A Sandwich‐Structured Double‐Modified Gel Separator Enables Shuttle‐Inhibition and Dendrite‐Free Quasi‐Solid‐State Li‐Sulfur Batteries with Ultralong Lifespan

Abstract Li‐dendrite growth and polysulfides shuttle are two core problems that restrict the applications of lithium‐sulfur batteries (LSBs). Here, a double‐layer‐modified gel separator (DMS) is proposed to enable a shuttle‐inhibition and dendrite‐free quasi‐solid‐state LSB, where the polypropylene separator is sandwiched between an ultra‐thin VS 2 layer (3 um) and a ceramic/polymer layer (6 um). On the cathode side, VS 2 layer can inhibit the polysulfides shuttle and boost their conversion kinetics. Meanwhile, on the anode side, the Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP)/PMMA/PVDF gel polymer electrolyte with the high‐elastic‐modulus and the homogenized Li‐ion flux could effectively avoid dendrite growth. Last but not least, the quasi‐solid‐state LSB effectively prevents the evaporation of flammable ether‐based electrolyte. Consequently, the quasi‐solid‐state‐LSBs assembled with DMS show a high‐capacity of 1197 mA h g −1 at 0.2 C and ultra‐stable cycling performance over 800 cycles at 2 C with the decay rate of just 0.032% per cycle. Even with the high‐sulfur‐loading of 2.5 mg cm −2 , the LSB still delivers the high‐capacity of 640.5 mA h g −1 at 2 C with stable cycling over 500 cycles. What's more, the assembled pouch cells still function properly even on the nail penetration and folding test, verifying the gel layer's integrity, and retention of electrochemical function under realistic conditions.