Baumgärtner Julian Felix, Wörle Michael, Guntlin Christoph P, Krumeich Frank, Siegrist Sebastian, Vogt Valentina, Stoian Dragos C, Chernyshov Dmitry, van Beek Wouter, Kravchyk Kostiantyn V, Kovalenko Maksym V
Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, CH-8093, Switzerland.
Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science & Technology, Dübendorf, CH-8600, Switzerland.
Adv Mater. 2023 Dec;35(49):e2304158. doi: 10.1002/adma.202304158. Epub 2023 Nov 5.
Pyrochlore-type iron (III) hydroxy fluorides (Pyr-IHF) are appealing low-cost stationary energy storage materials due to the virtually unlimited supply of their constituent elements, their high energy densities, and fast Li-ion diffusion. However, the prohibitively high costs of synthesis and cathode architecture currently prevent their commercial use in low-cost Li-ion batteries. Herein, a facile and cost-effective dissolution-precipitation synthesis of Pyr-IHF from soluble iron (III) fluoride precursors is presented. High capacity retention by synthesized Pyr-IHF of >80% after 600 cycles at a high current density of 1 A g is obtained, without elaborate electrode engineering. Operando synchrotron X-ray diffraction guides the selective synthesis of Pyr-IHF such that different water contents can be tested for their effect on the rate capability. Li-ion diffusion is found to occur in the 3D hexagonal channels of Pyr-IHF, formed by corner-sharing FeF (OH) octahedra.
烧绿石型羟基氟化铁（III）（Pyr-IHF）是一种很有吸引力的低成本固定式储能材料，因为其组成元素的供应几乎无限、能量密度高且锂离子扩散速度快。然而，目前合成成本和阴极结构过高，阻碍了它们在低成本锂离子电池中的商业应用。在此，我们展示了一种从可溶性氟化铁（III）前驱体出发，通过简便且经济高效的溶解-沉淀法合成Pyr-IHF的方法。在1 A g的高电流密度下循环600次后，合成的Pyr-IHF的容量保持率高于80%，无需复杂的电极工程。原位同步加速器X射线衍射指导了Pyr-IHF的选择性合成，从而可以测试不同含水量对倍率性能的影响。发现锂离子在由共角FeF(OH)八面体形成的Pyr-IHF的三维六边形通道中扩散。
