A Molecular‐Cage Strategy Enabling Efficient Chemisorption–Electrocatalytic Interface in Nanostructured Li2S Cathode for Li Metal‐Free Rechargeable Cells with High Energy

Abstract

AbstractUsing high‐capacity and metallic Li‐free lithium sulfide (Li2S) cathodes offers an alternative solution to address serious safety risks and performance decay caused by uncontrolled dendrite hazards of Li metal anodes in next‐generation Li metal batteries. Practical applications of such a cathode, however, still suffer from low redox activity, unaffordable cost, and poor processability of infusible and moisture‐sensitive Li2S. Herein, these difficulties are addressed by developing a molecular cage–engaged strategy that enables low‐cost production and interfacial engineering of Li2S cathodes for rechargeable Li2S//Si cells. An efficient chemisorption–electrocatalytic interface is built in extremely nanostructured Li2S cathodes by harnessing the confinement/separation effect of metal–organic molecular cages on ionic clusters of air‐stable, soluble, and low‐cost Li salt and their chemical transformation. It effectively boosts the redox activity toward Li2S activation/dissociation and polysulfide chemisorption–conversion in Li‐S batteries, leading to low activation voltage barrier, stable cycle life of 1000 cycles, ultrafast current rate up to 8 C, and high areal capacities of Li2S cathodes with high mass loading. Encouragingly, this highly active Li2S cathode can be applied for constructing truly workable Li2S//Si cells with a high specific energy of 673 Wh kg−1 and stable performance for 200 cycles at high rates against hollow nanostructured Si anode.