title: Reversible anionic redox chemistry in high-capacity layered-oxide electrodes.
abstract: Li-ion batteries have contributed to the commercial success of portable electronics and may soon dominate the electric transportation market provided that major scientific advances including new materials and concepts are developed. Classical positive electrodes for Li-ion technology operate mainly through an insertion-deinsertion redox process involving cationic species. However, this mechanism is insufficient to account for the high capacities exhibited by the new generation of Li-rich (Li(1+x)Ni(y)Co(z)Mn(1-x-y-z)O₂) layered oxides that present unusual Li reactivity. In an attempt to overcome both the inherent composition and the structural complexity of this class of oxides, we have designed structurally related Li₂Ru(1-y)Sn(y)O₃ materials that have a single redox cation and exhibit sustainable reversible capacities as high as 230 mA h g(-1). Moreover, they present good cycling behaviour with no signs of voltage decay and a small irreversible capacity. We also unambiguously show, on the basis of an arsenal of characterization techniques, that the reactivity of these high-capacity materials towards Li entails cumulative cationic (M(n+)→M((n+1)+)) and anionic (O(2-)→O₂(2-)) reversible redox processes, owing to the d-sp hybridization associated with a reductive coupling mechanism. Because Li₂MO₃ is a large family of compounds, this study opens the door to the exploration of a vast number of high-capacity materials.
authors.affiliation: 1] LRCS, CNRS UMR 7314, Université de Picardie Jules Verne, 80039 Amiens, France [2] ALISTORE-European Research Institute, FR CNRS 3104, France.
authors.forename: M
authors.initials: M
authors.lastname: Sathiya
authors.forename: G
authors.initials: G
authors.lastname: Rousse
authors.forename: K
authors.initials: K
authors.lastname: Ramesha
authors.forename: C P
authors.initials: CP
authors.lastname: Laisa
authors.forename: H
authors.initials: H
authors.lastname: Vezin
authors.forename: M T
authors.initials: MT
authors.lastname: Sougrati
authors.forename: M-L
authors.initials: ML
authors.lastname: Doublet
authors.forename: D
authors.initials: D
authors.lastname: Foix
authors.forename: D
authors.initials: D
authors.lastname: Gonbeau
authors.forename: W
authors.initials: W
authors.lastname: Walker
authors.forename: A S
authors.initials: AS
authors.lastname: Prakash
authors.forename: M
authors.initials: M
authors.lastname: Ben Hassine
authors.forename: L
authors.initials: L
authors.lastname: Dupont
authors.forename: J-M
authors.initials: JM
authors.lastname: Tarascon
mesh_terms: D000838:Anions / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy; D004867:Equipment Design; D008094:Lithium / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D015204:Spectroscopy, Mossbauer; D014961:X-Ray Diffraction
chemical_list: D000838:Anions; D010087:Oxides; D008094:Lithium