Boosting Sodium Storage Activity and Kinetics of Hard Carbon by Remodeling Oxygen Chemistry

ABSTRACT Biomass‐derived hard carbons have been widely regarded as an alluring anode material for sodium‐ion batteries on account of their resource sustainability and environmental benignity. However, it is of critical necessity yet challenge to achieve precise modulation of carbon microstructure toward enhanced sodium energy. In this study, the internal pseudographitic domains of hard carbon is finely regulated by remodeling oxygen chemistry of biomass precursors for high‐efficiency sodium storage. Oxygen‐containing functional groups are refined to fortify the lignocellulosic cross‐linking, which facilitates the expansion of carbon interlayers and the formation of closed pores. The structurally beneficial features enable a remarkable promotion of sodiation activity and kinetics, thus delivering an improved capacity of 360 mAh g −1 at 0.02 A g −1 , a high initial Coulombic efficiency of 87.4%, and a superb‐rate capacity of 225 mAh g −1 at 2 A g −1 . An in‐depth understanding of enhanced electrode kinetics and sodium storage mechanism is elaborated. The present work highlights the importance of oxygen chemistry remodeling for the development of high‐performance biomass‐derived hard carbon anodes toward sodium‐ion batteries.