Carbon-Coated Rice Husk-Derived SiO2/C Composites As Anodes for Lithium-Ion Batteries: Comparison between CTEP and PVC Carbon Coatings

Rice husks (RHs) are rich in silica and organic carbon components, which have been widely applied in lithium ion batteries. However, the natural structure of uneven dispersion between SiO2 and amorphous C in RHs leads to poor electrical conductivity and structural integrity. In this work, SiO2/C composites were prepared by mechanical mixing and high-temperature carbonization from RHs, with coal tar electronic pitch (CTEP) or polyvinyl chloride (PVC) as the carbon coating agent, which imparted some improvement in cycling performance, initial coulombic efficiency (ICE), and rate performance. Compared with the high electrical conductivity of CTEP, PVC with low viscosity coated uniformly the surface of BM-SiO2/C, which is beneficial to providing both elastic and mechanical stability and keeping the structural integrity. BM-SiO2/C-PVC-6 exhibits a more stable cycling performance and higher specific capacity of 730 mA h g-1 after 100 cycles at 0.1 A g-1, with the ICE of 60%. Hence, the application of carbon coating agent plays a vital role in improving the electrochemical performance of SiO2/C composites. PVC with excellent coating performance was selected to coat RHs-SiO2/C and the electrochemical performance was enhanced, which provides a method of converting biomass material into a useful storage device.