Temperature effects on the ionic conductivity in concentrated alkaline electrolyte solutions

TL;DR

This study uses advanced simulations to analyze how temperature influences ionic conductivity in concentrated alkaline electrolytes, revealing enhanced proton transfer and deviations from classical models at higher temperatures.

Contribution

It introduces reactive molecular dynamics simulations with a neural network potential to investigate temperature effects on ionic conductivity in concentrated NaOH solutions.

Findings

Elevated temperatures increase proton transfer contributions.

Deviations from Nernst-Einstein relation grow with temperature.

Results are relevant for alkaline electrochemical device performance.

Abstract

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 from 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.