A pseudocapacitive asymmetric supercapacitor assembled by hollow NiCo2O4 hierarchical micro-spheres and nickel-loaded hollow VN hierarchical micro-flowers
Abstract Designing novel complementary electrode combination is an effective way to improve the electrochemical performance of a supercapacitor (SC). In this work, a NiCo2O4 pseudocapacitive cathode material with a hollow hierarchical micro-sphere structure (HMS) was prepared. The obtained NiCo2O4 HMS sample possesses a high capacitance (1148 F g−1) and excellent rate capability. A metallic Ni-loaded VN hybrid (Ni/VN) pseudocapacitive anode material with a hollow hierarchical flower-like architecture (HHMF) was also synthesized. The Ni/VN hybrid anode exhibits a high capacitance and excellent rate capability. Due to the desirable electrochemical performance and complementary potential windows of the two electrodes, a high-voltage pseudocapacitive (−)Ni/VN//NiCo2O4(+) asymmetric supercapacitor (ASC) was fabricated. The obtained ASC with a pseudocapacitive electrode combination can be cycled reversibly in a wide potential window of 0–1.5 V, and exhibits a high specific capacitance of 52 F g−1, a maximum energy density of 16.25 Wh kg−1. These results show that the pseudocapacitive (−)Ni/VN//NiCo2O4(+) ASC have great potential for application in high-performance energy storage systems.