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 inAh/g (Si0.67Ge0.33) were retained after 100 cycles.