Ultralight Layer-by-Layer Self-Assembled MoS2-Polymer Modified Separator for Simultaneously Trapping Polysulfides and Suppressing Lithium Dendrites

Polysulfide shuttling and uncontrollable lithium dendrite growth have hampered the application of lithium-sulfur (Li-S) batteries. Although various materials have been utilized to overcome these obstacles, simple and scalable methods are still needed for Li-S battery commercialization. It is shown for the first time that the layer-by-layer (LbL) self-assembly of 2D nanomaterials can be used to controllably fabricate multifunctional separators that simultaneously trap polysulfides and suppress lithium dendrite growth. The double-sided nanobrick wall structure, constructed by MoS2/poly(diallyl dimethyl ammonium chloride) hybrid in conjunction with poly(acrylic acid) (PAA), provides a physical shield against polysulfides and the chemical adsorption of such species by MoS2 and PAA. At the same time, the robust and Li-ion conducting MoS2 layers strengthen the separator and regulate Li deposition, thereby effectively suppressing Li dendrite formation. As a result, a simple sulfur cathode battery with an ultralight separator coating (0.10 mg cm(-2)) is able to achieve an outstanding cycle stability with a capacity decay as low as 0.029% per cycle over 2000 cycles and a reversible areal capacity approximate to 2.0 mAh cm(-2) at 1 C. The proposed LbL approach opens the door to the simple, scalable, and economic fabrication of advanced functional separators for use in the real world.