Preparation of hard carbon from acid-treated biomass locust wood as anode material for sodium-ion batteries

Abstract Currently, sodium-ion batteries (SIBs) are favored by scientific researchers because of their abundance, low cost, and high safety. Furthermore, hard carbon has a low voltage plateau and a high sodium storage capacity when used as the anode material in SIBs. Given its affordability and variety of sources, biomass hard carbon has gained interest. Whereas, the low initial coulombic efficiency (ICE) of biomass hard carbon significantly hinders its development. Therefore, waste biomass locust wood was utilized to produce hard carbon at various carbonization temperatures. The appropriate carbonization temperature was selected for precursor modification using 6 M HCL, to look into how acid treatment affects the microstructure of carbon materials and how that affects their electrochemical characteristics. The experimental results proved that the HCL pretreated hard carbon could increase the carbon layer spacing, increase more surface active sites that favor Na⁺ storage and decrease the specific surface area. HC-1500 and HHC-1500 possessed a first lap charge specific capacity of 319.6 mAh/g and 382.3 mAh/g, respectively, with an increase in the ICE from 62% to 67%, and also had a significant improvement in the cycling performance. Therefore, treating waste biomass with hydrochloric acid is a direct and effective method to modify hard carbon and improve the electrochemical performance of it.