Currently, the fast growth and advancement in technologies demands promising supercapacitors, which urgently require a distinctive electrode material with unique structures and excellent electrochemical properties. Herein, binder-free manganese iron sulfide (Mn-Fe-S) nanostructures were deposited directly onto Ni-foam through a facile one-step electrodeposition route in potentiodynamic mode. The deposition cycles were varied to investigate the effect of surface morphologies on Mn-Fe-S. The optimized deposition cycles result in a fragmented porous nanofibrous structure, which was confirmed using Field Emission Scanning Electron Microscopy (FE-SEM). X-ray photoelectron spectroscopy (XPS) confirmed the presence of Mn, Fe, and S elements. The energy dispersive X-ray spectroscopy and elemental mapping revealed a good distribution of Mn, Fe, and S elements across the Ni-foam. The electrochemical performance confirms a high areal capacitance of 795.7 mF cm-2 with a 24 μWh cm-2 energy density calculated at a 2 mA cm-2 current density for porous fragmented nanofiber Mn-Fe-S electrodes. The enhancement in capacitance is due to diffusive-controlled behavior dominating the capacitator, as shown by the charge-storage kinetics. Moreover, the assembled asymmetric coin cell device exhibited superior electrochemical performance with an acceptable cyclic performance of 78.7% for up to 95,000 consecutive cycles.
Keywords: Mn–Fe–S; asymmetric coin cell device; fragmented nanofibrous structure; mixed metal sulfides.