ABSTRACT
Silicon is an attractive material to replace graphite as the negative electrode in Li-ion batteries due to its 10 times higher theoretical specific capacity. However, the lithiation of silicon is also characterized by a large inherent increase in volume, which can lead to pulverization of the material and subsequent loss of electronic contact with the current collector. The end result is a large irreversible capacity loss in the first cycle and poor capacity retention in following cycles. Recently, there has been much interest in using nanostructured materials in Li-ion battery electrodes due to the advantages imparted by decreasing the Li-ion insertion distance, including improving the ionic and electronic transport properties of the material. Here we show that nanostructured silicon in the form of nanowires (NWs)
can exploit additional advantages of nanostructured materials: facile phase transformations, accommodation of lithiation-induced strain, and the ability to undergo large volume changes without pulverization. High specific capacities >3500 mAh/g have been achieved with good capacity retention. Detailed electrochemical and structural characterizations have been performed to understand the good performance of these silicon NW-based electrodes.
