Controlled Growth of 3D Interpenetrated Networks by NiCo₂O₄ and Graphdiyne for High-Performance Supercapacitor

In this paper, the 2D all-carbon graphdiyne, which possesses superior 2D strength and high mixed conductivities for both electrons and ions, is used to protect nickel cobalt oxide nanostructures with multidimensions. The in situ grown graphdiyne seamlessly wraps on nanostructures to form 3D interpenetrating networks, leading to significant improvement in the conductivity and avoidance of the structural degradation. The assembled hybrid asymmetric supercapacitor showed a high specific capacitance of 200.9 F g–1 at 1 A g–1 with an energy density of 62.8 Wh kg–1 and a power density of 747.9 W kg–1. The device also showed a preeminent rate capability (86.4% capacitance retention, while the current density was increased from 1 to 20 A g–1) and an ultrastable long-term cycling performance (the capacitance retention is about 97.7% after 10 000 cycles at a high current density of 20 A g–1).