▎ 摘　　要

NOVELTY - Preparing three-dimensional carbon-based composite material comprises (i) uniformly dispersing the hard template, carbon source and boric acid in the solvent, stirring for 6-24 hours, and removing the solvent to obtain the precursor material, and (ii) grinding and mixing the precursor material and metal magnesium, sintering at 500-700°C for 0.5-4 hours, and removing the hard template to obtain the finished product. USE - The material is useful in sodium ion battery cathode material (claimed). ADVANTAGE - The method: uses hard template as a pore template to provide a prerequisite for formation of porous carbon from a subsequent carbon source; utilizes boric acid as a boron source and auxiliary pore-forming template; generates mesoporous structure in porous carbon material formed by carbon source; and provides excellent environment for intercalation of sodium ion. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a three-dimensional carbon-based composite material prepared by the above-mentioned method.