Few-layered Ni(OH)2 nanosheets for high-performance supercapacitors

Few-layered Ni(OH)(2) nanosheets (4-5 nm in thickness) are synthesized towards high-performance supercapacitors. The ultrathin Ni(OH)(2) nanosheets show high specific capacitance and good rate capability in both three-electrode and asymmetric devices. In the three-electrode device, the Ni(OH)(2) nanosheets deliver a high capacitance of 2064 F g(-1) at 2 A g(-1), and the capacitance still has a retention of 1837 F g(-1) at a high current density of 20 A g(-1). Such excellent performance is by far one of the best for Ni(OH)2 electrodes. In the two-electrode asymmetric device, the specific capacitance is 248 F g(-1) at I A g(-1), and reaches 113 F g(-1) at 20 A g(-1). The capacitance of the asymmetric device maintains to be 166 F g(-1) during the 4000th cycle at 2 A g(-1), suggesting good cycling stability of the device. Besides, the asymmetric device exhibits gravimetric energy density of 22 Wh kg(-1) at a power density of 0.8 kW kg(-1). The present results demonstrate that the ultrathin Ni(OH)(2) nanosheets are highly attractive electrode materials for achieving fast charging/discharging and high-capacity supercapacitors. (C) 2015 Elsevier B.V. All rights reserved.