Crystallization Dynamics of Amorphous Solid Electrolytes using Large Scale Atomistic Simulations

LiPON ceramic glass electrolytes offer the possibility to increase the energy density of batteries thanks to their resistance to dendrite formation, a problem in batteries using Li-metal anodes, yet the conductivity of oxide glasses is relatively poor. This work studies the fundamental process of amorphization, crystallization, and ion conduction within a wide composition range of lithium phosphate systems. We employ atomistic force fields developed from ab-initio dynamics trajectories and validated on lithium phosphates with comparison to ab-initio trajectories and experimental characterization. Using large-scale dynamics simulations we predict the structural relaxation and conductivity of glass electrolyte materials, reaching timescales and system sizes inaccessible to ab-initio methods. We show how the Li content determines both the ionic conductivity and the degree of corner-sharing, which in turn determines the ease of amorphization and provides insight into optimal glass processing conditions.