Investigating the effect of sulfur and selenium on the electrochemical properties of nickel-cobalt oxides: enhanced charge capacity and composition-property relationships

摘要

Nickel and cobalt oxides, sulfides, selenides are widely studied as active materials in the application of energy storage and enhanced capacity are obtained as the atomic number of the non-metal element increase. In this study, Nickel and cobalt oxides (NiCoO2), sulfides and selenides are prepared via ion-exchange method and they are investigated as electrode materials for aqueous battery applications. From the perspective of electrochemistry, a detailed study of the fundamental relationships between composition, properties, and electrochemical performance are carried out. The results reveal that the enhanced charge capacity is associated with a more active property of nickel and cobalt as well as higher diffusivity of electrolyte after introducing different anions (S or Se). However, the reversible specific capacity decreases for sulfides and selenides and X-ray photoelectron spectroscopy results after long-term cycling tests indicate that the dissolution of S and Se may be responsible for the severe degrading in charge capacity.