The invention discloses a preparation method of a
phosphorus-doped hard carbon
composite material for a
sodium battery. The preparation method comprises the following steps: preparing a hard carbon precursor, preparing a
phosphorus-doped precursor, preparing a catalyst precursor, preparing a hard carbon
composite material, and carrying out
pickling purification. Through pre-oxidation treatment on the
biomass raw material,
oxygen-containing free radicals can be introduced, the structural disorder can be improved, the
sodium storage space and the capacity can be improved,
phosphorus elements are uniformly distributed into the hard carbon material through a vapor deposition method, meanwhile,
graphene and carbon nanotubes are formed in the material, closed pores are increased, the
sodium storage space is improved, and the performance of the hard carbon material is improved. According to the present invention, the
ion transmission path is shortened, the sodium
ion transmission is accelerated, the capacity and the
conductivity of the material are enhanced, the material is coated with the
amorphous carbon formed by the
asphalt, such that the phosphorus expansion can be inhibited, the contact with the
electrolyte can be avoided, the capacity and the first effect can be improved, and the phosphorus and the
coating layer can be re-distributed while the
asphalt coating is performed so as to form the small amount of the phosphorus
fiber crystal; and the
conductivity and the capacity are improved.