Unveiling one-dimensional mixed-metallic oxysulfide nanorods as an advanced cathode material for hybrid supercapacitors

Abstract

Mixed-metallic oxyphosphides and oxysulfides are prominent electrode candidates for energy storage devices owing to the synergistic benefits of metal oxides and metal sulfides. Herein, we explore nickel-molybdenum oxyphosphides and oxysulfides (NMOP/NMOS) by a one-step hydrothermal technique, followed by an anion exchange process. As a result, the materials consist of one-dimensional nanorods (1D NRs) which promote charge transportation. Both the materials with 1D NR morphology exhibit superior electrochemical performance to the nickel-molybdenum oxides (NMO) NRs due to the incorporation of phosphorus and sulfur anions. Particularly, the NMOS material demonstrates better specific capacity (38.3 mA h/g, 338.7 F/g) compared with the NMO and NMOP materials. The feasibility of NMOS NRs as a cathode material is explored by fabricating the hybrid supercapacitor (HSC). By exploiting an intriguing feature of NMOS (cathode) and activated carbon (anode) materials, the HSC delivers maximum energy and power densities of 58.9 W h/kg and 3502.5 W/kg, respectively. An HSC shows excellent cycling stability even after 10,000 cycles (90.6% retention). The suitability of HSC in real-time applications is also verified by powering various electronic components. This work promotes the rational design of novel mixed-metallic oxysulfides-based electrode materials with beneficial morphologies for high-capacity SCs.