Molybdenum disulfide-coated lithium lanthanum zirconium oxide composite solid electrolyte material and preparation method thereof

Abstract

The embodiment of the present application relates to a kind of molybdenum disulfide coated lithium lanthanum zirconium oxygen composite solid electrolyte material and its preparation method.The preparation method includes: ammonium tetrathiomolybdate is dissolved in pure water and dissolved, to obtain ammonium tetrathiomolybdate solution;Lithium lanthanum zirconium oxygen solid electrolyte is added to ammonium tetrathiomolybdate solution, and slurry is prepared by ultrasonic dispersion and stirring;The slurry is spray dried into dry powder;The powder is heat treated in the atmosphere of hydrogen mixed protective gas, to obtain molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium battery materials, in particular to a molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material and a preparation method thereof. BACKGROUND

[0002] Fossil fuels account for a large portion of the world's energy demand, including electricity. But fossil fuels are running out, and burning fossil fuels also results in direct emissions of carbon dioxide and other pollutants such as toxic nitrogen oxides into the atmosphere. There is a global demand for a shift to cleaner, renewable energy sources. But renewable energy sources like wind and solar power are primarily intermittent - the wind is not always blowing, and there is no sunlight at night. Therefore, advanced energy storage systems are needed to make more efficient use of renewable, intermittent energy. Since Sony commercialized lithium-ion batteries in 1991, it has had a profound impact on modern society, powering many portable electronic devices and home appliances. However, the use of this battery in electric vehicles still requires substantial improvements in the capacity and safety of the most advanced lithium-ion technology.

[0003] Lithium metal anodes have a higher theoretical capacity than the currently commercially used graphite anodes, but there are still technical obstacles to lithium metal anodes. For example, in liquid batteries, lithium dendrites can grow, causing short circuits in the battery, and even causing fires and explosions. In contrast, solid-state inorganic electrolytes are significantly safer, and garnet-type ceramic Li7La3Zr2O 12 Lithium lanthanum zirconium oxide (LLZO) is now widely considered a promising solid-state electrolyte material because of its high ionic conductivity and compatibility with lithium metal. However, the brittle LLZO electrolyte has poor physical contact with the electrode material, resulting in high interfacial resistance, which greatly limits its application in all-solid-state lithium metal batteries. SUMMARY

[0004] The purpose of the present application is to provide a molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material and a preparation method thereof, which effectively improves the interface contact, reduces the interface resistance, and prevents the destruction of the electrolyte to the LLZO. At the same time, the molybdenum disulfide coating layer reacts with lithium ions to partially generate LixMoS2 (where x is between 0.5 and 1), which helps to improve the ionic conductivity.

[0005] To this end, in a first aspect, the embodiments of the present application provide a preparation method of a molybdenum sulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material, comprising:

[0006] Dissolve ammonium tetrathiomolybdate in pure water to obtain an ammonium tetrathiomolybdate solution;

[0007] The lithium lanthanum zirconium oxide solid electrolyte is added into an ammonium tetrathiomolybdate solution, and is dispersed by ultrasonic and stirred to prepare a slurry;

[0008] The slurry is spray dried into dry powder;

[0009] The powder is heat treated in a hydrogen mixed protective atmosphere to obtain a molybdenum dioxide coated lithium lanthanum zirconium oxide composite solid electrolyte material.

[0010] Preferably, the concentration of the ammonium tetrathiomolybdate solution is 0.1wt%-1wt%, and the mass ratio of the ammonium tetrathiomolybdate to the lithium lanthanum zirconium oxide solid electrolyte is 1.625:1000-8.125:100.

[0011] Preferably, the ultrasonic dispersion time is 5-30min, and the stirring time is 1-12 hours.

[0012] Preferably, the inlet temperature of the spray drying equipment is 250-280℃, and the outlet temperature is 100-200℃.

[0013] Preferably, the hydrogen mixed protective atmosphere includes hydrogen and argon, wherein the volume ratio of hydrogen is 10%-20%.

[0014] Preferably, the heat treatment equipment includes one of a box furnace, a tube furnace, a roller kiln, a push plate kiln and a rotary furnace.

[0015] Preferably, the heating rate of the heat treatment is 0.1-20℃ / min, the heat treatment temperature is 350℃-400℃, the holding time is 1-24 hours, and the heat treatment is naturally cooled to room temperature.

[0016] In a second aspect, the present application provides a molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material prepared by the method of the first aspect.

[0017] Preferably, the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material is one or more of spherical, spherical-like, flaky, needle-like or irregular shape, and the particle size is 10nm-10μm; wherein the content of the molybdenum disulfide layer is 0.1%-5%.

[0018] In a third aspect, the present application provides a lithium battery including the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material of the second aspect.

[0019] The preparation method of the molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material provided by the embodiment of the present application is as follows: ammonium tetrathiomolybdate is used as a precursor and is dispersed with a lithium lanthanum zirconium oxygen solid electrolyte by ultrasonic to prepare a slurry, and then the slurry is dried by spraying and is heat treated to obtain the molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material. The molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material obtained by the above method can effectively improve the interface contact between the solid electrolyte material and the electrode material, reduce the interface resistance, and effectively prevent the destruction of the electrolyte to the LLZO. Meanwhile, the reaction of the molybdenum disulfide coating layer with lithium ions can partially generate LixMoS2 (wherein x is between 0.5 and 1), which helps to improve the ionic conductivity. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The preparation method of the molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material provided by the embodiment of the present application is as follows: ammonium tetrathiomolybdate is used as a precursor and is dispersed with a lithium lanthanum zirconium oxygen solid electrolyte by ultrasonic to prepare a slurry, and then the slurry is dried by spraying and is heat treated to obtain the molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material. The molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material obtained by the above method can effectively improve the interface contact between the solid electrolyte material and the electrode material, reduce the interface resistance, and effectively prevent the destruction of the electrolyte to the LLZO. Meanwhile, the reaction of the molybdenum disulfide coating layer with lithium ions can partially generate LixMoS2 (wherein x is between 0.5 and 1), which helps to improve the ionic conductivity. DETAILED DESCRIPTION

[0021] The present application will be further described below by means of the accompanying drawings and specific embodiments, but it should be understood that these embodiments are only used for more detailed description and should not be understood as limiting the present application in any form, i.e. not intended to limit the protection scope of the present application.

[0022] The embodiment of the present application provides a molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material, as shown in the formula: Figure 1 The main steps include:

[0023] In step 110, ammonium tetrathiomolybdate is dissolved in pure water to obtain an ammonium tetrathiomolybdate solution.

[0024] In step 120, the lithium lanthanum zirconium oxygen solid electrolyte is added to the ammonium tetrathiomolybdate solution, ultrasonic dispersion and stirring are performed to prepare a slurry.

[0025] The concentration of the ammonium tetrathiomolybdate solution is 0.1wt%-1wt%, and the mass ratio of the added ammonium tetrathiomolybdate to the lithium lanthanum zirconium oxygen solid electrolyte is 1.625:1000-8.125:100.

[0026] The ultrasonic dispersion time is 5-30min, and the stirring time is 1-12 hours.

[0027] In step 130, the slurry is dried by spraying to obtain a dry powder.

[0028] The spraying drying is performed by using a spray dryer, the inlet temperature of the equipment is 250-280℃, and the outlet temperature is 100-200℃.

[0029] In step 140, the powder is heat treated in a hydrogen mixed protective gas atmosphere to obtain the molybdenum dioxide coated lithium lanthanum zirconium oxygen composite solid electrolyte material.

[0030] The atmosphere of the hydrogen mixed protective gas includes hydrogen and argon, wherein the volume ratio of hydrogen is 10%-20%.

[0031] The equipment for heat treatment includes one of a box furnace, a tube furnace, a roller hearth, a push plate kiln and a rotary furnace.

[0032] The heating rate of the heat treatment is 0.1-20℃ / min, the temperature of the heat treatment is 350℃-400℃, the holding time is 1-24 hours, and the temperature is naturally decreased to room temperature after the heat treatment.

[0033] The molybdenum disulfide coated lithium lanthanum zirconium oxygen composite solid electrolyte material obtained by the above method has a core-shell structure, the inner core is lithium lanthanum zirconium oxygen, and the outer layer is a molybdenum disulfide layer; the molybdenum disulfide layer is composed of closely arranged nano molybdenum disulfide particles; the content of the molybdenum disulfide layer is 0.1%-5%. The obtained molybdenum disulfide coated lithium lanthanum zirconium oxygen composite solid electrolyte material is one or more of spherical, spherical-like, flaky, needle-like or irregular shape, and the particle size is 10nm-10μm.

[0034] The molybdenum disulfide coated lithium lanthanum zirconium oxygen composite solid electrolyte material obtained by the application can be used in lithium ion batteries, can effectively improve the interface contact between the solid electrolyte material and the electrode material, reduce the interface resistance, and effectively prevent the destruction of the electrolyte to the LLZO; at the same time, the reaction of the molybdenum disulfide coating layer with lithium ions can partially generate LixMoS2 (wherein x is between 0.5-1), which helps to improve the ionic conductivity.

[0035] In order to better understand the technical solutions provided by the application, the following describes the specific process of preparing the molybdenum disulfide coated lithium lanthanum zirconium oxygen composite solid electrolyte material by the method provided by the above embodiments of the application, and the electrochemical properties obtained by testing.

[0036] Example 1

[0037] 3.25g of ammonium tetrathiomolybdate is dissolved in 1L of pure water solvent, 200g of lithium lanthanum zirconium oxygen solid electrolyte is added to the ammonium tetrathiomolybdate solution, ultrasonic dispersion is performed for 10min, and stirring is performed for 2 hours to prepare a precursor slurry, the inlet temperature of a spray dryer is set to 280℃, the outlet temperature is set to 120℃, and the slurry is dried by the spray dryer to prepare a solid electrolyte powder coated with a molybdenum disulfide precursor. The powder is transferred to a box furnace, 10% hydrogen containing nitrogen protective gas is introduced at a flow rate of 1L / min, after the air is excluded, the gas supply is continuously maintained, the temperature is increased to 350℃ at a rate of 5℃ / min, and the temperature is maintained for 5 hours, then the temperature is naturally cooled to room temperature, and the gas source is closed to obtain the molybdenum disulfide coated lithium lanthanum zirconium oxygen composite solid electrolyte material of the example.

[0038] Example 2

[0039] The 6.5 g of ammonium tetrathiomolybdate was dissolved in 1.3 L of pure water solvent, 200 g of lithium lanthanum zirconium oxide solid electrolyte was added into the ammonium tetrathiomolybdate solution and dispersed by ultrasonic for 10 min, and stirred for 2 h to prepare a precursor slurry. The inlet temperature of the spray dryer was set to 280°C, and the outlet temperature was set to 120°C. The slurry was passed through the spray dryer to prepare a solid electrolyte powder coated with a molybdenum disulfide precursor. The powder was transferred to a box furnace, and 20% hydrogen-containing nitrogen protective gas was introduced at a flow rate of 1 L / min. After excluding air, the gas supply was continuously maintained, the temperature was increased to 360°C at a rate of 4°C / min, and then the temperature was maintained for 4.5 h. Then, the temperature was naturally cooled to room temperature, and the gas source was closed to obtain the molybdenum disulfide-coated lithium lanthanum zirconium oxide composite solid electrolyte material of the present embodiment.

[0040] Example 3

[0041] The 9.75 g of ammonium tetrathiomolybdate was dissolved in 1.5 L of pure water solvent, 200 g of lithium lanthanum zirconium oxide solid electrolyte was added into the ammonium tetrathiomolybdate solution and dispersed by ultrasonic for 10 min, and stirred for 4 h to prepare a precursor slurry. The inlet temperature of the spray dryer was set to 280°C, and the outlet temperature was set to 120°C. The slurry was passed through the spray dryer to prepare a solid electrolyte powder coated with a molybdenum disulfide precursor. The powder was transferred to a box furnace, and 10% hydrogen-containing nitrogen protective gas was introduced at a flow rate of 1 L / min. After excluding air, the gas supply was continuously maintained, the temperature was increased to 350°C at a rate of 3°C / min, and then the temperature was maintained for 6 h. Then, the temperature was naturally cooled to room temperature, and the gas source was closed to obtain the molybdenum disulfide-coated lithium lanthanum zirconium oxide composite solid electrolyte material of the present embodiment.

[0042] Example 4

[0043] The 13 g of ammonium tetrathiomolybdate was dissolved in 2.2 L of pure water solvent, 200 g of lithium lanthanum zirconium oxide solid electrolyte was added into the ammonium tetrathiomolybdate solution and dispersed by ultrasonic for 10 min, and stirred for 2 h to prepare a precursor slurry. The inlet temperature of the spray dryer was set to 280°C, and the outlet temperature was set to 120°C. The slurry was passed through the spray dryer to prepare a solid electrolyte powder coated with a molybdenum disulfide precursor. The powder was transferred to a box furnace, and 20% hydrogen-containing nitrogen protective gas was introduced at a flow rate of 1 L / min. After excluding air, the gas supply was continuously maintained, the temperature was increased to 400°C at a rate of 2°C / min, and then the temperature was maintained for 6 h. Then, the temperature was naturally cooled to room temperature, and the gas source was closed to obtain the molybdenum disulfide-coated lithium lanthanum zirconium oxide composite solid electrolyte material of the present embodiment.

[0044] Example 5

[0045] 15 g of ammonium tetrathiomolybdate was dissolved in 2.2 L of pure water solvent, 200 g of lithium lanthanum zirconium oxide solid electrolyte was added into the ammonium tetrathiomolybdate solution, dispersed by ultrasonic for 10 min, stirred for 2 h to prepare a precursor slurry, the inlet temperature of the spray dryer was set to 270 ℃, the outlet temperature was set to 130 ℃, and the slurry was passed through the spray dryer to prepare a solid electrolyte powder coated with a molybdenum disulfide precursor. The powder was transferred to a box furnace, a nitrogen protective gas containing 20% hydrogen was introduced at a flow rate of 1 L / min, after excluding air, the gas supply was continued, the temperature was increased to 400 ℃ at a rate of 2 ℃ / min, and then the temperature was kept for 8 h, and then naturally cooled to room temperature, and then the gas source was closed to obtain the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material of the present embodiment.

[0046] Comparative Example

[0047] The lithium lanthanum zirconium oxide solid electrolyte was used as a comparative example.

[0048] The ion conductivity of the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material obtained in each of the above embodiments and the comparative example was tested. The ion conductivity was tested by using the commonly used method of blocking electrode, testing the alternating current impedance to calculate and obtain. The results are shown in Table 1 below.

[0049] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example Ionic conductivity 0.61 mS / cm 0.68 mS / cm 0.78 mS / cm 0.70 mS / cm 0.67 mS / cm 0.55 mS / cm

[0050] Table 1

[0051] It can be seen that the ion conductivity of the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material prepared by the present application is improved.

[0052] The lithium iron phosphate, the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material of each of the above embodiments and the lithium lanthanum zirconium oxide solid electrolyte material of the comparative example, polyvinylidene fluoride and conductive additive acetylene black were mixed in a ratio of 6:2:1:1 to prepare a slurry, which was uniformly coated on a clean aluminum foil by a doctor blade, and then dried to prepare a lithium iron phosphate positive electrode sheet. The lithium iron phosphate positive electrode sheet was used as a battery positive electrode, and a lithium sheet was used as a negative electrode to make a button CR2032 half battery. The charging current was 1 mA, the charging cutoff voltage was ≥4.3 V, and the discharge cutoff voltage was ≤2.5 V, and the button CR2032 half battery was tested.

[0053] The chemical impedance of the button CR2032 half battery after different cycles at 0.2C rate was tested at room temperature, and the test results are shown in Table 2.

[0054]

[0055] Table 2

[0056] It can be seen that the impedance performance of the button CR2032 half battery prepared by using the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material of the present application is better, which is significantly better than that of the comparative example, and shows better battery performance.

[0057] The cycle retention rate was tested after 1000 cycles at 1C rate according to the above conditions, and the results were as follows

[0058] Table 3.

[0059] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example Capacity retention 88％ 91％ 92％ 90％ 89％ 82％

[0060] Table 3

[0061] It can be seen that the cycle retention rate of the button cell prepared by using the positive electrode sheet of the lithium lanthanum zirconium oxide composite solid electrolyte material coated with the molybdenum disulfide according to the present application after 1000 cycles at 1C rate is obviously improved compared with the comparative example using the untreated lithium lanthanum zirconium oxide electrolyte.

[0062] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a molybdenum sulfide-coated lithium lanthanum zirconium oxide composite solid electrolyte material, characterized by, The preparation method comprises: Dissolving ammonium tetrathiomolybdate in pure water to obtain an ammonium tetrathiomolybdate solution; Adding lithium lanthanum zirconium oxide solid electrolyte into the ammonium tetrathiomolybdate solution, and ultrasonic dispersion and stirring to prepare a slurry; Spray drying the slurry into dry powder; Heat treating the powder in a hydrogen mixed protective gas atmosphere to obtain a molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material; the molybdenum disulfide layer is composed of closely arranged nanometer molybdenum disulfide particles, and reacts with lithium ions to form LixMoS2, x being between 0.5 and 1.

2. The production method according to claim 1, characterized by, The concentration of the ammonium tetrathiomolybdate solution is 0.1wt%-1wt%, and the mass ratio of ammonium tetrathiomolybdate to lithium lanthanum zirconium oxide solid electrolyte is 1.625:1000-8.125:

100.

3. The preparation method according to claim 1, characterized in that The ultrasonic dispersion time is 5-30min, and the stirring time is 1-12 hours.

4. The method of claim 1, wherein, The inlet temperature of the spray drying equipment is 250-280℃, and the outlet temperature is 100-200℃.

5. The production method according to claim 1, characterized by, The hydrogen mixed protective gas atmosphere comprises: Hydrogen and argon, wherein the volume ratio of hydrogen is 10%-20%.

6. The method of claim 1, wherein, The heat treatment equipment comprises one of a box furnace, a tube furnace, a roller kiln, a push plate kiln and a rotary furnace.

7. The preparation method according to claim 1, characterized in that The heating rate of the heat treatment is 0.1-20℃ / min, the heat treatment temperature is 350℃-400℃, the holding time is 1-24 hours, and the heat treatment is naturally cooled to room temperature after the heat treatment.

8. The molybdenum sulfide-coated lithium lanthanum zirconium oxide composite solid-state electrolyte material obtained by the preparation method of any one of claims 1-7, characterized in that, The molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material has a core-shell structure, the inner core is lithium lanthanum zirconium oxide, and the outer layer is a molybdenum disulfide layer; the molybdenum disulfide layer is composed of closely arranged nanometer molybdenum disulfide particles, and reacts with lithium ions to form LixMoS2, x being between 0.5 and 1.

9. The molybdenum disulfide-coated lithium lanthanum zirconium oxide composite solid-state electrolyte material of claim 8, wherein, The molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material is one or more of spherical, spherical-like, flaky, needle-like or irregular shape, and the particle size is 10nm-10μm; wherein the content of the molybdenum disulfide layer is 0.1%-5%.

10. A lithium battery, characterized by, The lithium battery comprises the molybdenum disulfide coated lithium lanthanum zirconium oxide composite solid electrolyte material according to claim 8 or 9.

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