Lithium-induced conversion reaction in wüstite Fe1-xO studied by 57Fe Mössbauer spectroscopy.

Laurent Aldon (1) , Jean-Claude Jumas (1)

1 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

Fe1-xO wüstite as negative electrode material for Li-ion batteries has been studied. The aim of this work is to get a better understanding of the insertion mechanism involved during reduction/oxidation processes. Electrochemical tests have been done in SwagelockTM cells and shown a high specific capacity of 800 Ah/kg for the first discharge. X-ray diffraction and 57Fe Mössbauer spectroscopy provide us valuable information on both local and long range order. Hence, Li reaction with wüstite induces formation of highly divided metallic iron (alpha-Fe and nano-Fe) and Li2O with a small amount of Fe2O3 occurring in a diffusion layer at the surface of the primary particles. Based on the X-ray and Mössbauer spectroscopic analyses, a core-shell model is proposed in order to explain the irreversible capacity of about 1 Li observed at the first cycle. It involves cation diffusion induced by lithium acting as an "electronic pressure‟.

Mots clés: Wüstite; Mössbauer spectroscopy; Conversion reaction; Lithium; Electrochemical mechanism; Disproportionation; Irreversible capacity

Domaines: Matériaux

Laurent Aldon, Jean-Claude Jumas. Lithium-induced conversion reaction in wüstite Fe1-xO studied by 57Fe Mössbauer spectroscopy.. Solid State Sciences, 2012, 14 (3), pp.354-361. ⟨10.1016/j.solidstatesciences.2011.12.006⟩. ⟨hal-00664208⟩