The invention discloses a
biomass-based hard carbon material with a closed-pore structure optimized by a
boron-based template agent, a preparation method of the
biomass-based hard carbon material and application of the
biomass-based hard carbon material in a
sodium-
ion battery. The preparation method comprises the following steps: (1) carrying out
solid-liquid mixing on biomass and an
aqueous solution of a
boron template agent, and
drying; the selected
boron template agent comprises at least one of
boric acid,
borax,
triethyl borate,
trimethyl borate,
metaboric acid,
sodium metaborate and
potassium borate. And (2) carbonizing the dried mixed material twice, naturally cooling,
pickling, and removing the template to leave a rich pore structure. And performing high-temperature re-
carbonization on the carbon material, cooling, and sequentially performing crushing, acid
pickling,
water washing and
drying. The obtained biomass-based hard carbon material has a pore structure with a large specific surface area and closed pore volume, the defect density of a
graphite structure is reduced to slow down
sodium death caused by an SEI film, and more pore-filled sodium storage sites are provided, so that the first coulombic efficiency and sodium storage performance of a battery are improved.