Carbon-coated lithium sulfide nanocrystalline composite material, its preparation method and application
A technology of nano-crystals and composite materials, applied in the field of electrochemistry, can solve the problems of serious first-time charging polarization and the inability to solve the problem of the first-time charging barrier of lithium sulfide positive electrode materials, and achieve mild conditions, uniform coating, repeatability and good stability effect
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[0024] An aspect of the embodiments of the present invention provides a method for preparing a carbon-coated lithium sulfide nanocrystal composite material, which includes:
[0025] (1) Dissolving lithium sulfide in a first solvent to form a lithium sulfide solution, and dissolving a polymer material in a second solvent to form a polymer solution, the first solvent and the second solvent are miscible, and at room temperature lithium sulfide is the solubility in the second solvent is less than the solubility in the first solvent, while the second solvent has a higher boiling point than the first solvent;
[0026] (2) Adding the lithium sulfide solution to the polymer solution in batches while keeping the polymer solution continuously and strongly disturbed to form a uniform dispersion;
[0027] (3) keeping the state that the uniform dispersion is disturbed, and removing the solvent in the dispersion by heating to form a composite powder of polymer-coated lithium sulfide nanopar...
Embodiment 1
[0057] Dissolve 1 g of commercially available lithium sulfide powder in 50 mL of ethanol to obtain solution 1, add 1 g of polyacrylonitrile (PAN) to 50 mL of N,N-dimethylformamide (DMF) and stir to disperse to obtain solution 2. Under stirring, solution 1 was slowly added dropwise to solution 2. Since DMF and ethanol were miscible, a uniform dispersion could be formed. The uniform dispersion liquid is heated at 150° C. to volatilize the solvent, and after drying, PAN-coated lithium sulfide nanoparticles are obtained. Afterwards, the prepared PAN-coated lithium sulfide nanoparticles were calcined under the protection of argon, maintaining a heating rate of 5°C / min to 700°C, and maintaining a constant temperature for 2 hours. After cooling, carbon-coated lithium sulfide nanocrystals (also known as carbon-coated lithium sulfide nanocrystal composites) are obtained. like Figure 1a-Figure 1b As shown, observed with a transmission electron microscope, the product is granular, and...
Embodiment 2
[0060] 1 g of commercially available lithium sulfide powder was dissolved in 50 mL of ethanol to obtain solution 1. Add 1 g of polyethylene glycol (PEG) into 50 mL of ethanol and stir to disperse to obtain solution 2. Solution 1 was slowly added dropwise to solution 2 under stirring. Since the same solvent is selected, a uniform dispersion can be formed. The product was heated at 100°C to evaporate the solvent, and dried to obtain PAN-coated lithium sulfide nanoparticles. The obtained PAN-coated lithium sulfide nanoparticles were calcined under the protection of argon, maintaining a heating rate of 5°C / min to 600°C, and maintaining a constant temperature for 2 hours. After cooling, carbon-coated lithium sulfide nanocrystals (also known as carbon-coated lithium sulfide nanocrystal composite materials) are obtained.
[0061] Afterwards, referring to Example 1, the above-mentioned carbon-coated lithium sulfide nanocrystal composite material was made into a cathode material for...
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