Direct Synthesis of Alloyed Si1-xGex Nanowires for Performance-Tunable Lithium Ion Battery Anodes.

Here we report the formation of high capacity Li-ion battery anodes from Si1-xGex alloy nanowire arrays that are grown directly on stainless steel current collectors, in a single-step synthesis. The direct formation of these Si1-xGex nanowires (ranging from Si0.20Ge0.80 to Si0.67Ge0.33) represents a simple and efficient processing route for the production of Li-ion battery anodes possessing the benefits of both Si (high capacity) and Ge (improved rate performance and capacity retention). The nanowires were characterized through SEM, TEM, XRD and ex situ HRSEM/HRTEM. Electrochemical analysis was conducted on these nanowires, in half-cell configurations, with capacities of up to 1360 mAh/g (Si0.67Ge0.33) sustained after 250 cycles and in full cells, against a commercial cathode, where capacities up to 1364 mAh/g (Si0.67Ge0.33) were retained after 100 cycles.