Performances of Co²⁺-Substituted NiMoO₄ Nanorods in a Solid-State Hybrid Supercapacitor

A hydrothermal method was conducted to synthesize Ni(1-alpha)Co(alpha)MoO4 (alpha = 0, 0.1, 0.3, and 0.5 M) nanorods, which were proven as excellent electrode materials in a hybrid supercapacitor. Their electrochemical properties were also dependent on the Ni/Co ratio as demonstrated by different electrochemical techniques. Ni0.5Co0.5MoO4 (alpha = 0.5 M) offered specific capacity (Qg) = 354 Cg-1@1 Ag-1, a remarkable specific capacity with a notable retention capacity of 92% after 8000 repeated cycles at 10 Ag-1. Ni0.5Co0.5MoO4 with a high surface area outperformed the mono-metallic (NiMoO4) and bimetallic (Ni0.9Co0.1MoO4 and Ni0.7Co0.3MoO4) nanostructures. The hybrid supercapacitor (Ni0.5Co0.5MoO4//activated carbon) delivered a maximum Qcell of 53 Cg-1 at 1 Ag-1 with an energy density of 16.2 Wh kg-1 and power density of 725 W kg-1.