Ni(OH)2 nanosheets grown on a 3D graphene framework as an excellent cathode for flexible supercapacitors

Abstract

Ni(OH)₂ nanosheet/3D graphene (3DG) framework hybrid materials have been prepared by combining chemical vapor deposition (CVD) technology and a facile hydrothermal method. The free-standing Ni(OH)₂ nanosheet/3DG composite was investigated as the cathode material for supercapacitors without the need for addition of either binder or metal-based current collector. Consequently, the obtained Ni(OH)₂ nanosheet/3DG composite electrode exhibits superior specific capacitance and rate capability to the Ni(OH)₂ nanosheet/Ni foam and Ni(OH)₂ nanosheet/carbon fiber cloth composite electrodes. This novel structure brings the composite an electrochemical capacitance as high as 2860 F g⁻¹ at a current density of 2 A g⁻¹, and maintains 1791 F g⁻¹ at 30 A g⁻¹. Moreover, the composite electrode also exhibits a high specific capacitance of 2461 F g⁻¹ at a scan rate of 5 mV s⁻¹.