Fundamentals

Fundamentals

Inherent Limits on Ion Transport In Solid-state Electrolytes Ionic mobility within solid-state electrolytes strongly depends on a materials structural and energy landscapes as well as site connectivity. In disordered glassy solids and glass-ceramics, variations in local bonding and coordination create a heterogeneous potential energy surface that removes the directional bias of ion motion found in most crystalline materials. Disordered phases and interfaces exhibit improved ionic conductivity by facilitating lithium-ion exchange between disordered and crystalline phases and enhancing cooperative migration of lithium ions within the crystalline phase. Due to the complexity of the local coordination environments of disordered systems, machine learning is utilized to relate atomic dynamic properties to local structure.

Temperature dependence of lithium diffusion and comparing ionic conductivity of systems with varying degrees of disorder.

Here, the term ‘softnessʼ is used to connect ion hopping dynamics and the amount of structural disorder. Disorder is a mechanism that can improve ion mobility as the lithium ions are more likely to rearrange. Glass

Crystalline

Interface

Lithium migration trajectories across phases with varying degrees of disorder.

Disorder can create a more uniform energy landscape that increases the number of mobile ion carriers and enables cooperative diffusion. A machine learning structural descriptor termed ‘softnessʼ connects diffusion dynamic characteristics to insights about ionic conductivity and the development of advanced solid-state battery electrolytes.

Source: Chen, Z., Du, T. Krishnan, N. M. A. et. al. Nature, 2025.

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