Design principles for amorphous solid-state electrolytes

TL;DR

This paper establishes universal design principles for amorphous solid-state electrolytes using atomistic simulations, identifying key structural features, transport mechanisms, and stability factors to guide the development of high-performance batteries.

Contribution

It introduces a comprehensive framework and design diagram based on atomistic simulations that elucidate structure-property relationships in amorphous SSEs, advancing rational design strategies.

Findings

Four structure types governed by M-X group saturation and charge.

Identification of paddle-wheel and cooperative migration as key transport mechanisms.

Oxides and fluorides as optimal for stability and performance.

Abstract

Amorphous solid-state electrolytes (SSEs) offer unique advantages for next-generation batteries, but their rational design is hindered by an unclear structure-property relationship. This study establishes universal design principles through atomistic simulations of 32 amorphous Li-M-X systems (M = B, Al, Si, P; X = F, Cl, Br, I, O, S, Se, N). We identify four structure types governed by a rule that saturated M-X groups with more negative charges preferentially form M-X-M chains, identify paddle-wheel and cooperative migration as two favorable transport mechanisms that are significantly enhanced in amorphous structures. We also pinpoint Oxides and fluorides as optimal for electrochemical and hydrolytic stability, and reveal bulk modulus as a simple predictor for $Li^+$ mobility. These insights are integrated into a practical design diagram, providing a novel and valuable framework for advancing high-performance amorphous SSEs.