Polypyrrole Modified Cobalt Oxide for Electrochemical Energy Storage

Electrochemical capacitors have attracted significant attention for their promising potential applications ranging from portable electronic devices to hybrid electrical vehicles and large industrial equipments.^1-5 Two cobalt oxides with three-dimensional flower- and ball-like morphologies, respectively, were prepared by a facile solvothermal method for electrochemical capacitor applications. Binder free electrodes were obtained by drop casting cobalt oxide suspensions in the ethanol solvent onto carbon paper to evaluate the electrochemical performances. The flower-like cobalt oxide exhibits better capacitive performances due to the unique mesoporous structure compared to the non-porous ball-like cobalt oxide, as confirmed by SEM and TEM images. Furthermore, conductive polymer, polypyrrole (PPy), was in situ electropolymerized to the flower-like cobalt oxide via the cyclic voltammetry techniques. A significant enhancement in the performances in terms of both energy and power density has been witnessed by the PPy coated flower-like cobalt oxide. Reduced charge transfer resistance is inferred to be responsible for the superior performances as confirmed by the electrochemical empedance spectroscopy.

References

(1)   Wei, H.; Gu, H.; Guo, J.; Wei, S.; Guo, Z. ECS Journal of Solid State Science and Technology 2013, 2, M3008.

(2)    Wei, H.; Gu, H.; Guo, J.; Wei, S.; Guo, Z. Journal of The Electrochemical Society 2013, 160, G3038.

(3)   Zhu, J.; Chen, M.; Qu, H.; Zhang, X.; Wei, H.; Luo, Z.; Colorado, H. A.; Wei, S.; Guo, Z. Polymer 2012, 53, 5953.

(4)    Wei, H.; Yan, X.; Wu, S.; Luo, Z.; Wei, S.; Guo, Z. The Journal of Physical Chemistry C 2012, 116, 25052.

(5)    Wei, H.; Zhu, J.; Wu, S.; Wei, S.; Guo, Z. Polymer 2013, 54, 1820.