Laurence Athouël

Doping of Cobalt into Multilayered Manganese Oxide for Improved Pseudocapacitive Properties

Anodic electrodeposition of layered manganese oxides has been carried out in a MnSO 4 solution heated at various bath temperatures from 25 to 80°C. The crystallinity of the deposits increased with an increase in the bath temperature. Although Co 2+ ions were not involved in the deposition reaction at room temperature, at the elevated temperature the addition of Co 2+ gave rise to a catalytic current suggesting the formation of Co/Mn mixed oxide. No new X-ray diffraction peaks appeared with the insertion of Co 2+ ions in the structure, but their addition caused broadening of the peaks due to the Mn dioxide phase. This indicates that Co ions are not accommodated in the interlayer space but are well dispersed within the MnO 2 layers composed of edge-shared Mn0 6 octahedra. The Co-doped Mn oxide film thus obtained exhibited much better pseudocapacitive performance than the undoped counterpart.