Structural control of activated carbons derived from rice husks for sustainable and enhanced lithium-ion battery anodes

Abstract

Activated carbon (AC) derived from rice husk is synthesized through a chemical activation method using dual activation agents of KOH and NaOH. The resulting AC materials demonstrate a moderate degree of graphitization, a large specific surface area, and are enriched with abundant oxygenate surface functional groups. These characteristics make them promising candidates as anode materials for Li ion batteries. Upon evaluating the performance of the synthesized ACs as anode materials, remarkable charge/discharge properties are observed, showcasing reversible capacities surpassing the theoretical value of graphite by 1.77 to 2.27 times. Notably, the AC sample obtained with the weight ratio of KOH/NaOH/char of 2 : 2 : 1 (designated as RH-K2N2) exhibits the highest reversible capacities, reaching an impressive 857 mAh⋅g⁻¹ at a current density of 50 mA⋅g⁻¹. Additionally, even after 100 fully discharge-charge cycles at the current density of 100 mA⋅g⁻¹, the reversible capacity remains as high as 525 mAh⋅g⁻¹.