title: Dual lithium insertion and conversion mechanisms in a titanium-based mixed-anion nanocomposite.
abstract: The electrochemical reaction of lithium with a vacancy-containing titanium hydroxyfluoride was studied. On the basis of pair distribution function analysis, NMR, and X-ray photoelectron spectroscopy, we propose that the material undergoes partitioning upon initial discharge to form a nanostructured composite containing crystalline Li(x)TiO(2), surrounded by a Ti(0) and LiF layer. The Ti(0) is reoxidized upon reversible charging to an amorphous TiF(3) phase via a conversion reaction. The crystalline Li(x)TiO(2) is involved in an insertion reaction. The resulting composite electrode, Ti(0)-LiF/Li(x)TiO(2) ⇔ TiF(3)/ Li(y)TiO(2), allows reaction of more than one Li per Ti, providing a route to higher capacities while improving the energy efficiency compared to pure conversion chemistries.
authors.affiliation: Chemical Sciences and Engineering Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States. damien_dambournet@yahoo.fr
authors.forename: Damien
authors.initials: D
authors.lastname: Dambournet
authors.forename: Karena W
authors.initials: KW
authors.lastname: Chapman
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Chupas
authors.forename: Rex E
authors.initials: RE
authors.lastname: Gerald
authors.forename: Nicolas
authors.initials: N
authors.lastname: Penin
authors.forename: Christine
authors.initials: C
authors.lastname: Labrugere
authors.forename: Alain
authors.initials: A
authors.lastname: Demourgues
authors.forename: Alain
authors.initials: A
authors.lastname: Tressaud
authors.forename: Khalil
authors.initials: K
authors.lastname: Amine