Bello, A.Fashedemi, O. O.Lekitima, J. N. et al2016-11-282016-11-282013Bello, A., Fashedemi,O. O., Lekitima,J. N., Fabiane,M., Dodoo-Arhin,D., Ozoemena,K. I., Gogotsi,Y., Charlie-Johnson,A. T., Manyala,N.. High-performance symmetric electrochemical capacitor based on graphene foam and nanostructured manganese oxide; AIP Advances 3, 082118 (2013)2158-3226Yhttp://dx.doi.org/10.1063/1.4819270http://repository.tml.nul.ls/handle/20.500.14155/52We have fabricated a symmetric electrochemical capacitor with high energy and power densities based on a composite of graphene foam (GF) with ?80 wt% of manganese oxide (MnO2) deposited by hydrothermal synthesis. Raman spectroscopy and X-ray diffraction measurements showed the presence of nanocrystalline MnO2 on the GF, while scanning and transmission electron microscopies showed needle-like manganese oxide coated and anchored onto the surface of graphene. Electrochemical measurements of the composite electrode gave a specific capacitance of 240 Fg?1 at a current density of 0.1 Ag?1 for symmetric supercapacitors using a two-electrode configuration. A maximum energy density of 8.3 Whkg?1 was obtained, with power density of 20 kWkg?1 and no capacitance loss after 1000 cycles. GF is an excellent support for pseudo-capacitive oxide materials such as MnO2, and the composite electrode provided a high energy density due to a combination of double-layer and redox capacitance mechanisms.EnCreative Commons CC BYSymmetric electrochemical capacitorArticle