Flash Graphene from Sugarcane Bagasse with Acid Pretreatment and KOH Activation for Durable High-Rate Lithium-Ion Battery Anodes
Abstract
Biomass-derived carbon materials are attractive as lithium-ion battery anodes because of their low cost, sustainability, and tunable structure. This work reports the synthesis of flash graphene from sugarcane bagasse through acid pretreatment, KOH activation, and flash Joule heating, with bagasse-derived graphite, commercial graphite, and commercial graphene used as references. The effectiveness of the pretreatment was evaluated by X-ray fluorescence (XRF), which confirmed substantial removal of inorganic impurities, particularly Si from 42.47% to 10.64% and Ca from 13.43% to 9.23%, indicating effective deashing of the biomass precursor. Structural and textural characterization by BET, SEM, and Raman spectroscopy showed that the resulting bagasse-derived flash graphene possessed a higher surface area (769.378 m² g⁻¹), larger pore volume (0.4213 cc g⁻¹), more open and wrinkled morphology, and higher defect density (ID/IG = 1.03) than the more ordered graphitic counterparts. Electrochemical performance was investigated using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic cycling. Although commercial graphene exhibited the highest initial and absolute capacities, bagasse-derived flash graphene showed stable cycling behavior and favorable capacity retention under repeated high-rate operation. In particular, B-FG retained 87.43% of its capacity after 100 cycles under a 1C charge/1C discharge protocol. Under a more severe 10C charge/1C discharge protocol, it showed an apparent capacity retention of 129.14% after 100 cycles, which is cautiously attributed to activation-related behavior during repeated high-rate cycling. These findings demonstrate that acid-pretreated and KOH-activated sugarcane bagasse is a viable sustainable precursor for flash graphene and that its defect-rich porous framework is highly promising for durable high-rate lithium-ion battery anodes.