Study of germanium as electrode in thin-film battery

Sputter-deposited gemanium thin films were investigated as negative electrode material for lithium-ion batteries. X-ray diffraction, scanning electron microscopy, and secondary-ion mass spectroscopy have been carried out. Doped and nondoped films were cycled vs lithium electrode. Diffusion coefficients, reaction potential, and cycling life were measured. The effect of doping and electrode thickness was also studied. The stable capacity is similar to 1460 mAh g(-1), with an increase over the 180 first cycles for n-doped germanium coatings. (c) 2007 The Electrochemical Society.