26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Ion Transport Mechanisms in Disordered Electrolytes: A Unified Framework from Nanoscale Thermodynamics

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Condensed Matter & Materials (CMM)

Speaker

Xinkai Sun (School of Physics, The University of Sydney)

Description

Nanoscale thermodynamics governs how ions move through disordered electrolytes, yet connecting this atomistic-scale behaviour to macroscopic, experimentally observable transport remains a central challenge for developing next-generation energy storage technologies such as batteries. Predicting how ions navigate a landscape shaped by microscopic fluctuations in the local thermodynamic environment is essential for understanding practical challenges including battery polarisation and material degradation, and for informing the design of future electrolytes.
Classical approaches typically assume ion motion that is governed by a single, well-defined energy barrier and struggle to capture the nonlinear temperature dependence of ionic conductivity and diffusivity that arises from structural disorder. More recent theoretical treatments have attempted to account for this disorder but generally assume that the distribution of barriers is symmetric and that individual ion movements are uncorrelated. These assumptions break down once natural asymmetry and correlation present in real disordered materials are taken into account.
We present a new theoretical framework that directly models the asymmetrical barrier distribution. Rate and dielectric expressions describing the temperature and frequency dependence of ion transport through disordered media were derived by incorporating the statistical distribution of site energies and transition-state barriers obtained from molecular dynamics simulations. The resulting model was benchmarked against both experimental and simulation data across the full spectrum of alkali silicate glasses (Li, Na, K, Rb, and Cs), achieving high accuracy throughout.
This study reveals how nanoscale thermodynamics is extracted directly from bulk experimental observables, providing a predictive, physically grounded framework for understanding ion transport in disordered materials. These mechanistic insights offer a route towards the design of next-generation electrolytes with optimised ionic conductivity and accelerate the development of future battery and electrochemical technologies critical to the transition to sustainable energy.