Preparation method of silicon-carbon composite material as well as silicon-carbon composite material and application thereof

The invention discloses a preparation method of a silicon-carbon composite material, the silicon-carbon composite material and application of the silicon-carbon composite material, nanometer silicon is directly deposited on porous lithium metaaluminate, and then a carbon layer is deposited, the preparation method of the porous lithium metaaluminate comprises the following operation steps: S1) preparing organic aluminum salt, an organic solvent and organic alkali, uniformly dispersing, transferring into a high-pressure reaction kettle, reacting for at least 1 hour, filtering, drying in vacuum, and sintering for 1-6 hours to obtain porous aluminum oxide; s2) adding porous aluminum oxide into the lithium solution, and reacting for at least 10 hours; the specific porous lithium metaaluminate prepared by the invention has surprising high ionic conductivity characteristic and can directly replace porous carbon adopted in the prior art, and by depositing nano silicon in the porous lithium metaaluminate, the expansio