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

Using 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.