Researchers Ata Utku Özkan, Talip Serkan Kasırga, and Aykut Erbaş from the Department of Chemical and Biological Engineering at Koc University in Turkey have published a study in the journal Nature Communications that sheds light on ionic transport in a specific type of material that could have significant implications for the energy sector.
The study focuses on understanding ionic transport under strong confinement, which is crucial for designing next-generation energy materials, such as solid electrolytes used in batteries. Conventional solid electrolytes often degrade with repeated use due to field-driven ion motion. The researchers investigated an alternative material: van der Waals layered structures, which provide resilient ion-transport channels. Specifically, they studied sodium-intercalated layered MnO2, a model self-intercalated van der Waals solid, using advanced computer simulations.
The researchers found that ionic conductivity in these materials depends nonlinearly on several factors, including the applied electric field, interlayer spacing, water content, and lattice flexibility. They discovered that the applied electric field induces spatial segregation of water, coupled with distortions of the MnO2 sheets. This creates regions with highly hydrated and weakly hydrated ions, with the latter exhibiting suppressed conductivity. Interestingly, the total amount of intercalated water also affects ionic transport, with boundary domains of weakly hydrated ions showing relatively higher mobility.
Moreover, the study revealed that in fluctuation-free layers, ion transport transitions from single-particle motion to a collective conduction regime. This regime is characterized by elongated, same-charge ionic clusters that violate Nernst-Einstein behavior, a fundamental principle in electrochemistry that relates ionic conductivity to diffusion.
The findings provide a molecular-level mechanism linking confinement-induced electrostatic correlations and structural response to the nonlinear transport observed experimentally in ion-intercalated MnO2. These insights suggest general design principles for robust, water-assisted ionic conductors, which could lead to more durable and efficient solid electrolytes for batteries and other energy storage devices.
The research was published in the journal Nature Communications, a highly respected peer-reviewed journal that covers all areas of the natural sciences. The study’s findings could have practical applications in the energy sector, particularly in the development of advanced materials for energy storage and conversion technologies.
This article is based on research available at arXiv.