SiO2/C Composite as a High Capacity Anode Material of LiNi0.8Co0.15Al0.05O2 Battery Derived from Coal Combustion Fly Ash

Abstract

Abundantly available SiO2 (silica) has great potential as an anode material for lithium-ion batteries because it is inexpensive and flexible. However, silicon oxide-based anode material preparation usually requires many complex steps. In this article, we report a facile method for preparing a SiO2/C composite derived from coal combustion fly ash as an anode material for Li-ion batteries. SiO2 was obtained by caustic extraction and HCl precipitation. Then, the SiO2/C composite was successfully obtained by mechanical milling followed by heat treatment. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Electrochemical properties were tested using an 18650 cylindrical cell utilizing LiNi0.8Co0.15Al0.05O2 (NCA) as the counter electrode. Based on the obtained results, the physiochemical characteristics and electrochemical performance, it was determined that SiO2/C composites were greatly affected by the temperature of heat treatment. The best result was obtained with the SiO2 content of 10% w/w, heating temperature of 500 °C, initial specific discharge capacity of 586 mAh g−1 at 0.1 C (1 C = 378 mAh g−1), and reversible capacity of 87% after 20 cycles. These results confirmed that the obtained materials had good initial discharge capacity, cyclability, high performance, and exhibited great potential as an anode material for LIBs.