Solution-Grown Germanium Nanowire Anodes for Lithium-Ion Batteries

Solution-grown germanium (Ge) nanowires were tested as high capacity anodes in lithium ion (Li-ion) batteries. Nanowire films were formulated and cast as slurries with conductive carbon (7:1 Ge:C w/w), PVdF binder and 1.0 M LiPF6 dissolved in various solvents as electrolyte. The addition of fluorethylene carbonate (FEC) to the electrolyte was critical to achieving stable battery cycling and reversible capacities as high as 1248 mA h g(-1) after 100 cycles, which is close to the theoretical capacity of 1,384 mA h g(-1).Ge nanowire anodes also exhibited high rate capability, with reversible cycling above 600 mA h g(-1) for 1200 cycles at a rate of 1C. The batteries could also be discharged at 10C with a capacity of 900 mA h g(-1) when charged at 1C.