Conversion of waste denim fabrics into high-performance carbon fiber anodes for sodium-ion batteries

Hard carbon materials are attracted as excellent anode materials for sodium-ion batteries due to their good electrical conductivity, high reversible capacity, low operating voltage and stable cycling performance. Herein, waste denim fabrics were used as raw material to prepare denim-based hard carbon (DHC) via a one-step carbonization method, and its sodium storage performance as an anode material for sodium-ion batteries was investigated. The effects of carbonization temperature on the microstructure and electrochemical sodium storage performance of DHC were investigated using X-ray diffraction, N₂ adsorption–desorption isotherms, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry and galvanostatic charge–discharge methods. The results demonstrate that DHC derived at a carbonization temperature of 1300 °C with an optimal graphitic microcrystal size, pore structure and surface defect, exhibits the best electrochemical performance. At a current density of 50 mAh·g⁻¹, it has a reversible specific capacity of 317.1 mAh·g⁻¹ and an initial Coulombic efficiency of 87.76%. After 1000 cycles at a current density of 1000 mA·g⁻¹, the capacity retention rate is 84.5%. This study demonstrates the potential of converting waste textile resources into high-performance materials for sodium-ion batteries, which could contribute to sustainable development by promoting the high-value utilization of textile waste and supporting environmental protection.