Computational Discovery of Fast Interstitial Oxygen Conductors

TL;DR

This paper introduces a new approach combining simulations and experiments to discover fast interstitial oxygen conductors, leading to the identification of materials with superior ionic conductivity for energy applications.

Contribution

It presents a novel methodology for discovering interstitial oxygen conductors, resulting in the synthesis of a new material with high ionic conductivity and surface oxygen exchange rates.

Findings

LMS has higher oxygen ionic conductivity than YSZ.

LMS exhibits among the highest surface oxygen exchange rates.

Multiple new families of interstitial oxygen conductors were identified.

Abstract

New highly oxygen-active materials may enhance many energy-related technologies by enabling efficient oxygen-ion transport at lower temperatures, e.g., below 400 Celsius. Interstitial oxygen conductors have the potential to realize such performance but have received far less attention than vacancy-mediated conductors. Here, we combine physically-motivated structure and property descriptors, ab initio simulations, and experiments to demonstrate an approach to discover new fast interstitial oxygen conductors. Multiple new families were found which adopt completely different structures from known oxygen conductors. From these families, we synthesized and studied oxygen kinetics in La4Mn5Si4O22+d (LMS), a representative member of perrierite/chevkinite family. We found LMS has higher oxygen ionic conductivity than the widely used yttria-stabilized ZrO2, and among the highest surface oxygen exchange rates at intermediate temperature of known materials. The fast oxygen kinetics is the result of simultaneously active interstitial and interstitialcy diffusion pathways. This work developed and demonstrated a powerful approach for discovering new families of interstitial oxygen conductors and suggests many more such materials remain to be discovered.