solution, and then an alkaline solution is added to the solution to initiate precipitation. By controlling parameters such as pH, stirring rate, and temperature during the reaction process, the morphology and composition of the precipitate are controlled. After filtering the precipitate, it is then calcined at a high temperature. The co-precipitation method has the advantages of a wider range of raw material selection, a large synthesis output, and simple process control compared with the sol-gel method. However, the particle nucleation and growth during the co-precipitation method have the disadvantage that the nucleation and growth rate are too fast to be controlled compared with the sol-gel method. Therefore, the co-precipitation method usually prepares materials with particle sizes between nano and micron levels. Summary of the Invention

[0008] Based on this, the object of the present invention is to provide a lithium-ion solid electrolyte, a lithium-ion ternary cathode material, and their preparation methods to solve the above problems.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention first provides a preparation method of a lithium-ion solid electrolyte, which includes the following steps:

[0011] S1. Dissolve an aqueous thickener in pure water to obtain a colloid, divide the colloid into two parts and denote them as colloid A1 and colloid A2 respectively;

[0012] S2. Add a lithium salt, an aluminum salt, and a titanium salt to the colloid A1, and add an organic chelating agent under a water bath;

[0013] S3. Neutralize an alkaline substance A with purified phosphoric acid to form a phosphate solution and add the phosphate solution to the colloid A2;

[0014] S4. Mix the colloid A1 and the colloid A2, and add the alkaline substance B under stirring in a water bath to adjust the pH to obtain a mixed colloid solution; then raise the temperature and increase the stirring speed to obtain a suspension;

[0015] S5. Filter the suspension, wash and dry it to obtain the LATP precursor, and calcine and ball-mill the LATP precursor to obtain the LATP powder material.

[0016] In the present invention, an aqueous thickener is first used to prepare a colloid and the colloid is used to dissolve soluble salts, and then the coprecipitation method is used to obtain a precipitate in the colloid liquid phase. The precipitate is finally dried and calcined to obtain LATP, which has the advantages of both the sol-gel method and the coprecipitation method. The present invention combines the advantages of the sol-gel method and the coprecipitation method to prepare LATP. An aqueous thickener is used to prepare a colloid. This kind of colloid has a certain viscosity but can also dissolve soluble salts. Different from a conventional aqueous solution, the ions dissolved in it cannot migrate quickly. Therefore, using this kind of colloid for liquid-phase reaction can play a role in controlling the ion reaction rate to control the nucleation rate and growth rate, so as to obtain a nano-level precipitate; this kind of colloid loses its colloid properties under high-speed stirring and heating, and is similar to an aqueous solution and can extract the solids therein through a filtration device.

[0017] As a further improvement of the above solution of the present invention, in step S1, the aqueous thickener is one of hydroxypropyl methylcellulose, hydroxymethylcellulose, sodium hydroxymethylcellulose, carboxymethylcellulose, and sodium carboxymethylcellulose;

[0018] And / or, in the colloid, the mass percentage of the aqueous thickener is 1%-2.5%, and the viscosity of the colloid is 2000-3000 mPa·s.

[0019] As a further improvement of the above solution of the present invention, in step S2, the lithium salt is lithium nitrate or lithium chloride;

[0020] And / or, in step S2, the aluminum salt is aluminum nitrate;

[0021] And / or, in step S2, the titanium salt is one of potassium oxalate titanate, titanium oxalate, and titanium oxysulfate;

[0022] And / or, in step S2, the organic chelating agent is citric acid or oxalic acid;

[0023] And / or, in step S2, the temperature of the water bath is 1-10 °C;

[0024] And / or, in step S2, according to the chemical formula of LATP, Li 1+x Al x Ti 2-x(PO4)3 Calculate the addition amounts of the lithium salt, aluminum salt, and titanium salt, where the concentration of Al element is 0.065 - 0.36 mol / l and 1.3 ≤ x ≤ 1.8;

[0025] And / or, in step S2, the amount of substance of the organic chelating agent is 0.5 - 2 times the total amount of substance of the titanium and aluminum metal ions.

[0026] As a further improvement of the above solution of the present invention, in step S3, the basic substance A is ammonia water, sodium hydroxide, or potassium hydroxide;

[0027] And / or, in step S3, according to the chemical formula of LATP, Li 1+x Al x Ti 2-x (PO4)3 Calculate the addition amount of the phosphate solution, and the concentration of the phosphate solution is 0.15 - 0.6 mol / l.

[0028] As a further improvement of the above solution of the present invention, in step S4, the temperature of the water bath is 1 - 10 °C;

[0029] And / or, in step S4, the basic substance B is ammonia water, sodium hydroxide, or potassium hydroxide;

[0030] And / or, in step S4, the molar concentration of the basic substance B is 0.01 - 1 mol / l, and the pH of the mixed colloidal solution is 6 - 10;

[0031] And / or, in step S4, the stirring speed under the water bath is lower than 60 rpm / min, and the reaction time is 2 - 8 h;

[0032] And / or, in step S4, the temperature increase is to raise the temperature of the mixed colloidal solution to 70 - 90 °C, and the increase in the stirring speed is to increase the stirring speed to not less than 200 rpm / min;

[0033] And / or, in step S4, the viscosity of the suspension is less than 500 mPa·s.

[0034] As a further improvement of the above solution of the present invention, in step S5, the drying temperature is 110 - 180 °C;

[0035] And / or, in step S5, the calcination temperature is 700 - 1100 °C.

[0036] The present invention also provides a lithium-ion solid electrolyte, which is prepared by using the preparation method of the lithium-ion solid electrolyte as described above.

[0037] The present invention also provides a method for preparing a lithium-ion ternary cathode material, which includes the following steps: mixing the lithium-ion solid electrolyte as described above with a ternary high-nickel material, and calcining to obtain a lithium-ion ternary cathode material coated with LATP.

[0038] As a further improvement of the above solution of the present invention, the mass ratio of the LATP powder material to the ternary high-nickel material is 0.2-1.5%;

[0039] And / or, in the ternary high-nickel material, the content ratio of Ni in Ni, Co, and Mn exceeds 80%;

[0040] And / or, the calcination temperature is 550-650 °C.

[0041] The present invention also provides a lithium-ion ternary cathode material, which is prepared by using the method for preparing a lithium-ion ternary cathode material as described above.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention combines the advantages of the sol-gel method and the co-precipitation method to prepare LATP. First, an aqueous thickener is used to prepare a colloid. This colloid has a certain viscosity and can dissolve soluble salts. However, different from a conventional aqueous solution, the ions dissolved in it cannot migrate quickly. Therefore, using this colloid for a liquid-phase reaction can control the ion reaction rate to control the nucleation rate and growth rate, thereby obtaining nano-scale precipitates. And this colloid loses its colloid characteristics under high-speed stirring and heating, and is similar to an aqueous solution and can extract the solids therein through a filtration device; then the co-precipitation method is used to obtain precipitates in the liquid phase, and finally LATP is obtained. The present invention first uses an aqueous thickener to prepare a colloid and uses the colloid to dissolve soluble salts, and then uses the co-precipitation method to obtain precipitates in the colloid liquid phase. The precipitates are dried and calcined to finally obtain LATP, which has the advantages of both the sol-gel method and the co-precipitation method.

[0044] The present invention can control the reaction nucleation and growth process like the sol-gel method, but avoids the processing and manufacturing difficulties brought by the formation of solids in the sol-gel method. It can also obtain precipitates in the liquid phase like the co-precipitation method, but avoids the problem that the reaction nucleation and growth process rate in the liquid phase method is difficult to control. It can prepare the required materials in large quantities in a manner similar to precipitation, washing, and drying in the liquid phase method, and has the advantages of both. Description of the Drawings

[0045] Figure 1 SEM image of the LATP powder material prepared in Example 1;

[0046] Figure 2SEM image of the LATP-coated lithium-ion ternary cathode material prepared in Example 1. Detailed implementation mode

[0047] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0049] Example 1

[0050] This example presents a lithium-ion ternary cathode material, and its preparation method includes the following steps:

[0051] S1. Dissolve hydroxyethyl cellulose in pure water to form an aqueous colloid with a viscosity of 2000 mPa·s, and the mass percentage of hydroxyethyl cellulose in the aqueous colloid is 1.5%; divide the aqueous colloid into two parts and denote them as colloid A1 and colloid A2 respectively.

[0052] S2. Add lithium nitrate, aluminum nitrate, and titanium oxalate to colloid A1. The addition amounts of lithium nitrate, aluminum nitrate, and titanium oxalate satisfy the proportional relationship of each element in the chemical formula Li 2.8 Al 1.8 Ti 0.2 (PO4)3, where the concentration of Al element is 0.144 mol / l, control the solution temperature at 5-6 °C through a water bath, and at the same time add citric acid as an organic chelating agent. The amount of citric acid is 1 times the sum of the amounts of substance of aluminum nitrate and titanium oxalate.

[0053] S3. Neutralize ammonia water and purified phosphoric acid to form an ammonium dihydrogen phosphate solution and add the ammonium dihydrogen phosphate solution to colloid A2. The addition amount of the ammonium dihydrogen phosphate solution satisfies the proportional relationship of each element in the chemical formula Li 2.8 Al 1.8 Ti 0.2 (PO4)3, and the molar concentration of the ammonium dihydrogen phosphate is 0.24 mol / l.

[0054] S4. Slowly add Colloid A2 into Colloid A1, and stir and mix at a low speed of 30 rpm / min. While stirring, add 1 mol / l ammonia water to adjust the pH of the colloid to 7 - 8, so that the metal ions in Colloid A1 react with the phosphate groups in Colloid A2 to form a precipitate. Control the reaction temperature at 5 - 6 °C by means of a water bath. After reacting with low-speed stirring for 6 h, raise the temperature of the reaction solution to 80 °C, and increase the stirring speed to 200 rpm / min. Stir at a high speed to inactivate the thickener, and obtain a suspension with a viscosity lower than 500 mPa·s.

[0055] S5. Filter the suspension, and further wash the obtained solid with pure water. After washing, carry out vacuum drying at 110 °C to obtain the LATP precursor.

[0056] S6. Calcinate the obtained LATP precursor at 800 °C and carry out ball milling to obtain the LATP powder material Li 2.8 Al 1.8 Ti 0.2 (PO4)3.

[0057] S7. Mix the obtained LATP powder material with the ternary high-nickel material (the molar ratio of Ni, Co, and Mn in NCM is 88:7:5) at a mass ratio of 1.5:98.5, and carry out high-speed mixing using a high-speed mixer. Calcinate at 600 °C to obtain the lithium-ion ternary cathode material coated with LATP.

[0058] Figure 1 This is the SEM image of the LATP powder material prepared in step S6 of this example. From Figure 1 it can be seen that the LATP powder material prepared in this example presents highly nano-sized spherical particles, with a particle diameter of 100 - 200 nm. There are some small broken particles among the spherical particles, which are caused by ball milling.

[0059] Figure 2 This is the SEM image of the lithium-ion ternary cathode material coated with LATP prepared in step S7 of this example. From Figure 2 it can be seen that after the LATP prepared in this example is further coated onto the high-nickel ternary material, a relatively dense dark area can be seen on the micron-sized particles of the ternary material in the SEM. This is the two-phase interface region formed on the surface of the micron-sized particles of the ternary material after the nano-sized LATP and the ternary material are calcined and fused. Since the properties of this two-phase interface region are different from those of the pure ternary material, different contrasts are presented in the SEM.

[0060] Example 2

[0061] This example proposes a lithium-ion ternary cathode material, and its preparation method includes the following steps:

[0062] S1. Dissolve hydroxymethyl cellulose in pure water to form an aqueous colloid with a viscosity of 2500 mPa·s. The mass percentage of hydroxymethyl cellulose in the aqueous colloid is 2%. Divide the aqueous colloid into two parts and label them as colloid A1 and colloid A2 respectively.

[0063] S2. Add lithium chloride, aluminum nitrate, and titanium oxysulfate to colloid A1. The addition amounts of lithium chloride, aluminum nitrate, and titanium oxysulfate satisfy the chemical formula of LATP, Li 2.5 Al 1.5 Ti 0.5 (PO4)3, where the molar concentration of Al element is 0.15 mol / l. Control the solution temperature at 3 - 4 °C through a water bath. At the same time, add oxalic acid as an organic chelating agent. The amount of oxalic acid is 1 times the sum of the molar amounts of aluminum nitrate and titanium oxysulfate.

[0064] S3. Neutralize sodium hydroxide with purified phosphoric acid to form a sodium dihydrogen phosphate solution, and add the sodium dihydrogen phosphate solution to colloid A2. The addition amount of the ammonium dihydrogen phosphate solution satisfies the chemical formula of LATP, Li 2.5 Al 1.5 Ti 0.5 (PO4)3. The molar concentration of the sodium dihydrogen phosphate solution is 0.3 mol / l.

[0065] S4. Slowly add colloid A2 to colloid A1, and stir and mix at a low speed of 20 rpm / min. While stirring, add 0.1 mol / l sodium hydroxide to adjust the pH of the colloid to 8 - 9, so that the metal ions in A1 react with the phosphate radicals in colloid A2 to form a precipitate. Control the reaction temperature at 3 - 4 °C through a water bath. After reacting with low-speed stirring for 4 h, raise the temperature of the reaction solution to 90 °C, and increase the stirring speed to 300 rpm / min. Stir at a high speed to inactivate the thickener, and obtain a suspension with a viscosity lower than 500 mPa·s.

[0066] S5. Filter the suspension, and further wash the obtained solid matter with pure water. After washing, carry out vacuum drying at 150 °C to obtain the LATP precursor.

[0067] S6. High-temperature calcine the obtained LATP precursor at 900 °C and carry out ball milling to obtain the LATP powder material Li 2.5 Al 1.5 Ti 0.5 (PO4)3.

[0068] S7. Mix the obtained LATP powder material with a ternary high-nickel material (the molar ratio of Ni, Co, and Mn in NCM is 88:7:5) at a mass ratio of 1:99, and perform high-speed mixing using a high-speed mixer, and calcine at 620 °C to obtain a lithium-ion ternary cathode material coated with LATP.

[0069] Example 3

[0070] This example presents a lithium-ion ternary cathode material, and its preparation method includes the following steps:

[0071] S1. Dissolve hydroxymethyl cellulose in pure water to form an aqueous colloid with a viscosity of 3000 mPa·s, and the mass percentage of hydroxymethyl cellulose in the aqueous colloid is 2.5%; divide the aqueous colloid into two parts and record them as colloid A1 and colloid A2 respectively.

[0072] S2. Add lithium sulfate, aluminum chloride, and potassium titanyl oxalate to colloid A1. The addition amounts of lithium sulfate, aluminum chloride, and potassium titanyl oxalate satisfy the chemical formula of LATP, Li 2.3 Al 1.3 Ti 0.7 (PO4)3 ratio, where the molar concentration of Al element is 0.156 mol / l, control the solution temperature at 1-2 °C through a water bath, and at the same time add citric acid and oxalic acid as (1:1) organic chelating agents. The amount of citric acid is 1 times the sum of the amounts of aluminum chloride and potassium titanyl oxalate.

[0073] S3. Neutralize sodium hydroxide with purified phosphoric acid to form a potassium dihydrogen phosphate salt solution, and add the potassium dihydrogen phosphate salt solution to colloid A2. The addition amount of the ammonium dihydrogen phosphate salt solution satisfies the chemical formula of LATP, Li 2.3 Al 1.3 Ti 0.7 (PO4)3, and the molar concentration of the potassium dihydrogen phosphate salt solution is 0.36 mol / l.

[0074] S4. Slowly add colloid A2 to colloid A1, and stir and mix at a low speed of 40 rpm / min. While stirring, add a 0.1 mol / l potassium hydroxide solution to adjust the pH of the colloid to 9-10, so that the metal ions in A1 react with the phosphate radicals in colloid A2 to form a precipitate, and control the reaction temperature at 1-2 °C through a water bath method. After low-speed stirring and mixing for 2 h, raise the temperature of the reaction solution to 95 °C, and increase the stirring speed to 600 rpm / min to inactivate the thickener, obtaining a suspension with a viscosity lower than 500 mPa·s.

[0075] S5. Filter the suspension, and further wash the obtained solid matter with pure water. After washing, perform heating and vacuum drying at 160 °C to obtain an LATP precursor.

[0076] S6. The obtained LATP precursor is calcined at 1000 °C and ball-milled to obtain the LATP powder material Li 2.3 Al 1.3 Ti 0.7 (PO4)3.

[0077] S7. The obtained LATP powder material and the ternary high-nickel material (the molar ratio of Ni, Co, and Mn in NCM is 88:7:5) are mixed at a mass ratio of 0.5:99.5 using a high-speed mixer and calcined at 650 °C to obtain the lithium-ion ternary cathode material coated with LATP.

[0078] Comparative Example

[0079] The lithium-ion ternary cathode material of this comparative example uses an uncoated ternary high-nickel material (the molar ratio of Ni, Co, and Mn in NCM is 88:7:5).

[0080] Test Example

[0081] The lithium-ion ternary cathode materials of Examples 1-3 and the comparative example are used to prepare batteries. The preparation method of the batteries is as follows: (1) The high-nickel ternary cathode material coated with LATP and conductive carbon black are ground and mixed evenly to obtain a mixed powder. The binder PVDF is dissolved in NMP to form a colloid, and then the mixed powder is added to the colloid and stirred evenly to form a slurry with good fluidity. Among them, by mass ratio, the high-nickel ternary cathode material coated with LATP: conductive carbon black: PVDF = 8:1:1; (2) The slurry is coated on the aluminum foil to form a positive electrode sheet; (3) The positive electrode sheet is dried to remove the solvent in the slurry, and then punched to obtain a circular sheet required for coin cell testing; (4) The positive electrode sheet, separator, and lithium metal negative electrode are assembled into a coin cell.

[0082] The prepared batteries are subjected to performance tests, and the test results are shown in Table 1.

[0083] Table 1 Test Results of Battery Performance

[0084]

[0085] It can be seen from the results in Table 1 that:

[0086] After coating the high-nickel ternary cathode material with LATP prepared in this example, not only the charge-discharge capacity of the material is increased. This is because the surface coating layer of LATP increases the ionic conductivity of the material, and lithium ions can migrate rapidly through the coating layer during the charge-discharge process. In addition, the coating layer has better chemical stability to the electrolyte and can better protect the structural stability of the internal material during the cycling process, thereby improving the cycle retention rate.

[0087] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the various technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0088] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of a lithium-ion solid electrolyte, characterized in that, It includes the following steps: S1. Dissolve the aqueous thickener in pure water to obtain a colloid, divide the colloid into two parts and record them as colloid A1 and colloid A2 respectively; S2. Add lithium salt, aluminum salt, and titanium salt to the colloid A1, and add an organic chelating agent under a water bath; S3. Neutralize the basic substance A with purified phosphoric acid to form a phosphate solution and add the phosphate solution to the colloid A2; S4. Mix the colloid A1 and the colloid A2, and add the basic substance B under stirring in a water bath to adjust the pH to obtain a mixed colloidal solution; Then increase the temperature and the stirring speed to obtain a suspension; S5. Filter the suspension, wash and dry it to obtain an LATP precursor, and calcine and ball-mill the LATP precursor to obtain a lithium-ion solid electrolyte.

2. The preparation method of the lithium-ion solid electrolyte according to claim 1, characterized in that In step S1, the aqueous thickener is one of hydroxypropyl methylcellulose, hydroxymethylcellulose, sodium hydroxymethylcellulose, carboxymethylcellulose, and sodium carboxymethylcellulose; And / or, in the colloid, the mass percentage of the aqueous thickener is 1%-2.5%, and the viscosity of the colloid is 2000-3000 mPa·s.

3. The preparation method of the lithium ion solid electrolyte according to claim 1, wherein, In step S2, the lithium salt is lithium nitrate or lithium chloride; And / or, in step S2, the aluminum salt is aluminum nitrate; And / or, in step S2, the titanium salt is one of potassium oxalotitanate, oxalic acid titanium, and titanium oxysulfate; And / or, in step S2, the organic chelating agent is citric acid or oxalic acid; And / or, in step S2, the temperature of the water bath is 1-10°C; And / or, in step S2, according to the chemical formula of LATP, Li 1+x Al x Ti 2-x (PO4)3, calculate the addition amounts of the lithium salt, aluminum salt, and titanium salt, where the concentration range of the Al element is 0.065 - 0.36 mol / l, and 1.3 ≤ x ≤ 1.8; And / or, in step S2, the amount of substance of the organic chelating agent is 0.5-2 times the total amount of substance of titanium and aluminum metal ions.

4. The preparation method of the lithium-ion solid electrolyte according to claim 1, wherein, In step S3, the basic substance A is ammonia water, sodium hydroxide, or potassium hydroxide; And / or, in step S3, according to the chemical formula of LATP, Li 1+x Al x Ti 2-x (PO4)3, calculate the addition amount of the phosphate solution, and the concentration of the phosphate solution is 0.15 - 0.6 mol / l.

5. The preparation method of the lithium-ion solid electrolyte according to claim 1, wherein, In step S4, the temperature of the water bath is 1-10°C; And / or, in step S4, the basic substance B is ammonia water, sodium hydroxide, or potassium hydroxide; And / or, in step S4, the molar concentration of the basic substance B is 0.01-1 mol / l, and the pH of the mixed colloidal solution is 6-10; And / or, in step S4, the stirring speed under the water bath is lower than 60 rpm / min, and the reaction time is 2-8 h; And / or, in step S4, the temperature increase is to raise the temperature of the mixed colloidal solution to 70-90°C, and the increase in the stirring speed is to increase the stirring speed to not less than 200 rpm / min; And / or, in step S4, the viscosity of the suspension is less than 500 mPa·s.

6. The preparation method of the lithium-ion solid electrolyte according to claim 1, wherein In step S5, the drying temperature is 110-180°C; And / or, in step S5, the calcination temperature is 700-1100°C.

7. A lithium-ion solid electrolyte, characterized in that, It is prepared by using the preparation method of the lithium-ion solid electrolyte according to any one of claims 1-6.

8. A preparation method of a lithium-ion ternary cathode material, characterized in that, It includes the following steps: Mix the lithium-ion solid electrolyte according to claim 7 with a ternary high-nickel material, and calcine to obtain an LATP-coated lithium-ion ternary cathode material.

9. The preparation method of the ternary cathode material for lithium ion according to claim 8, wherein, The mass ratio of the LATP powder material to the ternary high-nickel material is 0.2-1.5%; And / or, in the ternary high-nickel material, the content ratio of Ni in Ni, Co, and Mn exceeds 80%; And / or, the calcination temperature is 550-650 °C.

10. A lithium-ion ternary cathode material, characterized in that, It is prepared by using the preparation method of the lithium-ion ternary cathode material according to any one of claims 8-9.

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