A method for preparing oxide solid electrolyte

Abstract

The present invention relates to the technical field of inorganic materials and new energy battery materials, and specifically to a method for preparing an oxide solid electrolyte. The high-temperature melt homogeneous reaction plus high-pressure blowing process of the present invention is used to prepare solid electrolyte ultrafine powders. First, zirconium oxide and lanthanum oxide are subjected to a high-temperature melt reaction, and then the temperature is appropriately lowered. Then, lithium oxide is added to the system and liquid phase homogenization reaction is carried out again. This can avoid the super-boiling temperature loss of lithium oxide, thereby improving the quality of lithium lanthanum zirconium oxide solid electrolyte ultrafine powders. The above process has the advantages of short process, low production cost, and less environmental pollution. The product produced has good particle size consistency, good dispersibility, and high surface activity. The uniformity, surface energy, and conductivity of the solid electrolyte powder are greatly improved, and the electrolyte conductivity can reach ≥10 ‑3 S / cm, which improves the performance and stability of ultrafine oxide solid electrolyte powders in the fields of new energy battery materials and so on.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic materials and new energy battery materials, and in particular to a method for preparing an oxide solid electrolyte. Background Art

[0002] In recent years, lithium-ion batteries have shone brightly in the energy sector, bolstered by their relatively superior performance and commercial viability. However, they suffer from a critical flaw: continuous heat release during use. Prolonged heat release can destabilize the liquid electrolyte, leading to combustion and, in more serious cases, explosion. Furthermore, the narrow electrochemical window of liquid electrolytes and poor battery cycling performance hinder their potential for use in high-capacity, high-power energy storage devices, hampering their future in electric vehicles. Currently, the electrolytes used in commonly used lithium-ion batteries are flammable and explosive liquid electrolytes, making them highly unstable and prone to safety incidents. Furthermore, the energy density of liquid electrolytes has reached a limit of 300 Wh kg⁻¹, necessitating the emergence of inorganic solid electrolytes with higher energy density and greater stability, which offer a perfect solution to these challenges. While there are many types of inorganic solid electrolytes, LiₐLa₃Zr₂O₁₂ (LLZO) has become one of the most sought-after lithium-ion solid electrolytes by researchers due to its relatively high ionic conductivity and excellent stability against lithium metal anodes.

[0003] LLZO solid electrolytes can be prepared by many methods. The main preparation methods currently used by researchers include high-temperature solid-phase method, chemical co-precipitation method, sol-gel method, etc. Among them, the wet preparation process requires a large amount of solution, the production process is complex, a large amount of wastewater is generated during the process that needs to be treated, the production cycle is long, the cost is high, and it is not conducive to energy conservation, environmental protection and large-scale production. The existing mainstream dry production process mainly prepares electrolyte powders through processes such as mixing, grinding, and calcination. The preparation process is relatively long, and the composition uniformity and original particle size growth of the process materials are difficult to effectively control. Summary of the Invention

[0004] Provided is a method for preparing an oxide solid electrolyte with a short process flow and low production cost.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for preparing an oxide solid electrolyte comprises the following steps:

[0007] Step 1: Lanthanum oxide and zirconium oxide are melted and reacted in a vacuum arc furnace at a temperature greater than 2700° C. to obtain a lanthanum-zirconium-oxygen melt;

[0008] Step 2: Lowering the temperature in the vacuum arc furnace to less than 2600° C., adding lithium oxide to the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid-phase homogenization reaction to obtain a lithium lanthanum zirconium oxygen high-temperature melt;

[0009] Step 3: Blow out of the furnace through ultra-high pressure oxygen injection to obtain ultra-fine powder of lithium lanthanum zirconium oxygen solid electrolyte.

[0010] Furthermore, in the preparation method of the above oxide solid electrolyte, the mass ratio of lithium oxide: lanthanum oxide: zirconium oxide is 7.5:3:2.

[0011] Furthermore, in the above-mentioned method for preparing the oxide solid electrolyte, the step 1 is specifically as follows:

[0012] Lanthanum oxide and zirconium oxide are pre-loaded into an electric arc furnace, lithium oxide is loaded into a secondary feeding system, the electric arc furnace is closed, and vacuum is evacuated to a vacuum degree of ≤0.05Pa. Oxygen is filled into the furnace to ≥15000Pa. The power is increased to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of >2700°C in the vacuum arc furnace. After complete melting, the homogeneous reaction time is ≥5 minutes to obtain a lanthanum-zirconium-oxygen melt.

[0013] Furthermore, in the above-mentioned method for preparing the oxide solid electrolyte, the step 2 is specifically as follows:

[0014] Adjust the power and lower the temperature of the vacuum furnace to <2600°C. Quickly add the lithium oxide pre-existing in the secondary feeding system into the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid-phase homogenization reaction for ≥1 minute to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0015] Furthermore, in the above-mentioned method for preparing the oxide solid electrolyte, the step 3 is specifically as follows:

[0016] Ultrafine powder of lithium lanthanum zirconium oxide solid electrolyte is obtained by blowing out of the furnace at ultra-high pressure oxygen of 13MPa-15MPa.

[0017] Furthermore, in the preparation method of the above oxide solid electrolyte, the purity of the lanthanum oxide, lithium oxide and zirconium oxide are all ≥99.9wt%.

[0018] Furthermore, in the above-mentioned method for preparing the oxide solid electrolyte, before step 1, the method further includes the step of pre-drying the lanthanum oxide, lithium oxide and zirconium oxide at 110° C. for later use.

[0019] Furthermore, in the above-mentioned method for preparing the oxide solid electrolyte, step 1 is: melting lanthanum oxide and zirconium oxide in a vacuum arc furnace at a temperature of 2750°C-3000°C to obtain a lanthanum-zirconium-oxygen melt.

[0020] Furthermore, in the preparation method of the above-mentioned oxide solid electrolyte, step 2 is: lowering the temperature in the vacuum arc furnace to 2520°C-2585°C, adding lithium oxide to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid phase homogenization reaction to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0021] Furthermore, the preparation method of the above-mentioned oxide solid electrolyte specifically includes the following steps:

[0022] Step 1: pre-drying lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt%, and zirconium oxide with a purity of ≥99.9wt% at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; placing the lanthanum oxide and zirconium oxide into an electric arc furnace; pre-loading the lithium oxide into a secondary feeding system, sealing the furnace body and evacuating the furnace to a vacuum degree of 0.027-0.045Pa, and filling the furnace with oxygen to 15000-16000Pa; increasing the power to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 2750-3000°C in the vacuum arc furnace, and after complete melting, the homogeneous reaction time is 5-10 minutes to obtain a lanthanum-zirconium-oxygen melt;

[0023] Step 2: Adjust the power and lower the vacuum furnace temperature to 2520-2580°C. Rapidly add the lithium oxide pre-existing in the secondary feeding system to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid phase homogenization reaction for 1.5-3.0 minutes to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0024] Step 3: Ultra-fine lithium lanthanum zirconium oxide solid electrolyte powder is obtained by blowing out of the furnace at an ultra-high pressure of 13.5MPa-15MPa; the solid electrolyte ultra-fine powder in the oxygen-rich dust chamber is collected as a product and sealed for storage.

[0025] The beneficial effects of the present invention are: the high-temperature melt homogeneous reaction plus high-pressure blowing process of the present invention is used to prepare solid electrolyte ultrafine powder. In the specific process, zirconium oxide and lanthanum oxide are first subjected to a high-temperature melt reaction, and then the temperature is appropriately lowered, and lithium oxide is added to the system to conduct a liquid phase homogenization reaction again. This process can avoid the super-boiling temperature loss of lithium oxide, thereby improving the quality of lithium lanthanum zirconium oxide solid electrolyte ultrafine powder. The above process has the advantages of short process, low production cost, and less environmental pollution. The product produced has good particle size consistency, good dispersibility, and high surface activity. The uniformity, surface energy, and conductivity of the solid electrolyte powder are greatly improved, and the electrolyte conductivity can reach ≥10 - 3 S / cm, which improves the performance and stability of ultrafine oxide solid electrolyte powders in the fields of new energy battery materials and so on. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an electron microscope microscopic morphology image of the electrolyte prepared by the preparation method of the oxide solid electrolyte involved in Example 1 of the present invention; DETAILED DESCRIPTION

[0027] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the embodiments and accompanying drawings.

[0028] A specific embodiment of the present invention relates to a method for preparing an oxide solid electrolyte, comprising the following steps:

[0029] Step 1: Lanthanum oxide and zirconium oxide are melted and reacted in a vacuum arc furnace at a temperature greater than 2700° C. to obtain a lanthanum-zirconium-oxygen melt;

[0030] Step 2: Lowering the temperature in the vacuum arc furnace to less than 2600° C., adding lithium oxide to the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid-phase homogenization reaction to obtain a lithium lanthanum zirconium oxygen high-temperature melt;

[0031] Step 3: Blow out of the furnace through ultra-high pressure oxygen injection to obtain ultra-fine powder of lithium lanthanum zirconium oxygen solid electrolyte.

[0032] As an optional embodiment, the mass ratio of lithium oxide: lanthanum oxide: zirconium oxide is 7.5:3:2.

[0033] As an optional implementation, the step 1 is specifically as follows:

[0034] Lanthanum oxide and zirconium oxide are pre-loaded into an electric arc furnace, lithium oxide is loaded into a secondary feeding system, the electric arc furnace is closed, and vacuum is evacuated to a vacuum degree of ≤0.05Pa. Oxygen is filled into the furnace to ≥15000Pa. The power is increased to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of >2700°C in the vacuum arc furnace. After complete melting, the homogeneous reaction time is ≥5 minutes to obtain a lanthanum-zirconium-oxygen melt.

[0035] As an optional implementation, the step 2 is specifically as follows:

[0036] Adjust the power and lower the temperature of the vacuum furnace to <2600°C. Quickly add the lithium oxide pre-existing in the secondary feeding system into the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid-phase homogenization reaction for ≥1 minute to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0037] As an optional implementation, step 3 is specifically as follows:

[0038] Ultrafine powder of lithium lanthanum zirconium oxide solid electrolyte is obtained by blowing out of the furnace at ultra-high pressure oxygen of 13MPa-15MPa.

[0039] As an optional embodiment, the purity of the lanthanum oxide, lithium oxide and zirconium oxide are all ≥99.9wt%.

[0040] As an optional embodiment, before step 1, the method further comprises the step of pre-drying lanthanum oxide, lithium oxide and zirconium oxide at 110° C.

[0041] As an optional embodiment, the step 1 is: melting lanthanum oxide and zirconium oxide in a vacuum arc furnace at a temperature of 2750° C. to 3000° C. to obtain a lanthanum-zirconium-oxygen melt.

[0042] As an optional embodiment, step 2 is: lowering the temperature in the vacuum arc furnace to 2520°C-2585°C, adding lithium oxide to the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid phase homogenization reaction to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0043] As an optional implementation, the following steps are specifically included:

[0044] Step 1: pre-drying lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt%, and zirconium oxide with a purity of ≥99.9wt% at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; placing the lanthanum oxide and zirconium oxide into an electric arc furnace; pre-loading the lithium oxide into a secondary feeding system, sealing the furnace body and evacuating the furnace to a vacuum degree of 0.027-0.045Pa, and filling the furnace with oxygen to 15000-16000Pa; increasing the power to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 2750-3000°C in the vacuum arc furnace, and after complete melting, the homogeneous reaction time is 5-10 minutes to obtain a lanthanum-zirconium-oxygen melt;

[0045] Step 2: Adjust the power and lower the vacuum furnace temperature to 2520-2580°C. Rapidly add the lithium oxide pre-existing in the secondary feeding system to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid phase homogenization reaction for 1.5-3.0 minutes to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0046] Step 3: Ultra-fine lithium lanthanum zirconium oxide solid electrolyte powder is obtained by blowing out of the furnace at an ultra-high pressure of 13.5MPa-15MPa; the solid electrolyte ultra-fine powder in the oxygen-rich dust chamber is collected as a product and sealed for storage.

[0047] In the above embodiment, zirconium oxide and lanthanum oxide are first subjected to a high-temperature melt reaction, and then the temperature is appropriately lowered, and lithium oxide is added to the system to carry out a liquid phase homogenization reaction again. This process can avoid the super-boiling temperature loss of lithium oxide, thereby improving the quality of the lithium lanthanum zirconium oxide solid electrolyte ultrafine powder.

[0048] The first embodiment of the present invention is:

[0049] A method for preparing an oxide solid electrolyte comprises the following steps:

[0050] Step 1: pre-drying lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt% and zirconium oxide with a purity of ≥99.9wt% at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; placing the lanthanum oxide and zirconium oxide into an electric arc furnace; pre-loading the lithium oxide into a secondary feeding system, sealing the furnace body and evacuating the vacuum to 0.045Pa, and filling the furnace with oxygen to 15000Pa; increasing the power to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 2750°C in the vacuum arc furnace, and after being completely melted, the homogeneous reaction time is 5 minutes to obtain a lanthanum-zirconium-oxygen melt;

[0051] Step 2: Adjust the power and lower the vacuum furnace temperature to 2585°C. Rapidly add the lithium oxide pre-existing in the secondary feeding system to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid phase homogenization reaction for 1.5 minutes to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0052] Step 3: Ultrafine powder of lithium lanthanum zirconium oxide solid electrolyte is obtained by blowing out of the furnace at 15MPa ultra-high pressure oxygen; the ultrafine powder of solid electrolyte in the oxygen-rich dust chamber is collected as the product and sealed for storage.

[0053] The test results show that the primary particle size of the product prepared in Example 1 is mainly concentrated between 30nm and 110nm, the specific surface area of ​​the powder is 76.4㎡ / g, and the conductivity of the solid electrolyte reaches 5.17*10 -3 S / cm.

[0054] Reference Figure 1 , Figure 1 This is an electron microscope microscopic morphology image of the electrolyte prepared by the preparation method of the oxide solid electrolyte involved in Example 1.

[0055] The second embodiment of the present invention is:

[0056] A method for preparing an oxide solid electrolyte comprises the following steps:

[0057] Step 1: pre-drying lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt% and zirconium oxide with a purity of ≥99.9wt% at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; placing the lanthanum oxide and zirconium oxide into an electric arc furnace; pre-loading the lithium oxide into a secondary feeding system, sealing the furnace body and evacuating the vacuum to 0.04Pa, and filling the furnace with oxygen to 15500Pa; increasing the power to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 2850°C in the vacuum arc furnace, and after complete melting, the homogeneous reaction time is 7 minutes to obtain a lanthanum-zirconium-oxygen melt;

[0058] Step 2: Adjust the power and lower the vacuum furnace temperature to 2550°C. Rapidly add the lithium oxide pre-existing in the secondary feeding system to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid-phase homogenization reaction for 2.0 minutes to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0059] Step 3: Ultrafine powder of lithium lanthanum zirconium oxide solid electrolyte is obtained by blowing out of the furnace at an ultra-high pressure of 14.2 MPa; the ultrafine powder of solid electrolyte in the oxygen-rich dust chamber is collected as the product and sealed for storage.

[0060] The test results show that the primary particle size of the product prepared in Example 2 is mainly concentrated between 15nm and 170nm, the specific surface area of ​​the powder is 87.7㎡ / g, and the conductivity of the solid electrolyte reaches 7.51*10 -3 S / cm.

[0061] The third embodiment of the present invention is:

[0062] A method for preparing an oxide solid electrolyte comprises the following steps:

[0063] Step 1: pre-drying lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt% and zirconium oxide with a purity of ≥99.9wt% at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; placing the lanthanum oxide and zirconium oxide into an electric arc furnace; pre-loading the lithium oxide into a secondary feeding system, sealing the furnace body and evacuating the vacuum to 0.027Pa, and filling the furnace with oxygen to 16000Pa; increasing the power to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 3000°C in the vacuum arc furnace, and after being completely melted, the homogeneous reaction time is 10 minutes to obtain a lanthanum-zirconium-oxygen melt;

[0064] Step 2: Adjust the power and lower the vacuum furnace temperature to 2520°C. Rapidly add the lithium oxide pre-existing in the secondary feeding system to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid-phase homogenization reaction for 3.0 minutes to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

[0065] Step 3: Ultrafine powder of lithium lanthanum zirconium oxide solid electrolyte is obtained by blowing out of the furnace at an ultra-high pressure of 13.5 MPa; the ultrafine powder of solid electrolyte in the oxygen-rich dust chamber is collected as the product and sealed for storage.

[0066] The test results show that the primary particle size of the product prepared in Example 3 is mainly concentrated between 25nm and 125nm, the specific surface area of ​​the powder is 71.3㎡ / g, and the conductivity of the solid electrolyte reaches 3.95*10 -3 S / cm.

[0067] The fourth embodiment of the present invention is:

[0068] A method for preparing an oxide solid electrolyte comprises the following steps:

[0069] Step 1: Lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt% and zirconium oxide with a purity of ≥99.9wt% are pre-dried at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; lithium oxide, lanthanum oxide and zirconium oxide are simultaneously placed in an electric arc furnace, the furnace body is sealed and evacuated to a vacuum degree of 0.027Pa, and oxygen is filled into the furnace to 16000Pa; the power is increased to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 3000°C in the vacuum arc furnace, and after complete melting, the homogeneous reaction time is 10min to obtain a lithium lanthanum zirconium oxygen high-temperature melt;

[0070] Step 2: Ultra-fine lithium lanthanum zirconium oxide solid electrolyte powder is obtained by blowing out of the furnace at an ultra-high pressure of 13.5 MPa; the solid electrolyte ultra-fine powder in the oxygen-rich dust chamber is collected as a product and sealed for storage.

[0071] The test results show that the primary particle size of the product prepared in Example 4 is mainly concentrated between 30nm and 140nm, the specific surface area of ​​the powder is 57.23㎡ / g, and the conductivity of the solid electrolyte reaches 6.11*10 -5 The main reasons for the low electrolyte conductivity are that the temperature exceeds the boiling point of lithium oxide, the lithium oxide sublimation loss is large, the electrolyte uniformity is poor, and the conductivity is low.

[0072] In summary, the high-temperature melt homogeneous reaction plus high-pressure blowing process of the present invention is used to prepare solid electrolyte ultrafine powder. In the specific process, zirconium oxide and lanthanum oxide are first subjected to high-temperature melt reaction, and then the temperature is appropriately lowered. Then lithium oxide is added to the system and liquid phase homogenization reaction is carried out again. This process can avoid the super-boiling temperature loss of lithium oxide, thereby improving the quality of lithium lanthanum zirconium oxide solid electrolyte ultrafine powder. The above process has the advantages of short process, low production cost, and less environmental pollution. The product produced has good particle size consistency, good dispersibility, high surface activity, and the electrolyte conductivity can reach ≥10 -3 S / cm. This greatly improves the uniformity, surface energy, and conductivity of solid electrolyte powders, and enhances the performance and stability of ultrafine oxide solid electrolyte powders in the fields of new energy battery materials.

[0073] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing an oxide solid electrolyte, characterized in that: The following steps are involved: Step 1: Lanthanum oxide and zirconium oxide are pre-charged into an electric arc furnace, lithium oxide is charged into a secondary charging system, the electric arc furnace is closed, and vacuum is evacuated to a vacuum degree of ≤0.05 Pa. Oxygen is introduced into the furnace to a pressure of ≥15000 Pa. The power is increased to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of >2700°C in the vacuum arc furnace. After complete melting, the homogeneous reaction time is ≥5 minutes to obtain a lanthanum-zirconium-oxygen melt. Step 2: Lowering the temperature in the vacuum arc furnace to less than 2600° C., adding lithium oxide to the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid-phase homogenization reaction to obtain a lithium lanthanum zirconium oxygen high-temperature melt; Step 3: Ultrafine powder of lithium lanthanum zirconium oxide solid electrolyte is obtained by blowing out of the furnace at an ultra-high pressure of 13MPa-15MPa oxygen.

2. The method for preparing an oxide solid electrolyte according to claim 1, wherein: The mass ratio of lithium oxide: lanthanum oxide: zirconium oxide is 7.5:3:

2.

3. The method for preparing an oxide solid electrolyte according to claim 1, wherein: The step 2 is specifically as follows: Adjust the power and lower the vacuum furnace temperature to <2600°C. Quickly add the lithium oxide pre-existing in the secondary feeding system into the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid-phase homogenization reaction for ≥1 minute to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

4. The method for preparing an oxide solid electrolyte according to claim 1, wherein: The purity of the lanthanum oxide, lithium oxide and zirconium oxide is ≥99.9 wt %.

5. The method for preparing an oxide solid electrolyte according to claim 1, wherein: Before step 1, the method further includes the step of drying lanthanum oxide, lithium oxide and zirconium oxide at 110° C. in advance.

6. The method for preparing an oxide solid electrolyte according to claim 1, wherein: The step 1 is: lanthanum oxide and zirconium oxide are melted and reacted at a temperature of 2750° C. to 3000° C. in a vacuum arc furnace to obtain a lanthanum-zirconium-oxygen melt.

7. The method for preparing an oxide solid electrolyte according to claim 1, wherein: The step 2 is: lowering the temperature in the vacuum arc furnace to 2520° C.-2585° C., adding lithium oxide to the lanthanum-zirconium-oxygen high-temperature melt to carry out a high-temperature liquid phase homogenization reaction to obtain a lithium lanthanum zirconium oxygen high-temperature melt.

8. The method for preparing an oxide solid electrolyte according to claim 1, wherein: The specific steps include: Step 1: pre-drying lithium oxide with a purity of ≥99.9wt%, lanthanum oxide with a purity of ≥99.9wt%, and zirconium oxide with a purity of ≥99.9wt% at 110°C in a stoichiometric ratio of lithium oxide: lanthanum oxide: zirconium oxide = 7.5:3:2; placing the lanthanum oxide and zirconium oxide into an electric arc furnace; pre-loading the lithium oxide into a secondary feeding system, sealing the furnace body and evacuating the furnace to a vacuum degree of 0.027-0.045Pa, and filling the furnace with oxygen to 15000-16000Pa; increasing the power to allow the lanthanum oxide and zirconium oxide to undergo a melt reaction at a temperature of 2750-3000°C in the vacuum arc furnace, and after complete melting, the homogeneous reaction time is 5-10 minutes to obtain a lanthanum-zirconium-oxygen melt; Step 2: Adjust the power and lower the vacuum furnace temperature to 2520-2580°C. Rapidly add the lithium oxide pre-existing in the secondary feeding system to the lanthanum-zirconium-oxygen high-temperature melt for a high-temperature liquid-phase homogenization reaction for 1.5-3.0 minutes to obtain a lithium lanthanum zirconium oxygen high-temperature melt. Step 3: Ultra-fine lithium lanthanum zirconium oxide solid electrolyte powder is obtained by blowing out of the furnace at an ultra-high pressure of 13.5MPa-15MPa; the solid electrolyte ultra-fine powder in the oxygen-rich dust chamber is collected as a product and sealed for storage.

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