Scalable approach to multi-dimensional bulk Si anodes via metal-assisted chemical etching

Abstract

Specific design and optimization of the configuration of micro-scale materials can effectively enhance battery performance, including volumetric density. Herein, we employed commercially available low-cost bulk silicon powder to produce multi-dimensional silicon composed of porous nanowires and micro-sized cores, which can be used as anode materials in lithium-ion batteries, by combining a metal deposition and metal-assisted chemical etching process. Nanoporous silicon nanowires of 5–8 μm in length and with a pore size of ∼10 nm are formed in the bulk silicon particle. The silicon electrodes having multi-dimensional structures accommodate large volume changes of silicon during lithium insertion and extraction. These materials show a high reversible charge capacity of ∼2400 mAh g−1 with an initial coulombic efficiency of 91% and stable cycle performance. The synthetic route described herein is simple, low-cost, and mass producible (high yield of 40–50% in tens of gram scale), and thus, provides an effective method for producing high-performance anode materials.