Solid-state electrolyte and preparation method and application thereof

Abstract

The application discloses a solid-state electrolyte and a preparation method and application thereof, and relates to the technical field of solid-state electrolyte, and specifically discloses a solid-state electrolyte which comprises rare earth doped modified lithium titanate nanosheets prepared by a hydrothermal method, polyethylene oxide, an alkali metal salt solution and acetonitrile. The modified lithium titanate nanosheets have a high specific surface area and are rich in electric charges on the surface, can provide abundant ion transmission channels for the solid-state electrolyte, and have negative charges and abundant oxygen vacancies on the surface, can promote the dissociation of the alkali metal salt, increase the free metal ion concentration, and can well prevent the rearrangement and crystallization of the polyethylene oxide chain segments, reduce the crystallinity of the polyethylene oxide, and improve the ion transmission capacity of the polyethylene oxide, so that the ion conductivity of the solid-state electrolyte is improved. The lithium titanate doped with the lanthanide series rare earth element has high stability and is not easy to decompose in the charging and discharging process, can be better compatible with the polyethylene oxide, and can form physical crosslinking points, so that the mechanical strength of the solid-state electrolyte is improved. The process is simple, the yield is high, the cost is low, the repeatability is good, and the performance control means is rich.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid electrolyte, in particular to a solid electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Currently, commercially available electrolytes are mostly liquid electrolytes, which are mostly organic substances, and have the safety hazards of flammability and explosiveness. Solid electrolytes have the characteristics and advantages of safety and stability, easy assembly, etc., and are the ideal development direction of the next generation of battery technology. Solid electrolyte is the core component of all-solid-state battery and is the technical key on the commercialization road of all-solid-state battery.

[0003] However, the existing several solid electrolytes such as inorganic ceramic electrolyte, polymer electrolyte and composite electrolyte have the following defects:

[0004] (1) Inorganic ceramic oxide electrolyte has a high room temperature conductivity (≥10 -3 S / cm), but it is high in brittleness, not resistant to shock and poor in interface contact, resulting in high interface impedance, which is not conducive to the transmission of ions on the interface, and thus causes industrialization difficulties.

[0005] (2) The polymer electrolyte has good toughness and good interface compatibility, and can be bent to prepare flexible battery devices, but its room temperature conductivity is too low (≤10 -6 S / cm), which makes it difficult to realize normal charging and discharging at room temperature, limiting its use in commerce.

[0006] (3) The composite solid electrolyte is made by mixing two or more different types of electrolytes, which can balance and optimize the overall performance of the electrolyte. For example, mixing polymer solid electrolyte and ceramic oxide electrolyte can solve the problems of high interface impedance of ceramic oxide electrolyte and low room temperature conductivity of polymer electrolyte at the same time. However, even so, the comprehensive conductivity still cannot meet the commercial use requirements (must be ≥10 -3 S / cm at room temperature), limiting its development. SUMMARY

[0007] In view of the technical problem of insufficient room temperature conductivity of the existing solid electrolyte, the present application provides a solid electrolyte and a preparation method and application thereof, which have the advantages of easy mass production and high room temperature conductivity.

[0008] To solve the above problems, the present application provides the following technical scheme:

[0009] A solid electrolyte comprises rare earth element doped modified lithium titanate nanosheet, polyethylene oxide, alkali metal salt solution and acetonitrile.

[0010] Further, the rare earth element is preferably a lanthanide series rare earth element, and the lanthanide series rare earth element-doped lithium titanate is obtained by a hydrothermal method.

[0011] Further, the mass of the lanthanide series rare earth element-doped lithium titanate is 0.5-10% of the mass of the polyethylene oxide, the number of moles of the alkali metal salt solution is 5%-20% of the number of moles of the polyethylene oxide, and the mass of the acetonitrile is 10-20 times the mass of the polyethylene oxide.

[0012] Further, the thickness of the solid-state electrolyte is 50-300 um.

[0013] The preparation method of the above solid-state electrolyte comprises the following steps:

[0014] (1) preparing a lanthanide series rare earth element-doped lithium titanate by a hydrothermal method;

[0015] (2) mixing the lanthanide series rare earth element-doped lithium titanate, acetonitrile, and an alkali metal salt solution to obtain a mixture;

[0016] (3) mixing the mixture with polyethylene oxide (PEO) powder uniformly to obtain an electrolyte dispersion liquid; and drying the electrolyte dispersion liquid to obtain a solid-state electrolyte.

[0017] Further, step (1) specifically comprises:

[0018] (a) stirring lithium hydroxide into anhydrous ethanol to obtain solution A;

[0019] (b) stirring a lanthanide series rare earth element chloride into anhydrous ethanol to obtain solution B;

[0020] (c) adding tetrabutyl titanate to solution A to obtain solution C;

[0021] (d) stirring solution C thoroughly, then stirring after pouring into solution B to prepare solution D;

[0022] (e) pouring solution D into a reaction kettle, performing a hydrothermal reaction after sealing, then collecting a precipitate, drying, and calcining to obtain a lanthanide series rare earth element-doped lithium titanate.

[0023] Further, in step (a), the amount ratio of lithium hydroxide to anhydrous ethanol is 0.005-0.02 mol:40-70 ml.

[0024] Further, in step (b), the ratio of the amount of lanthanide series rare earth element to the amount of anhydrous ethanol is 0.0005-0.0015 mol:30-60 ml; the lanthanide series rare earth element chloride includes pure chlorides such as lanthanum chloride (LaCl3) or hydrated chlorides containing crystal water, such as lanthanum chloride heptahydrate (LaCl3·7H2O), ytterbium chloride hexahydrate (YbCl3·6H2O), and the like.

[0025] Further, in step (c), the ratio of the amount of tetrabutyl titanate to the amount of solution A is 0.005-0.02 mol LiOH:2.8-3.8 ml tetrabutyl titanate.

[0026] Further, in step (d), the molar ratio of lithium element to lanthanum element in solution C to solution B is 10-2:1.

[0027] Further, in step (e), the temperature of the hydrothermal reaction is 160-200℃, and the time is 30-42 h; the temperature of the calcination is 650-750℃, and the time is 6-8 h.

[0028] Further, step (2) specifically comprises: adding the lanthanide series rare earth element-doped lithium titanate in acetonitrile and mixing uniformly, and then adding the alkali metal salt solution and mixing uniformly; or adding the alkali metal salt solution in acetonitrile and mixing uniformly, and then adding the lanthanide series rare earth element-doped lithium titanate and mixing uniformly.

[0029] Further, the electrolyte dispersion liquid is dried to obtain a solid-state electrolyte, specifically comprising: pouring the electrolyte dispersion liquid into a mold, and after standing at room temperature for 12-24 hours, placing the mold with the electrolyte dispersion liquid into a vacuum oven, and vacuum drying at 50-70℃ for 30-42 hours.

[0030] Further, the amounts of the substances are as follows: the ratio of the number of moles of the repeating units of polyethylene oxide to the number of moles of the alkali metal salt is 1:0.05-0.1 (preferably 1:0.067-0.1); the mass of the lanthanide series rare earth element-doped lithium titanate is 0.5%-10% of the mass of the polyethylene oxide; and the mass of the acetonitrile is 10-20 times the mass of the polyethylene oxide.

[0031] The above solid-state electrolyte or the solid-state electrolyte obtained by the above preparation method can be used in the preparation of a rechargeable battery.

[0032] The beneficial effects of the present application are as follows:

[0033] (1) The lanthanide rare earth element doped lithium titanate of the present application has a higher specific surface area, more surface charges, and a more compact structure than untreated lithium titanate, and has a good nanosheet structure compared to other preparation methods, which can provide a larger specific surface area for reducing the crystallinity of polyethylene oxide, facilitate the transmission of metal cations on the polyethylene oxide segment, is not easy to decompose during charging and discharging, and can form physical crosslinking points, thereby improving the mechanical strength of the solid-state electrolyte; the composite solid-state electrolyte not only has the advantages of mass production, stability at room temperature, high room temperature conductivity, high voltage window, and stability to lithium, but also has the characteristics of large current long cycle high capacity retention rate when applied to full solid-state lithium batteries.

[0034] (2) The lanthanide rare earth element doped lithium titanate nanosheet as a solid-state electrolyte additive can well promote the dissociation of alkali metal salt, increase free metal ions, and the sheet structure can well disrupt the periodic arrangement of the polyethylene oxide segment, provide a higher amorphous proportion, promote ion transmission during charging and discharging, and further improve ion conductivity.

[0035] (3) The lanthanide rare earth element doped lithium titanate nanosheet has a larger specific surface area to interact with polyethylene oxide, providing adsorption sites and improving the overall mechanical properties of the solid-state electrolyte due to its unique sheet structure.

[0036] (4) The present application has the advantages of simple process, safety and environmental protection, storage resistance, low cost and easy mass production. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a preparation method flowchart of the solid-state electrolyte of the present application.

[0038] Figure 2 is the Nyquist curve of the solid-state electrolyte obtained in Example 1 of the present application.

[0039] Figure 3 is the Nyquist curve of the solid-state electrolyte obtained in Example 2 of the present application.

[0040] Figure 4 is the Nyquist curve of the solid-state electrolyte obtained in Example 3 of the present application.

[0041] Figure 5 is the Nyquist curve of the solid-state electrolyte obtained in Example 4 of the present application.

[0042] Figure 6 is the charging and discharging test graph of the solid-state electrolyte obtained in Example 4 of the present application.

[0043] Figure 7is a charge-discharge test diagram of the solid-state electrolyte obtained in Embodiment 4 of the present application. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with specific embodiments and with reference to the drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0045] As shown in Figure 1 the method of the present application comprises steps S101-S104.

[0046] Step S101, preparation of lanthanide rare earth element doped lithium titanate nanosheet is obtained by uniformly mixing lanthanide rare earth element chloride, lithium hydroxide and tetrabutyl titanate, and then obtaining a precursor under sealed hydrothermal reaction, and then calcining in air, and the synthesis of each step is as follows:

[0047] Dissolve 0.01 mol of lithium hydroxide in 50 ml of anhydrous ethanol to obtain solution A; according to the proportion of 0.001 mol of rare earth element: 40 ml of anhydrous ethanol, pour the lanthanide rare earth element containing chloride into the anhydrous ethanol and stir to prepare solution B;

[0048] Prepare solution C by mixing tetrabutyl titanate with solution A according to the proportion of 0.01 mol of LiOH: 3.3 ml of tetrabutyl titanate;

[0049] Prepare solution D by mixing solution C and solution B according to the proportion of 10:1 to 2:1 of lithium element to lanthanum element;

[0050] It should be noted that the proportion of lithium hydroxide and rare earth element chloride solution is controlled within the above range, mainly to adjust the proportion of rare earth element doped in lithium titanate.

[0051] Slowly drop the stirred mixed solution D into 50 ml of deionized water and stir for 25 min;

[0052] Pour the solution into a reaction kettle and heat under high temperature and sealing;

[0053] Preferably, the temperature is raised at a rate of 10℃ / min to 180℃, and the temperature is maintained at this temperature for 36 hours.

[0054] Wash the precipitate after hydrothermal reaction with alcohol three times;

[0055] Preferably, one of the washings is in an ultrasonic cleaner for 10 minutes;

[0056] Dry the washed powder sample;

[0057] Preferably, the drying temperature is 80℃;

[0058] The dried powder is placed in a corundum porcelain boat for calcination.

[0059] Preferably, the heating rate is 10℃ / min, the calcination temperature is set to 700℃, and the temperature is maintained for 7 hours to obtain lanthanum-doped lithium titanate.

[0060] In step S102, the lanthanum-doped lithium titanate nanosheet, acetonitrile, and alkali metal salt solution are mixed to obtain a mixture. The lanthanum-doped lithium titanate nanosheet is added to the acetonitrile and mixed uniformly, and then the alkali metal salt solution is added and mixed uniformly to obtain the mixture. Alternatively, the alkali metal salt solution is added to the acetonitrile and mixed uniformly, and then the lanthanum-doped lithium titanate nanosheet is added and mixed uniformly to obtain the mixture.

[0061] In step S103, the mixture is mixed uniformly with polyethylene oxide powder to obtain an electrolyte dispersion.

[0062] The lanthanum-doped lithium titanate nanosheet, acetonitrile, and alkali metal salt solution are mixed to obtain a mixture, and then the mixture and polyethylene oxide are mixed. This allows the alkali metal salt to be uniformly promoted to dissociate and adsorb on the lanthanum-doped lithium titanate nanosheet in the acetonitrile, and then the high-viscosity polyethylene oxide is mixed. This allows the polymer to be well dispersed, further improving the ionic conductivity of the solid-state electrolyte prepared.

[0063] For example, the mixture and polyethylene oxide powder are stirred for more than 12 hours to ensure uniform dispersion.

[0064] In step S104, the electrolyte dispersion is dried to obtain a solid-state electrolyte.

[0065] Specifically, the electrolyte dispersion is dried to obtain a solid-state electrolyte, including:

[0066] The electrolyte dispersion is poured into a mold or coated on a non-woven fabric, and after being placed at room temperature for 6-18 hours, the mold with the electrolyte dispersion or the non-woven fabric coated with the electrolyte dispersion is placed in a vacuum oven and dried at 60℃ for 36 hours.

[0067] Preferably, the mold is a fluorotetra plate mold. Since the electrolyte dispersion has a relatively high viscosity, it will not stick to the mold when placed on the fluorotetra plate mold. After drying, the solid-state electrolyte can be easily separated from the mold.

[0068] Preferably, the electrolyte dispersion liquid is coated on the non-woven fabric, a part of the electrolyte dispersion liquid can permeate the non-woven fabric uniformly, and the non-woven fabric is located in the middle of the electrolyte dispersion liquid, so that the obtained solid electrolyte can play a supporting role after drying, and the mechanical strength of the solid electrolyte is further improved.

[0069] Preferably, the size of the non-woven fabric is 20g / m 2 , and the shape and effect of the obtained solid electrolyte are the best. If the size is less than 20g / m 2 , the electrolyte dispersion liquid will flow to the lower part of the non-woven fabric, although it can also play a supporting role, but the effect is not obvious, and if the size is more than 10g / m 2 , the pore of the non-woven fabric is relatively large, and the electrolyte dispersion liquid coated on the non-woven fabric will leak out through the pores. Only the size of 20g / m 2 can make the upper surface and the lower surface of the non-woven fabric have some electrolyte dispersion liquid, so that the mechanical property of the non-woven fabric is improved more obviously, and the obtained solid electrolyte is easier to process into a predetermined shape.

[0070] Example 1

[0071] YbCl3·6H2O is used as a doping raw material to dope ytterbium element in lithium titanate.

[0072] 0.378g of LiOH·H2O is poured into 50ml of anhydrous ethanol, and sealed and stirred for 30min;

[0073] 0.2984g of YbCl3·7H2O is poured into 40ml of anhydrous ethanol, and sealed and stirred for 30min;

[0074] 3.3ml of tetrabutyl titanate is added into the LiOH·H2O solution, stirred for 10min, then poured into 25ml of YbCl3·7H2O solution, sealed and stirred for 24h;

[0075] The mixed solution after stirring is slowly dropped into 50ml of deionized water, and stirred for 25min;

[0076] The solution is poured into a reaction kettle and heated at high temperature in a sealed state;

[0077] Preferably, the heating rate is selected as 10℃ / min to 180℃, and the temperature is kept for 36h.

[0078] The precipitate after hydrothermal treatment is cleaned with alcohol for three times;

[0079] Preferably, one cleaning is performed in an ultrasonic cleaner for 10min;

[0080] The cleaned powder sample is dried at a temperature of 80℃.

[0081] The dried powder is placed in a corundum porcelain boat for calcination, the heating rate is 10℃ / min, the calcination temperature is set to 700℃, and the temperature is kept for 7 hours at this temperature to obtain ytterbium element doped lithium titanate.

[0082] The obtained ytterbium element doped lithium titanate is added to the electrolyte dispersion liquid at 2% of the mass of PEO to prepare a solid-state electrolyte containing ytterbium element doped lithium titanate, the thickness of the solid-state electrolyte is 150-200μm, then a battery is assembled, the positive and negative electrodes of the battery are connected to an electrochemical workstation, the alternating current impedance of the battery at 25-60℃ is measured, and the Nyquist diagram of the electrolyte is obtained. As shown in the figure, Figure 2 , wherein the coordinate axis corresponds to a complex plane, the abscissa on the complex plane represents the real part, which corresponds to the resistance of the electrolyte, and the ordinate represents the imaginary part, which corresponds to the reactance of the electrolyte.

[0083] In the figure, the alternating current impedance is composed of a semicircle and a straight line with an inclination angle of about 45°, wherein the intersection of the two ends of the semicircle with the x-axis is represented as the resistance value of the electrolyte.

[0084] The lithium ion conductivity can be calculated by the following formula.

[0085]

[0086] wherein σ (S cm -1 ) represents the ion conductivity, S (cm 2 ) represents the working electrode area of the battery (referring to the area of the positive electrode of the battery or the area of the negative electrode of the battery), which is 2.01cm 2 in the embodiment, and l (cm) represents the thickness of the solid-state polymer electrolyte film, and Rb represents the resistance value of the electrolyte.

[0087] According to the above formula, the resistance value of the electrolyte is about 21Ω and the lithium ion conductivity is 0.59×10 -3 S cm -1 under the test environment when the temperature outside the battery is 60℃.

[0088] Example 2

[0089] Gadolinium (Gd) is used as a doping raw material to dope gadolinium element into lithium titanate.

[0090] 0.378g of LiOH·H2O is poured into 50ml of anhydrous ethanol, sealed and stirred for 30min;

[0091] 0.2984g of GdCl3·7H2O is poured into 40ml of anhydrous ethanol, sealed and stirred for 30min;

[0092] Add 3.3 ml of tetrabutyl titanate into the LiOH·H2O solution, stir for 10 min, pour into 25 ml of GdCl3·7H2O solution, seal and stir for 24 h;

[0093] Slowly drop the stirred mixed solution into 50 ml of deionized water and stir for 25 min;

[0094] Pour the solution into the reaction kettle and heat at high temperature under seal;

[0095] Preferably, the temperature is raised at a rate of 10℃ / min to 180℃, and the temperature is maintained at this temperature for 36 h.

[0096] Wash the precipitate after hydrothermal treatment with alcohol three times;

[0097] Preferably, one washing is performed in an ultrasonic cleaner for 10 min;

[0098] Dry the washed powder sample;

[0099] Preferably, the drying temperature is 80℃;

[0100] Put the dried powder into a corundum boat and calcine;

[0101] Preferably, the temperature is raised at a rate of 10℃ / min, the calcination temperature is set to 700℃, and the temperature is maintained at this temperature for 7 h to obtain gadolinium element doped lithium titanate.

[0102] Add the obtained gadolinium element doped lithium titanate to the electrolyte dispersion liquid at a mass fraction of 2% of PEO to prepare a solid-state electrolyte containing gadolinium element doped lithium titanate, the thickness of the solid-state electrolyte is 180 μm-280 μm, then assemble into a battery, connect the positive and negative electrodes of the battery to an electrochemical workstation, measure the alternating current impedance of the battery at 25-60℃, and obtain the Nyquist diagram of the electrolyte. As shown in Figure 3 .

[0103] According to the above formula, the resistance value of the electrolyte is about 18Ω and the lithium ion conductivity is 0.69×10 -3 S cm -1 .

[0104] Example 3

[0105] Lanthanum (La) is used as a doping raw material to dope lithium titanate with lanthanum element.

[0106] Pour 0.378 g of LiOH·H2O into 50 ml of anhydrous ethanol, seal and stir for 30 min;

[0107] 0.2984g LaCl3·7H2O was poured into 40ml anhydrous ethanol, and sealed and stirred for 30min;

[0108] 3.3ml tetrabutyl titanate was added into the LiOH·H2O solution, and after stirring for 10min, 5ml LaCl3·7H2O solution (Ti 4+ :La 3+ The molar ratio was 110:1, and sealed and stirred for 24h;

[0109] The mixed solution was slowly dripped into 50ml deionized water, and stirred for 25min;

[0110] The solution was poured into a reaction kettle, and sealed and heated at high temperature, the heating rate was 10℃ / min, and the temperature was raised to 180℃, and kept at this temperature for 36h.

[0111] The precipitate after hydrothermal treatment was washed with alcohol three times, and one of the washing was in an ultrasonic cleaner for 10min;

[0112] The washed powder sample was dried at 80℃;

[0113] The dried powder was placed in a corundum boat and calcined, the heating rate was 10℃ / min, the calcination temperature was set to 700℃, and kept at this temperature for 7h, to obtain lanthanum-doped lithium titanate.

[0114] The obtained lanthanum-doped lithium titanate was added to the electrolyte dispersion liquid at 2% of the mass of PEO to prepare a solid-state electrolyte containing ytterbium-doped lithium titanate, the thickness of the solid-state electrolyte was 150μm-200μm, and then assembled into a battery, and the positive and negative electrodes of the battery were connected to an electrochemical workstation, and the alternating current impedance of the battery at 25-60℃ was measured, and the Nyquist diagram of the electrolyte was obtained, as shown in Figure 4 .

[0115] Under the test environment, when the temperature outside the battery was 60℃, the resistance value of the electrolyte was about 18Ω, and the lithium ion conductivity was 0.69×10 -3 S cm -1 .

[0116] Example 4

[0117] Lanthanum (La) was used as a doping raw material to dope lanthanum into lithium titanate.

[0118] 0.378g LiOH·H2O was poured into 50ml anhydrous ethanol, and sealed and stirred for 30min;

[0119] 0.2984g LaCl3·7H2O was poured into 40ml anhydrous ethanol, and sealed and stirred for 30min;

[0120] Add 3.3ml of tetrabutyl titanate into the LiOH.H2O solution, stir for 10 minutes, then pour into 40ml of LaCl3.7H2O (Ti 4+ :La 3+ molar ratio of 110:8) solution, seal and stir for 24 hours;

[0121] Slowly drop the mixed solution into 50ml of deionized water and stir for 25 minutes;

[0122] Pour the solution into a reaction kettle, heat at a high temperature under seal, the heating rate is 10℃ / min, and the temperature is raised to 180℃, and keep the temperature for 36 hours.

[0123] Wash the precipitate after hydrothermal treatment with alcohol three times, and one of the washing is in an ultrasonic cleaner for 10 minutes;

[0124] Dry the washed powder sample at 80℃;

[0125] Put the dried powder into a corundum boat for calcination, the heating rate is 10℃ / min, the calcination temperature is set to 700℃, and keep the temperature for 7 hours to obtain lanthanum-doped lithium titanate.

[0126] Add the obtained lanthanum-doped lithium titanate to the electrolyte dispersion liquid at 2% of the mass of PEO to prepare a solid-state electrolyte containing lanthanum-doped lithium titanate, the thickness of the solid-state electrolyte is 180μm-280μm, then assemble into a battery, connect the positive and negative electrodes of the battery to an electrochemical workstation, measure the alternating current impedance of the battery at 25-60℃, and obtain the Nyquist diagram of the electrolyte, as Figure 5 shown.

[0127] Through the above formula, it is obtained that the resistance value of the electrolyte is about 15Ω and the lithium ion conductivity is 0.8×10 -3 S cm -1 under the test environment when the temperature outside the battery is 60℃.

[0128] The 0.8C rate charge-discharge test at 30℃ under this concentration doping is as shown in Figure 6 , and the 2C rate charge-discharge curve at 60℃ is as shown in Figure 7 , wherein the capacity retention rate is still 83% after 800 cycles of 60℃ 2C current density.

Claims

1. A solid state electrolyte, characterized by, The solid-state electrolyte comprises rare earth element doped lithium titanate nanosheets, polyethylene oxide, alkali metal salt solution and acetonitrile; the rare earth element is a lanthanide element La, Yb and Gd; the rare earth element doped lithium titanate is obtained by a hydrothermal method; the mass of the lanthanide element doped lithium titanate is 0.5%-10% of the mass of the polyethylene oxide; the number of moles of the alkali metal salt solution is 5%-20% of the number of moles of the polyethylene oxide; and the mass of the acetonitrile is 10-20 times of the mass of the polyethylene oxide.

2. The solid-state electrolyte of claim 1, wherein, The thickness of the solid-state electrolyte is 50-300 um.

3. The method of producing a solid-state electrolyte according to claim 1 or 2, characterized by, The method comprises the following steps: (1) preparing the lanthanide element doped lithium titanate by a hydrothermal method; (2) mixing the lanthanide element doped lithium titanate, acetonitrile and alkali metal salt solution to obtain a mixture; (3) mixing the mixture with polyethylene oxide powder to obtain an electrolyte dispersion liquid; and drying the electrolyte dispersion liquid to obtain the solid-state electrolyte.

4. The method of claim 3, wherein the solid-state electrolyte is prepared by a method comprising: Step (1) specifically comprises: (a) stirring lithium hydroxide into anhydrous ethanol to obtain solution A; (b) stirring a lanthanide element chloride into anhydrous ethanol to obtain solution B; (c) adding tetrabutyl titanate into solution A to obtain solution C; (d) stirring solution C, then stirring solution C into solution B to prepare solution D; (e) pouring solution D into a reaction kettle, performing a hydrothermal reaction after sealing, collecting precipitates, drying and calcining to obtain the lanthanide element doped lithium titanate.

5. The method of claim 4, wherein the solid-state electrolyte is prepared by a method comprising: In step (a), the amount ratio of lithium hydroxide to anhydrous ethanol is 0.005-0.02 mol:40-70 ml; in step (b), the amount ratio of the lanthanide element to anhydrous ethanol is 0.0005-0.0015 mol:30-60 ml; in step (c), the amount ratio of tetrabutyl titanate to solution A satisfies 0.005-0.02 mol LiOH:2.8-3.8 ml tetrabutyl titanate; in step (d), solution C and solution B satisfy the molar ratio of lithium element to lanthanum element is 10-2:1; in step (e), the hydrothermal reaction temperature is 160-200 DEG C, and the time is 30-42 h; the calcining temperature is 650-750 DEG C, and the time is 6-8 h.

6. The method of claim 3, wherein the solid-state electrolyte is prepared by a method comprising: Step (2) specifically comprises: adding the lanthanide element doped lithium titanate into acetonitrile and mixing uniformly, then adding the alkali metal salt solution and mixing uniformly; or adding the alkali metal salt solution into acetonitrile and mixing uniformly, then adding the lanthanide element doped lithium titanate and mixing uniformly.

7. The method of claim 3, wherein the solid-state electrolyte is prepared by a method comprising: Drying the electrolyte dispersion liquid to obtain the solid-state electrolyte specifically comprises: pouring the electrolyte dispersion liquid into a mold, and placing the mold with the electrolyte dispersion liquid into a vacuum oven after standing at room temperature for 12-24 hours, and vacuum drying at 50-70 DEG C for 30-42 hours.

8. The method of claim 3, wherein the solid-state electrolyte is prepared by a method comprising: The molar ratio of the number of moles of the repeating units in the polyethylene oxide to the number of moles of the alkali metal salt is 1:0.05-0.1, the mass of the lanthanide element doped lithium titanate is 0.5-10% of the mass of the polyethylene oxide, and the mass of the acetonitrile is 10-20 times of the mass of the polyethylene oxide.

9. Use of the solid-state electrolyte of claim 1 or the solid-state electrolyte obtained by the preparation method of any one of claims 2 to 8 in the preparation of a solid-state electrolyte battery.

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