▎ 摘　　要

The hierarchically sea urchin-like structured reduced graphene oxide (RGO)-manganese dioxide (MnO2) nanocomposites have been assembled through an electrochemical deposition. MnO2 particles are uniformly grown and directly deposited onto the surface of three dimensional (3D) RGO. The crystalline phase, size and composition of MnO2 nanoparticles are gamma phase, about 6 nm and 60 wt%, respectively. The specific capacitance of 125.93 F g(-1) of 3D RGO-MnO2 composite is higher than 38.45 F g(-1) of MnO2. The composite reveals the good rate capability of 70.29% and cyclic stability of similar to 80% after 5000 cycles. (C) 2016 Elsevier B.V. All rights reserved.