Defect-driven anomalous transport in fast-ion conducting solid electrolytes

AD Poletayev and JA Dawson and MS Islam and AM Lindenberg, NATURE MATERIALS, 21, 1066-+ (2022).

DOI: 10.1038/s41563-022-01316-z

Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. The mechanistic connections between material processing, defect chemistry, transport dynamics and practical performance are of considerable importance but remain incomplete. Here, inspired by studies of fluids and biophysical systems, we re-examine anomalous diffusion in the iconic two-dimensional fast-ion conductors, the beta- and beta ''-aluminas. Using large-scale simulations, we reproduce the frequency dependence of alternating-current ionic conductivity data. We show how the distribution of charge-compensating defects, modulated by processing, drives static and dynamic disorder and leads to persistent subdiffusive ion transport at macroscopic timescales. We deconvolute the effects of repulsions between mobile ions, the attraction between the mobile ions and charge-compensating defects, and geometric crowding on ionic conductivity. Finally, our characterization of memory effects in transport connects atomistic defect chemistry to macroscopic performance with minimal assumptions and enables mechanism-driven 'atoms-to-device' optimization of fast-ion conductors. Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. A quantitative framework for ionic conduction between atomistic and macroscopic timescales in beta- and beta ''-aluminas is now proposed for 'atoms-to-device' multiscale modelling and optimization.

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