Preparation method of expanded graphite/silicon@carbon negative electrode material for lithium ion batteries

The invention relates to a preparation method of an expanded graphite/silicon@carbon negative electrode material for lithium ion batteries. The method comprises the following steps: introducing oxygen-containing functional groups to the lamellae of expanded graphite subjected to acid treatment to obtain oxidized expanded graphite, soaking the oxidized expanded graphite in an ethanol solution to obtain an oxidized expanded graphite ethanol solution mixture containing rich hydroxyls on the surface, stirring the mixture with a silane coupling agent to obtain an alkylated expanded graphite ethanol solution mixture, adding silicon nanoparticles to obtain an alkylated expanded graphite/silicon ethanol mixed solution, adding the mixed solution into an amorphous carbon precursor, reacting, collecting the precipitate, drying, carbonizing, and soaking in a hydrofluoric acid solution to obtain the expanded graphite/silicon@carbon negative electrode material for lithium ion batteries. The method has the advantages of favorable loop stability and favorable magnification property.