Temperature effects on the ionic conductivity in concentrated alkaline electrolyte solutions

YQ Shao and M Hellstrom and A Yllo and J Mindemark and K Hermansson and J Behler and C Zhang, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 22, 10426-10430 (2020).

DOI: 10.1039/c9cp06479f

Alkaline electrolyte solutions are important components in rechargeable batteries and alkaline fuel cells. As the ionic conductivity is thought to be a limiting factor in the performance of these devices, which are often operated at elevated temperatures, its temperature dependence is of significant interest. Here we use NaOH as a prototypical example of alkaline electrolytes, and for this system we have carried out reactive molecular dynamics simulations with an experimentally verified high- dimensional neural network potential derived from density-functional theory calculations. It is found that in concentrated NaOH solutions elevated temperatures enhance both the contributions of proton transfer to the ionic conductivity and deviations from the Nernst-Einstein relation. These findings are expected to be of practical relevance for electrochemical devices based on alkaline electrolyte solutions.

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