Temperature effects on the ionic conductivity in concentrated alkaline electrolyte solutions

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Alkaline electrolyte solutions are crucial for energy storage and conversion devices like batteries and fuel cells.
• Ionic conductivity, particularly its temperature dependence, is a key factor limiting device performance at elevated temperatures.

Purpose of the Study:

• To investigate the temperature dependence of ionic conductivity in concentrated sodium hydroxide (NaOH) solutions.
• To understand the underlying mechanisms, including proton transfer and deviations from the Nernst-Einstein relation.

Main Methods:

• Reactive molecular dynamics simulations were employed.
• An experimentally verified high-dimensional neural network potential, derived from density-functional theory, was utilized.

Main Results:

• Elevated temperatures significantly enhance proton transfer contributions to ionic conductivity in concentrated NaOH solutions.
• Increased temperatures also lead to greater deviations from the Nernst-Einstein relation, indicating complex ion transport.

Conclusions:

• The temperature dependence of ionic conductivity in alkaline electrolytes like NaOH is complex and influenced by proton transfer.
• Findings have practical implications for optimizing the performance of electrochemical devices operated at higher temperatures.