High-rate silicon-carbon composite negative electrode material and preparation method and application thereof

The invention provides a high-rate silicon-carbon composite negative electrode material as well as a preparation method and application thereof. According to the invention, sodium alginate is inserted between montmorillonite layers; the preparation method comprises the following steps: intercalating montmorillonite with sodium alginate, stabilizing the structure of the montmorillonite intercalated with the sodium alginate by using freeze drying, calcining to carbonize the sodium alginate among montmorillonite layers into amorphous carbon containing a large number of mesopores and micropores, and then carrying out magnesiothermic reduction reaction, water washing, acid pickling and other treatments to obtain the porous carbon-cavity-silicon nanosheet. Finally, secondary granulation is carried out by adopting a spray drying technology, the porous carbon, the cavity and the silicon nanosheet are bonded into a fluffy porous spherical matrix by utilizing asphalt, the cycle performance and the first coulombic effic