Fabrication of efficient electrochemical capacitors rooted in sol-gel derived NiMn2O4 nanoparticles

Abstract

NiMn 2 O 4 (NMO) nanoparticles are prepared by the sol–gel method. The electrode fabricated by drop casting the NMO nanoparticles onto Ni-foam showed specific capacitance of 658 Fg −1 in 1 M NaOH electrolyte. • NiMn 2 O 4 (NMO) nanoparticles are synthesized by sol–gel method. • Electrochemical properties of NMO-Ni foam are investigated in NaOH, KOH, and Na 2 SO 4 . • NMO-Ni foam exhibit specific capacitance of 658 Fg −1 in 1 M NaOH. • NMO-Ni foam showed 96.4 % cyclic stability for 1000 cycles in 1 M NaOH. NiMn 2 O 4 (NMO) nanoparticles (NPs) with a cubic spinel structure have been synthesized via the sol–gel method. The surface morphology study explored the porous nature of the NMO NPs. The compositional analysis displayed the constituent elements Ni, Mn, and O in NMO NPs. Electrochemical properties of the electrodes prepared from NMO NPs are investigated in 1 M KOH, 1 M NaOH, and 1 M Na 2 SO 4 electrolytes. At a scan rate of 5 mVs −1 , a specific capacitance of 658 Fg −1 is obtained for the NMO-Ni foam electrodes in 1 M NaOH electrolyte. At a current density of 0.5 mAcm −2 , the determined values of specific energy and specific power for the NMO-Ni foam electrodes are 13.4 Whkg −1 and 523.8 Wkg −1 , respectively, in 1 M NaOH electrolyte. The NMO-Ni foam electrodes showed 96.4 % capacitance retention in 1 M NaOH for 1000 cycles.