title: Single step transformation of sulphur to Li2S2/Li2S in Li-S batteries.
abstract: Lithium-sulphur batteries have generated tremendous research interest due to their high theoretical energy density and potential cost-effectiveness. The commercial realization of Li-S batteries is still hampered by reduced cycle life associated with the formation of electrolyte soluble higher-order polysulphide (Li2Sx, x = 4-8) intermediates, leading to capacity fading, self-discharge, and a multistep voltage profile. Herein, we have realized a practical approach towards a direct transformation of sulphur to Li2S2/Li2S in lithium-sulphur batteries by alteration of the reaction pathway. A coconut shell derived ultramicroporous carbon-sulphur composite cathode has been used as reaction directing template for the sulphur. The lithiation/delithiation and capacity fading mechanism of microporous carbon confined sulphur composite was revealed by analyzing the subsurface using X-ray photoelectron spectroscopy. No higher-order polysulphides were detected in the electrolyte, on the surface, and in the subsurface of the cathode composite. The altered reaction pathway is reflected by a single-step profile in the discharge/charge of a lithium-sulphur cell.
authors.affiliation: Helmholtz Institute Ulm (HIU), D-89081 Ulm, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Helen
authors.affiliation: Helmholtz Institute Ulm (HIU), D-89081 Ulm, Germany.
authors.forename: M Anji
authors.initials: MA
authors.lastname: Reddy
authors.affiliation: Institute of Surface Chemistry and Catalysis, Ulm University, D-89081 Ulm, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Diemant
authors.affiliation: Electron Microscopy Group of Materials Science, Central Facility for Electron Microscopy, Ulm University, D-89081 Ulm, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Golla-Schindler
authors.affiliation: Helmholtz Institute Ulm (HIU), D-89081 Ulm, Germany.|Institute of Surface Chemistry and Catalysis, Ulm University, D-89081 Ulm, Germany.
authors.forename: R Jürgen
authors.initials: RJ
authors.lastname: Behm
authors.affiliation: Electron Microscopy Group of Materials Science, Central Facility for Electron Microscopy, Ulm University, D-89081 Ulm, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Kaiser
authors.affiliation: Helmholtz Institute Ulm (HIU), D-89081 Ulm, Germany.|Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Fichtner