Advances of the top-down synthesis approach for high-performance silicon anodes in Li-ion batteries

With a remarkable theoretical specific capacity of similar to 4200 mA h g(-1), silicon anodes are at the forefront of enabling lithium-ion batteries (LIBs) with ultra-high energy density. However, we have yet to see the wide utilization of silicon anodes in commercial LIBs due to several challenges, categorized as intrinsic and extrinsic problems. The intrinsic problems originate from the intrinsic properties of silicon, which include its low conductivity and massive volume expansion upon alloying with lithium. The extrinsic problems of silicon anodes are primarily associated with the laborious fabrication processes. Instead of bottom-up approaches, which involve relatively expensive and complicated synthesis routes, the top-down methods provide an affordable, controllable, and simple procedure for large-scale fabrication. The present review aims to collate the recent studies on the fabrication of silicon anodes via top-down approaches that involve etching, metallothermic reduction, and high energy ball milling. Extensive synthesis routes along with their synthesis parameters are reviewed. The morphology and the electrochemical performances of the silicon anodes prepared from various starting materials are also highlighted. Finally, perspectives on the potential future challenges and development of the top-down synthesis of silicon-based anodes are presented.