Electrochemical Na Extraction/Insertion of Na3V2O2x(PO4)2F3–2x
Electrochemical Na Extraction/Insertion of Na3V2O2x(PO4)2F3–2x
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DOI：
10.1021/cm403679b
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发表时间：
2013-12
影响因子：
8.6
通讯作者：
P. Serras;V. Palomares;J. Alonso;N. Sharma;J. L. Amo;P. Kubiak;M. L. Fdez-Gubieda;T. Rojo
中科院分区：
文献类型：
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作者：
P. Serras;V. Palomares;J. Alonso;N. Sharma;J. L. Amo;P. Kubiak;M. L. Fdez-Gubieda;T. Rojo
合成了一种属于Na 3 V 2 O 2 x（PO 4）2 F 3 - 2 x/C族的混合价态V 3 +/V 4+复合材料，并结合高分辨同步X射线衍射（XRD）数据、X射线吸收光谱（XAS）、23 Na和19 F固体核磁共振（NMR）数据确定了电化学Na抽插机理，双滴定（用于阐明钒的氧化态）和电化学测量。钒的氧化态被认为是+3.8的制备样品。阴极结构演变的详细分析表明，在2.8 V和4.3 V之间的电化学循环过程中，V4+/V5+对在该化合物中是活跃的。本研究演示了如何使用几种实验技术来跟踪（和验证）阴极材料中的钠离子提取和插入途径，特别是当多个潜在的氧化态存在于母体化合物中时。
A mixed-valence V3+/V4+ composite material belonging to the Na3V2O2x(PO4)2F3–2x/C family is synthesized and the electrochemical Na extraction/insertion mechanism is determined using a combination of high-resolution synchrotron X-ray diffraction (XRD) data, X-ray absorption spectroscopy (XAS), 23Na and 19F solid state nuclear magnetic resonance (NMR), double titration (for the elucidation of the vanadium oxidation state), and electrochemical measurements. The vanadium oxidation state is found to be +3.8 for the as-prepared sample. Detailed analysis of the cathode structural evolution illustrated that the V4+/V5+ couple is active in this compound during electrochemical cycling between 2.8 V and 4.3 V. This study demonstrates how the sodium-ion extraction and insertion pathways in cathode materials can be followed (and verified) using several experimental techniques, especially when multiple potential oxidation states are present in the parent compound.