One-Step In Situ Self-Assembly of Cypress Leaf-Like Cu(OH)2 Nanostructure/Graphene Nanosheets Composite with Excellent Cycling Stability for Supercapacitors

Transition metal hydroxides and graphene composite holds great promise to be the next generation of high performance electrode material for energy storage applications. Here we fabricate the cypress leaf-like Cu(OH)2 nanostructure/graphene nanosheets composite through one-step in situ synthesis process, employed as a new type of electrode material for high efficiency electrochemical energy storage in supercapacitors. A solution-based two-electrode system is applied to synthesize Cu(OH)2/graphene hybrid nanostructure, where anodic graphene nanosheets firmly anchor cathodic Cu(OH)2 nanostructure due to the electrostatic interaction. The in situ self-assembly of Cu(OH)2/graphene ensures good structural robustness and the cypress leaf-like Cu(OH)2 nanostructure prompt to form the open and porous morphology. The hybrid structure would facilitate charge transport and effectively mitigate the volume changes during long-term charging/discharging cycles. As a consequence, the Cu(OH)2/graphene composite exhibits the highest capacitance of 317 mF/cm2 at the current density of 1 mA/cm2 and superior cyclic stability with no capacitance decay over 20,000 cycles and remarkable rate capability at increased current densities.