The electrochemical behavior of silica and activated carbon materials derived from the rice husk waste for li-ion cells

In this work, an amorphous silica powders (1-SiO2 and 2-SiO2) and activated carbon with few-layer graphene were derived from rice husk using simple and efficient process. Synthesized samples were characterized by means of TGA SEM, XRD, XRF, nitrogen low-temperature adsorption/desorption, Raman, and EDAX. Rice husk calcination yields in 18 and 14 wt% of 1-SiO2 and 2-SiO2, correspondingly. Carbonization of rice husk followed by activation yielded about 11 wt% of activated carbon with large specific surface area (SBET = 3292 m2 g-1). Feasibility of resulting materials as anode materials for Li-ion batteries grounded on a high theoretical capacity of silica and high charge/discharge stability of activated carbon. We present here a 2-SiO2 material with large specific surface area of 980 m2 g-1, of high purity above 99 %, and large pore volume (1.20 cm3 g-1), which results in a reversible capacity of about 841 and 442 mAh g-1 (1st and 50th cycle) with coulombic efficiency higher than 95 %. Activated carbon demonstrated the highest initial discharge specific capacity and stable reversible capacity after 50 cycles as 1462 and 477 mAh g-1 (1st and 50th cycle), and coulombic efficiency higher than 90 %.