An efficient and closed-loop approach to convert silicon tetrachloride to silicon nanospheres anode materials via hydrogen thermal plasma

Solar energy is growing due to global "carbon peak and neutrality" targets. Silicon tetrachloride (SiCl4) is mass-produced from polycrystalline silicon (p-Si), an important solar material. Therefore, an efficient and cost-effective process is needed to transform this byproduct into a higher-value product. In this work, we present a new approach utilizing hydrogen thermal plasma (H-plasma) to directly convert SiCl4 into silicon nanospheres (Si NSs) and analyzed the reaction process by optical emission spectroscopy diagnostic. The Si NSs produced possess a spherical shape, with a smooth surface and a compact interior. With a diameter of ∼90 nm, Si NSs exhibits exceptional electrochemical performance when used as anode materials. Significantly, H-plasma is expected to be combined with the current tail gas recovery system of the p-Si industry to form a closed circuit, increasing yield and lowering costs. Our work demonstrates economically viable and widespread nano-silicon fabrication for sustainable energy solutions.