Application of high-performance MnO2 nanocomposite electrodes in ionic liquid hybrid supercapacitors

This work reports the synthesis of novel nanocomposite electrodes based on MnO2 nanosheets, Pt, Au, or Pd nanoparticles (NPs), exfoliated carbon nanotubes (CNTs), and Ni foam (NF) substrates. The MnO2-Pd-CNT-NF electrode in 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIM-PF6)/N, N-dimethylformamide (DMF) electrolyte exhibits a high specific capacitance of 559.1 F/g based on MnO2 with a wide potential window (2.1 V). To the best of our knowledge, this is one of the highest capacitance for MnO2 in ionic liquid (IL) electrolytes ever reported. The IL hybrid supercapacitors are assembled using MnO2-Pd-CNTs-NF positive electrode, activated carbon (AC) negative electrode, and BMIM-PF6/DMF electrolyte displaying high operating voltage (3 V), high energy density (78.4 Wh/kg) and high power density (12.7 kW/kg). The superior performances of the MnO2 IL hybrid supercapacitors suggest their potential application for the future generation of electrochemical power sources. (C) 2013 Elsevier B.V. All rights reserved.