High-performance symmetric electrochemical capacitor based on graphene foam and nanostructured manganese oxide

Bello, A.; Fashedemi, O. O.; Lekitima, J. N. et al

High-performance symmetric electrochemical capacitor based on graphene foam and nanostructured manganese oxide

Date

2013

Authors

Bello, A.

Fashedemi, O. O.

Lekitima, J. N. et al

Publisher

AIP Publishing

Abstract

We 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.

Keywords

Symmetric electrochemical capacitor

Citation

Bello, 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)