High-Temperature Neutron and X-ray Diffraction Study of Fast Sodium Transport in Alluaudite-type Sodium Iron Sulfate

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• 作者：Shin-ichi Nishimura ; Yuya Suzuki ; Jiechen Lu ; Shuki Torii ; Takashi Kamiyama ; Atsuo Yamada
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：April 12, 2016
• 年：2016
• 卷：28
• 期：7
• 页码：2393-2399
• 全文大小：484K
• 年卷期：0
• ISSN：1520-5002

文摘

Sodium-ion battery is a potential alternative to replace lithium-ion battery, the present main actor in electrical energy storage technologies. A recently discovered cathode material Na_2.5Fe_1.75(SO₄)₃ (NFS) derives not only high energy density with very high voltage generation over 3.8 V, but also high-rate capability of reversible Na insertion as a result of large tunnels in the alluaudite structure. Here we applied high-temperature X-ray/neutron diffraction to unveil characteristic structural features related to major Na transport pathways. Thermal activation and nuclear density distribution of Na demonstrate one-dimensional Na diffusion channels parallel to [001] direction in full consistence with computational predictions. This feature would be common for the related (sulfo-)alluaudite system, forming emerging functional materials group for electrochemical applications.