Environmental Sustainability of Metal-Assisted Chemical Etching of Silicon Nanowires for Lithium-Ion Battery Anode

Abstract

Abstract Silicon nanowires (SiNWs) with three different average diameters of 90, 120, and 140 nm were synthesized by a metal-assisted chemical etching (MACE) method. Environmental sustainability of the MACE process was studied by investigating material consumptions, gas emissions, and silver nanoparticle concentrations in nitric acid solutions for 1 g of SiNWs and 1 kW h of lithium-ion battery (LIB) electrodes. It was found that the process for 90 nm SiNWs has the best sustainability performance compared with the other two processes. Specifically, in this study for 1 g of 90 nm SiNWs, 8.845 g of Si wafer is consumed, 1.09 g of H2 and 1.04 g of NO are produced, and 54.807 mg of Ag nanoparticles are found in the HNO3 solution. Additionally, for 1 kW h of LIB electrodes, the process for 90 nm SiNWs results in 1.943 kg of Si wafer consumption, 239.455 g of H2 and 239.455 g of NO emissions, and 12.040 g of Ag nanoparticles concentrations. By quantitatively investigating the material consumptions and emissions, this study assesses the sustainability performance of the MACE process for synthesizing SiNWs for use in LIBs, and thus it provides process data for the analysis and the development of sustainable production methods for SiNWs and similar anode materials for next-generation LIBs.