球形硬碳的可控制备及高性能钠存储

Spherical hard carbon materials have shown great potential in sodium-ion batteries (SIBs) due to their abundant raw material sources，excellent performance，and structural stability. Starch，as a common hard carbon precursor，possesses a spherical-like structure that can maintain the consistency of the hard carbon framework while controlling costs. However， during high-temperature carbonization， the polysaccharide molecules in starch break down， leading to structural expansion and foaming， which damages its spherical shape. To address this issue，the treatment of starch with phosphorus-containing polymer molecules is proposed. This process promotes cyclization and crosslinking of surface functional groups on the starch， forming a soft carbon coating layer during high-temperature pyrolysis，effectively preventing the foaming phenomenon. As a result，a soft carbon-coated spherical hard carbon material was successfully synthesized. When used as an anode material for SIBs，it exhibited a high reversible capacity of 289 mAh/g，and even at a high current density of 1 A/g，it maintained a reversible capacity of 189 mAh/g. This synthesis strategy offers a new avenue for developing high-performance spherical hard carbon materials.