A modularly-assembled interlayer to entrap polysulfides and protect lithium metal anode for high areal capacity lithium–sulfur batteries

Polysulfide shuttle effect and the formation of lithium metal dendrite during the discharge-charge process are two primary challenges that limit the application of lithium sulfur (Li-S) batteries. To solve them effectively, a modularly assembled interlayer was prepared by agglomerating Vulcan XC72 carbon black nanoparticles into ellipsoidal superstructures through a double Fischer esterification reaction. The MAXC interlayer can efficiently trap soluble intermediate polysulfides and provide space to store electrolyte and reaction products. More importantly, it can keep lithium anode compact and stable, enabling prolonged cell cycling. A Li/MAXC-MAXC/Li symmetrical cell sustained stable 180-cycles test and delivered only a 20 mV overpotential with a depositing/stripping capacity of 1 mA h/cm² at 1 mA/cm². At a high sulfur loading of approximately 5.3 mg/cm², Li-S coin cells with the assembled MAXC interlayer maintained a high reversible capacity of 909.0 mAh/g and a high areal capacity of 4.75 mAh/cm² after 100 cycles at 0.1 C. This multi-functional interlayer affords a viable strategy for the fabrication of high-energy-density batteries with protected metal anodes.