Toward Environmentally Friendly Lithium Sulfur Batteries: Probing the Role of Electrode Design in MoS ₂ -Containing Li-S Batteries with a Green Electrolyte

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 MoS ₂ 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 MoS ₂ chemistry and binder-free electrode engineering. In the coating configuration, the MoS ₂ -containing cell evinced better rate performance and more stable cyclability than the cell without MoS ₂ . 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 MoS ₂ nanosheets.