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 SiO 2 and amorphous C in RHs leads to poor electrical conductivity and structural integrity. In this work, SiO 2 /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-SiO 2 /C, which is beneficial to providing both elastic and mechanical stability and keeping the structural integrity. BM-SiO 2 /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 SiO 2 /C composites. PVC with excellent coating performance was selected to coat RHs-SiO 2 /C and the electrochemical performance was enhanced, which provides a method of converting biomass material into a useful storage device.
This work designed a facile preparation for an SiO2/C composite as the anode material for lithium ion battery. Both SiO2 and carbon are amorphous. SiO2 and carbon are mixed uniformly. The SiO2/C composite shows high specific capacity, cycle stability, and rate capability in lithium ion battery charge–discharge test. A stable reversible capacity of 1024 mA h/g at the current density of 100 mA/g is reached. The capacity retains 83% after 100 cycles. The uniform mixture of SiO2 and carbon leads to reduced volume change during the lithiation and delithiation of SiO2, together with the amorphous nature of SiO2 explains the high cycling stability. The carbon coating is a key factor for the high capacity and stability due to the increased electrical conductivity and reduced volume change. The resistance of the solid electrolyte interface film and charge transfer resistance of the SiO2/C composite are much smaller than those of pure carbon, which is a direct proof of the improved conductivity of the material by the carbon coating.
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