title: Li(V0.5Ti0.5)S2 as a 1 V lithium intercalation electrode.
abstract: Graphite, the dominant anode in rechargeable lithium batteries, operates at ∼ 0.1 V versus Li(+)/Li and can result in lithium plating on the graphite surface, raising safety concerns. Titanates, for example, Li4Ti5O12, intercalate lithium at ∼ 1.6 V versus Li(+)/Li, avoiding problematic lithium plating at the expense of reduced cell voltage. There is interest in 1 V anodes, as this voltage is sufficiently high to avoid lithium plating while not significantly reducing cell potential. The sulfides, LiVS2 and LiTiS2, have been investigated as possible 1 V intercalation electrodes but suffer from capacity fading, large 1st cycle irreversible capacity or polarization. Here we report that the 50/50 solid solution, Li1+x(V0.5Ti0.5)S2, delivers a reversible capacity to store charge of 220 mAhg(-1) (at 0.9 V), 99% of theoretical, at a rate of C/2, retaining 205 mAhg(-1) at C-rate (92% of theoretical). Rate capability is excellent with 200 mAhg(-1) at 3C. C-rate is discharge in 1 h. Polarization is low, 100 mV at C/2. To the best of our knowledge, the properties/performances of Li(V0.5Ti0.5)S2 exceed all previous 1 V electrodes.
authors.affiliation: Departments of Materials and Chemistry, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Clark
authors.affiliation: Departments of Materials and Chemistry, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
authors.forename: Da
authors.initials: D
authors.lastname: Wang
authors.affiliation: School of Chemistry and EastChem, University of St Andrews, North Haugh, Fife, Saint Andrews KY16 9ST, UK.
authors.forename: A Robert
authors.initials: AR
authors.lastname: Armstrong
authors.affiliation: Departments of Materials and Chemistry, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Bruce