What dictates soft clay-like Lithium superionic conductor formation from rigid-salts mixture

TL;DR

This study combines computational and experimental methods to understand how soft clay-like lithium superionic conductors form from rigid salt mixtures, revealing key microscopic features and a general creation strategy.

Contribution

It introduces a novel deep learning-based molecular dynamics approach and elucidates the microscopic mechanisms behind soft clay formation from ionic solid mixtures.

Findings

Salt mixtures forming molecular solid units enable soft clay-like behavior.

Slow reaction kinetics are crucial for clay formation.

Molecular solid units act as shear transformation zones.

Abstract

Soft clay-like Li-superionic conductors have been recently synthesized by mixing rigid-salts. Through computational and experimental analysis, we clarify how a soft clay-like material can be created from a mixture of rigid-salts. Using molecular dynamics simulations with a deep learning-based interatomic potential energy model, we uncover the microscopic features responsible for soft clay-formation from ionic solid mixtures. We find that salt mixtures capable of forming molecular solid units on anion exchange, along with the slow kinetics of such reactions, are key to soft-clay formation. Molecular solid units serve as sites for shear transformation zones, and their inherent softness enables plasticity at low stress. Extended X-ray absorption fine structure spectroscopy confirms the formation of molecular solid units. A general strategy for creating soft clay-like materials from ionic solid mixtures is formulated.