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

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

doi:10.1038/ncomms10898

Steve J Clark, A Robert Armstrong + Show 2 more

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https://doi.org/10.1038/ncomms10898

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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.

Highlights

Graphite, the dominant anode in rechargeable lithium batteries, operates at B0.1 V versus Li þ /Li and can result in lithium plating on the graphite surface, raising safety concerns
In order to avoid the potential danger of Li plating[1,2] on the widely used graphite anodes[3,4,5] in Li-ion batteries, which intercalate Li at 0.1 V versus Li þ /Li, important efforts have been made to identify anodes operating at 1 V, including organic intercalation compounds[10] and conversion reactions[11,12]
Inorganic intercalation electrodes operate by a well-established mechanism, without the drastic changes that accompany conversion reactions, without involving nanoparticles and with higher densities than organic intercalation compounds

Summary

Introduction

The dominant anode in rechargeable lithium batteries, operates at B0.1 V versus Li þ /Li and can result in lithium plating on the graphite surface, raising safety concerns. 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. LiTiS2 exhibits a massive 1st cycle irreversible loss of capacity of over 180 mAhg À 1

Results

Conclusion