Redox mediators for high performance Li–S batteries

Presenter: Roza Bouchal
Co-authors: S. Sànchez, A. Boulaoued and P. Johansson
Title: Redox mediators for high performance Li–S batteries
Affiliation: Department of Physics, Chalmers University of Technology

Abstract

The lithium-sulfur battery is a promising next-generation battery (NGB) technology, but with a common major complication of irreversible loss of active material (AM). This is much due to the insulating nature of both sulfur (S8) and the precipitated short polysulfides (PSs, especially Li2S). Here we use redox mediators (RMs) as electrolyte additives to facilitate the electrochemical processes. Several RMs were studied, with a selection based first on the chemical stability vs. the electrolyte and the PSs created. Second, the Li-S battery cell performance including cycle-life was studied using different electrochemical analysis methods. Third, to further improve the RM selection, we studied the effect of RMs on various possible AMs; starting from S8 and all the way to Li2S including intermediate PSs. Overall, the RMs can indeed control the precipitation of S8/Li2S – resulting in improved capacity, and hence their use might be a path to achieve a more complete Li-S reaction scheme.

References:
(1) J. Scheers et al., J. Power Sources, 2014, 255, 204–218
(2) Z.-W. Zhang et al., Adv. Funct. Mater, 2018, 28, 1707536.

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