High capacity Li ion battery anodes using ge nanowires.

Ge nanowire electrodes fabricated by using vapor-liquid-solid growth on metallic current collector substrates were found to have good performance during cycling with Li. An initial discharge capacity of 1141 mA.h/g was found to be stable over 20 cycles at the C/20 rate. High power rates were also observed up to 2C with Coulombic efficiency > 99%. Structural characterization revealed that the Ge nanowires remain intact and connected to the current collector after cycling. Nanowires connected directly to the current collector have facile strain relaxation and material durability, short Li diffusion distances, and good electronic conduction. Thus, Ge nanowire anodes are promising candidates for the development of high-energy-density lithium batteries.