Silicone for Lithium-Ion Battery Anode Derived from Geothermal Waste Silica through Magnesiothermic Reduction and Double Stages in Acid Leaching

Abstract

The utilization of geothermal silica as the silica source to synthesize silicone as lithium-ion battery anode component was comprehensively studied. Silicone conversion was performed using magnesiothermic reduction at a temperature of 650 °C for 7 h. The applied Mg:SiO2 mole ratio on magnesiothermic reduction were 1.6:1, 2:1, and 2.5:1. The purification treatments of silicone product were conducted using two stages of acid leaching using HCl and a mixture of HF and acetic acid. In lithium-ion battery anode preparation, the ratio of Si to graphite employed 100:0; 90:10; 50:50; 10:90; and 0:100. The best yield and the conversion of silicone were 26.46% for the yield and 85.60% for the conversion by using 2:1 of Mg:SiO2 ratio. In the purification treatments, silicone yield of 29.45% with silicone purity of 58.9% was achieved using HCl, and silicone yield of 25.97% with silicone purity of 98% was achieved by using mixed solution of HF and acetic acid. The best battery performance in term of specific capacity was found by applying Si:graphite ratio of 100:0 with the value of first cycle of 358.5 mAh/g in this research. These findings present the reliability and feasibility of the geothermal solid waste and acid leaching treatments to generate the high quality of silicone for lithium-ion battery anode component.