Hydrothermal facile Synthesis of Mn-Co-Ni Ternary Metal Oxide Composite with Graphene Nanoplatelets as Electrode Material for Supercapacitor

Abstract

Metal oxides and their composites are considered as most promising class of electrode material for future generation supercapacitor. Investigations have revealed that use of Transition metal oxides (TMOs) such as Ru2O3, NiO, MnO2, Fe2O3 and Co2O3 etc. in supercapacitors yields high specific capacitance, energy density and thermal chemical stability along with environmental compatibility. However, apart from all the development in the field of supercapacitor, limitations like lower energy density, lower capacitive performance of EDLCs, poor life durability of pseudocapacitors and high resistivity lowers their rate capabilities are adversely affecting electrochemical performance. To achieve a higher charge storage capability electrode material with highly accessible surface area and excellent conductivities, carbon material such as graphene, graphene nanoplatelets and carbon nanotubes along with TMO’s are used. We have made an effort of synthesizing composite of graphene nanoplatelets with ternary metal oxide of manganese, nickel and cobalt through a simple, facile and cost effective hydrothermal process and further compositional, morphological and electrochemical properties are investigated. Resulting composite of MNC-GNP showed excellent electrochemical properties owing to the high porosity offered by graphene nanoplatelets and synergistic effects produced by individual components of the composite. For comparative studies, ternary oxide MNC was prepared by the same hydrothermal route. XRD confirms the cubic structure of MNC-GNP composite with a crystallite size ranging between 8.66-9.30 nm. SEM showed distinct hierarchical dendritic structures which showed increase in density by the addition of graphene nanoplatelets. Electrochemical testing revealed that MNC-GNP exhibited enhanced supercapacitive behavior with a higher specific capacitance of 1816 Fg-1 as compared to MNC which exhibited 1455.5 Fg-1 at current density of 2 A/g. GCD also showed increased charge discharge time in the case of MNC-GNP as compared to its counterpart. MNC-GNP has also shown charge stability up to 99.5% of capacity retention up to 1000 cycles. These enhanced electrochemical properties endorse that the synthesized composite can be used as an effective electrode material for supercapacitor