Low-Cost and Sustainable Hard Carbon Derived from the Peony Shell for the Stable Sodium-Ion Anode

Abstract

Sodium-ion batteries (SIBs) have significant potential for large-scale energy storage, driving increased demand for hard carbon materials. It is vital to explore the environmental, economic, and sustainability value of biomass carbon. Herein, we propose peony shell-derived hard carbon (PHC) as an easily accessible anode material for SIBs. Utilizing the water solubility of p-toluene sulfonic acid, the lignocellulose content in peony shells can be accurately regulated, and the macromolecules are cleaved into shorter fragments. As a result, the PHC exhibits enlarged interlayer spacing, reduced carbon microcrystal size, and optimized pore structure, which enable the PHC to showcase a 333 mAh g−1 reversible capacity at 0.1 C and 90.39% capacity retention after 100 cycles. More importantly, such a transformation not only enhances the value of peony shells but also reduces environmental pollution. This finding provides significant insights into the construction of a low-cost, sustainable hard carbon anode and injects new vitality into the large-scale application of SIBs in energy storage systems.