Nano porous silicon-carbon composite material and preparation method thereof

The invention discloses a nano porous silicon-carbon composite material and a preparation method thereof. The preparation method comprises the following steps: washing rice husks with water to remove surface impurities, drying, and carrying out high-temperature carbonization under the protection of inert gas to obtain rice husk carbon; the method comprises the following steps: crushing and grading rice husk carbon by using air flow, pickling, cleaning by using deionized water until the pH is 6-7, and drying in a drying oven after cleaning to obtain rice husk porous carbon; placing the rice hull porous carbon in a reactor, heating silicon under vacuum to form silicon steam, introducing the silicon steam into the reactor, and obtaining a precursor after the reaction is finished; and mixing the precursor and a high-temperature carbonization coating agent, and heating under the protection of an inert atmosphere to obtain the nano porous silicon-carbon composite negative electrode material. The biological source r