Preparation of nanoporous SiO2/C derived from rice husk as anode material in SiO2/C||LiFePO4 full-cell through alkaline activation treatment

Abstract Silicon-based materials such as pure silicon (Si), silicon monoxide (SiO), silica (SiO 2 ), are considered promising anode for future high power energy Li-ion batteries. Among them, SiO 2 has garnered attention owing to its outstanding features such as high theoretical capacity (1961 mAh g −1 ), abundant reserve, and low-cost processing. However, the large expansion and shrinkage of the Si and SiO 2 volume during lithiation/delithiation reaction are still the main barriers for practical application. In this study, SiO 2 derived from rice husks and activated by KOH displayed a nanoporous structure with a porous matrix carbon that can absorb the volume expansion during lithiation process and facilitate the diffusion of Li + ion along the pores to minimise the dendrite growth at the local area. Through activation treatment, the surface area of SiO 2 increases up to 278.875 m 2 g −1 with a pore volume of 0.191 cm 3 g −1 and the average pore diameter is about 0.771 nm. The cycling results showed that rice husk ash mixed with KOH at a ratio of 1:0.5 offered the best capacity retention of SiO 2 /C anode material in half-cell. In full-cell configuration of SiO 2 /C||LiFePO 4 , the the negative electrode/positive electrode capacity ratio ( N / P ) ratio of 1.2 exhibited the most stable performance with the highest capacity retention.