Cuisinier, M., Dupre, N., Moreau, P. & Guyomard, D. (2013) NMR monitoring of electrode/electrolyte interphase in the case of air-exposed and carbon coated LiFePO4. J. Power Sources, 243 682–690.
Added by: Laurent Cournède (2016-03-10 21:23:29)
|Type de référence: Article
Numéro d'identification (ISBN etc.): 0378-7753
Clé BibTeX: Cuisinier2013
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Mots-clés: composite electrodes, diamond-like carbon, electrochemical-behavior, Interface, ion battery electrolytes, li-7 mas nmr, Lithium batteries, Lithium battery, MAS NMR, Positive electrode, positive electrode interface, room-temperature, surface-layers, thermal-stability
Créateurs: Cuisinier, Dupre, Guyomard, Moreau
Collection: J. Power Sources
Consultations : 6/538
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Degradation of the electrochemical performance of LiFePO4 upon air exposure, assigned to a corrosion-type aging mechanism, implies the incorporation of hydroxyl groups and the formation of an amorphous tavorite-like phase at the surface. Using a carbon coating provides an efficient protection from this detrimental process but also modifies the surface in contact with the electrolyte. The formation and evolution of electrode/electrolyte interphases forming on both air-aged and carbon coated LiFePO4 are discussed based on combined quantitative Li-7, F-19 MAS NMR, EIS and EELS measurements. Concerning the air-aged LiFePO4, the electrode/electrolyte interactions are dominated by the dissolution of the active material and an exacerbated reaction of incorporated hydroxyl groups with the electrolyte salt, resulting in a LiF rich interphase. This dissolution of the outer part of active material particles is accompanied by the departure of the previously formed interphase and a new interphase is then formed on a newly exposed surface. The resistive LiF rich interphase passivates the active material particles during cycling, forming a resistive film, hindering both Li ion transfer and material corrosion. Cellulose acetate based carbon coating prevents air-aging but yields to an accumulation of organic lithiated species, allowing Li transfer and maintaining good electrochemical performance. (C) 2013 Elsevier B.V. All rights reserved.
Added by: Laurent Cournède