Scientists at HSE University Devise More Accurate Method for Predicting the Electrical Conductivity of Electrolyte Solutions
Researchers at HSE MIEM have developed a model for calculating the electrical conductivity of aqueous electrolyte solutions; for the first time, it considers the spatial distribution of ion charges instead of assuming their localisation at a single point. The model remains effective even at high electrolyte concentrations and across a wide temperature range. This breakthrough will contribute to the development of more efficient batteries and enable the calculation of electrical conductivity without the need for experimental testing. The study has been published in the Journal of Chemical Physics.
Electrolytes are substances that dissolve in water to produce charged particles known as ions. When exposed to an electric field, ions in a solution can move and generate an electric current. Thanks to this property, ions play a crucial role in nerve and muscle function, maintaining water balance, storing and releasing energy in batteries, and purifying water in desalination systems.
The electrical conductivity of an electrolyte solution measures its ability to conduct an electric current. Classical theories for calculating electrical conductivity are effective at low concentrations, but as concentration increases, effects arise that these theories do not account for, resulting in discrepancies with experimental data. As a result, obtaining accurate information in systems with limited data on electrical conductivity or where measurements are challenging becomes difficult.
Scientists at HSE University have developed a new model that calculates the electrical conductivity of aqueous electrolyte solutions based on the Debye–Hückel–Onsager theory. Their model accounts for ion specificity, including steric interactions, hydration effects, and spatial charge distributions. Unlike the classical Debye–Hückel–Onsager theory, the modified theory assumes that ion charges are not concentrated at a single point but are instead distributed as clouds, which can be described using a specialised mathematical function.
'We chose not to perform complex calculations of the ion charge distribution function based on first-principles quantum chemistry. Instead, we decided to adjust it by modifying the charge smearing parameter,' explains Yury Budkov, co-author of the paper and Leading Research Fellow at the MIEM HSE Laboratory for Computational Physics.
According to him, incorporating the ion charge distribution function into the theory aligns with modern concepts of matter's structure, based on the quantum theory of multi-electron systems. The new model not only accurately reproduces the experimental relationship between electrical conductivity and concentration at a fixed temperature but also predicts the electrical conductivity of aqueous electrolytes across different temperatures and ion charges. For solutions of sodium, potassium, and lithium chloride salts, the obtained data aligns with experimental results up to concentrations of 4 mol/litre, which represents the best result to date.
In the future, scientists plan to refine the model for non-aqueous electrolyte solutions and adapt it for multicomponent electrolyte systems. This is important from a practical standpoint, as such systems are used in batteries, supercapacitors, and other energy storage devices, where precise calculations of electrical conductivity are essential to improving efficiency and durability.
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