Chemically synthesized mesoporous nickel cobaltite electrodes of different morphologies for high-performance asymmetric supercapacitors

Abstract

A facile, inexpensive, and template-free strategy has been investigated for the synthesis of nickel cobaltite (NiCo2O4; NCO) for different morphologies on conducting nickel foam using two different complexing agents' ammonia solution (AMM) and hexamethyltetrammine (HMT) and investigated for supercapacitor applications. The nickel cobaltite exhibits a mesoporous structure with pore diameters of 16 and 19 nm and provides a high specific surface area of 150, and 100 m2·g−1 for NCO-AMM and NCO-AMM, respectively. The NCO-HMT electrode exhibit higher specific capacities (2195.8 C·g−1/2744.8 F g−1 at 4 A.g−1) than the NCO-AMM electrode (1579.7 C·g−1/ 1974.6 F g−1 at 4 A. g−1) with high capacity retention ( ̴ 86 %). Excellent cyclic stabilities of 95 and 97 % are obtained from NCO-AMM and NCO-HMT electrodes over 10,000 cycles. A fabricated ASC coin cell (NCO-HMT//rGO) enables a high operation potential window (1.6 V), and an excellent energy density of 60 Wh·kg−1 with a power density of 5500 W·kg−1. The NCO-HMT//rGO also exhibits outstanding cyclic stability of 90 % over 10,000 charge-discharge cycles at 10 A·g−1 current density. This facile synthesis approach provides a superior strategy for producing mesoporous nanomaterials for high-performance ASC.