Ammonium Vanadium Bronze as a Potassium-Ion Battery Cathode with High Rate Capability and Cyclability
Ammonium Vanadium Bronze as a Potassium-Ion Battery Cathode with High Rate Capability and Cyclability
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DOI：
10.1002/smtd.201800349
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发表时间：
2019-08-14
期刊：
影响因子：
12.4
通讯作者：
Lei, Yong
中科院分区：
文献类型：
--
作者：
Xu, Yang;Dong, Huishuang;Lei, Yong
K离子电池（KIB）是锂离子电池的一种有前途的替代品。尽管KIB阳极发展迅速，但由于K离子嵌入的缓慢动力学，阴极尚未发展到相同的程度。在这里，铵钒青铜NH_4V_4O_10（NVO）被提议作为潜在的KIB阴极材料。合成的NVO具有9.8埃的大层间距和自组装的花状结构。阴极提供136 mAh g（-1）的高容量（50 mA g（-1）），在1-3.8 V范围内，200次循环后，衰减率为0.02%。（80 mAh g（-1））。此外，它表现出快速率能力，在高达3 A g（-1）（2-3.8 V）的速率下提供51 mAh g（-1），是0.1 A g（-1）时容量的90%。电化学机理研究表明，钾离子在NVO中的存储是一个拓扑结构的过程，其中发生V4+和V5+之间的过渡。他们还表明，在接近4.2 V的较高电压下防止脱氨对于NVO的结构稳定性至关重要。这项工作可能会刺激未来开发钒氧化物在KIB和更多的了解钾离子存储的机制。
K-ion batteries (KIBs) are a promising alternative to lithium-ion batteries. Despite the rapid development of KIB anodes, cathodes have not developed to the same extent due to the sluggish kinetics of K-ion intercalation. Here, ammonium vanadium bronze NH4V4O10 (NVO) is proposed as a potential KIB cathode material. The as-synthesized NVO features a large interlayer spacing of 9.8 angstrom and self-assembled flower-like architecture. The cathode delivers a high capacity of 136 mAh g(-1) (50 mA g(-1)) and a decay rate of 0.02% per cycle over 200 cycles in the range of 1-3.8 V. It retains 94% capacity (80 mAh g(-1)) after 200 cycles in the range of 2-3.8 V. Moreover, it exhibits fast rate capability by delivering 51 mAh g(-1) at a rate as high as 3 A g(-1) (2-3.8 V), being 90% of the capacity at 0.1 A g(-1). Electrochemical mechanism studies suggest that K-ion storage in NVO is a topotactic process, where transition between V4+ and V5+ occurs. They also show that prevention of deammoniation at a higher voltage toward 4.2 V is critical for the structural stability of NVO. This work may stimulate future exploitation of vanadium oxides in KIBs and more insights into the mechanisms of K-ion storage.