The role of lithium in preventing the detrimental effect of iron on alkaline battery nickel hydroxide electrode: A mechanistic aspect
✍ Scribed by Alexander A. Kamnev
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 886 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0013-4686
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✦ Synopsis
The behaviour of iron hydroxo derivatives in alkaline solutions under the conditions of battery positive electrode performance and the effect of iron hydroxo species on the latter are considered together with the specificity of the lithium cation. This specificity has been revealed, in particular, in its influence on the dissolution/crystallization kinetics of ferric hydroxide in alkaline electrolytes using Miissbauer spectroscopic measurements. The conclusion is drawn that lithium hydroxide suppresses the two main processes which lead to alkaline battery nickel hydroxide electrode degradation upon accumulation of the iron impurity during cycling, ie, (i) the well-known decrease in anodic oxygen evolution overpotential (equivalent to a lower efftciency of the charging process) due to electrocatalysis by iron species, and (ii) the formation of a certain ferric oxyhydroxide structure (a-FeOOH), which affects the kinetics of phase transitions in the electrode active material, via recrystallization of labile poorly crystallized and/or amorphous forms.