Preparation of solid-state electrolyte and method for testing electrochemical performance

Abstract

The application discloses a kind of preparation and electrochemical performance test method of solid electrolyte, comprising the following steps: step one, raw material preparation: lithium nitrate, lanthanum nitrate hexahydrate, zirconyl nitrate, iron nitrate nonahydrate, ammonium molybdate are used as raw materials, wherein lithium nitrate is 10at% excess to compensate lithium loss, and the raw materials are prepared into aqueous solution with cation concentration of 1.0M;Step two, sol preparation: 10% of dispersing agent ethylene glycol of solution volume is sequentially added to the aqueous solution of step one, and the complexing agent citric acid is equal to the mass of ethylene glycol, and the metal ion complex is formed by magnetic stirring for 1h, the system pH is adjusted to 6.5 by ammonia water, and the sol is obtained after 6h of reaction in 80 DEG C water bath and 1h of standing;The application relates to the technical field of solid electrolyte.The preparation and electrochemical performance test method of the solid electrolyte can completely inhibit the generation of tetragonal phase of LLZO by Fe and Mo element cooperative doping, stabilize single cubic phase structure, and avoid the decrease of ionic conductivity caused by phase transition.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, specifically to a method for preparing solid electrolytes and testing their electrochemical performance. Background Technology

[0002] Lithium-ion batteries have been widely used in consumer electronics, new energy vehicles, and other fields due to their advantages such as high energy density and long cycle life. However, traditional liquid electrolytes have safety hazards such as leakage, flammability, and lithium dendrite puncture, which limit their application in high-capacity scenarios. Solid-state electrolytes, with their high safety and wide electrochemical window, have become one of the core materials for next-generation lithium-ion batteries.

[0003] Garnet-type Li7La3Zr2O 12 (LLZO) is one of the most widely studied solid electrolytes, with a room temperature ionic conductivity of up to 10. -4 ~10 -3 S・cm -1 It exhibits excellent stability to lithium metal. However, pure LLZO has the following problems: First, it is prone to a tetragonal-cubic phase transition (cubic phase has higher ionic conductivity, but requires high temperature stability); second, it has high grain and grain boundary impedance, which limits ion transport efficiency; third, it has poor compatibility with lithium metal interface and high interface impedance; and fourth, it has insufficient resistance to lithium dendrite formation and a low critical current density.

[0004] To optimize LLZO performance, existing technologies often employ single-element doping (such as Al, Ga, and Fe). However, single doping cannot simultaneously address issues like phase transition, impedance, and interfacial compatibility. For example, Fe doping can improve the reduction resistance of LLZO, but it easily introduces impurity phases (such as LaFeO3) and reduces density; Mo doping can refine grains, but excessive doping can lead to lattice distortion. Furthermore, existing preparation processes (such as solid-state methods) suffer from defects such as uneven raw material mixing, high sintering temperatures, and significant lithium loss, further limiting LLZO performance improvement. Therefore, developing a multi-element synergistically doped, simple, and high-performance LLZO solid electrolyte has become a key research focus in the current solid-state battery field. Summary of the Invention (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing solid electrolytes and testing their electrochemical performance, thus solving the problems mentioned in the background section.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a solid electrolyte, comprising the following steps: Step 1: Raw material preparation: Using lithium nitrate, lanthanum nitrate hexahydrate, zirconium oxynitrate, ferric nitrate nonahydrate, and ammonium molybdate as raw materials, with lithium nitrate in excess of 10 at% to compensate for lithium loss, the raw materials are prepared into an aqueous solution with a cation concentration of 1.0 M. Step 2, Sol preparation: Add 10% by volume of dispersant ethylene glycol and an equal amount of complexing agent citric acid to the aqueous solution from Step 1. Stir magnetically for 1 hour to form a metal ion complex. Adjust the pH of the system to 6.5 with ammonia. React in an 80°C water bath for 6 hours and then let stand for 1 hour to obtain the sol. Step 3, Precursor Preparation: The sol from Step 2 was dried at 120℃ for 36 hours to obtain a dark brown Fe... 0.2 Mo x Precursor, where x = 0.1~0.3; Step 4, Powder Processing: The precursor is pre-calcined in a muffle furnace at 500℃, ground, and then passed through a 200-mesh sieve to obtain Fe. 0.2 Mo x Powder; Step 5, Shaping and Sintering: Fe 0.2 Mo x The powder was isostatically pressed into a disc with a diameter of 18.12 mm and a thickness of 0.98 mm. The Fe / Mo co-doped LLZO solid electrolyte sheet was obtained by sintering the master powder at 1050 °C for 6 h in a N2 atmosphere using the master powder embedding method.

[0006] Preferably, in step one, the purity requirements of the raw materials are: lithium nitrate ≥ 99%, lanthanum nitrate hexahydrate ≥ 99%, zirconium oxynitrate ≥ 99%, and ferric nitrate nonahydrate ≥ 98.5%.

[0007] Preferably, in step five, the pressure of isostatic pressing is controlled at 150~200MPa, and the holding time is 5~10min.

[0008] The electrochemical performance testing method for solid electrolytes includes the following steps: S1. Sample pretreatment: Polish the prepared electrolyte sheet with 800-grit sandpaper to remove surface impurities and oxide layer; S2. Battery Assembly: In an Ar-filled glove box, polished electrolyte sheets are sandwiched between two lithium metal sheets to assemble a Li / Fe battery. 0.2 Mo x @LLZO / Li symmetrical CR2032 button cell; S3. Impedance test: Using an electrochemical workstation, the AC impedance spectrum of the battery is tested under the conditions of frequency range of 0.1Hz~1MHz and AC amplitude of 100mV. The impedance value is read and the ionic conductivity is calculated. S4. Critical Current Density Test: Using a battery testing system, the battery voltage changes by gradually increasing the current density at room temperature. The current density corresponding to the voltage drop is the critical current density. S5. Activation Energy Test: Within a temperature range of 30~95℃, the ionic conductivity was tested in stages at different temperatures. The activation energy for lithium-ion migration was calculated by fitting the Arrhenius equation. Preferably, in step S3, the ionic conductivity is calculated using the formula σ=L / (R×S), where L is the thickness of the electrolyte sheet, S is the effective contact area between the current collector electrode and the electrolyte sheet, and R is the impedance value.

[0009] Preferably, in step S4, the current density increase gradient is 0.05 mA·cm⁻¹. -2 Data was recorded after each gradient had been running stably for 2-3 hours.

[0010] Preferably, the Fe-Mo co-doped LLZO solid electrolyte has the chemical formula Li 6.4-2x Fe 0.2 La3Zr 2-x Mo x O 12 (x=0.2), it has a single cubic phase structure, space group Ia3d, cell parameter a=12.9451Å, relative density ≥95.59%, and room temperature ionic conductivity ≥1.97×10 -3 S・cm -1 The activation energy for lithium-ion migration is ≤0.19eV.

[0011] Preferably, the electrolyte has a grain size of 8~10μm and an interfacial impedance with lithium metal ≤71.4Ω・cm. 2 Critical current density ≥ 0.5 mA·cm -2 .

[0012] (III) Beneficial Effects This invention provides a method for preparing a solid electrolyte and testing its electrochemical performance. Compared with existing technologies, it has the following advantages: (1) The preparation and electrochemical performance testing method of this solid electrolyte, through the synergistic doping of Fe and Mo, can completely suppress the formation of the tetragonal phase of LLZO, stabilize the single cubic phase structure, and avoid the decrease in ionic conductivity caused by phase transition; at the same time, Mo 6+ Fe 3+ The lattice replacement allows for adjustable cell parameters, providing a smoother channel for lithium-ion transport.

[0013] (2) This method for preparing and testing the electrochemical performance of a solid electrolyte promotes uniform growth of LLZO grains through Fe / Mo co-doping. Combined with a specific sintering process, it significantly reduces the proportion of pores and defects inside the electrolyte, improves the overall density, and thus optimizes the ion conduction efficiency, meeting the ion transport requirements of solid-state batteries. The co-doping strategy can regulate the surface chemical properties of LLZO, reduce its interfacial impedance with lithium metal, and improve interfacial stability; at the same time, it optimizes the energy barrier for lithium ion migration and improves the ion transport kinetics. Attached Figure Description

[0014] Figure 1 Fe provided by the present invention 0.2 Mo x XRD and Fe values ​​for (x=0, 0.1, 0.2, 0.3) 0.2 Mo x XPS spectra of (x=0, 0.2); Figure 2 Fe provided by the present invention 0.2 Mo x (x=0,0.1,0.2,0.3) SEM images of the cross-section of the electrolyte sheet and its local interfaces magnified; Figure 3 Fe provided by the present invention 0.2 Mo x HRTEM and SAED plots for (x=0,0.2); Figure 4 Fe provided by the present invention 0.2 Mo x Electrochemical performance spectra of @LLZO (x = 0, 0.1, 0.2, 0.3); Figure 5 The Li / Fe provided by the present invention 0.2 Mo 0.2 Electrochemical performance spectra of @LLZO / Li symmetric cells. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1 Raw material preparation: Lithium nitrate (LiNO3, purity 99%), lanthanum nitrate hexahydrate (La(NO3)3・6H2O, purity 99%), zirconium oxynitrate (ZrO(NO3)2, purity 99%), ferric nitrate nonahydrate (Fe(NO3)3・9H2O, purity 98.5%), and ammonium molybdate (H 24 Mo7N6O 24 • 4H₂O (analytical grade) was used as the raw material. Based on the chemical formula Li 5.8 Fe 0.2 La3Zr 1.8 Mo 0.2 O 12 Calculate the amount of each raw material, with lithium nitrate in excess by 10 at% to compensate for lithium loss during sintering.

[0017] Sol preparation: The above raw materials were added to deionized water and stirred to dissolve, preparing an aqueous solution with a cation concentration of 1.0 M. 10% (by volume) of ethylene glycol (dispersant) and an equimolar amount of citric acid (complexing agent) were added sequentially to the solution, and the mixture was magnetically stirred for 1 hour to form a homogeneous metal ion complex. The pH of the system was slowly adjusted to 6.5 using 25% ammonia solution. The mixture was then placed in an 80°C constant temperature water bath for 6 hours, and after removal, allowed to stand for 1 hour to obtain a homogeneous and transparent sol.

[0018] Precursor preparation: The sol was transferred to a forced-air drying oven and dried continuously at 120℃ for 36 hours to remove moisture and volatile components, yielding a dark brown, porous Fe... 0.2 Mo 0.2 Precursor.

[0019] Powder processing: The precursor was placed in an alumina crucible and then placed in a muffle furnace for pre-calcination at 500°C for 2 hours in air to remove organic impurities and nitrate decomposition products. The pre-calcined powder was then ground in an agate mortar for 30 minutes and passed through a 200-mesh standard sieve to obtain Fe particles with uniform particle size. 0.2 Mo 0.2 Powder.

[0020] Forming and sintering: The sieved powder is placed into a circular mold and placed in an isostatic press. It is pressed at 180 MPa for 8 minutes to form a circular blank with a diameter of 18.12 mm and a thickness of 0.98 mm. Using the master powder embedding method, the blank and powder of equal composition are placed together in an alumina sintering boat and placed in a tube furnace. High-purity N2 gas (purity ≥99.99%) is introduced, and the temperature is raised to 1050℃ at a heating rate of 5℃ / min, held for 6 hours, and then cooled to room temperature in the furnace to obtain Fe. 0.2 Mo 0.2 @LLZO solid electrolyte sheet.

[0021] Comparative Example 1 Following the preparation steps of Example 1, only the ammonium molybdate raw material is omitted; the amounts of the remaining raw materials are based on the chemical formula Li 6.4 Fe 0.2 La3Zr2O 12 Calculations were performed to prepare undoped Mo Fe. 0.2 @LLZO solid electrolyte sheet, used as a performance comparison sample.

[0022] Comparative Example 2 Referring to the preparation process of Example 1, the amount of ammonium molybdate was adjusted according to the chemical formula Li 6.2 Fe 0.2 La3Zr 1.9 Mo 0.1 O 12 and Li 5.4 Fe 0.2 La3Zr 1.7 Mo 0.3 O 12 Calculate the proportions of each raw material, keeping other preparation parameters unchanged, and obtain Fe. 0.2 Mo 0.1 @LLZO and Fe 0.2 Mo 0.3 @LLZO solid electrolyte sheet.

[0023] (a) Structural characterization Crystal structure analysis: The phase composition of the prepared electrolyte powders was analyzed using a powder X-ray diffractometer (PANalytica X'Pert PRO). The scanning angle was 2θ = 5˚~80˚, CuKα radiation (λ = 0.154 nm), and the scanning rate was 5˚ / min. The cell parameters and phase composition were refined using Rietveld, and the results are as follows: Figure 1 As shown.

[0024] Microstructure observation: The electrolyte sheet was cut along the cross-section, sputter-coated with gold, and the microstructure of the cross-section was observed using a field emission scanning electron microscope (ZEISS Sigma 300) to analyze the grain size and density; Fe was selected. 0.2 @LLZO and Fe 0.2 Mo 0.2 @LLZO samples were examined using a transmission electron microscope (JEOL JEM-2100Plus) to observe lattice fringes and crystal structure. The phase composition was verified by selected area electron diffraction (SAED). Results are as follows: Figure 2 , Figure 3 As shown.

[0025] Elemental composition and valence state analysis: Fe was analyzed using an X-ray photoelectron spectrometer (Thermo Scientific ESCALAB250Xi). 0.2 Mo0.2 @LLZO samples were subjected to wide-field scanning and high-resolution spectroscopy to analyze the chemical valence states and distributions of Fe and Mo. The results are as follows: Figure 1 As shown.

[0026] Density test: The relative density of each electrolyte tablet was determined using the Archimedes water displacement method with ethanol as the medium. Each sample was tested three times and the average value was taken.

[0027] (II) Electrochemical performance testing Sample pretreatment: Each electrolyte tablet was gently polished with 800-mesh silicon carbide sandpaper to remove the surface oxide layer and impurities, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and then dried in a glove box for later use.

[0028] Symmetrical battery assembly: In a glove box filled with Ar (O2 content ≤ 0.1 ppm, H2O content ≤ 0.1 ppm), a polished electrolyte sheet is sandwiched between two lithium metal sheets (thickness 0.3 mm, purity 99.9%) to assemble a CR2032 type Li / electrolyte / Li symmetric battery, as shown below. Figure 4 As shown.

[0029] AC impedance testing: An electrochemical workstation (CHI760) was used to perform AC impedance testing on the symmetrical cell at room temperature (25℃). The test frequency range was 0.1Hz~1MHz, and the AC amplitude was 100mV. The total impedance value was read from the impedance spectrum, and the ionic conductivity was calculated using the formula σ=L / (R×S) (where L is the thickness of the electrolyte sheet, and S is the effective contact area between the lithium sheet and the electrolyte sheet). The results are as follows: Figure 4 As shown.

[0030] Critical current density test: Using a battery testing system (LANDCT2001A), a constant current charge-discharge test was performed on a symmetrical battery at room temperature, with current densities starting from 0.05 mA·cm⁻¹. -2 Initially, the gradient increase is 0.05 mA·cm. -2 The battery was operated stably for 2 hours at each current density level, and the battery voltage change was recorded. The current density at which the voltage suddenly dropped was the critical current density. The results are as follows: Figure 5 As shown.

[0031] Activation energy test: Fe was tested at five temperature points: 30℃, 45℃, 60℃, 75℃, and 95℃. 0.2 Mo x The ionic conductivity of the electrolyte @LLZO (x=0,0.1,0.2,0.3) is determined according to the Arrhenius equation σ=Aexp(-E a / (RT)) (where A is the frequency factor, E a(where R is the molar gas constant and T is the absolute temperature). Plot lnσ against 1000 / T and perform a linear fit. The absolute value of the slope multiplied by R is the activation energy E. a The result is as follows Figure 4 As shown.

[0032] Test Results and Analysis: Crystal structure: XRD test results show ( Figure 1 ), Fe 0.2 The LLZO sample showed LaFeO3 and ZrO2 impurities, while Fe... 0.2 Mo x The LLZO samples (x≥0.1) all exhibited a single cubic phase structure (space group Ia3d). When x=0.2, the impurity phase completely disappeared, the cell parameter shrank to 12.9451 Å, and the crystallinity was at its highest. XPS analysis confirmed that Mo entered the LLZO lattice in the +6 valence state and Fe in the +3 valence state, achieving effective doping.

[0033] Microstructure: SEM observations show that ( Figure 2 ), Fe 0.2 Mo 0.2 @LLZO electrolyte sheets have uniform grain size of 8~10μm, no obvious pores in the cross-section, and a relative density of 95.59%; while Fe 0.2 The @LLZO sample exhibits interconnected pores, with a density of only 92.57%. TEM testing shows ( Figure 3 Fe 0.2 @LLZO has a tetragonal phase structure, Fe 0.2 Mo 0.2 @LLZO has a cubic phase structure with clear lattice fringes and no lattice distortion.

[0034] Electrochemical performance: AC impedance testing shows that Fe 0.2 Mo 0.2 @LLZO exhibits a room-temperature ionic conductivity of 1.97 × 10⁻⁶. - 3 S・cm -1 Compared to Fe 0.2 @LLZO improved by 49%; interface impedance as low as 71.4Ω・cm² ​​( Figure 4 Critical current density tests show that Fe 0.2 Mo 0.2 @LLZO's CCD value is 0.5 mA·cm⁻¹ -2 ( Figure 5 ), higher than Fe 0.2 @LLZO's 0.35mA・cm -2 This indicates that it has a stronger ability to suppress lithium dendrite formation. Activation energy test results show that Fe... 0.2 Mo 0.2@LLZO has a lithium-ion migration activation energy as low as 0.19 eV, which is beneficial for rapid lithium-ion transport.

[0035] Figure 1 In the middle, (a) Fe was prepared by sintering at 1050°C for 6 hours in nitrogen. 0.2 Mo x (a) XRD pattern of (x=0, 0.1, 0.2, 0.3); (b) Enlarged view of the range of 2θ=33~35° in Figure (a); (c) Sample Fe 0.2 Wide-field XPS scan spectrum; (d) Fe sample 0.2 Mo 0.2 Wide-field XPS scan spectrum; (e) Sample Fe 0.2 Mo 0.2 Mo 3d;(f)Fe in the spectrum 0.2 Mo 0.2 Fe2p in the spectrum.

[0036] Figure 2 In, (a)(b)Fe 0.2 (c)(d)Fe 0.2 Mo 0.1 ,(e)(f)Fe 0.2 Mo 0.2 ,(g)(h)Fe 0.2 Mo 0.3 .

[0037] Figure 3 In the middle, (a) HRTEM image of Fe 0.2 @LLZO, (c)SAED of Fe 0.2 @LLZO; (c) HRTEMimage of Fe 0.2 Mo 0.2 @LLZO, (d)SAED of Fe 0.2 Mo 0.2 @LLZO.

[0038] Figure 4 In, (a) Fe 0.2 Mo x AC impedance spectra of @LLZO (x=0, 0.1, 0.2, 0.3); Fe 0.2 Mo x Packing density and ionic conductivity of @LLZO (x=0, 0.1, 0.2, 0.3); (c)Fe 0.2 Mo x @LLZO (x=0, 0.1, 0.2, 0.3) Arrhenius curve; (d) Fe 0.2 Mo xActivation energy curves of @LLZO (x=0, 0.1, 0.2, 0.3).

[0039] Figure 5 In, (a) Fe 0.2 @LLZO Nyquist impedance plot of the sample; (c)Fe 0.2 Mo 0.2 @LLZO sample Nyquist impedance plot; (b) Fe 0.2 Critical current density plot of the @LLZO sample; (d)Fe 0.2 Mo 0.2 @LLZO Critical Current Density Plot.

[0040] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a solid electrolyte, characterized in that, Includes the following steps: Step 1: Raw material preparation: Using lithium nitrate, lanthanum nitrate hexahydrate, zirconium oxynitrate, ferric nitrate nonahydrate, and ammonium molybdate as raw materials, with lithium nitrate in excess of 10 at% to compensate for lithium loss, the raw materials are prepared into an aqueous solution with a cation concentration of 1.0 M. Step 2, Sol preparation: Add 10% by volume of dispersant ethylene glycol and an equal amount of complexing agent citric acid to the aqueous solution from Step 1. Stir magnetically for 1 hour to form a metal ion complex. Adjust the pH of the system to 6.5 with ammonia. React in an 80°C water bath for 6 hours and then let stand for 1 hour to obtain the sol. Step 3, Precursor Preparation: The sol from Step 2 was dried at 120℃ for 36 hours to obtain a dark brown Fe... 0.2 Mo x Precursor, where x = 0.1~0.3; Step 4, Powder Processing: The precursor is pre-calcined in a muffle furnace at 500℃, ground, and then passed through a 200-mesh sieve to obtain Fe. 0.2 Mo x Powder; Step 5, Shaping and Sintering: Fe 0.2 Mo x The powder was isostatically pressed into a disc with a diameter of 18.12 mm and a thickness of 0.98 mm. The Fe / Mo co-doped LLZO solid electrolyte sheet was obtained by sintering the master powder at 1050 °C for 6 h in a N2 atmosphere using the master powder embedding method.

2. The method for preparing a solid electrolyte according to claim 1, characterized in that: In step one, the purity requirements for the raw materials are: lithium nitrate ≥ 99%, lanthanum nitrate hexahydrate ≥ 99%, zirconium oxynitrate ≥ 99%, and ferric nitrate nonahydrate ≥ 98.5%.

3. The method for preparing a solid electrolyte according to claim 1, characterized in that: In step five, the pressure for isostatic pressing is controlled at 150~200MPa, and the holding time is 5~10min.

4. The method for testing the electrochemical performance of a solid electrolyte according to claim 1, characterized in that, Includes the following steps: S1. Sample pretreatment: Polish the prepared electrolyte sheet with 800-grit sandpaper to remove surface impurities and oxide layer; S2. Battery Assembly: In an Ar-filled glove box, polished electrolyte sheets are sandwiched between two lithium metal sheets to assemble a Li / Fe battery. 0.2 Mo x @LLZO / Li symmetrical CR2032 button cell; S3. Impedance test: Using an electrochemical workstation, the AC impedance spectrum of the battery is tested under the conditions of frequency range of 0.1Hz~1MHz and AC amplitude of 100mV. The impedance value is read and the ionic conductivity is calculated. S4. Critical Current Density Test: Using a battery testing system, the battery voltage changes by gradually increasing the current density at room temperature. The current density corresponding to the voltage drop is the critical current density. S5. Activation Energy Test: Within a temperature range of 30~95℃, the ionic conductivity at different temperatures is tested in stages, and the activation energy of lithium-ion migration is calculated by fitting the Arrhenius equation.

5. The method for testing the electrochemical performance of a solid electrolyte according to claim 4, characterized in that: In S3, the ionic conductivity is calculated using the formula σ=L / (R×S), where L is the thickness of the electrolyte sheet, S is the effective contact area between the current collector electrode and the electrolyte sheet, and R is the impedance value.

6. The method for testing the electrochemical performance of a solid electrolyte according to claim 4, characterized in that: In step S4, the current density increase gradient is 0.05 mA·cm⁻¹. -2 Data was recorded after each gradient had been running stably for 2-3 hours.

7. The method for testing the electrochemical performance of a solid electrolyte according to claim 4, characterized in that: The chemical formula of the Fe-Mo co-doped LLZO solid electrolyte is Li 6.4-2x Fe 0.2 La3Zr 2-x Mo x O 12 (x=0.2), it has a single cubic phase structure, space group Ia3d, cell parameter a=12.9451Å, relative density ≥95.59%, and room temperature ionic conductivity ≥1.97×10 -3 S・cm -1 The activation energy for lithium-ion migration is ≤0.19eV.

8. The method for testing the electrochemical performance of a solid electrolyte according to claim 7, characterized in that: The electrolyte has a grain size of 8~10μm and an interfacial impedance with lithium metal of ≤71.4Ω・cm. 2 Critical current density ≥ 0.5 mA·cm -2 .

Images