Composite modified graphite negative electrode material and preparation method thereof

The invention discloses a composite modified graphite negative electrode material and a preparation method thereof. The preparation method comprises the following steps: 1) mixing graphite, an oxidantand an intercalator according to a certain mass ratio to obtain a mixed solution; 2) carrying out stirring reaction on the mixed solution under a constant temperature condition to obtain an intercalation product; and 3) repeatedly washing the intercalation product with deionized water until the pH value of the filtrate is 57, drying the washed intercalation product, heating to a target temperature in an inert atmosphere, and keeping the temperature for a specific time to obtain the target object. The composite modified graphite negative electrode material prepared by the method disclosed by the invention is manganese oxide loaded sulfur-free micro-expanded graphite, and has nanopores and properly enlarged graphite lamellar spacing. The method has the advantages of being high in operability, easy to produce, low i