NiO nanoparticles supported on graphene 3D network current collector for high-performance electrochemical energy storage

Owing to the faradaic oxidation and reduction reactions mainly taking place on surface, enlarging the specific surface of redox materials is one of the most effective ways to achieve excellent electrochemical performance. Here we report a binder-free three dimensional (3D) architecture electrode consisting of a graphene 3D network (G3DN) structure growing on flexible carbon paper (CP) by chemical vapor deposition and NiO nanoparticles growing on the G3DN by in-situ thermal decomposition for high rate battery and high-performance electrochemical capacitors. Such a nanostructure provides a large specific surface and fast electronic transmission channels. The unique structure design for this electrode enables outstanding performance, showing high specific capacity of 89.1 mAh cm−2 (119.2 mAh/g) at current density of 0.5 mA cm−2 (0.67 A/g) with the NiO loading of 0.7471 mg cm−2. Meanwhile the electrode displays excellent rate capability and cycling stability, which keeps 85.48% of initial capacity after 3000 deep-discharge cycles. Furthermore, a solid-state symmetric electrochemical capacitor based on two NiO/G3DN/CP electrodes with an area of 4 cm2 each is fabricated, and two pieces of them in series can light up 100 green LEDs for 2 min. The architecture of G3DN loaded with NiO might be generally applied to different kinds of nanomaterials for high-rate energy storage to improve their overall electrochemical performance.