Valence modulated nickel oxynitride network as integrated bifunctional electrodes for enhanced energy storage

Abstract As promising electrode materials, transition metal oxides have attracted considerable attention owing to their excellent performance in electrochemical energy storage. However, their poor conductivity and fragile structure limit their practical application. In this study, a binder-free nickel oxide/oxynitride network (NiON WS) bifunctional electrodes with cation multivalent states that exhibit high energy storage performance were synthesized for the first time. The massive active sites, high specific surface areas, and multiple cation valence states of NiON WS were advantageous for electrochemical redox reaction during its application in supercapacitors (1283.5 mF cm−2) and lithium-ion batteries (1345.0 mA h g−1). Particularly, the NiON WS based flexible asymmetric SCs exhibit excellent capacitance and energy densities. First-principle calculations were employed to study the mechanism of the electrochemical performance improvement of NiON WS. This study demonstrates the potential of transition metal oxides electrode with high capacity and activity for electrochemical energy storage and conversion.