Preparation of biomass-derived hard carbon with uniform ultramicropores for development of fast charging Li-ion batteries

Biomass-based hard carbon is the material of choice for fabricating fast charging anodes. However, their low initial coulombic efficiency (~70%) must be improved to increase energy density. In this study, the pore structure of hard carbon was tuned by pretreatment. The ultramicropores (< 0.4 nm) in modified hard carbon inhibited electrolyte decomposition and enhanced the diffusion kinetics. The hard carbon pretreated at 500 °C under 6 MPa for seven days showed a high capacity retention rate of 82%, despite fast charging and a low irreversible capacity. This strategy can help realize efficient lithium storage and diffusion.