title: Multiscale phase mapping of LiFePO4-based electrodes by transmission electron microscopy and electron forward scattering diffraction.
abstract: LiFePO4 and FePO4 phase distributions of entire cross-sectioned electrodes with various Li content are investigated from nanoscale to mesoscale, by transmission electron microscopy and by the new electron forward scattering diffraction technique. The distributions of the fully delithiated (FePO4) or lithiated particles (LiFePO4) are mapped on large fields of view (>100 × 100 μm(2)). Heterogeneities in thin and thick electrodes are highlighted at different scales. At the nanoscale, the statistical analysis of 64 000 particles unambiguously shows that the small particles delithiate first. At the mesoscale, the phase maps reveal a core-shell mechanism at the scale of the agglomerates with a preferential pathway along the electrode porosities. At larger scale, lithiation occurs in thick electrodes "stratum by stratum" from the surface in contact with electrolyte toward the current collector.
authors.affiliation: CEA, DRT, LITEN, DEHT , Minatec, 17 Rue des Martyrs, 38054 Grenoble, France.
authors.forename: Donatien
authors.initials: D
authors.lastname: Robert
authors.forename: Thierry
authors.initials: T
authors.lastname: Douillard
authors.forename: Adrien
authors.initials: A
authors.lastname: Boulineau
authors.forename: Guillaume
authors.initials: G
authors.lastname: Brunetti
authors.forename: Pawel
authors.initials: P
authors.lastname: Nowakowski
authors.forename: Denis
authors.initials: D
authors.lastname: Venet
authors.forename: Pascale
authors.initials: P
authors.lastname: Bayle-Guillemaud
authors.forename: Cyril
authors.initials: C
authors.lastname: Cayron