Low-cost silicon cutting waste reused as a high-power-density silicon-based anode

Abstract

With the rapid development of electric vehicle technology, commercial graphite anodes (theoretical capacity of 372 mA h g⁻¹) of lithium-ion batteries cannot meet the needs for high power density. Silicon has high theoretical capacity (4200 mA h g⁻¹), low working voltage (about 0.4 V vs. Li/Li⁺), rich resources and environmental friendly nature; hence, it is regarded as a potential negative electrode material. During repeated charging and discharging, silicon particles continuously pulverize, which leads to the volume expansion of electrode materials (up to 400%) and a decrease in conductivity. In this study, high-purity nano-silicon was prepared via a calcination-ball milling-pickling process with low-cost silicon cutting waste (SiCW) as a raw material to meet the needs of lithium-ion batteries for high-purity and nano-scale silicon-based anodes. At the same time, silicon@graphite nanocomposites with different mass ratios were prepared via a low-cost industrialized ball-milling process. The easy intercalation and softness of the graphite layer structure realized the coating and joining of nano-silicon, which improved the conductivity of nano-silicon and restrained the rapid degradation of cycling performance caused by the expansion and pulverization of the silicon-based anode. Adopting low-cost raw materials and industrialization-based preparation processes can effectively control the production cost of silicon-based anode materials and lay a solid foundation for their practicality.