One-pot synthesize Al-doped α-Ni(OH)2/reduced graphene oxide composite for high-performance asymmetric supercapacitors

A unique 3D hierarchical mesoporous Al-doped α-Ni(OH)2/reduced graphene oxide (NH/rGO) composite for supercapacitor has been successfully synthesized via homogeneous precipitation method. In this process, urea as the alkali source and mild reducing agent, to make graphene oxide (GO) convert into rGO. Thus, The NH uniformly grew on the rGO nanosheets. The as-prepared mesoporous NH/rGO composite exhibited high capacitance performance with a specific capacitance of 2558 F g−1 at the current density of 1 A g−1, and presented good rate capability with still held 75.3% capacity at 30 A g−1. Moreover, we used the NH/rGO as the positive electrode and the rGO aerogel as the negative electrode to assemble an asymmetric supercapacitor (ASC) device. This ACS device showed excellent specific energy of 166.97 Wh kg−1 at the power density of 0.38 kW kg−1, and it still retains the specific energy of 100.91 Wh kg−1 under the higher specific power of 7.76 kW kg−1. And it also displayed high rate performance and cycling durability with keeps 72% of the initial capacity after 3000 cycles (at 3 A g−1). •A unique 3D hierarchical mesoporous Al-doped composite is synthesized by a one-pot method.•The graphene content has a significant effect on the electrochemical performance.•The composite exhibits a high specific capacitance of 2558 F g−1 at 1 A g−1.•An asymmetric supercapacitor with higher energy density is successfully assembled.