A high-energy aqueous asymmetric electrochemical capacitor was developed using manganese dioxide
(-MnO2)/graphene oxide (GO) nanocomposites. The nanostructured -MnO2 was prepared from
micron-sized commercial electrolytic manganese dioxide (EMD) via a hydrothermal reaction in the presence
and absence of sodium dodecylsulphate (SDS), -MnO2(SDS) and -MnO2, respectively. Unlike the
as-prepared -MnO2, the presence of SDS during the hydrothermal reaction conferred different morphologies
on the intermediate precursors for the -MnO2(SDS). Also, the XRD patterns showed that the
-MnO2(SDS) are more crystalline than the as-prepared -MnO2. The superior electrochemical performance
of the -MnO2(SDS)/GO composite (280 F g−1, 35Wh kg−1, and 7.5 kWkg−1 at 0.5Ag−1) coupled
with excellent long cycle life clearly indicates that this electrode system has the potential of being
developed as an efficient aqueous asymmetric electrochemical capacitor. The high performance of the
-MnO2(SDS)/GO composite was interpreted in terms of the enhanced crystallinity of the -MnO2(SDS).
Interestingly, the electrochemical performance is comparable to or even better than those reported for
the more conductive graphene/MnO2 composites.
© 2013 El