Temperature limitation of primary and secondary alkaline battery electrodes. Final report
This report contains the results of studies of the mechanisms of dissolution and passivation of Fe and Zn electrodes in concentrated KOH, as these processes effect the charge/discharge characteristics of alkaline batteries. The experimental techniques principally employed were: potentiodynamic sweep voltammetry and coulometry, rotating disk and rotating ring disk electrode studies under constant velocity and constant acceleration rotation conditions, and AC impedance studies. The results obtained on Fe electrodes have enabled us to postulate a detailed mechanism for the formation and discharge of an oxide film on iron via a number of dissolved intermediate species. The mechanisms are different at high and low temperatures, but at all temperatures pathways via dissolved phase intermediates result in substantial dissolution of metal and oxide. At 75/sup 0/C dissolution processes account for more than 7.5% of the total charge stored per cycle. AC impedance measurements were used to characterize the nature of the oxide film, and to determine an effective exchange current density for the Fe/Fe(II) Redox process. It is apparent from the measured values of i/sub 0/ that the kinetic constraints for the charge/discharge process are reduced with increasing temperature. However, the principal kinetic limitations of charge and discharge originate within the oxide film, not with the interfacial charge-transfer reaction process. Experiments were performed to study the influence of convection and zincate concentration on the discharge (dissolution and passivation) kinetics of zinc electrodes in concentrated KOH. AC impedance and rotating ring disk studies were performed to determine the mechanism of dissolution, and the nature of the dissolved product.
- Research Organization:
- SRI International, Menlo Park, CA (USA). Materials Research Lab.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5932244
- Report Number(s):
- LBL-16141; ON: DE83015009
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
250903* -- Energy Storage-- Batteries-- Materials
Components
& Auxiliaries
ALKALI METAL COMPOUNDS
DATA
DISSOLUTION
ELECTRIC BATTERIES
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTROLYTES
ELEMENTS
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROXIDES
IMPEDANCE
INFORMATION
IRON
METALS
NUMERICAL DATA
OXYGEN COMPOUNDS
PASSIVATION
POTASSIUM COMPOUNDS
POTASSIUM HYDROXIDES
TEMPERATURE EFFECTS
TRANSITION ELEMENTS
VOLTAMETRY
ZINC