Starch as a Closed Pore Regulator to Boost the Initial Coulombic Efficiency and Rate Performance of Wood-Derived Hard...

Biomass-derived hard carbon (HC) with economic sustainability and abundant resources as quite appropriate anode candidates in sodium-ion batteries still suffers the undesirable electrochemical performance. Herein, waste wood is selected as a biomass precursor to fabricate HC with rich closed pore content, in which starch acts as the closed pore modulating agent. A clear relationship is established between the fraction of closed pore volume and starch addition. Among them, AP-0.5 exhibits the considerable initial Coulombic efficiency of 89.57% with an ideal capacity retention of 92.3% (300 cycles) under 150 mA g^-1. Additionally, an excellent rate performance of 213.3 mAh g^-1 is obtained at 600 mA g^-1. High fraction of closed pore volume enables AP-0.5 to have a superior plateau contribution of 61.8% for total capacity. Subsequently, the Na⁺ adsorption-intercalation-filling mechanism is thoroughly verified using in situ Raman spectroscopy. This study employs starch as a closed pore modulating agent, providing a cost-efficient route for designing high-capacity biomass-derived HC withrich closed pores.