Solid electrolyte and preparation method and application thereof

The invention discloses a solid electrolyte, which is prepared from the following raw materials in percentage by weight: 40 to 75 weight percent of lithium source, 10 to 30 weight percent of cellulose, 5 to 20 weight percent of polymer, 5 to 15 weight percent of cyclotriphosphazene-nano ceramic compound and 15 to 50 mL of first solvent. By introducing the cyclotriphosphazene derivative-nano ceramic composite material, the prepared solid electrolyte is applied to the lithium-sulfur battery, shuttling of a sulfur positive electrode is effectively blocked through chemical adsorption, corrosion of a lithium negative electrode and generation of lithium dendrites are avoided, the attenuation rate of the battery capacity is reduced, and the cycle life of the lithium-sulfur battery is prolonged. The particle size of the nano ceramic silicon dioxide in the cyclotriphosphazene derivative-nano ceramic composite material is controlled to be 50-1000 nm, so that the lithium-sulfur battery can maintain good charge-discharge