Solvent-free high-temperature electrolyte material for lithium battery and preparation method of solvent-free high-temperature electrolyte material

Abstract

The invention belongs to the field of new energy, particularly relates to a solvent-free high-temperature electrolyte material for a lithium battery and a preparation method of the solvent-free high-temperature electrolyte material, and particularly relates to a solvent-free high-temperature electrolyte material obtained by mixing solvent-free fluid aluminum oxide and lithium salt. The solvent-free high-temperature electrolyte material is obtained by mixing solvent-free fluid aluminum oxide and lithium salt according to the ratio of ether bonds (EO) to lithium ions (EO: Li < + >) of (4-32): 1. The solvent-free fluid aluminum oxide provided by the invention has good fluidity in a high-temperature environment, and can well infiltrate the surface of an electrode and reduce the interface resistance, and a long chain of a canopy of the solvent-free fluid aluminum oxide has rich ether bonds, so that lithium ions can freely move in the canopy of the solvent-free fluid; long chains on the surfaces of the particles are mutually entangled and staggered to form a lithium ion migration channel, so that lithium ions can be transmitted among different solvent particles and move along with macroscopic movement of solvent-free fluid.

Description

Technical Field

[0001] This application belongs to the field of new energy, especially in the field of lithium batteries. Specifically, it is a solvent-free high-temperature electrolyte material for lithium batteries and its preparation method. Background Art

[0002] The emergence of lithium batteries has changed the energy structure and energy storage method to a certain extent. However, due to material limitations, lithium batteries have strict requirements for operating temperature. The thermal runaway behavior of lithium battery electrolytes, electrode materials, and battery separators severely restricts the application of lithium batteries in high-temperature environments.

[0003] Traditional liquid organic electrolytes use ethers or esters as solvents, which have good interfacial wettability and high ionic conductivity. However, the organic electrolyte is prone to side reactions with electrode materials, causing lithium battery swelling and leakage. Moreover, the flammability of the organic electrolyte makes lithium batteries more likely to explode and catch fire, posing a greater safety hazard.

[0004] As a substitute for traditional liquid electrolytes, solid-state ceramic-based electrolytes have good high-temperature stability and flame retardancy, overcoming the disadvantages of flammability and easy leakage of liquid electrolytes. However, their poor interfacial contact and low ionic conductivity are the key factors hindering the commercial application of solid-state ceramic-based electrolytes.

[0005] To broaden the operating temperature of lithium batteries and improve their safety, the present invention aims to provide a solvent-free high-temperature electrolyte material for lithium batteries. Based on the use of nanoparticles with a specific structure as a solvent, it effectively overcomes the problems of easy leakage and flammability of ether and ester organic solvents at high temperatures. Moreover, this electrolyte material has good fluidity at high temperatures, can infiltrate electrode materials, and improve ionic conductivity, showing broad application prospects in the field of lithium battery materials. Summary of the Invention

[0006] Aiming at the related defects in lithium battery-related materials in the prior art, especially the safety hazards caused by electrolyte defects, the present invention intends to provide a solvent-free high-temperature electrolyte material for lithium batteries and its preparation method to solve the above problems.

[0007] Furthermore, the concept of the present invention is that the high-temperature electrolyte material includes a solvent-free fluid and lithium ions. The solvent-free fluid aluminum trioxide is aluminum trioxide (Al 2 O 3 ) modified with an ether-containing surfactant.

[0008] Furthermore, another concept of the present invention is to provide a preparation method of solvent-free fluid aluminum trioxide. By surface-modifying aluminum trioxide and grafting a surfactant with an ether bond, and then separating, solvent-free fluid aluminum trioxide is obtained.

[0009] Specifically, to achieve the above concept, the present invention provides a method for preparing solvent-free fluid aluminum oxide, comprising the following steps:

[0010] 1. Dispersion of aluminum oxide;

[0011] Disperse aluminum oxide in water and adjust the pH to 9-11 to obtain an aluminum oxide dispersion;

[0012] 2. Surface modification of aluminum oxide;

[0013] Dropwise add a silicone quaternary ammonium salt surfactant to the aluminum oxide dispersion obtained in step 1 to perform surface modification on the aluminum oxide;

[0014] 3. Collection of modified aluminum oxide

[0015] Wash the aluminum oxide surface modification solution prepared in step 2, and collect the precipitate and dry it.

[0016] 4. Etherification modification of aluminum oxide

[0017] Add a surfactant with an ether bond to the precipitate obtained in step 3, disperse, react, and evaporate the solvent to obtain solvent-free fluid aluminum oxide.

[0018] Further, the aluminum oxide in step 1 is aluminum oxide after etching;

[0019] In step 1, the pH is adjusted to 9-11 with ammonia water;

[0020] The proportion of aluminum oxide in the aluminum oxide dispersion is 2-5%, preferably 3-4%;

[0021] The ultrasonic dispersion operation is also included in step 1;

[0022] Further, the silicone quaternary ammonium salt surfactant added in step 2 is DC5700;

[0023] In step 2, the silicone quaternary ammonium salt surfactant is dispersed in a methanol solvent;

[0024] The concentration of the methanol solution of the silicone quaternary ammonium salt surfactant in step 2 is 1-4%;

[0025] The time for surface modification of aluminum oxide in step 2 is 10-48h; preferably 15-36h.

[0026] Further, in step 3, the washing operation is to use water washing and ethanol washing;

[0027] Further, in step 4, the number of ether bonds in the molecular chain of the surfactant with an ether bond is 15 - 70, and preferably the number of ether bonds in the molecular chain is 20 - 70;

[0028] Further, the surfactant with an ether bond in step 4 is NPES;

[0029] Among them, the dosage of NPES is 3 - 5 times that of the aluminum oxide raw material, and preferably 4 times;

[0030] Further, an organic solvent is added in step 4; the organic solvent is chloroform; the addition amount of the organic solvent is 15 - 25 times that of aluminum oxide;

[0031] The reaction time in step 4 is 10 - 48 h; preferably 15 - 36 h.

[0032] In some other embodiments, the present invention further includes a purification process for the solvent - free fluid aluminum oxide obtained in step 4, and the purification process includes

[0033] S1. Add the solvent - free fluid aluminum oxide obtained in step 4 to an organic solvent for dispersion, centrifuge and take the supernatant, and then dry the solvent to obtain the first - purified solvent - free fluid aluminum oxide;

[0034] The organic solvent in step S1 is tetrahydrofuran; the dosage of tetrahydrofuran is 15 - 25 times;

[0035] S2. Add an organic solvent to dissolve the first - purified solvent - free fluid aluminum oxide obtained in step S1, then add deionized water for layering, and take the lower - layer liquid to obtain the second - purified solvent - free fluid aluminum oxide.

[0036] Among them, the chloroform in step S2 is chloroform, and the dosage of chloroform is 30 - 50 times that of aluminum oxide;

[0037] The dosage of water added in step S2 is 12 - 25 times that of aluminum oxide

[0038] S3. Add deionized water to the second - purified solvent - free fluid aluminum oxide obtained in step S2 for further extraction, and evaporate the collected mixture to dryness to obtain the purified solvent - free fluid aluminum oxide.

[0039] In another embodiment, the present invention further provides a solvent - free high - temperature electrolyte material, and the solvent - free high - temperature electrolyte material is prepared from a solvent - free fluid and a lithium salt according to the ratio of ether bonds (EO) to lithium ions (EO:Li +)Mix them in a ratio of (4 - 32:1) to obtain a solvent-free high-temperature electrolyte material for lithium batteries.

[0040] It should be noted that the number of ether bonds in the solvent-free fluid aluminum trioxide is determined according to the number of ether bonds in NPES. In the present invention, NPES with different numbers of ether bonds can be used to adjust the number of ether bonds in the solvent-free fluid aluminum trioxide. For example, the reagent used is NPES-50, that is, there are 50 ether bonds on one NPES long chain. In addition, in the solvent-free fluid aluminum trioxide, the mass of NPES accounts for the vast majority of the solvent-free fluid aluminum trioxide, while the proportion of aluminum trioxide is relatively small. Therefore, in the present invention, the molar amount of NPES is calculated based on the mass of the solvent-free fluid aluminum trioxide and the molecular weight of NPES, and then the number of ether bonds in the solvent-free fluid aluminum trioxide is determined, so as to further determine the ratio of ether bonds (EO) to lithium ions (EO:Li+) as (4 - 32:1) for mixing.

[0041] In another embodiment, the present invention also provides a lithium battery that uses the aforementioned solvent-free high-temperature electrolyte material.

[0042] Compared with the prior art, the present invention provides a solvent-free fluid aluminum trioxide and its preparation method, and a solvent-free high-temperature electrolyte material is obtained by mixing the solvent-free fluid aluminum trioxide with a lithium salt. The solvent-free fluid prepared by the present invention has good fluidity in a high-temperature environment, can better wet the electrode surface, and reduce the interfacial resistance. The long chain of the solvent-free fluid crown layer has abundant ether bonds, enabling lithium ions to move freely in the solvent-free fluid crown layer. Since the long chains on the particle surface are entangled and interlaced with each other, forming a lithium ion migration channel, lithium ions can be transmitted between different solvent particles and move along with the macroscopic movement of the solvent-free fluid. Description of the Drawings

[0043] Figure 1 It is a diagram showing the influence of the EO:Li+ ratio on the performance of the electrolyte;

[0044] Figure 2 It is a diagram showing the influence of the ambient temperature on the performance of the electrolyte. Detailed Embodiments

[0045] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the following will describe the present disclosure in detail, clearly, and completely with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not used to limit the present disclosure.

[0046] The present invention provides a preparation method for a solvent-free fluid aluminum trioxide, including the following steps:

[0047] 1. Dispersion of aluminum oxide;

[0048] Disperse aluminum oxide in water and adjust the pH to 9 - 11 to obtain an aluminum oxide dispersion;

[0049] Among them, the aluminum oxide is an etched aluminum oxide powder. The etched aluminum oxide powder has a rougher surface and an increased specific surface area, enabling more sites for the attachment and linkage of surfactants to modify inorganic particles;

[0050] Furthermore, the proportion of aluminum oxide in the aluminum oxide dispersion is 2 - 5%, preferably 3 - 4%, for example, it can be 2%, 3%, 4%;

[0051] Specific operations can be as follows: Take 3 g of etched Al 2 O 3 Put it in 80 mL of deionized water, and ultrasonicate for 30 min at 30 °C to form a homogeneous Al 2 O 3 dispersion, and adjust the pH to 10 with ammonia water.

[0052] 2. Surface modification of aluminum oxide;

[0053] Dropwise add an organosilicon quaternary ammonium salt surfactant to the aluminum oxide dispersion obtained in step 1 to perform surface modification on aluminum oxide;

[0054] Among them, in the present invention, an organosilicon surfactant is further used to adjust the interface of the aluminum oxide surface layer. Organosilicon can further increase the dispersion of aluminum oxide and prevent deposition. At the same time, the quaternary ammonium salt surfactant belongs to an ionic surfactant and can have various bonding effects with aluminum oxide.

[0055] Furthermore, the organosilicon quaternary ammonium salt surfactant added in step 2 is DC5700;

[0056] The organosilicon quaternary ammonium salt surfactant in step 2 is dispersed in a methanol solvent;

[0057] The concentration of the methanol solution of the organosilicon quaternary ammonium salt surfactant in step 2 is 1 - 4%, for example, it can be 1%, 2%, 4%;

[0058] The time for surface modification of aluminum oxide in step 2 is 10 - 48 h; preferably 15 - 36 h, for example, it can be 15 h, 24 h, 30 h.

[0059] Specifically, 2.81 g of DC5700 was poured into 14.05 g of methanol for dilution to obtain a DC5700 methanol solution. Then, the DC5700 methanol solution was slowly added dropwise to the Al 2 O 3 dispersion obtained in Step 1, and the mixture was shaken and stirred at 35 °C for 24 h to complete the reaction.

[0060] 3. Collection of modified aluminum oxide

[0061] The aluminum oxide surface modification solution prepared in Step 2 was washed, and the precipitate was collected and dried.

[0062] During the collection of the modified aluminum oxide, since the organosilicon surfactant is not guaranteed to be completely bound to the surface layer of aluminum oxide, a washing process is required to remove the solvent and surfactant. In the present invention, water and ethanol were used to wash the product obtained in Step 2.

[0063] Furthermore, in Step 3, the washing operation was performed using water washing and ethanol washing;

[0064] Furthermore, the number of washing times can be adjusted as needed.

[0065] Specifically, the operation in Step 3 was to wash the mixture after the reaction in Step 2 three times with deionized water and twice with ethanol, and the precipitate was collected. The precipitate was dried in a vacuum oven at 60 °C for 24 h to make it completely dry, and the washed precipitate was obtained.

[0066] 4. Etherification modification of aluminum oxide

[0067] A surfactant with an ether bond was added to the precipitate obtained in Step 3, dispersed, reacted, and the solvent was evaporated to obtain solvent-free fluid aluminum oxide.

[0068] Furthermore, in Step 4, the number of ether bonds in the molecular chain of the surfactant with an ether bond was 15 - 70, and preferably the number of ether bonds in the molecular chain was 20 - 70;

[0069] Furthermore, in Step 4, the surfactant with an ether bond was sodium bis(hexadecyl) polyoxyethylene ether sulfate (NPES);

[0070] Among them, the dosage of NPES was 3 - 5 times that of the aluminum oxide raw material, and preferably 4 times;

[0071] Furthermore, in Step 4, an organic solvent was also added; the organic solvent was chloroform; the addition amount of the organic solvent was 15 - 25 times that of the aluminum oxide;

[0072] In step 4 described above, the reaction time is 10 - 48 h; preferably 15 - 36 h.

[0073] Specifically, the operation of step 4 is to add 12.26 g of NPES and 50 mL of chloroform to the washed precipitate obtained in step 3, ultrasonically dissolve it, and then stir and react at 35 °C for 24 h. After the reaction is completed, the solvent is evaporated to dryness and the precipitate is collected.

[0074] Aluminum oxide was modified by the method of steps 1 - 4 above. The surface of aluminum oxide was bonded with an organosilicon surfactant and a surfactant with an ether bond, which changed the physical form of aluminum oxide and presented a fluid state under solvent-free conditions, achieving a better wetting effect.

[0075] However, since the final product was not purified in the process of preparing the solvent-free fluid aluminum oxide in steps 1 - 4, the present invention further provides a purification process for the solvent-free fluid aluminum oxide. The purification process includes,

[0076] S1. Add the solvent-free fluid aluminum oxide obtained in step 4 to an organic solvent for dispersion, centrifuge and take the supernatant, and then dry the solvent to obtain the first purified solvent-free fluid aluminum oxide;

[0077] The organic solvent in step S1 is tetrahydrofuran; the dosage of tetrahydrofuran is 15 - 25 times;

[0078] S2. Add an organic solvent to dissolve the first purified solvent-free fluid aluminum oxide obtained in step S1, then add deionized water for layering, and take the lower layer liquid to obtain the second purified solvent-free fluid aluminum oxide.

[0079] Among them, the chloroform in step S2 is chloroform, and the dosage of chloroform is 30 - 50 times that of aluminum oxide;

[0080] The dosage of water added in step S2 is 12 - 25 times that of aluminum oxide

[0081] S3. Add deionized water to the second purified solvent-free fluid aluminum oxide obtained in step S2 for further extraction, and evaporate the collected mixture to dryness to obtain the purified solvent-free fluid aluminum oxide.

[0082] In another embodiment, the present invention also provides a solvent-free high-temperature electrolyte material. The solvent-free high-temperature electrolyte material is prepared by mixing a solvent-free fluid and a lithium salt in a ratio of ether bond (EO) to lithium ion (EO:Li+) of (4 - 32:1) to obtain a solvent-free high-temperature electrolyte material that can be used in lithium batteries.

[0083] In another embodiment, the present invention also provides a lithium battery that uses the solvent-free high-temperature electrolyte material provided above.

[0084] Specifically, the present invention provides the following specific embodiments

[0085] Example 1

[0086] According to the above-mentioned purification method of solvent-free fluid aluminum oxide, the present invention prepared a solvent-free fluid aluminum oxide, and the specific steps are as follows:

[0087] Step 1: Take 3 g of etched Al 2 O 3 and place it in 80 mL of deionized water. Ultrasonic for 30 min at 30 °C to form a homogeneous Al 2 O 3 dispersion. Adjust the pH to 10 with ammonia water.

[0088] Step 2: Pour 2.81 g of DC5700 into 14.05 g of methanol for dilution to obtain a DC5700 methanol solution. Then slowly add the DC5700 methanol solution drop by drop to the Al 2 O 3 dispersion, and stir it oscillatingly at 35 °C for 24 h to complete the reaction.

[0089] Step 3: Wash the above-mentioned reaction-completed mixture three times with deionized water and twice with ethanol, and collect the precipitate. Place the precipitate in a vacuum oven at 60 °C for 24 h to dry it completely.

[0090] Step 4: Add 12.26 g of NPES and 50 mL of chloroform to the above-mentioned precipitate, ultrasonically dissolve it, and then stir and react at 35 °C for 24 h. After the reaction is completed, evaporate the solvent and collect the precipitate.

[0091] Step 5: Add 50 mL of tetrahydrofuran to the precipitate collected in the previous step, ultrasonically stir to form a dispersion, centrifuge the dispersion at a speed of 10000 r / min for 10 min, repeat centrifugation three times, take the supernatant, and then evaporate the solvent at 60 °C.

[0092] Step 6: First add 100 mL of chloroform to the product of the previous step and ultrasonically dissolve it; then add 40 mL of deionized water to it, stir evenly for 2 h, let it stand, wait for it to layer, and take the lower layer liquid.

[0093] Step 7: Extraction. Use 40 mL of deionized water to extract the mixture obtained in the previous step (extract twice); after the extraction is completed, evaporate the collected mixture to obtain the solvent-free fluid aluminum oxide.

[0094] Example 2

[0095] A solvent-free high-temperature electrolyte material for lithium batteries, and the preparation method is carried out according to the following steps:

[0096] Mix the above solvent-free fluid aluminum oxide and lithium salt (LiTFSI) in a ratio of ether bond to lithium ion (EO:Li + ) of 4:1, 8:1, 16:1, 24:1, 32:1, add an equal volume of ethylene glycol dimethyl ether for dilution, stir at 100 rpm for 1 h to obtain a homogeneous dispersion; take 400 μL of the dispersion and drop it into a glass fiber separator with a diameter of 12 mm and a thickness of 435 μm, let it stand for 10 min, put it into a vacuum drying oven at 60 °C, and vacuum dry for 24 h to remove the diluent ethylene glycol dimethyl ether to obtain a solvent-free high-temperature electrolyte; in the glove box, assemble it into a 2016-type button battery in the order of positive electrode, electrolyte, negative electrode, and gasket. The test results of the above 5 kinds of solvent-free high-temperature electrolytes with different ratios are as follows:

[0097] Table 1 Ionic conductivity of solvent-free high-temperature electrolytes with different ratios at 120 °C

[0098] <![CDATA[Ratio (EO:Li + )]]> 4:1 8:1 16:1 24:1 32:1 R (Ω) 42.07 28.77 7.32 31.28 57.41 σ (S / cm) <![CDATA[5.28*10 -4 > <![CDATA[7.72*10 -4 > <![CDATA[3.03*10 -3 > <![CDATA[7.10*10 -4 > <![CDATA[3.85*10 -4 >

[0099] Table 2 EO:Li + Ionic conductivity of the solvent-free high-temperature electrolyte with EO:Li

[0100] Temperature (°C) 40 60 80 100 120 R (Ω) 67.92 17.3 10.11 7.35 5.16 σ (S / cm) <![CDATA[3.27*10 -4 > <![CDATA[1.28*10 -3 > <![CDATA[2.20*10 -3 > <![CDATA[3.02*10 -3 > <![CDATA[4.30*10 -3 >

[0101] Table 2 EO:Li + Ionic conductivity of the solvent-free high-temperature electrolyte with EO:Li

[0102] After testing, the ratio of EO:Li + and temperature are the key factors affecting the performance of this electrolyte.

[0103] As can be seen from Table 1, at 120 °C, after testing 5 kinds of solvent-free high-temperature electrolytes with different ratios, when EO:Li+ = 16:1, the internal resistance of this solvent-free electrolyte is the smallest, which is 7.32 Ω. After calculation, the ionic conductivity is 3.03*10 - 3 Scm -1 , meeting the usage requirements of commercial electrolytes.

[0104] At different temperatures, measure EO:Li +A solvent-free high-temperature electrolyte with a ratio of EO:Li of 16:1 was prepared, and the measurement results are shown in Table 2. The ionic conductivity of this electrolyte decreases with the increase of temperature. When the test temperature is 120 °C, the internal resistance of the electrolyte is 5.16 Ω, and the ionic conductivity is 4.30*10 -3 Scm -1 .

[0105] Five different ratios of solvent-free high-temperature electrolytes were assembled into 2016-type button batteries with a positive electrode (lithium iron phosphate) and a negative electrode (lithium sheet) in the order of positive electrode, electrolyte, negative electrode, and gasket. The 100-cycle charge-discharge performance test was carried out on them, and the test results are as follows:

[0106] It can be seen from Figure 1 and Figure 2 that for the solvent-free high-temperature electrolyte prepared by the above method, the ratio of EO:Li + and the ambient temperature have a greater impact on the performance of this electrolyte, which is mainly manifested in the charge-discharge capacity and capacity retention rate.

[0107] It should be noted that in the case where the embodiments of the present application do not conflict with each other and the technical solutions can coexist, they can be arbitrarily combined into new embodiments.

[0108] The above has introduced the present application in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the present application and its core idea. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing solvent-free fluid aluminum oxide, characterized in that: The steps include: Step 1, dispersion of aluminum oxide; Dispersing aluminum oxide in water and adjusting the pH to 9-11 to obtain an aluminum oxide dispersion; Step 2, surface modification of aluminum oxide; Adding a quaternary ammonium salt surfactant containing organic silicon to the aluminum oxide dispersion obtained in step 1 to modify the surface of the aluminum oxide; Step 3: Collection of surface modified aluminum oxide The aluminum oxide surface modification solution prepared in step 2 is washed, and the precipitate is collected and dried; Step 4: Etherification modification of aluminum oxide A surfactant having an ether bond is added to the precipitate obtained in step 3, dispersed, reacted, and the solvent is evaporated to obtain solvent-free fluid aluminum oxide.

2. The method for preparing the solvent-free fluid aluminum oxide according to claim 1, characterized in that: The aluminum oxide in step 1 is aluminum oxide that has been etched; In the step 1, the pH is adjusted to 9-11 by using ammonia water; The proportion of aluminum oxide in the aluminum oxide dispersion is 2-5%, preferably 3-4%; The step 1 also includes an ultrasonic dispersion operation.

3. The method for preparing the solvent-free fluid aluminum oxide according to claim 1, characterized in that: The organosilicon quaternary ammonium salt surfactant added in step 2 is DC5700; In the step 2, the organosilicon quaternary ammonium salt surfactant is dispersed in the methanol solvent; The concentration of the methanol solution of the organosilicon quaternary ammonium salt surfactant in step 2 is 1-4%; The time for surface modification of aluminum oxide in step 2 is 10-48 hours, preferably 15-36 hours.

4. The method for preparing the solvent-free fluid aluminum oxide according to claim 1, characterized in that: In the step 4, the number of ether bonds in the molecular chain of the surfactant having ether bonds is 15-70, and preferably the number of ether bonds in the molecular chain is 20-70.

5. The method for preparing solvent-free fluid aluminum oxide according to claim 4, characterized in that: The surfactant having an ether bond in step 4 is NPES; The dosage of NPES is 3-5 times of the aluminum oxide raw material, preferably 4 times.

6. The method for preparing solvent-free fluid aluminum oxide according to claim 5, characterized in that: In step 4, an organic solvent is further added; the organic solvent is chloroform; the amount of the organic solvent added is 15-25 times that of aluminum oxide; The reaction time in step 4 is 10-48h; preferably 15-36h.

7. The method for preparing the solvent-free fluid aluminum oxide according to any one of claims 1 to 6, characterized in that: The solvent-free fluid aluminum oxide obtained in step 4 also includes a purification process, and the purification process includes the following steps: S1, adding an organic solvent to the solvent-free fluid aluminum oxide obtained in step 4 to disperse it, centrifuging it and taking the supernatant, and then drying the solvent to obtain the first purified solvent-free fluid aluminum oxide; The organic solvent in step S1 is tetrahydrofuran; the amount of tetrahydrofuran is 15-25 times; S2, adding an organic solvent to the first purified solvent-free fluid aluminum oxide obtained in step S1 to dissolve it, then adding deionized water to separate the layers, and taking the lower layer of liquid to obtain the second purified solvent-free fluid aluminum oxide; The chloroform in step S2 is chloroform, and the amount of chloroform is 30-50 times that of aluminum oxide; The amount of water added in step S2 is 12-25 times that of aluminum oxide. S3. Deionized water is added to the second purified solvent-free fluid aluminum oxide obtained in step S2 for further extraction, and the collected mixed solution is evaporated to dryness to obtain purified solvent-free fluid aluminum oxide.

8. A solvent-free fluid aluminum oxide, characterized in that Obtained using the preparation method according to any one of claims 1 to 7.

9. A solvent-free high-temperature electrolyte material, characterized in that: Using the solvent-free fluid aluminum oxide as described in claim 8, the solvent-free high-temperature electrolyte material is prepared by mixing the solvent-free fluid aluminum oxide with a lithium salt in a ratio of ether bond (EO) to lithium ion (EO:Li+) of 4 to 32:1 to obtain a solvent-free high-temperature electrolyte material that can be used in lithium batteries.

10. A lithium battery, characterized in that: Use the solvent-free high-temperature electrolyte material as claimed in claim 9.

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