Solid-state electrolyte material and method for producing the same

Abstract

The application relates to the technical field of battery materials, and particularly provides a solid-state electrolyte material and a preparation method thereof. 6.25‑x‑y La3Zr 2‑x‑y Al 0.25 Fe x Ti y O 12 , wherein 0 < x <= 0.4, 0 < y <= 0.4, and 0 < x+y <= 0.8. The conductivity of the aluminum-iron-titanium co-doped garnet-type cubic-phase LLZO material is up to 1.51*10 ‑3 S / cm. In addition, the doped metal elements do not include precious metals, the production cost is low, the types of raw materials used are less, the process is simple, and the application is suitable for large-scale mass production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, and more particularly to a solid-state electrolyte material and a preparation method thereof. BACKGROUND

[0002] Lithium ion batteries are considered to be the best battery energy storage system in recent years in terms of comprehensive performance, and have been widely used in portable electronic products, electric vehicles and smart grid energy storage. However, with the development of modern science and technology and the further growth of human demand, people also correspondingly put forward higher requirements for the energy density, cycle life and safety of lithium ion batteries. The traditional commercial lithium ion battery uses organic electrolyte, which has safety hazards such as electrolyte leakage, combustion and explosion. Lithium ion batteries or lithium secondary batteries using all-solid-state electrolyte become an inevitable trend to improve the energy density and safety of the battery. For solid-state electrolyte materials with high energy density and high safety, inorganic solid-state electrolyte materials are undoubtedly the best candidate. Inorganic solid-state electrolyte materials include NASICON type, perovskite type, LISICON type and garnet type, among which the garnet type solid-state electrolyte has obvious advantages, and the LLZO solid-state electrolyte has high ionic conductivity (up to 10 -4 S / cm ~ 10 -3 S / cm) at room temperature; good chemical stability to metal lithium; wide electrochemical stability window, etc., so it is expected to become the core material of the next generation of batteries-all-solid-state batteries.

[0003] The most critical problem hindering the application of LLZO material is its low conductivity. LLZO has two crystal structures, cubic phase and tetragonal phase, and the ionic conductivity of tetragonal phase LLZO is two orders of magnitude lower than that of cubic phase, about 10 -6 S / cm. Since the LLZO electrolyte is in a tetragonal phase structure at room temperature, its ionic conductivity at room temperature is low, which affects the performance of the battery. Some experiments show that under sintering conditions of more than 1150°C, the LLZO material can form a cubic phase structure, but under this condition, a lot of energy will be consumed and the particle size of the obtained LLZO material will be relatively large, which will affect the performance of the battery.

[0004] In view of the low conductivity of LLZO material, the existing solution is to perform element doping modification. Element doping is an effective means to stabilize the cubic phase and improve the density of the ceramic sample. At present, single-element substitution of LLZO or double-site doping of LLZO is more studied, and the specific researches are as follows:

[0005] Patent CN202011165806 several raw materials are weighed according to the proportion, then mixed by wet ball milling, and then tabletting and sintering are carried out after obtaining the precursor material, so as to obtain the double-doped cubic phase LLZO material. This method dopes Ga and Al two metals, which has high cost, and the calcination temperature is as high as 1150 DEG C and the calcination time is as long as 12h. Under this reaction condition, the energy consumption is high, which is not conducive to energy saving.

[0006] Patent CN202210169431 several raw materials are mixed and dried to obtain a first mixture, then a lanthanum-containing compound is added to the first mixture for ball milling to obtain a mixed powder, and finally the mixed powder is sintered to obtain a modified cubic phase LLZO material. The reactants of this method are as high as 7 and the process is complicated, which has low yield and slow production speed.

[0007] Patent CN202011381415 adopts solvent-gel method, several raw materials are stirred and mixed in liquid phase environment, then put into the oven for drying to obtain green powder, and finally the green powder is sintered to obtain the finished product. The sintering temperature of this method is too high, the sintering time is too long, and the energy consumption is too much, which is not conducive to energy saving. Moreover, the solvent nitric acid is not evaporated and dried again in this method, which will cause the oven to be easily damaged.

[0008] The applicant notices that there is less research on three-site doped LLZO in the industry. Three-site doping can greatly improve the electrical conductivity of LLZO material, and can also reduce the energy required for cubic phase crystallization, thereby reducing the sintering temperature. However, the doping element method generally needs to introduce elements such as tantalum, niobium and germanium, most of which are expensive, greatly increasing the cost and industrialization difficulty of the material. SUMMARY

[0009] In order to solve the above technical problems of low electrical conductivity of LLZO material and expensive doping elements, the purpose of the present application is to provide a solid-state electrolyte material which has the advantages of high electrical conductivity and low preparation cost.

[0010] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0011] A solid-state electrolyte material, whose chemical formula is Li 6.25-x-y La3Zr 2-x-y Al 0.25 Fe x Ti y O 12 , wherein 0

[0012] Another purpose of the present application is to provide a preparation method of a solid-state electrolyte material, which comprises the following steps:

[0013] S1: Grind lithium carbonate, lanthanum oxide, zirconyl nitrate, aluminum nitrate, iron oxide and titanium oxide according to the chemical formula of claim 1 to obtain a mixed raw material;

[0014] S2: Add the mixed raw material to a dilute nitric acid solution, then add citric acid and ethylene glycol, and stir in a 50-60°C water bath for 8-12h to obtain a mixed solution;

[0015] S3: Continue heating the mixed solution in a 110°C water bath for 1-2h to obtain a lithium lanthanum zirconium oxide gel;

[0016] S4: Dry the lithium lanthanum zirconium oxide gel in a 150-200°C oven for 2h to obtain a solid, then grind to obtain a precursor material powder;

[0017] S5: Sinter the precursor material powder at 700-850°C for 4-6h to obtain a pre-sintered powder;

[0018] S6: Weigh 0.7g of pre-sintered powder and 0.2-0.4ml of PVB, and press the tablet under a pressure of 10-12MPa to obtain a LALZTO ceramic sheet;

[0019] S7: Sinter the LALZTO ceramic sheet at 400-600°C for 2-3h to remove the binder;

[0020] S8: Place the LALZTO ceramic sheet after binder removal into a crucible lined with pre-sintered powder and sinter at 1000-1100°C for 10-16h. The ceramic sample obtained by sintering is the solid-state electrolyte material.

[0021] Further, in step S1, 5-10% excess lithium carbonate is added to compensate for the evaporation of lithium during high-temperature sintering.

[0022] Further, the dilute nitric acid in step S2 is prepared by mixing deionized water and concentrated nitric acid in a mass ratio of 3:(1.0-1.5).

[0023] Further, the mass percentage of PVB in step S6 is 5%.

[0024] Further, the heating rate in step S7 is 1°C / min.

[0025] Further, the heating rate in step S8 is 5°C / min.

[0026] The lithium carbonate, lanthanum oxide, zirconium oxynitrate, aluminum nitrate, iron oxide and titanium oxide are fully mixed and then dissolved in a dilute nitric acid solution; the aluminum nitrate, iron oxide and titanium oxide are used for doping, can stabilize the cubic phase of LLZO and have low cost, so that the conductivity of the finished product is improved, citric acid and ethylene glycol are further added as complexing agents, so that the raw materials can be completely dissolved in the dilute nitric acid, so that the several metal compounds are fully dissolved and mixed, and in the subsequent high-temperature calcination process, the lanthanum and zirconium elements in the precursor are uniformly mixed due to the low calcination temperature, so that the finally prepared cubic phase LLZATFO material has single crystal phase, uniform particle size distribution and does not consume too much energy, thereby improving the stability and conductivity of the finished product.

[0027] The doping of Al elements on the Li site of the LLZO solid-state electrolyte can stabilize the formation of the cubic phase LLZO, and there is a critical value of the doping amount of Al elements; researches show that the doping amount of Al elements is about 0.25, the introduction of an appropriate amount of Al elements replaces the Li site and thus generates a certain amount of Li vacancies to promote the formation of the cubic phase LLZO, but a large amount of Al elements will hinder the transmission of Li in the Li ion lattice and thus lead to the reduction of the ion conductivity of the LLZO, so the doping amount of Al elements should not be too high.

[0028] In the LLZO solid-state electrolyte, the introduction of Fe elements can generate Li vacancies and stabilize the formation of the cubic phase LLZO, and Fe will not hinder the transmission of Li ions in the lattice like Al elements, and Fe elements are relatively low in price and are more suitable for industrialization. The introduction of Ti elements can improve the electrical conductivity, shrinkage and relative density of the LLZO to a certain extent. Due to the increase of the shrinkage and relative density, the porosity is reduced, so that a more dense morphology is formed at the grain boundary, and the ion conductivity is increased.

[0029] On the basis of the Fe and Al co-doped LLZO experiment, a three-doped combination of Fe, Al and Ti is reasonably designed, by adjusting the content of Ti, the shrinkage and relative density of the LLZO can be improved, and a pure cubic phase with almost no secondary phase, uniform grain structure and excellent lithium ion conductivity can be obtained. Therefore, the Ti, Al and Fe co-doped method is adopted, which stabilizes the formation of the cubic phase LLZO and thus improves the phase purity and density of the product, and also improves the ion conductivity and has low cost, is easy to industrialize and has wide application prospect.

[0030] In summary, the application has the following beneficial effects: the cubic phase LLZO material is obtained by doping three different elements into the material, and the ionic conductivity of the material is improved; due to the reduction of the sintering temperature, the lanthanum and zirconium elements in the precursor are uniformly mixed, so that the cubic phase LLZAFTO material finally prepared has single crystal phase, uniform particle size distribution and does not consume too much energy; the doped metal elements do not include noble metals (such as tantalum, niobium, germanium, etc.), and the production cost is lower; the types of raw materials used are less, and the process is simple, which is more suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 SEM images of the examples and comparative examples in the application;

[0032] Figure 2 XRD images of the examples and comparative examples in the application;

[0033] Figure 3 Densification comparison chart of the examples and comparative examples in the application;

[0034] Figure 4 AC impedance chart of the examples and comparative examples in the application;

[0035] Figure 5 Conductivity comparison chart of the examples and comparative examples in the application. DETAILED DESCRIPTION

[0036] The application will be further described in detail below in combination with the drawings and examples.

[0037] Example 1

[0038] A solid-state electrolyte material, and a preparation method thereof, includes the following steps:

[0039] S1: 0.79g of lithium carbonate, 1.91g of lanthanum oxide, 1.6g of zirconium oxynitrate, 0.37g of aluminum nitrate, 0.021g of iron oxide and 0.03g of titanium oxide are weighed and mixed after grinding, wherein the lithium carbonate is 10% excessive to compensate for the volatilization of lithium at high temperature sintering.

[0040] S2: the mixed raw materials are added to a dilute nitric acid solution with a deionized water and concentrated nitric acid ratio of 3:1, citric acid and ethylene glycol are further added, and stirring is carried out in a 50℃ water bath for 8h to obtain a mixed solution.

[0041] S3: the mixed solution is further heated in a 110℃ water bath for 1.5h to obtain lithium lanthanum zirconium oxide gel.

[0042] S4: the lithium lanthanum zirconium oxide gel is further dried in a 200℃ oven for 2h to obtain a solid which is ground to obtain a precursor material powder.

[0043] S5: sinter the precursor material powder at 800℃ for 4h to obtain a pre-sintered powder.

[0044] S6: weigh 0.7g of the pre-sintered powder and 0.3ml of 5% PVB, and press the mixture into a ceramic sheet under a pressure of 10M Pa.

[0045] S7: sinter the LLZAFTO ceramic sheet at 400℃ for 2h to remove the binder, with a heating rate of 1℃ / min.

[0046] S8: place the ceramic sheet after binder removal into a crucible coated with the pre-sintered powder in step S5, and sinter at 1000℃ for 10h with a heating rate of 5℃ / min, to obtain a ceramic sample (ceramic sheet) as a solid-state electrolyte material.

[0047] Example 2

[0048] A solid-state electrolyte material, and a preparation method thereof, the preparation method comprising the following steps:

[0049] S1: weigh 0.84g of lithium carbonate, 1.91g of lanthanum oxide, 1.67g of zirconium oxide nitrate, 0.37g of aluminum nitrate, 0.015g of iron oxide, and 0.025g of titanium oxide, and then mix and grind the mixture, wherein the lithium carbonate is in excess by 10% to compensate for the volatilization of lithium at high-temperature sintering.

[0050] S2: add the mixed raw materials to a dilute nitric acid solution with a deionized water to concentrated nitric acid ratio of 3:1, and then add citric acid and ethylene glycol, and place in a 50℃ water bath to stir for 8h to obtain a mixed solution.

[0051] S3: continue to heat the mixed solution in a 110℃ water bath for 1.5h to obtain a lithium lanthanum zirconium oxide gel.

[0052] S4: place the lithium lanthanum zirconium oxide gel into a 200℃ oven to dry for 2h to obtain a solid, and then grind the solid to obtain a precursor material powder.

[0053] S5: sinter the precursor material powder at 850℃ for 4h to obtain a pre-sintered powder.

[0054] S6: weigh 0.7g of the pre-sintered powder and 0.3ml of 5% PVB, and press the mixture into a ceramic sheet under a pressure of 10M Pa.

[0055] S7: sinter the LLZAFTO ceramic sheet at 500℃ for 2h to remove the binder, with a heating rate of 1℃ / min.

[0056] S8: Put the ceramic sheet after the glue into the crucible paved with the pre-sintered powder in step S5, the heating rate is 5℃ / min, sinter at 1000℃ for 12h, the sintered ceramic sample (ceramic sheet) is the solid-state electrolyte material.

[0057] Example 3

[0058] A solid-state electrolyte material, the preparation method comprising the following steps:

[0059] S1: Take 0.72g of lithium carbonate, 1.88g of lanthanum oxide, 1.58g of zirconium oxide nitrate, 0.39g of aluminum nitrate, 0.025g of iron oxide and 0.032g of titanium oxide, and then grind and mix, wherein the lithium carbonate is 10% excessive to compensate for the volatilization of lithium during high-temperature sintering.

[0060] S2: Put the mixed raw materials into a dilute nitric acid solution with a deionized water and concentrated nitric acid ratio of 3:1, then add citric acid and ethylene glycol, and put into a 50℃ water bath for stirring for 8h to obtain a mixed solution.

[0061] S3: Continue to heat the mixed solution in a 110℃ water bath for 1.5h to obtain a lithium lanthanum zirconium oxide gel.

[0062] S4: Put the lithium lanthanum zirconium oxide gel into a 200℃ oven for drying for 2h to obtain a solid, which is ground to obtain a precursor material powder.

[0063] S5: Sinter the precursor material powder at 800℃ for 4h to obtain a pre-sintered powder.

[0064] S6: Take 0.7g of the pre-sintered powder and 0.3ml of 5% PVB, and press the tablet under a pressure of 10M Pa to obtain an LLZAFTO ceramic sheet.

[0065] S7: Sinter the LLZAFTO ceramic sheet at 400℃ for 2h for glue removal, and the heating rate is 1℃ / min.

[0066] S8: Put the ceramic sheet after the glue into the crucible paved with the pre-sintered powder in step S5, the heating rate is 5℃ / min, sinter at 1000℃ for 12h, the sintered ceramic sample (ceramic sheet) is the solid-state electrolyte material.

[0067] Comparative Example 1

[0068] A solid-state electrolyte material, the preparation method comprising the following steps:

[0069] S1: Take 1.18g of lithium carbonate, 2.02g of lanthanum oxide, 1.87g of zirconium oxide nitrate, 0.045g of iron oxide, and 0.37g of aluminum nitrate, and then grind and mix, wherein the lithium carbonate is 10% excessive to compensate for the volatilization of lithium during high-temperature sintering.

[0070] S2: The mixed raw materials are added to a dilute nitric acid solution with a deionized water and concentrated nitric acid ratio of 3:1, and then citric acid and ethylene glycol are added. The mixture is stirred in a 50°C water bath for 8 hours to obtain a mixed solution.

[0071] S3: The mixed solution is continuously heated in a 110°C water bath for 1.5 hours to obtain a lithium lanthanum zirconium oxide gel.

[0072] S4: The lithium lanthanum zirconium oxide gel is placed in a 200°C oven for drying for 2 hours to obtain a solid which is ground to obtain a precursor material powder.

[0073] S5: The precursor material powder is sintered at 800°C for 4 hours to obtain a presintered powder.

[0074] S6: 0.7g of the presintered powder and 0.3ml of 5% PVB are weighed and tabletted under a pressure of 10M Pa to obtain an LLZO ceramic sheet.

[0075] S7: The LLZO ceramic sheet is sintered at 400°C for 2 hours for degassing, with a heating rate of 1°C / min.

[0076] S8: The degassed ceramic sheet is placed in a crucible lined with the presintered powder of step S5, and sintered at 1000°C for 12 hours with a heating rate of 5°C / min. The sintered ceramic sample (ceramic sheet) is a solid-state electrolyte material.

[0077] Comparative Example 2

[0078] A solid-state electrolyte material, a preparation method thereof, and a lithium battery including the same.

[0079] S1: 1.18g of lithium carbonate, 2.02g of lanthanum oxide, 1.87g of zirconium oxide nitrate, 0.066g of iron oxide, and 0.44g of aluminum nitrate are weighed and mixed, with an excess of 10% of lithium carbonate to compensate for the volatilization of lithium at high temperature sintering.

[0080] S2: The mixed raw materials are added to a dilute nitric acid solution with a deionized water and concentrated nitric acid ratio of 3:1, and then citric acid and ethylene glycol are added. The mixture is stirred in a 50°C water bath for 8 hours to obtain a mixed solution.

[0081] S3: The mixed solution is continuously heated in a 110°C water bath for 1.5 hours to obtain a lithium lanthanum zirconium oxide gel.

[0082] S4: The lithium lanthanum zirconium oxide gel is placed in a 200°C oven for drying for 2 hours to obtain a solid which is ground to obtain a precursor material powder.

[0083] S5: The precursor material powder is sintered at 800°C for 4 hours to obtain a presintered powder.

[0084] S6: 0.7 g of the pre-sintered powder and 0.3 ml of 5% PVB were weighed, and tabletting was performed under a pressure of 10 MPa to obtain LLZO ceramic tablets.

[0085] S7: The LLZO ceramic tablets were sintered at 400°C for 2 h to perform degassing, and the temperature increasing rate was 1°C / min.

[0086] S8: The ceramic tablets after degassing were placed in a crucible paved with the pre-sintered powder in step S5, the temperature increasing rate was 5°C / min, and sintering was performed at 1000°C for 12 h, and the ceramic sample (ceramic tablet) obtained by sintering was the solid-state electrolyte material.

[0087] Comparative Example 3

[0088] A solid-state electrolyte material, and a preparation method thereof, the preparation method comprising the following steps:

[0089] S1: 1.18 g of lithium carbonate, 2.02 g of lanthanum oxide, 1.87 g of zirconium oxide nitrate, 0.025 g of titanium oxide, and 0.37 g of aluminum nitrate were weighed and mixed after grinding, and the lithium carbonate was in an excess of 10% to compensate for the volatilization of lithium at high-temperature sintering.

[0090] S2: The mixed raw materials were added to a dilute nitric acid solution in which the ratio of deionized water to concentrated nitric acid was 3:1, and citric acid and ethylene glycol were further added, and stirring was performed in a 50°C water bath for 8 h to obtain a mixed solution.

[0091] S3: The mixed solution was further heated in a 110°C water bath for 1.5 h to obtain a lithium lanthanum zirconium oxide gel.

[0092] S4: The lithium lanthanum zirconium oxide gel was further dried in a 200°C oven for 2 h to obtain a solid, which was ground to obtain a precursor material powder.

[0093] S5: The precursor material powder was sintered at 800°C for 4 h to obtain a pre-sintered powder.

[0094] S6: 0.7 g of the pre-sintered powder and 0.3 ml of 5% PVB were weighed, and tabletting was performed under a pressure of 10 MPa to obtain LLZO ceramic tablets.

[0095] S7: The LLZO ceramic tablets were sintered at 400°C for 2 h to perform degassing, and the temperature increasing rate was 1°C / min.

[0096] S8: The ceramic tablets after degassing were placed in a crucible paved with the pre-sintered powder in step S5, the temperature increasing rate was 5°C / min, and sintering was performed at 1000°C for 12 h, and the ceramic sample (ceramic tablet) obtained by sintering was the solid-state electrolyte material.

[0097] Comparative Example 4

[0098] A solid-state electrolyte material, a preparation method thereof comprising the following steps:

[0099] S1: After weighing 0.72 g of lithium carbonate, 1.88 g of lanthanum oxide, 1.58 g of zirconium oxide nitrate, 0.39 g of aluminum nitrate, 0.025 g of iron oxide and 0.018 g of magnesium oxide, the mixture is ground, wherein the lithium carbonate is 10% excessive to compensate for the volatilization of lithium at high-temperature sintering.

[0100] S2: The mixed raw materials are added to a dilute nitric acid solution with a deionized water and concentrated nitric acid ratio of 3:1, citric acid and ethylene glycol are added, and stirring is performed in a 50℃ water bath for 8h to obtain a mixed solution.

[0101] S3: The mixed solution is continuously heated in a 110℃ water bath for 1.5h to obtain a lithium lanthanum zirconium oxide gel.

[0102] S4: The lithium lanthanum zirconium oxide gel is further dried in a 200℃ oven for 2h to obtain a solid which is ground to obtain a precursor material powder.

[0103] S5: The precursor material powder is sintered at 800℃ for 4h to obtain a presintered powder.

[0104] S6: 0.7 g of the presintered powder and 0.3 ml of 5% PVB are weighed, and tabletting is performed under a pressure of 10 MPa to obtain LLZAFTO ceramic tablets.

[0105] S7: The LLZAFTO ceramic tablets are sintered at 400℃ for 2h for degassing, and the heating rate is 1℃ / min.

[0106] S8: The degassed ceramic tablets are placed in a crucible lined with the presintered powder in step S5, the heating rate is 5℃ / min, and sintering is performed at 1000℃ for 10h, and the sintered ceramic sample (ceramic tablet) is the solid-state electrolyte material.

[0107] Performance detection

[0108] The solid-state electrolyte materials prepared in Examples 1-3 and Comparative Examples 1-4 are subjected to SEM analysis, and it is found that Figure 1 As can be seen from the figure, the materials doped with only Al and Fe, and not doped with Ti element, and the materials doped with only Al and Ti, and not doped with Fe, have larger particles, lower shrinkage rate and lower relative density, which may result in larger impedance and lower conductivity. When the materials are doped with Al, Ti and Fe, the morphology of the sample becomes better, the crystal particle size of the material becomes smaller, the sample is densified, the density of the material gradually increases, which may reduce the impedance of the material and further increase the conductivity of the material.

[0109] The solid-state electrolyte materials prepared in Examples 1-3 and Comparative Examples 1-4 are subjected to X-ray diffraction analysis, and it is found that Figure 2As shown in the figure, with co-doping of Ti, Al, and Fe, all samples conform to the standard card, and all samples exhibit a cubic garnet-type structure. The samples show relatively strong diffraction peaks at 2θ = 16.8°, 25.8°, 27.6°, 31.0°, 34.1°, 38.2°, and 43.2°, indicating that the synthesized material possesses the 1a-3d space group. However, when the samples are undoped with Ti, impurity peaks appear. These undoped peaks have a small amount of impurity, which affects the conductivity of the samples. With Ti doping, the impurity peaks decrease, thereby increasing the conductivity of the material.

[0110] Figure 3 The figures show a density comparison of the solid electrolyte materials prepared in Examples 1-3 and Comparative Examples 1-4. As can be seen from the figures, the Ti-doped samples have a higher density than the undoped samples. The densities of Comparative Examples 1, 2, 3, 4 and Examples 1, 2, 3 are 72.4%, 75.1%, 75.2%, 76.5%, 79.2%, 83.2%, and 81.1%, respectively. The undoped samples have a lower density, and the density increases with Ti doping. This may be due to structural changes in the samples, thus increasing the density.

[0111] Figure 4 The figures show the AC impedance diagrams of the solid electrolyte materials prepared in Examples 1-3 and Comparative Examples 1-4. As can be seen from the figures, the impedances of Comparative Examples 1, 2, 3, and 4 are high, exceeding 2000 Ω, while the impedances of the materials doped with Ti are relatively low. This is because the co-doping of Fe, Ti, and Al increases the shrinkage rate and relative density of the material, thereby reducing the porosity and forming a denser morphology at the grain boundaries. This increases the lithium-ion transport channels, allowing more lithium ions to migrate and thus reducing the impedance. Calculations show that the conductivity of Comparative Examples 1, 2, 3, and 4 is 0.57 × 10⁻⁶. -4 S / cm, 1.0×10 -4 S / cm, 1.4×10 - 4 S / cm, 5.7×10 -4 S / cm. The conductivity was improved in materials co-doped with Fe, Ti, and Al. The conductivity of Examples 1, 2, and 3 was 1.2 × 10⁻⁶. -3 S / cm, 1.51×10 -3 S / cm, 1.38×10 -3 S / cm (see details) Figure 5 Because Fe, Ti and Al doping is incorporated into the garnet structure of LLZO, the lithium content in the framework decreases with increasing doping amount, thereby shortening the lithium ion migration channel and resulting in good lithium ion conductivity.

[0112] The above specific embodiments are only an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A solid state electrolyte material, characterized by, The chemical formula is Li 6.25-x-y La3Zr 2-x-y Al 0.25 Fe x Ti y O 12 wherein 0 < x < 0.4, 0 < y < 0.4, 0 < x + y < 0.

8.

2. A method of producing a solid-state electrolyte material, characterized by, The method comprises the following steps: S1: according to the chemical formula of claim 1, lithium carbonate, lanthanum oxide, zirconyl nitrate, aluminum nitrate, iron oxide and titanium oxide are weighed and ground to obtain mixed raw materials; S2: the mixed raw materials are added to a dilute nitric acid solution, and citric acid and ethylene glycol are added, and then the mixture is stirred in a 50-60 DEG C water bath for 8-12 h to obtain a mixed solution; S3: the mixed solution is heated in a 110 DEG C water bath for 1-2 h to obtain a lithium lanthanum zirconium oxide gel; S4: the lithium lanthanum zirconium oxide gel is dried in a 150-200 DEG C oven for 2 h to obtain a solid which is ground to obtain a precursor material powder; S5: the precursor material powder is sintered at 700-850 DEG C for 4-6 h to obtain a pre-sintered powder; S6: 0.7 g of the pre-sintered powder and 0.2-0.4 ml of PVB are weighed, and the mixture is pressed into a tablet under a pressure of 10-12 MPa to obtain an LALZTO ceramic tablet; S7: the LALZTO ceramic tablet is sintered at 400-600 DEG C for 2-3 h to remove the binder; S8: the LALZTO ceramic tablet after binder removal is placed in a crucible coated with pre-sintered powder and sintered at 1000-1100 DEG C for 10-16 h, and the obtained ceramic sample is the solid electrolyte material.

3. The method of claim 2, wherein the solid-state electrolyte material is prepared by a method comprising: In the step S1, 5-10% excess lithium carbonate is added to compensate for the volatilization of lithium during high-temperature sintering.

4. The method of claim 2, wherein the solid-state electrolyte material is prepared by a method comprising: The dilute nitric acid in step S2 is prepared by mixing deionized water and concentrated nitric acid at a mass ratio of 3: (1.0-1.5).

5. The method of claim 2, wherein the solid-state electrolyte material is prepared by a method comprising: mixing a lithium salt and a solvent to form a solution; and adding a lithium metal to the solution to form the solid-state electrolyte material. The mass percentage of PVB in step S6 is 5%.

6. The method of claim 2, wherein the solid-state electrolyte material is prepared by a process comprising: The temperature rising rate in step S7 is 1 DEG C / min.

7. The method of claim 2, wherein the solid-state electrolyte material is prepared by a method comprising: The temperature rising rate in step S8 is 5 DEG C / min. ​

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