High-Performance Asymmetric Supercapacitor Using Ni(OH)2–Carboxyl Graphene Porous Nanomaterial with a Nanosheet-Assembled Microstructure

A simple and cost-effective chemical bath deposition process is used to grow Ni(OH)2 on carboxyl graphene (CG) nanosheets. The Ni(OH)2–CG exhibits excellent electrochemical performance based on its unique nanosheet-assembled structure. For instance, a specific capacitance of 1902 F g–1 was achieved at a potential window of 0.5 V and a charging/discharging current density of 2 A g–1. Meanwhile, the Ni(OH)2–CG-based electrode exhibited an appreciable cycling life, maintaining 92.65% initial capacitance for 3000 cycles. Additionally, the asymmetric supercapacitor constructed by employing nitrogen-doped reduced graphene oxide (NRGO) as the negative electrode and Ni(OH)2–CG as the positive electrode can achieve reversible cycling in a potential region of 0–1.6 V. The maximum specific capacitance and energy density of the device are 118.4 F g–1 and 40.2 Wh kg–1, respectively. The implications of the results indicate that Ni(OH)2–CG porous nanomaterial holds great potential for future generation supercapacitors.