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Toward Environmentally Friendly Lithium Sulfur Batteries: Probing the Role of Electrode Design in MoS₂-Containing Li–S Batteries with a Green Electrolyte

Wang, Lei, Abraham, Alyson, Lutz, Diana M., Quilty, Calvin D., Takeuchi, Esther S., Takeuchi, Kenneth J., Marschilok, Amy C.
ACS sustainable chemistry & engineering 2019 v.7 no.5 pp. 5209-5222
batteries, electrochemistry, electrodes, electrolytes, energy density, foil, lithium, microwave treatment, molybdenum disulfide, nanosheets, porous media, propylene glycol, solvents, sulfur, toxicity
While lithium sulfur batteries (Li–S) hold promise as future high energy density low cost energy storage systems, barriers to implementation include low sulfur loading, limited cycle life, and the use of toxic electrolyte solvents. A comprehensive study of Li–S cells in the environmentally benign di(propylene glycol) dimethyl ether (DPGDME)-based electrolyte, using as-prepared MoS₂ nanosheets derived from a facile aqueous microwave synthesis as polysulfide trapping agents, is reported herein for the first time. Conventional coated foil electrodes and binder-free electrodes (BFEs) with various structures are systematically generated and tested to correlate electrode design with the resulting electrochemical behavior. Significantly improved Li–S electrochemistry is demonstrated through the synergy of MoS₂ chemistry and binder-free electrode engineering. In the coating configuration, the MoS₂-containing cell evinced better rate performance and more stable cyclability than the cell without MoS₂. In comparison with the coating counterparts, the BFE cells exhibited excellent cycle stability and superior rate capability (10-fold capacities and energy density per electrode weight with 20% higher retention rate) despite 2X higher areal sulfur loading. The BFE cell improvement can be attributed to the synergistic effect of the i) interconnected macroporous structure of CNT interlayers, providing a conductive framework, and ii) the efficient polysulfide trapping by the MoS₂ nanosheets.