NiMoO4 Nanocluster Carbon Composite for High Performance Asymmetric Supercapacitors

Abstract

Faradaic redox reaction governed with pseudocapacitance mechanism are better as compared to intercalation mechanism as it overcomes the diffusion limitations and results in improved power density. Further, the life cycle expectancy improves due to fast surface redox reactions. Metal oxides with battery behaviour are the best choice for pseudocapacitance by increasing surface to volume ratio. This can be achieved by synthesizing ultrasmall nanocluster of material. To this end, we report a facile synthesis of ultrasmall NiMoO4 nanoparticle on active carbon with high specific capacity and long-term cycle stability. The ultrasmall NiMoO4-active carbon composite (NiMo@AC) sample shows specific capacity of 665 C/g (1662.5 F/g or 184.7 mAh/g) at current density of 1 A/g. An asymmetric supercapacitor fabricated from NiMoO4@AC nanocomposite displayed specific capacity of 131.5 C/g (87.7 F/g or 36.5 mAh/g), energy density of 27.4 Wh/Kg and a power density of 184W/Kg at a current density of 1 A/g. This high capacity can be attributed to the improved specific area of electroactive material. The fabricated supercapacitor retains ~92% of initial capacity after 4000 cycles. Active carbon not only provide better dispersion to nanoparticle, but also contribute towards the structural stability due to embedment of the particles into the carbon matrix. The results indicate that NiMo@AC nanocomposite is a potential candidate for electrochemical energy storage. Figure 1