Enhanced electrochemical performance of lamellar structured Co-Ni(OH)2/reduced graphene oxide (rGO) via hydrothermal synthesis

Lamellar Co-Ni(OH)(2)/rGO structures were prepared by co-precipitation followed by hydrothermal synthesis. Lamellar and crystalline Co-Ni(OH)(2)/rGO delivered better specific capacitance (C-s) and rate capability than low-crystallinity composites due to improved ionic and electronic conductivity. A high value of the C-s was achieved with Co-Ni(OH)(2)/rGO prepared at 150 degrees C for 12 h with a graphite oxide (GO)-to-metal precursor ratio of 1 : 5. This condition gave a Cs of 617 F g(-1) at 2 mV s(-1) and 811 F g(-1) at 0.5 A g(-1) with the highest capacitance retention of 90% at 2 A g(-1) and good cycling stability (similar to 77% at 70 mV s(-1)) at 5000 cycles. Furthermore, high mass loading, similar to 4.5-5.5 mg cm(-2), was used in the fabrication of the electrodes, which is higher than that of most previous reports.