Combinatorial Investigations of Ni-Si Negative Electrode Materials for Li-Ion Batteries

Sputtered thin films in the Ni-Si system (0 <= x <= 0.65 in NixSi1-x) were studied for use as anode materials in Li-ion cells. All compositions were found to be amorphous. The Ni in Ni-Si films was found to suppress the lithiation voltage, resulting in a reduction in capacity. The delithiation voltage was not affected. No capacity was observed when Ni content was more than 50 at% because at this composition the lithiation voltage was suppressed to 0 V. In contrast to previous models of capacity in transition metal-Si films, all Si atoms were found to be active in Ni-Si films at all compositions. Capacity reduction is only caused by a suppression of the Si lithiation voltage. We attribute this voltage suppression to internal stress in the thin film during lithiation from the presence of Ni. (C) 2015 The Electrochemical Society. All rights reserved.