Résumé
The research of new electrode materials of high performance for Li-ion batteries requires a better understanding of the electrochemical reaction that take place during the charge/discharge process.
For this objective
in situ
measurements have been developed using complementary tools such as X-Ray Powder Diffraction (XRPD) and Transmission Mössbauer Spectrometry (TMS) allowing both structural and electronic characterization of materials under the conditions of the electrochemical cycling (
operando
mode). Up to now these measurements are carried out separately, ie, using a cell to record the X-ray diffraction data and another cell for the Mössbauer data. To overcome the drawback of working on two different cells, a new setup [1] combining XRPD and TMS has been designed allowing an alternative way for recording of these two kinds of data simultaneously. Thus a conventional TMS spectrometer has been associated to a X-Ray Diffractometer of θ-θ geometry (Figure 1) using a specific electrochemical cell derived initially designed for in situ analyse of Li-ion batteries [2].
Figure 1: 1
st
prototype of the setup combining XRPD diffractometer and TMS spectrometer.
On this prototype the electrochemical cell is fixed, thanks to the θ-θ geometry of the diffractometer. Connected to a potentiostat which is used to control electrochemical cycling. This cell allows measurements in both reflection mode (XRPD) and transmission mode (TMS). Since Mössbauer detector is saturated by the diffused X-rays, an software has been developed to allow collecting alternatively XRD patterns and Mössbauer spectra. The duration of the collection of each kind of data can be adjusted as a function of the investigated material.
Several examples are presented to illustrate the capabilities of this setup and how it can be used to illucidate complex mechanisms governing the electrochemical behaviour of Li- and Na-ion new electrode materials containing Fe or Sn.
References
[1] J.-C. Jumas, L. Stievano, M.T. Sougrati, J. Fullenwarth, B. Fraisse, J.-B. Leriche, Brevet Français
,
12 58086 (2012), PCT/FR2013/051981 (2013)
[2] J.B. Leriche, S. Hamelet, J. Shu, M. Morcrette, C. Masquelier, G. Ouvrard, M. Zerrouki, P. Soudan, S. Belin, E. Elkaïm, F. Baudelet, J. Electrochem. Soc., 157 (2010) A606.
Acknowledgements
The Mössbauer platform has been implemented at the University of Montpellier with supports from the EC (NoE ALISTORE SES6-CT-2003-503532), Région Languedoc Roussillon (Contracts n° 2006-Q086 and 2008-094192). The author is grateful to these institutions and to CNRS and RS2E (FR 3459) for financial supports.