Conformal Polymeric Multilayer Coatings on Sulfur Cathodes via the Layer-by-Layer Deposition for High Capacity Retention in Li–S Batteries

Abstract

We report on the conformal coating of thickness-tunable multilayers directly onto the sulfur (S₈) cathodes by the layer-by-layer (LbL) deposition for the significant improvement in the performances of Li–S batteries even without key additives (LiNO₃) in the electrolyte. Poly(ethylene oxide) (PEO)/poly(acrylic acid) (PAA) multilayers on a single poly(allylamine hydrochloride) (PAH)/PAA priming bilayer, deposited on the S₈ cathodes, effectively protected from the polysulfide leakage, while providing a Li⁺ ion diffusion channel. As a result, PAH/PAA/(PEO/PAA)₃ multilayer-coated cathodes exhibited the highest capacity retention (806 mAh g^–1) after 100 cycles at 0.5 C, as well as the high C-rate capability up to 2.0 C. Furthermore, the multilayer coating effectively mitigated the polysulfide shuttle effect in the absent of LiNO₃ additives in the electrolyte.