Fast and Energy Efficient Synthesis of ZnO@RGO and its Application in Ni–Zn Secondary Battery

ZnO with a uniform and complete coating of reduced graphene oxide (RGO) was prepared by a facile and rapid reaction using a solution synthesis scheme. A synthetic route that ZnO was first grown in situ on the GO surface and then reduced by NaBH4 was proposed, and an optimum coating structure was obtained by investigating the effect of precipitators, surfactant and additive amount of GO. After the reduction of NaBH4, 26.84% oxygen-containing groups were reduced and the weight ratio of RGO in the composite was 10.42 wt %, it was very close to the theoretical content of 11.8 wt %. The electrochemical measurements of ZnO@RGO negative electrode in the Zn–Ni secondary battery exhibited a stable cycle performance with a discharge capacity of 510 mAh g–1 after 300 cycles that it was 120 mAh g–1 higher than the capacity of bare ZnO. RGO layer effectively inhibited the direct contact between ZnO with the electrolyte and provided enough active area for the deposition of Zn which plays key roles to enhance the cycle discharge ability for Zn–Ni secondary battery.