High capacity peanut shell-based hard carbon as a negative electrode for sodium-ion batteries†

Biomass hard carbon, serving as a negative electrode material for sodium-ion batteries, boasts advantages such as abundant sources, low cost, and high sodium storage capacity, thus earning its reputation as a highly promising negative electrode material. We utilized discarded peanut shells as raw materials and prepared high-performance hard carbon through a two-step process involving hydrothermal treatment and high-temperature carbonization. The application of the hydrothermal method significantly enhanced the nanoscale structure of the material, resulting in a highly dispersed sheet-like structure that facilitates the infiltration of the electrolyte and enhances the sodium storage capacity. The prepared hard carbon exhibits a specific surface area of 7.1 m² g⁻¹ and an interlayer spacing of 0.406 nm. Serving as a negative electrode material for sodium-ion batteries, it demonstrates a reversible sodium storage capacity of up to 357.55 mA h g⁻¹ and a first coulombic efficiency of 63.4% at a current density of 30 mA g⁻¹. PSHC-2 exhibits superior rate performance and good structural stability. The GITT test shows that PSHC-2 has good diffusion kinetics, which is beneficial for the insertion and extraction of sodium ions. The development of this new and efficient hard carbon negative electrode material has certain positive significance for the development of sodium ion batteries.