Nanorod NiMoO4@NiCo2S4 as an advanced electrode material for high-performance supercapacitors

Nickel-cobalt sulfides exhibit good energy storage properties, but the poor stability affects the application of the material. In this work, we designed a simple route to synthesize NiMoO4 @NiCo2S4 composites by hydrothermal method combined with electrodeposition. The highly conductive NiCo2S4 nanorods and the highly reactive NiMoO4 showed good synergistic effects. NiMoO4 @NiCo2S4 exhibiting a high specific capacity of 1282.6 C g−1 (2565.2 F g−1) at 2 A g−1. The capacity retention of NiMoO4 @NiCo2S4 is increased from 75.93% to 84.7% after 5000 charge-discharge cycles compared with NiCo2S4 electrode. Further density functional theory (DFT) calculations show that the density of states (DOS) near the Fermi level of NiMoO4 @NiCo2S4 is significantly increased and the work function (WF) increases to 5.13 eV, which improves the electrochemical performance of the material. In addition, the NiMoO4 @NiCo2S4//Activated carbon asymmetric supercapacitor exhibits a high energy density of 75.3 Wh kg−1 at 800 W kg−1.