Facile synthesis of sulfur-doped nickel manganese oxide nanoflakes as an electrode material by ion exchange process for high-performance hybrid supercapacitors

Abstract

To address the hazardous environmental impacts of fossil fuels, green and renewable energy sources can solve these environmental complications. Herein, we reported the synthesis and properties of sulfur (S)-doped nickel manganese oxide (NMSx, where x is the millimolar concentration of the S source), which was prepared via a facile ion exchange process by maintaining the pH value of the solution. The optimized NMS20 nanoflakes (NFs) material possessed a highly porous morphology with a large active surface area (109.24 m2 g−1), enhancing its electrochemical performance. An NMS20 NFs electrode delivered an appreciable areal capacity of 175.02 µAh cm−2 in a 1 M KOH electrolytic solution. The electrode also exhibited good cycling stability with 85.8% capacity retention and 100% coulombic efficiency over 20,000 cycles. A hybrid supercapacitor (HSC) was constructed using NMS20 NFs as the positive electrode and activated carbon/nickel foam as the negative electrode. The HSC exhibited maximum areal energy and power densities of 84.47 µWh cm−2 and 15,000 µW cm−2, respectively, with 83.8% capacitance retention after 30,000 cycles. Practical application of the HSC device was demonstrated by powering various electronic devices.