Silica from kazakhstan rice husk as an anode material for LIBs

This paper reports the synthesis of the silica (SiO₂) from Kyzylorda rice husk (RH) and investigation of its electrochemical behaviour as an anode material for the lithium-ion battery. Rice husk, considered as agricultural waste material, contains a substantial amount of amorphous silica, carbon, and minor other mineral composition, which have potential industrial and scientific applications. Due to the high theoretical capacity of silicon (4200 mAh g^-1) and silicon dioxide (1965 mAh g^-1), Si-containing compounds are considered as a promising candidate for a new generation of anode materials for lithium-ion batteries. In this work, the technology of amorphous SiO₂ extraction from Kyzylorda region rice husk is developed. The silica powder was obtained by burning the rice husk and treating the obtained ash with the sodium hydroxide and hydrochloric acid. The extracted SiO₂ and intermediate products were studied by the SEM, XRD, XRF, XPS, TGA in comparison with commercial silica. The RH of the Kyzylorda region has 12% of Si. The electrochemical characteristics of assembled coin cell type battery were tested by using cyclic voltammetry and galvanostatic charge/discharge cycling. Results show that silica synthesized from agriculture waste has the same performance as commercial analog. The initial discharge capacity of the battery with synthesized silicon dioxide was 1049 mAhg^-1. The reversible discharge capacity in the second and subsequent cycles is about 438 mAhg^-1.