Supersaturated zincate solutions: A structural study
- Ecole Nationale Superieure de Chimie de Paris (France). Lab. d`Electrochimie
- CEN Saclay, Gif-sur-Yvette (France). Lab. Leon Brillouin
- Univ. d`Orsay (France)
The anodic oxidation of zinc electrodes in concentrated potassium hydroxide solutions that occurs during the discharge of alkaline zinc batteries leads to electrolytes with a Zn(II) content much higher than that obtained when a solid ZnO is equilibrated with KOH solutions of the same concentration at the same temperature. The Zn(II) excess slowly precipitates as ZnO from these supersaturated solutions, disturbing the working of the batteries. Undersaturated and supersaturated zincate solutions have been prepared electrochemically and chemically, and studied using nuclear magnetic resonance (NMR) spectrometry and extended X-ray absorption fine structure (EXAFS). {sup 67}Zn NMR spectroscopy shows only one resonance line, the area of which first increases with the Zn concentration until saturation and then remains constant for higher concentrations. EXAFS shows four oxygen neighbors at a distance of 1.979 {angstrom} of each zinc atom. Identical results were obtained with undersaturated and saturated zincate solutions. No Zn...Zn correlation was found indicating there is no polymeric species in the supersaturated solutions. It is proposed that in zincate solution (KOH 8M) the supersaturation is due to the presence of oxodihydroxozincate (ZnO(OH){sub 2}{sup 2{minus}}).
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 63174
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 5 Vol. 142; ISSN JESOAN; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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