▎ 摘　　要

A flower-like MnO2 nanocomposite embedded in nitrogen-doped graphene (NG-MnO2) is fabricated by a hydrothermal method. It is a mesoporous nanomaterial with a pore size of approximately 0.765 cm(3) g(-1) and specific surface area of 201.8 m(2) g(-1). NG-MnO2 exhibits a superior average specific capacitance of 220 F g(-1) at 0.5 A g(-1) and a preferable capacitance of 189.1 F g(-1), even at 10 A g(-1). After 1000 cycles, over 98.3% of the original specific capacitance retention of the NG-MnO2 electrode is maintained, and it can even activate a red light emitting diode (LED) after being charged, which indicates that it has excellent cycling stability as an electrode material. This prominent electrochemical performance is primarily attributed to the nitrogen doping and mesoporous structures of NG-MnO2, which can be attributed to its numerous electroactive sites as well as faster ion and electron transfer for redox reactions than general graphene-MnO2 nanocomposites (G-MnO2). (C) 2017 Published by Elsevier B.V.