Polysulfide Binding to Several Nanoscale Magnéli Phases Synthesized in Carbon for Long-Life Lithium–Sulfur Battery Cathodes

Usman Zubair, Julia Amici, Carlotta Francia, David McNulty, Silvia Bodoardo, Colm O'Dwyer

Research output: Contribution to journalArticlepeer-review

Abstract

In Li–S batteries, it is important to ensure efficient reversible conversion of sulfur to lithium polysulfide (LiPS). Shuttling effects caused by LiPS dissolution can lead to reduced performance and cycle life. Although carbon materials rely on physical trapping of polysulfides, polar oxide surfaces can chemically bind LiPS to improve the stability of sulfur cathodes. We show a simple synthetic method that allows high sulfur loading into mesoporous carbon preloaded with spatially localized nanoparticles of several Magnéli-phase titanium oxide (TinO2n−1). This material simultaneously suppresses polysulfide shuttling phenomena by chemically binding Li polysulfides onto several Magnéli-phase surfaces in a single cathode and ensures physical confinement of sulfur and LiPS. The synergy between chemical immobilization of significant quantities of LiPS at the surface of several TinO2n−1 phases and physical entrapment results in coulombically efficient high-rate cathodes with long cycle life and high capacity. These cathodes function efficiently at low electrolyte-to-sulfur ratios to provide high gravimetric and volumetric capacities in comparison with their highly porous carbon counterparts. Assembled coin cells have an initial discharge capacity of 1100 mAh g−1 at 0.1C and maintain a reversible capacity of 520 mAh g−1 at 0.2C for more than 500 cycles. Even at 1C, the cell loses only 0.06 % per cycle for 1000 cycles with a coulombic efficiency close to 99 %.

Original languageEnglish
Pages (from-to)1838-1848
Number of pages11
JournalChemSusChem
Volume11
Issue number11
DOIs
Publication statusPublished - 11 Jun 2018
Externally publishedYes

Keywords

  • batteries
  • magnéli phase
  • nanocrystals
  • nanoparticles
  • sulfur

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