Stabilization of a mixed iron vanadium based hexagonal tungsten bronze hydroxyfluoride HTB-(Fe0.55V0.45)F2.67(OH)0.33 as a positive electrode for lithium-ion batteries.
Stabilization of a mixed iron vanadium based hexagonal tungsten bronze hydroxyfluoride HTB-(Fe0.55V0.45)F2.67(OH)0.33 as a positive electrode for lithium-ion batteries.
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DOI：
10.1039/d0dt01310b
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发表时间：
2020-06
影响因子：
4
通讯作者：
Kévin Lemoine;R. Moury;J. Lhoste;A. Hémon-Ribaud;M. Leblanc;J. Greneche;J. Tarascon;V. Maisonneuve
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文献类型：
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作者：
Kévin Lemoine;R. Moury;J. Lhoste;A. Hémon-Ribaud;M. Leblanc;J. Greneche;J. Tarascon;V. Maisonneuve
在为锂电池寻找新的插入化合物的过程中，我们发现了一种新的混合铁钒基六方钨青铜(HTB)相。它的合成分为两步，首先用微波加热法制备混合金属水合氟化物Fe1.64V1.36F8(H2O)2，然后在空气中进行热处理，得到亚稳态HTB-(Fe0.55V0.45)F2.67(OH)0.33羟基氟化物。~(57)Fe穆斯堡尔谱表明，Fe1.64V1.36F8(H2O)2中存在Fe2+和Fe3+，而HTB-(Fe0.55V0.47)F2.67(OH)0.33中只有Fe3+。此外，在77K下记录的穆斯堡尔谱表明，由于V3+的存在分布在Fe3+的晶位上，所有化合物都没有表现出磁性有序。补充X射线光谱和Rietveld精修进一步证实了HTB-(Fe0.55V0.45)F2.67(OH)0.33的成功合成。在电化学方面，新的HTB-(Fe0.55V0.45)F2.67(OH)0.33首次放电容量为181 mA h g-1，循环后容量剩余67%。与HTB-FeF2.66(OH)0.34不同，结构在首次放电后保持稳定，证实了钒在HTB网络中的积极作用。
In our search for novel insertion compounds for Li-based batteries, we have identified a new mixed iron vanadium based Hexagonal Tungsten Bronze (HTB) type phase. Its synthesis involves two steps which consist first of preparing mixed metal hydrated fluoride Fe1.64V1.36F8(H2O)2 by a microwave assisted thermal process, followed by thermal treatment under air to obtain metastable HTB-(Fe0.55V0.45)F2.67(OH)0.33 hydroxyfluoride. 57Fe Mössbauer spectrometry demonstrates the presence of oxidation states Fe2+ and Fe3+ in Fe1.64V1.36F8(H2O)2 as opposed to only Fe3+ in HTB-(Fe0.55V0.47)F2.67(OH)0.33. Moreover, the Mössbauer spectra recorded at 77 K reveal that none of the compounds shows magnetic ordering owing to the presence of V3+ distributed over the crystallographic sites of Fe3+. Complementary X-ray spectroscopy and Rietveld refinement further confirm the successful synthesis of HTB-(Fe0.55V0.45)F2.67(OH)0.33. Electrochemically, the new HTB-(Fe0.55V0.45)F2.67(OH)0.33 shows a first discharge capacity of 181 mA h g-1 with 67% of this capacity remaining upon cycling. Unlike HTB-FeF2.66(OH)0.34, the structure remains stable after the first discharge confirming the positive effect of vanadium in the HTB network.