Electrostatic-spraying an ultrathin, multifunctional and compact coating onto a cathode for a long-life and high-rate lithium-sulfur battery

Serious shuttle effect of polysulfides is the main obstacle preventing the practical application of lithium sulfur batteries. Herein, we report an ultrathin yet multifunctional polysulfide blocking layer (MPBL) coated on the cathode to effectively restrain the polysulfides shuttling. This MPBL, which was prepared by a simple, one-step electrostatic spray deposition (ESD) technique, was fully and compactly coated on the electrode with controllable thickness, realizing the full protection of the whole cathode. It is noted that the MPBL can be very thin that guarantees the fast ion diffusion but still keeps a high efficiency of blocking polysulfides due to a combination of physical (from carbon) and chemical confinement (from conductive polymer). In addition, the MPBL with good conductivity can act as the upper current collector to reuse the captured polysulfides, and thus improve the sulfur utilization during cycling. With such multifunctional design, the MPBL-coated carbon-sulfur cathode exhibits long cyclic stability and high rate capability, which has only 0.042% capacity decay per cycle at 1C for 1000 cycles and a capacity of 615 mA h g⁻¹ even at a high rate of 3C.