Access to M[sup 3+]/M[sup 2+] Redox Couples in Layered LiMS[sub 2] Sulfides (M=Ti, V, Cr) as Anodes for Li-Ion Battery

The insertion of Li into layered sulfides has been reinvestigated with ethylene-carbonate-based carbonate electrolytes. The and redox couples in a sulfide were found to give a reversible insertion reaction at about 0.5 and 1.0 V vs , respectively, while Cr atoms are displaced from at 0.9 V vs . Comparison to a graphite anode indicates that a solid-electrolyte-interface (SEI) passivation layer is formed below 0.9 V during the first discharge of the before reaching the redox couple, while an SEI layer was formed after reaching the redox couple at 1.0 V during the first discharge of the electrode. The formation of a suitable SEI layer and therefore the reversibility and capacity of sulfide anodes are shown to depend on the composition of the electrolyte.