Kassem Mohammad, Bounazef Tinehinane, Sokolov Anton, Bokova Maria, Fontanari Daniele, Hannon Alex C, Alekseev Igor, Bychkov Eugene
Laboratoire de Physico-Chimie de l'Atmosphère, Université du Littoral Côte d'Opale, 59140 Dunkerque, France.
ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K.
Inorg Chem. 2022 Aug 15;61(32):12870-12885. doi: 10.1021/acs.inorgchem.2c02142. Epub 2022 Aug 1.
High-capacity solid-state batteries are promising future products for large-scale energy storage and conversion. Sodium fast ion conductors including glasses and glass ceramics are unparalleled materials for these applications. Rational design and tuning of advanced sodium sulfide electrolytes need a deep insight into the atomic structure and dynamics in relation with ion-transport properties. Using pulsed neutron diffraction and Raman spectroscopy supported by first-principles simulations, we show that preferential diffusion pathways in vitreous sodium and silver sulfides are related to isolated sulfur S, that is, the sulfur species surrounded exclusively by mobile cations with a typical stoichiometry of M/S ≈ 2. The S/S fraction appears to be a reliable descriptor of fast ion transport in glassy sulfide systems over a wide range of ionic conductivities and cation diffusivities. The S fraction increases with mobile cation content , tetrahedral coordination of the network former and, in case of thiogermanate systems, with germanium disulfide metastability and partial disproportionation, GeS → GeS + S, leading to the formation of additional sulfur, transforming into S. A research strategy enabling to achieve extended and interconnected pathways based on isolated sulfur would lead to glassy electrolytes with superior ionic diffusion.
高容量固态电池是大规模储能和能量转换领域未来很有前景的产品。包括玻璃和玻璃陶瓷在内的钠快离子导体是用于这些应用的无与伦比的材料。合理设计和调整先进的硫化钠电解质需要深入了解与离子传输特性相关的原子结构和动力学。通过第一性原理模拟支持的脉冲中子衍射和拉曼光谱，我们表明玻璃态硫化钠和硫化银中的优先扩散路径与孤立的硫S有关，即仅由典型化学计量比M/S≈2的移动阳离子包围的硫物种。在广泛的离子电导率和阳离子扩散率范围内，S/S分数似乎是玻璃态硫化物体系中快速离子传输的可靠描述符。S分数随移动阳离子含量、网络形成体的四面体配位增加，并且在硫代锗酸盐体系中，随着二硫化锗的亚稳定性和部分歧化反应GeS→GeS + S增加，导致额外硫的形成，转化为S。一种基于孤立硫实现扩展和相互连接路径的研究策略将导致具有优异离子扩散性能的玻璃态电解质。
