Electrochemical Characteristics of SiO<sub>2</sub>/C Prepared from Rice Husk and Its Model Materials as Anodes for Lithium-Ion Batteries

Silicon oxide-based anode materials have attracted increasing attention for nextgeneration lithium-ion batteries because of their high theoretical capacity and improved cycling stability compared with silicon anodes.In addition, the use of low-cost and environmentally benign biomass resources as precursors for silicon oxide anodes has emerged as an attractive strategy.In this study, SiO2/C nanocomposites were systematically investigated as anode materials using both a model system composed of commercially available SiO2 and lignin and biomass-derived materials prepared from rice husks.The model SiO2/C composites exhibited reversible capacities that increased with increasing SiO2 content, while sodium-ion battery measurements revealed that the reversible capacity observed in lithium-ion cells predominantly originated from the electrochemical activity of SiO2.Si K-edge X-ray absorption near-edge structure (XANES) analysis revealed that the extent of spectral changes for the rice-husk-derived SiO2/C was smaller than that for the model SiO2(50)/C.This result indicates a lower electrochemical activity of SiO2 in the biomass-derived composite, which is responsible for the reduced reversible capacity.Nevertheless, rice husk-derived SiO2/C delivered a reversible capacity exceeding 400 mAh g -1 with good cycling stability, demonstrating that rice husks are a promising precursor for the preparation of SiO2/C nanocomposites.