Garnet solid electrolyte ceramic and preparation method and application thereof

Abstract

The invention discloses garnet solid electrolyte ceramic as well as a preparation method and application thereof, and belongs to the technical field of ceramics and energy storage. The chemical formula of the garnet solid electrolyte ceramic is Li < 6 >. 2La3 (Zr < 0.2 > Hf < 0.2 > Sn < 0.2 > Nb < 0.2 > Ta < 0.2 >) 2O12. And the ionic conductivity is 1.78 * 10 <-4 >-4.5 * 10 <-4 > S / cm. The relative density of the high-entropy garnet solid electrolyte ceramic is 98%. Meanwhile, the preparation process disclosed by the invention is simple, the synthesized electrolyte is high in density, the ionic conductivity of the solid electrolyte can be improved, the electrolyte has excellent air stability, the cycling stability of a solid-state battery can be improved, and the electrolyte has a great prospect in actual production and application of the solid-state battery.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics and energy storage, and in particular to a garnet solid electrolyte ceramic and a preparation method and application thereof. Background Art

[0002] As the global resource shortage problem intensifies, people have put forward higher requirements for the range and safety performance of energy storage batteries. Although traditional lithium batteries using liquid electrolytes have high lithium ion conductivity, they are flammable, easy to leak electricity, easy to corrode, and easy to decompose at high temperatures. The energy density of the assembled battery is not high, and the safety is extremely low. There is a safety hazard of causing fire and explosion. Solid-state batteries can solve these problems due to their high energy density and high safety performance. The development of solid-state batteries depends on the performance of solid-state electrolytes. Garnet solid electrolytes have attracted widespread attention and research due to their high ionic conductivity and wide electrochemical window. However, they will produce a lithium carbonate contamination layer in the air that increases impedance. Part of the contamination layer can be removed by mechanical grinding, but there are problems such as the introduction of other impurities and incomplete removal of the contamination layer, which has certain limitations. Summary of the invention

[0003] The invention discloses a garnet solid electrolyte ceramic and a preparation method and application thereof, which solve the above problems.

[0004] The invention discloses a garnet solid electrolyte ceramic, wherein the chemical formula of the high entropy garnet solid electrolyte ceramic is Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 , the ionic conductivity is 1.78×10 -4 ~4.5×10 -4 S / cm.

[0005] Preferably, the relative density of the high entropy garnet solid electrolyte ceramic is 98%.

[0006] The present invention also provides a method for preparing the above-mentioned high entropy garnet solid electrolyte ceramic, characterized in that it comprises the following steps: (1) ball milling a lithium source, a lanthanum source, a zirconium source, a hafnium source, a tantalum source, a tin source and a niobium source to obtain a high entropy garnet precursor powder; (2) calcining the high entropy garnet precursor powder in magnesium oxide and aluminum oxide crucibles, respectively, to obtain two high entropy garnet electrolyte powders G1 and G2; (3) The two high entropy garnet electrolyte powders G1 and G2 are mixed and subjected to secondary ball milling to obtain a mixed high entropy garnet electrolyte powder G3; (4) mixing the mixed high entropy garnet electrolyte powder G3 and a binder, and molding the mixed high entropy garnet electrolyte powder to obtain a high entropy garnet electrolyte blank; (5) Sintering the high entropy garnet electrolyte green body to obtain a high entropy garnet solid electrolyte ceramic.

[0007] Preferably, the ball milling in step (1) and step (3) is wet milling.

[0008] Preferably, the mixing ratio of the two high entropy garnet electrolyte powders is G1:G2=1:1-5:1.

[0009] Preferably, in step (2), the calcination temperature is 700-900° C. and the holding time is 5-10 h.

[0010] Preferably, the molding pressure is 150-350 MPa, the molding temperature is room temperature, and the heat preservation and pressure holding time is 1-3 min.

[0011] Preferably, the sintering temperature is 1200-1250° C., and the holding time is 30 min-8 h.

[0012] Preferably, the heating rate from room temperature to the sintering temperature is 2-10° C. / min.

[0013] Preferably, the high entropy garnet solid electrolyte ceramic is used in solid-state batteries.

[0014] Therefore, the present invention provides a high entropy garnet solid electrolyte ceramic, the chemical formula of which is Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 The present invention uses magnesium oxide and aluminum oxide crucibles to calcine the same precursor to obtain high entropy garnet electrolyte powders G1 and G2, and mixes and calcines them in a certain proportion. The preparation method can improve the ionic conductivity and air stability of the garnet solid electrolyte. In addition, in Li7La3Zr2O 12 The high-entropy garnet solid electrolyte ceramics prepared by replacing the Zr sites with equimolar ratios (tetravalent elements tin and hafnium and pentavalent elements tantalum and niobium) can introduce lithium vacancies into the garnet lattice to promote the migration of lithium ions, thereby improving ionic conductivity and air stability.

[0015] The results of the examples show that the relative density of the high entropy garnet solid electrolyte ceramic provided by the present invention is 98%, which is much higher than the relative density of the electrolyte ceramic sintered after calcination in a single magnesium oxide crucible (68%), ensuring the compactness and stability of the material, making it have better mechanical strength and electrochemical properties in practical applications, reducing internal defects and porosity, and its ionic conductivity is as high as 4.12×10 -4 S / cm, and no lithium carbonate was found in the XRD spectrum after exposure to air for 30 days, showing good air stability. In addition, the high-entropy garnet solid-state battery showed excellent cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of a method for preparing a garnet solid electrolyte ceramic according to the present invention; Figure 2 1 is the XRD diagram of the garnet solid electrolyte ceramic in Example 1, Example 2 and Comparative Example 1; Figure 3 1 is a SEM image of the garnet solid electrolyte ceramic in Example 1, Example 2 and Comparative Example 1; Figure 4 The XRD patterns of the garnet solid electrolyte ceramics in Example 1, Example 2 and Comparative Example 1 at the initial stage and after 30 days; Figure 5 This is the EIS graph of the garnet solid electrolyte ceramic tested every five days in Example 2; Figure 6 This is the EIS graph of the garnet solid electrolyte ceramic in Comparative Example 1 tested every five days; Figure 7 This is a constant current charge and discharge long cycle diagram of the garnet solid electrolyte ceramic symmetrical battery in Example 2. DETAILED DESCRIPTION

[0017] The present invention will be further described below through specific examples, but it should be understood that these examples are only used for more detailed description and should not be understood as limiting the present invention in any form, that is, they are not intended to limit the protection scope of the present invention.

[0018] like Figure 1 As shown, the present invention provides a high entropy garnet solid electrolyte ceramic, the chemical formula of which is Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 .

[0019] In the present invention, the ionic conductivity of the high entropy garnet solid electrolyte ceramic is preferably 1.78×10 -4 ~4.5×10 -4 S / cm.

[0020] The present invention provides a method for preparing the high entropy garnet solid electrolyte ceramics described in the above technical solution, comprising the following steps: ball-milling a lithium source, a lanthanum source, a zirconium source, a hafnium source, a tantalum source, a tin source and a niobium source to obtain a high entropy garnet precursor powder; The high entropy garnet precursor powder is calcined in a magnesium oxide crucible and an aluminum oxide crucible, respectively, to obtain two high entropy garnet electrolyte powders; The two high entropy garnet electrolyte powders are mixed and ball-milled for a second time in a certain ratio to obtain a mixed high entropy garnet electrolyte powder; The mixed high entropy garnet electrolyte powder and the binder are mixed and molded to obtain a high entropy garnet electrolyte blank; The high entropy garnet electrolyte green body is sintered to obtain a high entropy garnet solid electrolyte ceramic.

[0021] The present invention ball-mills a lithium source, a lanthanum source, a zirconium source, a hafnium source, a tantalum source, a tin source and a niobium source to obtain a high entropy garnet precursor powder. In the present invention, the purity of the lithium source, the lanthanum source, the zirconium source, the hafnium source, the tantalum source, the tin source and the niobium source is preferably above 99wt%. In the present invention, the lithium source is preferably lithium carbonate or lithium oxide; the lanthanum source is preferably lanthanum oxide; the zirconium source is preferably zirconium oxide or zirconium oxynitrate; the hafnium source is preferably hafnium oxide; the tantalum source is preferably tantalum oxide; the tin source is preferably tin dioxide; and the niobium source is preferably niobium oxide.

[0022] The present invention preferably follows Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 The raw materials are weighed in a stoichiometric ratio, and lithium carbonate is used in excess of 10wt% to compensate for the volatilization of lithium at high temperature. In a specific embodiment of the present invention, the mass ratio of lithium carbonate, lanthanum oxide, zirconium oxide, hafnium oxide, tantalum oxide, tin dioxide and niobium oxide is 1.008:1.96:0.197:0.337:0.354:0.241:0.213.

[0023] In the present invention, ball milling is preferably wet milling. In the present invention, the dispersant used in wet milling preferably includes isopropanol or ethanol. In the present invention, the rotation speed of the ball mill is preferably 400-500r / min; the ball milling time is preferably 6-12h, more preferably 12h. In the present invention, the ball milling medium used in the ball milling is preferably zirconium ball. In the present invention, the mass ratio of the total mass of the lithium source, lanthanum source, zirconium source, hafnium source, tantalum source, tin source and niobium source to the dispersant and the ball milling medium is preferably 1:1:6-1:1:8, more preferably 1:1:8.

[0024] In the present invention, the ball milling is preferably carried out in a polytetrafluoroethylene ball milling jar. In the present invention, the ball milling method is preferably intermittent alternating ball milling, specifically preferably: firstly milling in forward rotation for half an hour, resting for 5 minutes, and then milling in reverse rotation for half an hour.

[0025] In the present invention, after ball milling, the obtained slurry is preferably dried to obtain a high entropy garnet precursor powder. In the present invention, the drying temperature is preferably 80° C. and the drying time is preferably 6 hours.

[0026] After obtaining the high entropy garnet precursor powder, the present invention calcines the high entropy garnet precursor powder in magnesium oxide and aluminum oxide crucibles, respectively, to obtain two high entropy garnet electrolyte powders G1 and G2. In the present invention, the calcination temperature is 700-900°C, and the holding time is 5-10h. In the present invention, the heating rate from room temperature to the calcination temperature is preferably 3-5°C / min, more preferably 5°C / min. In the present invention, the calcination atmosphere is preferably an air atmosphere.

[0027] In the present invention, calcination is preferably performed in a magnesia crucible or an alumina crucible in a tube furnace.

[0028] In the present invention, after calcination, the mixture is preferably cooled to room temperature to obtain a mixed high entropy garnet electrolyte powder. In the present invention, the cooling rate is preferably 1-3°C / min, more preferably 2°C / min.

[0029] In the present invention, the chemical formula of the mixed high entropy garnet electrolyte powder is Li 6.2 La3(Zr 0.2 Hf 0.2 Ti 0.2 Nb 0.2 Ta 0.2 )2O 12 In the present invention, the color of the mixed high entropy garnet electrolyte powder is white; the particle diameter of the mixed high entropy garnet electrolyte powder is preferably 5 to 20 μm.

[0030] After obtaining the mixed high entropy garnet electrolyte powder, the present invention mixes the mixed high entropy garnet electrolyte powder and a binder, and forms them to obtain a high entropy garnet electrolyte blank. In the present invention, the binder is preferably a polyvinyl butyral (PVB) solution. In the present invention, the concentration of the PVB solution is preferably 30-50 mg / mL, more preferably 40 mg / mL. In the present invention, the solvent of the PVB solution is preferably ethanol. In the present invention, the mass of the binder is preferably 1-3wt% of the mixed high entropy garnet electrolyte powder, more preferably 2wt%. In the present invention, the mixing of the mixed high entropy garnet electrolyte powder and the binder is preferably carried out under grinding conditions.

[0031] In the present invention, the molding is preferably cold isostatic pressing; the molding pressure is preferably 150-350 MPa, more preferably 310 MPa; the molding temperature is preferably room temperature, specifically preferably 20-25°C; the insulation time is preferably 1-3 min. In the present invention, the molding is preferably carried out in a mold; the inner diameter of the mold is preferably 13 mm. In a specific embodiment of the present invention, the inner diameter of the mold is determined according to the size of the button battery shell.

[0032] After obtaining the high entropy garnet electrolyte green blank, the present invention sintered the high entropy garnet electrolyte green blank to obtain a high entropy garnet solid electrolyte ceramic. In the present invention, the sintering temperature is preferably 1200-1250°C, more preferably 1230°C; the holding time is preferably 30min-7h, more preferably 5h. In the present invention, the sintering atmosphere is preferably an air atmosphere.

[0033] In the present invention, the heating rate from room temperature to the sintering temperature is preferably 2-10° C. / min, more preferably 3-5° C. / min.

[0034] In the present invention, sintering is preferably carried out in a magnesium oxide crucible of a tube furnace. In the present invention, a layer of high entropy garnet electrolyte powder is preferably laid on the bottom of the magnesium oxide crucible during the sintering process, and the surface of the high entropy garnet electrolyte blank is covered with mixed high entropy garnet electrolyte powder to prevent adhesion. In the present invention, during the sintering process, the high entropy garnet electrolyte particles grow and the ceramic is densified.

[0035] In the present invention, the temperature is preferably lowered to room temperature after sintering to obtain a high entropy garnet solid electrolyte ceramic. In the present invention, the cooling rate is preferably 1-3°C / min, more preferably 2°C / min.

[0036] In the present invention, the color of the high entropy garnet solid electrolyte ceramic is white.

[0037] The present invention provides the application of the high entropy garnet solid electrolyte ceramic described in the above technical solution or the high entropy garnet solid electrolyte ceramic prepared by the above preparation method in a solid-state battery, preferably in a lithium-ion solid-state battery. In the present invention, the application preferably includes: using the above high entropy garnet solid electrolyte ceramic as an electrolyte, a lithium sheet as an anode, and a lithium sheet as a cathode, and assembling a button battery in a glove box filled with argon. In the present invention, the high entropy garnet solid electrolyte ceramic is preferably pretreated first; the pretreatment preferably includes sandpaper polishing, ultrasonic cleaning and drying performed in sequence. In the present invention, ultrasonic cleaning is preferably carried out in an ethanol solution; the mass concentration of the ethanol solution is preferably 99.7%. In the present invention, the ultrasonic cleaning time is preferably 5~10s.

[0038] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1 This embodiment provides a high entropy garnet solid electrolyte ceramic, the chemical formula of which is Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 , its preparation process is as follows: (1) Weigh 1.008 g lithium carbonate, 1.96 g lanthanum oxide, 0.197 g zirconium oxide, 0.241 g tin dioxide, 0.337 g hafnium oxide, 0.354 g tantalum oxide and 0.213 g niobium oxide, and pour the above raw materials into a polytetrafluoroethylene ball mill; add 68 g zirconium balls and 10 mL of isopropanol in a mass ratio of raw materials, isopropanol and ball milling medium zirconium balls of 1:1:8; ball mill on a planetary ball mill at a speed of 400 r / min for 12 h; put the ball-milled slurry into an oven at 80 °C and dry for 6 h to obtain a high-entropy garnet precursor powder.

[0040] (2) The high entropy garnet precursor powder was placed in magnesium oxide and aluminum oxide crucibles respectively, heated to 900 °C in a tube furnace at a heating rate of 5 °C / min, calcined for 6 h, cooled to room temperature at a rate of 2 °C / min, and mixed in a ratio of G1:G2=3:1 to obtain high entropy garnet electrolyte powder G3.

[0041] (3) Weigh 800 mg of the mixed high-entropy garnet electrolyte powder G3 into an agate mortar, add 16 mg of the binder PVB solution (the solvent is ethanol, the concentration is 40 mg / mL), grind evenly, pour the mixed powder into a mold with an inner diameter of 13 mm, and keep it at 25°C and a pressure of 310 MPa for 3 min to obtain a high-entropy garnet electrolyte blank.

[0042] (4) A layer of mixed high-entropy garnet electrolyte powder was spread on the bottom of the magnesium oxide crucible, and the high-entropy garnet electrolyte blank was placed in the magnesium oxide crucible, and the blank was covered with the mixed high-entropy garnet electrolyte powder. The temperature was raised to 1250°C in a tube furnace at a heating rate of 5°C / min, sintered for 5h, and cooled to room temperature at a rate of 2°C / min to obtain a high-entropy garnet solid electrolyte ceramic. The ionic conductivity of the high-entropy garnet solid electrolyte ceramic prepared in this embodiment is 1.78×10 -4 S / cm.

[0043] The high-entropy garnet solid electrolyte ceramics prepared according to the above scheme were exposed to air for 30 days (relative humidity 40%, temperature at room temperature), and the morphological changes on the surface of the high-entropy garnet solid electrolyte ceramics were tested by XRD, and the impedance changes of the high-entropy garnet solid electrolyte ceramics were tested by electrochemical workstation.

[0044] Example 2 This embodiment provides a high entropy garnet solid electrolyte ceramic, the chemical formula of which is Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 , its preparation process is as follows: (1) Weigh 1.008 g lithium carbonate, 1.96 g lanthanum oxide, 0.197 g zirconium oxide, 0.241 g tin dioxide, 0.337 g hafnium oxide, 0.354 g tantalum oxide and 0.213 g niobium oxide, and pour the above raw materials into a polytetrafluoroethylene ball mill; add 68 g zirconium balls and 10 mL of isopropanol in a mass ratio of raw materials, isopropanol and ball milling medium zirconium balls of 1:1:8; ball mill on a planetary ball mill at a speed of 400 r / min for 12 h; put the ball-milled slurry into an oven at 80 °C and dry for 6 h to obtain a high-entropy garnet precursor powder.

[0045] (2) The high entropy garnet precursor powder was placed in magnesium oxide and aluminum oxide crucibles respectively, heated to 900 °C in a tube furnace at a heating rate of 5 °C / min, calcined for 6 h, cooled to room temperature at a rate of 2 °C / min, and mixed in a ratio of G1:G2=3:1 to obtain high entropy garnet electrolyte powder G3.

[0046] (3) Weigh 800 mg of mixed high-entropy garnet electrolyte powder into an agate mortar, then add 16 mg of binder PVB solution (solvent: ethanol, concentration: 40 mg / mL), grind evenly, pour the mixed powder into a mold with an inner diameter of 13 mm, and keep it at 20°C and a pressure of 310 MPa for 3 min to obtain a high-entropy garnet electrolyte blank.

[0047] (4) A layer of mixed high-entropy garnet electrolyte powder was spread on the bottom of the magnesium oxide crucible, and the high-entropy garnet electrolyte blank was placed in the magnesium oxide crucible, and the blank was covered with the mixed electrolyte powder. The temperature was raised to 1230°C in a tube furnace at a heating rate of 5°C / min, sintered for 5h, and cooled to room temperature at a rate of 2°C / min to obtain a high-entropy garnet solid electrolyte ceramic. The ionic conductivity of the high-entropy garnet solid electrolyte ceramic prepared in this embodiment is 4.12×10 -4 S / cm.

[0048] High entropy garnet solid electrolyte ceramics were prepared according to the above scheme and exposed to air for 30 days (relative humidity 40%, temperature at room temperature). The morphological changes on the surface of the high entropy garnet solid electrolyte ceramics were tested by XRD, and the impedance changes of the high entropy garnet solid electrolyte ceramics were tested by electrochemical workstation.

[0049] The high entropy garnet solid electrolyte ceramic prepared in this example was polished with sandpaper, placed in an ethanol solution for ultrasonic cleaning for 5 to 10 seconds, and then dried; a Li / garnet / Li symmetric battery was assembled in an argon-filled glove box, and the cycle performance of the symmetric battery was tested using a blue power test system.

[0050] Comparative Example 1 This comparative example provides a chemical formula of Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 The garnet solid electrolyte is prepared as follows: (1) Weigh 1.008 g lithium carbonate, 1.96 g lanthanum oxide, 0.197 g zirconium oxide, 0.241 g tin dioxide, 0.337 g hafnium oxide, 0.354 g tantalum oxide and 0.213 g niobium oxide, and pour the above raw materials into a polytetrafluoroethylene ball mill; add 68 g zirconium balls and 10 mL of isopropanol in a mass ratio of raw materials, isopropanol and ball milling medium zirconium balls of 1:1:8; ball mill on a planetary ball mill at a speed of 400 r / min for 12 h; put the ball-milled slurry into an oven at 80 °C and dry for 6 h to obtain a high entropy electrolyte precursor powder.

[0051] (2) The high entropy electrolyte precursor powder is placed in a magnesium oxide crucible, heated to 900° C. at a heating rate of 5° C. / min in a tube furnace, calcined for 6 h, and cooled to room temperature at a rate of 2° C. / min to obtain a high entropy electrolyte powder.

[0052] (3) Weigh 800 mg of the high entropy electrolyte powder and pour it into an agate mortar, then add 16 mg of the binder PVB solution (the solvent is ethanol and the concentration is 40 mg / mL), grind it evenly, pour the mixed powder into a mold with an inner diameter of 13 mm, and maintain it at a pressure of 310 MPa for 3 minutes to obtain a high entropy electrolyte blank.

[0053] (4) A layer of mixed high-entropy garnet electrolyte powder is spread on the bottom of a magnesium oxide crucible, the high-entropy electrolyte blank is placed in the magnesium oxide crucible, the blank is covered with the electrolyte powder, the temperature is increased to 1230°C at a heating rate of 5°C / min in a tubular furnace, the mixture is sintered for 5 h, and the temperature is decreased to room temperature at a rate of 2°C / min to obtain a high-entropy electrolyte ceramic.

[0054] High entropy electrolyte ceramics were prepared according to the above scheme and exposed to air for 30 days (relative humidity 40%, room temperature). The morphological changes on the surface of the high entropy electrolyte ceramics were tested by XRD, and the impedance changes of the high entropy electrolyte ceramics were tested by electrochemical workstation.

[0055] Test Results Figure 2 The XRD patterns of the garnet solid electrolyte ceramics prepared in Example 1, Example 2 and Comparative Example 1 are shown in FIG. Figure 2 It can be seen that Examples 1 and 2 of the present invention and Comparative Example 1 all generate pure garnet phase.

[0056] Figure 3 1 is a SEM image of the garnet solid electrolyte ceramic in Example 1, Example 2 and Comparative Example 1. Figure 3 It can be seen that compared with Comparative Example 1, Examples 1 and 2 have higher density and tighter grain bonding.

[0057] Figure 4 The XRD patterns of the garnet solid electrolyte ceramics in Example 1, Example 2 and Comparative Example 1 at the initial stage and after 30 days. Figure 4 It can be seen that no lithium carbonate peak appeared in Example 1 and Example 2 after 30 days, indicating better air stability, which means that the material can still maintain the integrity of its chemical structure and performance when exposed to air for a long time, and will not undergo obvious side reactions or degradation due to moisture or carbon dioxide in the environment. Therefore, it can be inferred that Example 1 and Example 2 have better air stability and longer service life in practical applications.

[0058] Figure 5 and Figure 6 The EIS graphs of the garnet solid electrolyte ceramics in Example 2 and Comparative Example 1 are the initial and 30-day EIS graphs, respectively. Figure 5 as well as Figure 6 It can be seen that compared with Comparative Example 1, the impedance change of Example 2 within 30 days is very small, indicating strong air stability.

[0059] Figure 7 The constant current charge and discharge long cycle diagram of the Li / garnet / Li symmetric battery assembled with the garnet solid electrolyte ceramic prepared in Example 2. It can be seen from the constant current cycle curve that at a current density of 0.1 mA / cm 2 Under the condition of 30°C, the Li / garnet / Li symmetrical battery prepared by Example 2 maintains stable cycling for more than 1600h. + The transmission is stable and smooth.

[0060] The specific implementation methods described above provide further information on the objectives, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific implementation method of the present invention and does not limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high entropy garnet solid electrolyte ceramic, characterized in that: The chemical formula of the high entropy garnet solid electrolyte ceramic is Li 6.2 La3(Zr 0.2 Hf 0.2 Sn 0.2 Nb 0.2 Ta 0.2 )2O 12 , the ionic conductivity is 1.78×10 -4 ~4.5×10 -4 S / cm.

2. A high entropy garnet solid electrolyte ceramic according to claim 1, characterized in that: The relative density of the high entropy garnet solid electrolyte ceramic is 98%.

3. A method for preparing a high entropy garnet solid electrolyte ceramic according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) ball milling a lithium source, a lanthanum source, a zirconium source, a hafnium source, a tantalum source, a tin source and a niobium source to obtain a high entropy garnet precursor powder; (2) calcining the high entropy garnet precursor powder in magnesium oxide and aluminum oxide crucibles, respectively, to obtain two high entropy garnet electrolyte powders G1 and G2; (3) The two high entropy garnet electrolyte powders G1 and G2 are mixed and subjected to secondary ball milling to obtain a mixed high entropy garnet electrolyte powder G3; (4) mixing the mixed high entropy garnet electrolyte powder G3 and a binder, and molding the mixed high entropy garnet electrolyte powder to obtain a high entropy garnet electrolyte blank; (5) Sintering the high entropy garnet electrolyte green body to obtain a high entropy garnet solid electrolyte ceramic.

4. The method for preparing a high entropy garnet solid electrolyte ceramic according to claim 3, characterized in that: The ball milling in step (1) and step (3) is wet milling, the dispersant is isopropanol or ethanol, the rotation speed of the ball mill is 400-500 r / min, and the ball milling time is 6-12 h.

5. The method for preparing a high entropy garnet solid electrolyte ceramic according to claim 4, characterized in that: In step (3), the mixing ratio of the two high entropy garnet electrolyte powders is G1:G2=1:1-5:

1.

6. The method for preparing a high entropy garnet solid electrolyte ceramic according to claim 3, characterized in that: In step (2), the calcination temperature is 700-900°C and the holding time is 5-10h.

7. The method for preparing a high entropy garnet solid electrolyte ceramic according to claim 3, characterized in that: In step (4), the molding pressure is 150-350 MPa, the molding temperature is room temperature, and the heat and pressure holding time is 1-3 min.

8. The method for preparing a high entropy garnet solid electrolyte ceramic according to claim 3, characterized in that: In step (5), the sintering temperature is 1200-1250°C and the holding time is 30 min-8 h.

9. The method for preparing a high entropy garnet solid electrolyte ceramic according to claim 3, characterized in that: In step (5), the heating rate from room temperature to the sintering temperature is 2-10°C / min.

10. An application of the high entropy garnet solid electrolyte ceramic according to any one of claims 1 to 2, characterized in that: The high entropy garnet solid electrolyte ceramic is applied in solid-state batteries.

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