  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.
