Reasonable design and synthesis of nickel manganese sulfide nanoparticles derived from metal organic frameworks as electrode materials for supercapacitors

Multi-element transition metal sulfides have higher electrical conductivity and specific capacitance compared with single metal sulfides, so they have greater application prospects in energy storage devices. Herein, we successfully synthesized bimetal sulfide Ni/Mn–S using Ni/Mn-74 as template by simple hydrothermal method and calcination method. The synthesized electrode NiMn–S exhibits higher specific capacitance (2510.15 F g−1 at 1 A g−1) and cycle rate performance (84.5% after 5000 cycles) than Ni2Mn–S and NiMn2–S electrodes. In addition, we assembled asymmetric supercapacitors with NiMn–S as positive electrode, activated carbon as negative electrode, and water electrolyte KOH and solid electrolyte PVA-KOH as electrolytes respectively. The results show that the capacitor exhibits high energy density and power density (82.2 Wh kg−1 at 800 W kg−1) under the condition of alkaline electrolyte KOH, but after 10,000 cycles at the current density of 10 A g−1, the cycle rate performance is only 81.1% lower than that of the solid asymmetric supercapacitor 90.2%. In short, this series of encouraging results demonstrates that we have successfully prepared a promising cathode material, providing a new method for constructing high-porformance energy storage devices.