Probing the Synergy of Ni(OH)2/NiO Nanoparticles Supported on rGO for Battery‐Type Supercapacitors

Abstract

Herein, a direct hydrothermal protocol for the synthesis of nickel‐based hydroxide/oxide nanocomposites grown on reduced graphene oxide (rGO) is presented. The materials are employed as a high‐performance active layer for advanced supercapacitors. Ni(OH)2/rGO and NiO/rGO nanocomposites demonstrate a high specific capacitance of 1255.12 and 636.84 F g−1 at 10 mV s−1 obtained from cyclic voltammetry curves while 1092.5 and 1070 F g−1 are estimated from galvanostatic charge–discharge at 1 A g−1, respectively. Subsequently, symmetric devices with a broad potential window of 1.4 V for both the materials are also fabricated. Symmetric devices deliver maximum specific capacitance of 115.71 and 80.28 F g−1 at 1 A g−1 with an energy density of 31. 5 and 22 Wh kg−1 at power density of 1.4 kW kg−1, which indicates the high‐rate capability of the devices. The devices have maximum capacity retention of 81% and 93%, when tested for 1000 discharge cycles at 3 A g−1, showing high cycle stability. The superlative performance of nanocomposites can be attributed to the synergistic effects they exhibit, demonstrating that they are appealing electrode materials for supercapacitor applications.