Deconstruction Engineering of Lignocellulosic Biomass for the Preparation of High‐performance Hard Carbon Anode Materials in Sodium‐Ion Batteries

ABSTRACT Lignocellulose biomass is an ideal precursor for the preparation of hard carbon (HC) due to its abundant resource and low‐cost advantages. However, the structure of HC prepared by direct carbonization of lignocellulosic biomass has a small closed‐pore volume and large pore size, resulting in low capacity and poor rate capability. Herein, we propose a low‐corrosive aqueous maleic acid hydrothermal pretreatment strategy, which effectively and efficiently removes hemicellulose from coconut shell tissues, while also recovering the liquid products of xylose and furfural. After high‐temperature carbonization of the obtained precursor rich in lignin and cellulose, the closed‐pore size of the HC decreased from 2.297 to 1.640 nm, and the closed‐pore volume increased from 0.202 to 0.236 cm 3 g −1 . A small closed‐pore size and a large‐pore volume are beneficial for the filling of sodium ions in the closed pores. The optimized HC provides a reversible specific capacity of 365 mAh g −1 and excellent rate performance (the capacity retention rate was 69% at a high current density of 5.0 A g −1 ). This study achieves the high‐value utilization of all the components of lignocellulosic biomass, and provides a new path for the preparation of HC anode in high‐performance sodium‐ion batteries.