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Li(V0.5Ti0.5)S2 as a 1 V lithium intercalation electrode

2016; Nature Portfolio; Volume: 7; Issue: 1 Linguagem: Inglês

10.1038/ncomms10898

2041-1723

Steve Clark, Da Wang, A. Robert Armstrong, Peter G. Bruce,

Advanced Battery Technologies Research

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, Li 4 Ti 5 O 12 , 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, LiVS 2 and LiTiS 2 , 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, Li 1+ x (V 0.5 Ti 0.5 )S 2 , 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(V 0.5 Ti 0.5 )S 2 exceed all previous 1 V electrodes.