Characterization of Sol‐Gel‐Derived Cobalt Oxide Xerogels as Electrochemical Capacitors

TLDR: Very fine cobalt oxide xerogel powders were prepared using a unique solution chemistry associated with the sol-gel process as mentioned in this paper, and the effect of thermal treatment on the surrace area, pore volume, crystallinity, particle structure, and corresponding electrochemical properties was investigated and found to have significant effects on all of these properties.

Abstract: Very fine cobalt oxide xerogel powders were prepared using a unique solution chemistry associated with the sol-gel process The effect of thermal treatment on the surrace area, pore volume, crystallinity, particle structure, and corresponding electrochemical properties of the resulting xerogels was investigated and found to have significant effects on all of these properties The xerogel remained amorphous as Co(OH) 2 up to 160°C, and exhibited maxima in both the surface area and pore volume at this temperature With an increase in the temperature above 200°C, both the surface area and pore volume decreased sharply, because the amorphous Co(OH) 2 decomposed to form CoO that was subsequently oxidized to form crystalline Co 3 O 4 In addition, the changes in the surface area, pore volume, crystallinity, and particle structure all had significant but coupled effects on the electrochemical properties of the xerogels A maximum capacitance of 291 F/g was obtained for an electrode prepared with the CoO x xerogel calcined at 150°C, which was consistent with the maxima exhibited in both the surface area and pore volume; this capacitance was attributed solely to a surface redox mechanism The cycle life of this electrode was also very stable for many thousands of cycles