Confining self-standing CoSe2 nanostructures and Fe3C wrapped N-doped carbon frameworks with enhanced energy storage performances

Transition metal selenides have been explored as suitable candidates for sustainable energy systems. More specific, designing battery-type and capacitor electrodes with exceptional structural, compositional and physiochemical properties is of a great significance to build battery-type supercapacitor hybrid (BSH) devices with high energy and power performances. In this study, a novel binder free positive electrode-based on nanostructured CoSe2 is prepared on a macroporous nickel foam (NF) current collector (CoSe2/NF) via a one-step chemical deposition route. A time-dependent in-situ growth reaction is executed to optimize the structural and electrochemical properties of electrodes. Interestingly, the uniformly constructed CoSe2/NF-9 crystallized into vertically aligned nanosheet arrays with unique porous features shows a higher specific capacitance (231 mAh g(-1) at a current density of 1 A g(-1)) and keeps about 83.7% of its initial capacitance after 3000 potential GCD cycles. As per strategy, Fe3C@N-CNTs composite is synthesized through a facile strategy and serves as a negative electrode material with a substantially high specific capacitance of 348 F g(-1) at 1 A g(-1) coupled with a remarkable rate capability. By paring the as-prepared CoSe2/NF-9 cathode and Fe3C@N-CNTs anode, an alkaline aqueous BSH system is fabricated with an enlarged potential window of 1.7 V. The integrated CoSe2/NF-9//Fe3C@N-CNTs BSH device exhibits a large energy density of 79.3 Wh kg(-1) at a power density of 1023.6 kW kg(-1). Moreover, the device has an improved cycling stability and retains around 80.7% of its initial capacitance after 8000 charge-discharge cycles. These results afford an effective rational guidance for developing materials with special compositional characteristics and electrochemical performances for energy storage applications.