Huang He, Chi Cheng, Zhang Jingyan, Zheng Xinqi, Wu Yanfei, Shen Jianxin, Wang Xiao, Wang Shouguo
Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
ACS Appl Mater Interfaces. 2022 Aug 17;14(32):36864-36874. doi: 10.1021/acsami.2c09814. Epub 2022 Aug 8.
The exploration of solid-state sodium superionic conductors with high sodium-ion conductivity, structural and electrochemical stability, and grand interface compatibility has become the key to the next-generation energy storage applications with high energy density and long cycling life. Among them, halide-based compounds exhibit great potential with the higher electronegativity of halogens than that of the sulfur element. In this work, combined with first-principles calculation and ab initio molecular dynamic simulation, the investigation of trivalent metal iodide-based Na superionic conductors 2/-NaXI (X = Sc, Y, La, and In) was conducted, including the fast ion transport mechanism, structural stability, and interface electrochemical compatibility with electrode materials. Along with the tetrahedral-center saddle site-predominant three-dimensional octahedral-tetrahedral-octahedral diffusion network, 2/-NaXI possesses the merits of high Na ionic conductivities of 0.36, 0.35, and 0.20 mS cm for NaScI, NaYI, and NaLaI, respectively. Benefiting from its structural stabilities, 2/-NaXI exhibits lower interface reaction energy and better electrochemical compatibility in contact with both Na metal and high-voltage poly-anion (fluoro)phosphate cathode materials than those of sulfide-based ones. Our theoretical work provides rational design principles for screening and guiding iodide-based 2/-NaXI (X = Sc, Y, La, and In) as promising Na superionic conductor candidates used in all-solid-state energy storage applications.
探索具有高钠离子传导率、结构和电化学稳定性以及良好界面兼容性的固态钠超离子导体，已成为实现高能量密度和长循环寿命的下一代储能应用的关键。其中，卤化物基化合物因其卤素的电负性高于硫元素而展现出巨大潜力。在这项工作中，结合第一性原理计算和从头算分子动力学模拟，对三价金属碘化物基钠超离子导体2/-NaXI（X = Sc、Y、La和In）进行了研究，包括快速离子传输机制、结构稳定性以及与电极材料的界面电化学兼容性。伴随着以四面体中心鞍点为主的三维八面体 - 四面体 - 八面体扩散网络，2/-NaXI分别具有NaScI、NaYI和NaLaI的高钠离子电导率，分别为0.36、0.35和0.20 mS/cm。受益于其结构稳定性，与硫化物基材料相比，2/-NaXI在与金属钠和高压聚阴离子（氟）磷酸盐阴极材料接触时表现出更低的界面反应能和更好的电化学兼容性。我们的理论工作为筛选和指导卤化物基2/-NaXI（X = Sc、Y、La和In）作为全固态储能应用中有前景的钠超离子导体候选材料提供了合理的设计原则。
