Porous NiO/CuCo2O4 nanocrystalline heterojunction composites derived from polymetallic coordination polymers for advanced supercapacitor

Abstract

NiO is considered as a promising electrode material owing to its high theoretical capacitance. However, the inherent low conductivity and huge volume expansion during cycling limit its practical application. Constructing composites is considered as an effective way to improve charge transfer efficiency and enhance electrochemical performance. Therefore, many researchers are devoted to combining NiO with other materials to build composites to solve this problem. However, the preparation of composites with uniformly distributed heterojunctions in a simple way remains a major challenge. Herein, porous NiO/CuCo₂O₄ composites with uniformly distributed heterojunctions were fabricated via a facile and cost-effective method. Benefiting from the porous structure and the synergistic effect of NiO and CuCo₂O₄, the NiO/CuCo₂O₄–450 electrode exhibits outstanding specific capacitance of 962 F g⁻¹ at the current density of 1 A g⁻¹. Additionally, with porous NiO/CuCo₂O₄–450 composites as anode and active carbon (AC) as cathode, the asymmetric supercapacitor (ASC) provides an energy density of 25.17 Wh kg⁻¹ at a power density of 400 W kg⁻¹ and an excellent cycle life. This study provides a facile and favourable strategy for the preparation of composites with distinguished electrochemical properties.