▎ 摘　　要

NOVELTY - Preparing sodium ion soft-pack battery comprises (1) taking the sodium ferric sulfate composite cathode material, super-p, and polyvinylidene fluoride, dispersing the above three materials in N-methylpyrrolidone solvent, uniformly mixing and coating on carbon-coated aluminum foil, and drying under vacuum at 120℃ for 12 hours to obtain anode piece, (2) taking the hard carbon anode material, super-p, styrene-butadiene rubber and carboxymethyl cellulose, uniformly mixing, coating on aluminum foil, and drying under vacuum at 80℃ for 12 hours to obtain negative pole piece, (3) rolling the pole piece to suitable compaction density before die-cutting, and die-cutting the pole piece to the appropriate size, and (4) welding the positive and negative pole pieces to the upper tabs with electric welding machine, stacking the positive pole piece, separator, and negative pole piece in the order, and collecting the surface-activated carbon-based material after drying. USE - The method is useful for preparing sodium ion soft-pack battery. ADVANTAGE - The method: solves the shortage of sodium ion batteries in the field of soft pack batteries; utilizes the surface wrapping modification of the carbon-based material carried by the sodium ferric sulfate composite anode material to improve the surface hydrophobicity of the active material; at the same time, can improve the surface and interface stability in the process of electrochemical sodium storage; ensures the transport of electrons and sodium ions, so as to obtain excellent electrochemical performance; and realizes its large-scale material mass production and practical application of batteries. DETAILED DESCRIPTION - Preparing sodium ion soft-pack battery comprises (1) taking the sodium ferric sulfate composite cathode material, super-p, and polyvinylidene fluoride in a mass ratio of 92:2:6, dispersing the above three materials in N-methylpyrrolidone solvent, uniformly mixing and coating on carbon-coated aluminum foil, where the thickness of the carbon-coated layer is 1 um, and drying under vacuum at 120℃ for 12 hours to obtain anode piece, (2) taking the hard carbon anode material, super-p, styrene-butadiene rubber, and carboxymethyl cellulose in a mass ratio of 95:1.5:2:1.5, dispersing the above four materials in pure water, uniformly mixing, coating on aluminum foil, and drying under vacuum at 80℃ for 12 hours to obtain negative pole piece, (3) rolling the pole piece to suitable compaction density before die-cutting, and die-cutting the pole piece to the appropriate size, (4) welding the positive and negative pole pieces to the upper tabs with electric welding machine, stacking the positive pole piece, separator, and negative pole piece in the order, fixing, placing into the semi-sealed aluminum plastic film together, transferring to 85℃ for drying under vacuum condition for 12 hours after completing the top and side sealing, adding electrolyte to the cell after drying, obtaining sodium-ion soft-pack cell battery after vacuum packaging, where the sodium ferric sulfate composite anode material is carbon-based sodium ferric sulfate anode material, comprising active sodium ferric sulfate material and carbon-based wrapping material, the mass ratio of the carbon-based wrapping material is 0.01-20%, the carbon-based wrapping material adopts carbon nanotubes, carbon fibers, reduced graphene oxide, graphene, conductive carbon black or activated carbon, the carbon-based wrapping material needs to be activated before use, and the activation method of the carbon-based wrapping material comprises adding the carbon-based material to certain concentration of acid solution, pouring into sealed polytetrafluoroethylene (PTFE)-lined stainless steel autoclave, hydrothermally treating, washing many times alternately with deionized water and ethanol, until the pH value is about 7, collecting the surface-activated carbon-based material after drying, where the active sodium ferric sulfate of formula NaxFe(SO4)y, y = (x+2)/2; and x = 1-3.