Predicting Reaction Sequences for Li-S Batteries

Computed enthalpy profile for the reaction between tetraglyme (TEGDME) and Li2S2, a likely species in Li-S systems, showing decomposition of the TEGDME. These reaction profiles involving the likely lithium polysulfide species will be used to identify more stable electrolytes for Li-S batteries.

Scientific Achievement

First comprehensive, high level and accurate quantum chemical predictions of (i) complex discharge reaction sequences that convert lithium (Li) and sulfur (S) to Li2S in Li-S batteries and (ii) harmful side reactions that consume the Li and S active components and break down the electrolyte.

Significance and Impact

Identifying these reaction sequences allows intentional design of the highest performing, most stable and longest-lasting Li-S battery systems at the atomic and molecular level.

Research Details

  • The discharge reaction sequence in Li-S batteries is notoriously complex and poorly understood, with up to six or eight intermediate steps. This comprehensive quantum chemical analysis establishes a quantitative framework for analyzing, designing and achieving the best performance.
  • This study identifies intermediate products that can break down the electrolyte needed to transport Li cations between the anode and cathode, removing essential materials needed in the Li-S battery.
  • This fundamental knowledge is required for new electrolyte discovery to maximize the performance and minimize the degradation of Li-S batteries.

Work performed at Argonne National Laboratory, JCESR managing partner., and the University of Illinois R. S. Assary, L. A Curtiss, and J. S. Moore, Towards a Molecular Understanding of Energetics in Li-S Batteries Using Non-Aqueous Electrolytes: A High-Level Quantum Chemical Study J. Phys. Chem. C., 2014.

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