Tetragonal Tungsten Bronze Framework as Potential Anode for Na-Ion Batteries

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• 作者：Yanlin Han ; Minghui Yang ; Ye Zhang ; Junjie Xie ; Dongguang Yin ; Chilin Li
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：May 10, 2016
• 年：2016
• 卷：28
• 期：9
• 页码：3139-3147
• 全文大小：764K
• 年卷期：0
• ISSN：1520-5002

文摘

Na-ion batteries (NIBs) are becoming more promising owing to potentially better rate performance than Li-ion batteries apart from resource abundance. However, activation of Na-storage electrochemistry remarkably depends on the modification or expansion of existing structure prototypes by adjusting the substituent and linkage of their ligand moieties or the redox transition metals. Recently the natural existence of mineral phases has inspired us to explore more plentiful artificial analogues, most of which possess open framework properties. Here for the first time we propose a novel bronze phase (tetragonal tungsten bronze, TTB) of oxyfluoride (KNb₂O₅F) as a potential NIB anode. This tunnel-type open framework is achieved by equimolar KF doping into T-Nb₂O₅ with K and F as channel supporter and ligand substituent, respectively. The improvement of intrinsic conductivity and near-zero strain sodiation enable a highly reversible capacity even by employing undecorated samples of less surface defects. Reduction of Nb⁵⁺ may cause a uniform precipitation of fine NbO₂ nanoparticles around larger solidated KNb₂O₅F.