Baumgärtner Julian F, Krumeich Frank, Wörle Michael, Kravchyk Kostiantyn V, Kovalenko Maksym V
Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, CH-8093, Zürich, Switzerland.
Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600, Dübendorf, Switzerland.
Commun Chem. 2022 Jan 11;5(1):6. doi: 10.1038/s42004-021-00622-y.
Towards enhancement of the energy density of Li-ion batteries, BiF has recently attracted considerable attention as a compelling conversion-type cathode material due to its high theoretical capacity of 302 mAh g, average discharge voltage of ca. 3.0 V vs. Li/Li, the low theoretical volume change of ca. 1.7% upon lithiation, and an intrinsically high oxidative stability. Here we report a facile and scalable synthesis of phase-pure and highly crystalline orthorhombic BiF via thermal decomposition of bismuth(III) trifluoroacetate at T = 300 °C under inert atmosphere. The electrochemical measurements of BiF in both carbonate (LiPF-EC/DMC)- and ionic liquid-based (LiFSI-PyrTFSI) Li-ion electrolytes demonstrated that ionic liquids improve the cyclic stability of BiF. In particular, BiF in 4.3 M LiFSI-PyrTFSI shows a high initial capacity of 208 mA g and capacity retention of ca. 50% over at least 80 cycles at a current density of 30 mA g.
为了提高锂离子电池的能量密度，BiF作为一种引人注目的转换型阴极材料最近受到了广泛关注，这是由于其具有302 mAh g的高理论容量、相对于Li/Li约3.0 V的平均放电电压、锂化时约1.7%的低理论体积变化以及固有的高氧化稳定性。在此，我们报告了一种通过在惰性气氛下于300°C热分解三氟乙酸铋(III)来简便且可扩展地合成纯相且高度结晶的正交晶系BiF的方法。在碳酸盐（LiPF-EC/DMC）和离子液体基（LiFSI-PyrTFSI）锂离子电解质中对BiF进行的电化学测量表明，离子液体提高了BiF的循环稳定性。特别是，在4.3 M LiFSI-PyrTFSI中的BiF在30 mA g的电流密度下显示出208 mA g的高初始容量和约50%的容量保持率，至少可循环80次。
