On the assumptions underlying theoretical models for flooded porous electrodes
✍ Scribed by E.A. Grens II
- Publisher
- Elsevier Science
- Year
- 1970
- Tongue
- English
- Weight
- 847 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0013-4686
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✦ Synopsis
The consequences of several s' "g lifylng assumptions often encountered in theoretical models for porous electrodes are examined y comparison of electrode performance chamcteristics calculated according to these assumptions with performance predicted by more complete electrode models. The assumptions considered include those of infinite electrode thickness, uniform concentration or conductivity of pore electrolyte, and negligible potential gradient in the pores. The comparisons are based on a metal/metal-hydroxide electrode in binary electrolyte that is generally representative of a large class of battery systems. It is found that all of the assumptions must be invoked with caution. In particular, the assumption of uniform electrolyte concentration has a very restricted range of validity while that of ,uniform conductivity, when combined with proper treatment of diffusion potentials, can be used effectively over a much greater set of conditions.
R&um&L'analyse thborique des electrodes poreuses utilize plusieurs hypoth&es simplii%atrices, dont les con&quences sont examin& ici sur la base d'une comparaison entre l'eBcacit6 calcul6e selon ces hypoth&ses et celle calcul& d'apr& des mod&% plus complets. Ces hypoth&es comprennent: 6paisseur iniinie pour l'blectrode; dans les pores une concentration ou une conductibilit6 cons&me pour l'&ctrolyte; absence de gradient de potentiel. On prend comme base de comparaison une &lectrode m&al/hydroxyde m&allique du type existant dans de nombreuses piles. On con&ate que l'emploi de ces hypoth&aes exige une grande prudence. En particulier uw concentration uniforme d'&ctrolyte n'est g&e valable, tandis qu'une conductibilitt uniforme avec un propre choix des potentiels de diffusion est d'une validitd raisonnable.
Zusammdassung-Die Folgen von vereinfachenden Annahmen, die oft in der theoretischen &handlung des Verhaltens port&r Elektroden gemacht werden, sind durch Vergleich mit Resultaten von