Computational and Experimental Investigations of Na-Ion Conduction in Cubic Na3PSe4

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• 作者：Shou-Hang Bo ; Yan Wang ; Jae Chul Kim ; William Davidson Richards ; Gerbrand Ceder
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：January 12, 2016
• 年：2016
• 卷：28
• 期：1
• 页码：252-258
• 全文大小：370K
• ISSN：1520-5002

文摘

All-solid-state Na-ion batteries that operate at or close to room temperature are a promising next-generation battery technology with enhanced safety and reduced manufacturing cost. An indispensable component of this technology is the solid-state electrolyte that allows rapid shuttling of the mobile cation (i.e., Na⁺) between the cathode and anode. However, there are very few fast Na-ion conductors with ionic conductivity approaching that of the liquid counterparts (i.e., 1 mS cm^–1). In this work, we present the synthesis and characterization of a fast Na-ion conductor, cubic Na₃PSe₄. This material possesses a room-temperature ionic conductivity exceeding 0.1 mS cm^–1 and does not require high-temperature sintering to minimize grain boundary resistance, making it a promising solid-state electrolyte candidate for all-solid-state Na-ion battery applications. On the basis of density functional theory, nudged elastic band, and molecular dynamics investigations, we demonstrate that the framework of cubic Na₃PSe₄ only permits rapid Na⁺ diffusion with the presence of defects, and that the formation of the Na vacancy (charge-balanced by slight Se^2– oxidation) is more energetically favorable among the various defects considered. This finding provides important guidelines to further improve Na-ion conductivity in this class of materials.