Papac Meagan, Stevanović Vladan, Zakutayev Andriy, O'Hayre Ryan
Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, USA.
Materials Science Center, National Renewable Energy Laboratory, Golden, CO, USA.
Nat Mater. 2021 Mar;20(3):301-313. doi: 10.1038/s41563-020-00854-8. Epub 2020 Dec 21.
Triple ionic-electronic conductors (TIECs) are materials that can simultaneously transport electronic species alongside two ionic species. The recent emergence of TIECs provides intriguing opportunities to maximize performance in a variety of electrochemical devices, including fuel cells, membrane reactors and electrolysis cells. However, the potential application of these nascent materials is limited by lack of fundamental knowledge of their transport properties and electrocatalytic activity. The goal of this Review is to summarize and analyse the current understanding of TIEC transport and electrochemistry in single-phase materials, including defect formation and conduction mechanisms. We particularly focus on the discovery criteria (for example, crystal structure and ion electronegativity), design principles (for example, cation and anion substitution chemistry) and operating conditions (for example, atmosphere) of materials that enable deliberate tuning of the conductivity of each charge carrier. Lastly, we identify important areas for further advances, including higher chemical stability, lower operating temperatures and discovery of n-type TIEC materials.
三离子电子导体（TIECs）是能够同时传输电子物种以及两种离子物种的材料。TIECs的近期出现为在包括燃料电池、膜反应器和电解槽在内的各种电化学装置中最大化性能提供了引人入胜的机会。然而，这些新兴材料的潜在应用受到对其传输性质和电催化活性缺乏基础知识的限制。本综述的目的是总结和分析目前对单相材料中TIEC传输和电化学的理解，包括缺陷形成和传导机制。我们特别关注能够有意调节每种电荷载流子电导率的材料的发现标准（例如晶体结构和离子电负性）、设计原则（例如阳离子和阴离子取代化学）和操作条件（例如气氛）。最后，我们确定了进一步发展的重要领域，包括更高的化学稳定性、更低的操作温度以及n型TIEC材料的发现。
