▎ 摘　　要

NOVELTY - Preparing naphthalimide polymer, comprises uniformly mixing naphthalimide compound (I) and ferric chloride and then performing solid-phase grinding in a mortar for 30-50 minutes, or in a ball-milling jar at a rotating speed of 500-1000 revolutions/minute for 20-30 minutes, washing the ball-milled solid and drying to obtain polynaphthalimide or dissolving (I) and ferric chloride in organic solvent, stirring at room temperature under the protective atmosphere for 30-50 hours, washing and drying to obtain polynaphthalimide and the mass ratio of naphthalimide and ferric chloride is 1:5-6. USE - The naphthalimide polymer is useful in lithium-sodium batteries (claimed), preferably sodium ion battery and organic lithium-ion battery anode material. ADVANTAGE - The method: prepares polynaphthalimide cathode material, which is macromolecular compound; has large conjugated system with the same number of active carbonyl groups; greatly reduces the solubility of the material in the electrolyte, improves the thermal stability and electronic conductivity after polymerization, and the assembled battery has excellent rate performance and cycle stability. DETAILED DESCRIPTION - Preparing naphthalimide polymer, comprises uniformly mixing naphthalimide compound of formula (I) and ferric chloride and then perform solid-phase grinding in a mortar for 30-50 minutes, or in a ball-milling jar at a rotating speed of 500-1000 revolutions/minute for 20-30 minutes, washing the ball-milled solid and drying to obtain polynaphthalimide or dissolving (I) and ferric chloride in organic solvent, stirring at room temperature under the protective atmosphere for 30-50 hours, washing and drying to obtain polynaphthalimide and the mass ratio of naphthalimide and ferric chloride is 1:5-6. R = benzene-1,4-diyl, biphenyl-4,4'-diyl or ethane-1,2-diyl. INDEPENDENT CLAIMS are also included for: Naphthalimide polymer prepared by above method; and Use of naphthalimide polymer in lithium/sodium battery comprising uniformly mixing naphthalimide polymer, conductive agent and binder in N-methyl-2-pyrrolidone, then coating on the current collector, drying, then cutting to obtain anode sheet, where the mass ratio of naphthalimide polymer, conductive agent and binder is 60-75:15-30:10, the conductive agent is mixture of arbitrary proportions of Super-P, conductive carbon, acetylene black, Ketjen black, conductive graphite, carbon brazing, carbon nanotubes and/or graphene, the binder is mixture of polyvinylidene fluoride and/or PTFE, the current collector is stainless steel, aluminum foil, copper foil, aluminum mesh or copper mesh and the loading amount of naphthalimide polymer on the current collector is 0.8-2 mg cm.-2