A room temperature study of the binary lithium-silicon and the ternary lithium-chromium-silicon system for use in rechargeable lithium batteries

Several binary lithium-silicon and ternary lithium-chromium-silicon samples were produced and then characterized by X-ray diffraction, as well as electrochemical methods at room temperature. The known lithium-silicon phases, as well as silicon-chromium phases, were found, but no ternary phases. The electrochemical characterization of the materials yielded behavior differing from that predicted from high temperature experiments. Experiments on highly lithiated samples yielded charge potentials in the realm of 300-650 mV vs. Li/Li+ and discharge potentials of about 20-300 mV vs. Li/Li+. The binary lithium-silicon materials showed reversible capacities of up to 550 mA h/g. The ternary materials showed higher reversible capacity of up to 800 mA h/g. The capacity is dependent on the initial stoichiometry of the material with Li:Si ratios of about 1:3.5 showing the highest reversible capacities. Good cycling performance could also be achieved. (C) 1999 Elsevier Science S.A. All rights reserved.