Augmenting the electrochemical performance of NiMn 2 O 4 by doping of transition metal ions and compositing with rGO.

The transition metal ions (TMIs) such as Co ²⁺ and Zn ²⁺ doped NiMn ₂ O ₄ (NMO)/rGO nanocomposite synthesized by facile sol-gel method was used for the fabrication of supercapacitor. The presence of metal ions in the nanocomposite was confirmed by X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscope (HR-TEM) mapping techniques. The fabricated electrode showed high specific capacitance of 710 F/g which was 3-fold higher than NMO (254 F/g). The addition of RGO in the nanocomposite increased the cycle stability of TMIs doped NMO significantly from 51 to 91%. In addition, the symmetric supercapacitor (SSC) fabricated using TMIs doped NMO/rGO nanocomposite with 3.5 M KOH as an electrolyte delivered a maximum energy density of 43 Wh/kg and power density of 10 kW/kg. Furthermore, the SSC device retained 90% of capacitance retention over 10,000 cycles with coulombic efficiency of 99% at 5 A/g. These result suggested that the TMIs doped NMO/rGO nanocomposite electrode is a promising material for high-energy supercapacitors.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2021 Elsevier Inc. All rights reserved.)