Probing hard carbon fiber fabric synthesized by CO2 laser for Na-ion battery anodes

This study investigates the optical and electrochemical performance of cotton-derived hard carbon fabrics structurally modified by CO 2 laser processing. The application of high laser power over a very short duration promotes rapid thermal treatment of materials, achieving up to 2000 °C. Despite the complexity of the hard carbon structure, detailed insights into its structural organization are significantly enhanced through complementary Raman mapping, which not only reveals the degree of structural ordering but also establishes correlations with the material's electrochemical performance as anodes in sodium-ion batteries. The results reveal that the material discharge capacity initially increases from 275 mAh g −1 at a current density of 18.6 mA g − 1 for a treatment temperature of 900 °C, to a value of 309 mAh g −1 at 1600 °C, before subsequently decreasing to 230 mAh g −1 at 2000 °C. • Carbonized Cotton fabrics converted into locally structured hard carbon via rapid CO 2 laser processing. • Laser treatment achieves structural reorganization up to 2000 °C within seconds. • Raman mapping reveals correlations between microstructure and electrochemistry. • Optimized treatment (1600 °C) yields high Na-ion storage capacity (254 mAh g −1 ). • Demonstrates scalable and energy-efficient route for sustainable anode materials.