E3S Web Conf.
Volume 16, 201711th European Space Power Conference
|Number of page(s)||5|
|Section||Energy Storage: Future Developments in Energy storage|
|Published online||23 May 2017|
Rhombohedral Iron Trifluoride with a Hierarchized Macroporous/Mesoporous Texture from Gaseous Fluorination of Iron Disilicide
1 Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France
2 CNRS, UMR 6296, ICCF, F-63171 Aubière, France
3 Université Paris Est Créteil, Institut de Chimie et des Matériaux Paris-Est, UMR CNRS 7182 Thiais, France
4 Université Montpellier II, Institut Charles Gerhardt de Montpellier, UMR CNRS 5253 Montpellier, France
5 Centre National d’Etudes Spatiales, Toulouse, France
Stable low temperature rhombohedral iron trifluoride has been obtained by the fluorination under the pure fluorine gas of iron disilicide. The combination of both unusual fluorination process and precursor avoids to get unhydrated crystalline FeF3 particles and allows the formation of hierarchized channels of mesoporous/macroporous texture favorable for lithium diffusion. The fluorination mechanism proceeds by temperature steps from the formation, for a fluorination temperature below 200 °C, of an amorphous phase and an intermediate iron difluoride identified mainly by 57Fe Mössbauer spectroscopy before getting, as soon as a fluorination temperature of 260 °C is reached, the rhombohedral FeF3. Both amorphous and crystallized samples display good ability for electrochemical process when used as cathode in lithium-ion battery. The low diameter of rhombohedral structure channels is balanced by an appropriate mesoporous texture and a capacity of 225 mAh.g−1 after 5 cycles for a discharge cut-off of 2.5 V vs. Li+/Li at a current density of C/20 has been obtained and stabilized at 95 mAh.g−1 after 116 cycles.
© The Authors, published by EDP Sciences, 2017
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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