1. Quantitative MAS NMR characterization of the LiMn1/2Ni1/2O2 electrode/electrolyte interphase
- Author
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Philippe Moreau, Ryoji Kanno, Thierry Epicier, Dominique Guyomard, Marine Cuisinier, Jean-Frédéric Martin, Nicolas Dupré, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo Institute of Technology [Tokyo] (TITECH), Matériaux, ingénierie et science [Villeurbanne] (MATEIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Nuclear and High Energy Physics ,Magnetic Resonance Spectroscopy ,Analytical chemistry ,Oxide ,02 engineering and technology ,Electrolyte ,Lithium ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Phase Transition ,chemistry.chemical_compound ,Electrolytes ,Materials Testing ,Instrumentation ,Electrodes ,Resistive touchscreen ,Manganese ,Radiation ,Chemistry ,Electron energy loss spectroscopy ,Oxides ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Transmission electron microscopy ,Electrode ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Interphase ,0210 nano-technology - Abstract
International audience; The conditions in which degradation processes at the positive electrode/electrolyte interface occur are still incompletely understood and traditional surface analytical techniques struggle to characterize and depict accurately interfacial films. In the present work, information on the growth and evolution of the interphases upon storage and cycling as well as their electrochemical consequences are gathered in the case of LiNi(1/2)Mn(1/2)O(2) with commonly used LiPF(6) (1M in EC/DMC) electrolyte. The use of (7)Li, (19)F and (31)P MAS NMR, made quantitative through the implementation of empirical calibration, is combined with transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) to probe the elements involved in surface species and to unravel the inhomogenous architecture of the interphase. At room temperature, contact with the electrolyte leads to a covering of the oxide surface first by LiF and lithiated organic species are found on the outer part of the interphase. At 55°C, not only the interphase proceeds in further covering of the surface but also thickens resulting in an increase of 240% of lithiated species and the presence of -POF(2) fluorophosphates. The composition gradient within the interphase depth is also strongly affected by the temperature. In agreement with the electrochemical performance, quantitative NMR surface analyses show that the use of LiBOB-modified electrolyte results in a Li-enriched interphase, intrinsically less resistive than the standard LiPF(6)-based interphase, comprised of a mixture of resistive LiF with non lithiated species.
- Published
- 2012