Asymmetric Supercapacitors Based on Graphene/MnO 2 and Activated Carbon Nanofiber Electrodes with High Power and Energy Density

Abstract Asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO 2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na 2 SO 4 electrolyte. Due to the high capacitances and excellent rate performances of graphene/MnO 2 and ACN, as well as the synergistic effects of the two electrodes, such asymmetric cell exhibits superior electrochemical performances. An optimized asymmetric supercapacitor can be cycled reversibly in the voltage range of 0–1.8 V, and exhibits maximum energy density of 51.1 Wh kg −1 , which is much higher than that of MnO 2 //DWNT cell (29.1 Wh kg −1 ). Additionally, graphene/MnO 2…

• NN
  National Natural Science Foundation of China
• FN
  Fonds National de la Recherche Luxembourg
• CP
  China Postdoctoral Science Foundation
• FR
  Fundamental Research Funds for the Central Universities