In recent years, supercapacitors have drawn considerable interest from researchers as an alternative energy storage device to secondary batteries. They offer advantages such as high power density, high columbic efficiency and long cycling life [1, 2]. Among the transition metal oxides investigated for redox reaction based supercapacitors (pseudocapacitors), Co₃O₄ is of special interest due to its high theoretical specific capacitance (up to 3560 F g^-1) and relatively low cost [3, 4]. However, low rate capability and poor cycling performance as a result of relatively low electrical conductivity limits its practical application in supercapacitors. Development of nanostructured Co₃O₄ materials offers a promising solution to this challenge as the transport pathways of electrons and ions are inherently short.

Nanostructured Co₃O₄ film deposited on nickel foam has been prepared by an economical and scalable flame combustion method in one step, namely reactive spray deposition technology (RSDT). The microstructure of the electrode is investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanostructured electrode provides high specific surface area and improves the kinetics of redox reaction [5]. The porous structure facilities the penetration of electrolyte and shortens the diffusion path of ions [6]. Electrochemical performance of the as-prepared Co₃O₄/Ni electrodes is evaluated by cyclic voltammetry, galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy in coin-type (CR2032) half-cells.

References:

1. X. Xia, Y. Zhang, D. Chao, C. Guan, Y. Zhang, L. Li, X. Ge, I.M. Bacho, J. Tu, H.J. Fan, Nanoscale, 6 (2014) 5008.
2. Z. Yu, L. Tetard, L. Zhai, J. Thomas, Energy Environ. Sci., 8 (2015) 702–730.
3. C.Z. Yuan, L. Yang, L. Hou, L. Shen, F. Zhang, D. Li, X. Zhang, J. Mater. Chem., 21 (2011) 18183–18185.
4. X.X. Qing, S.Q. Liu, K.L. Huang, Y.P. Yang, Z.G. Lu, D. Fang, X.X. Liang, Electrochim. Acta, 56 (2011) 4985–4991.
5. G. Wang, L. Zhang, J. Zhang, Chem. Soc. Rev., 41 (2012) 797–828.
6. C.Z. Yuan, J.Y. Li, L.R. Hou, X.G. Zhang, L.F. Shen, X.W. Lou, Adv. Funct. Mater., 22 (2012) 4592.