A robust sulfur host with dual lithium polysulfide immobilization mechanism for long cycle life and high capacity Li-S batteries

Abstract Beyond the physical lithium polysulfide (Li 2 S x ) entrapment of various 3D porous sulfur hosts, the importance of chemical interactions between sulfur host and Li 2 S x on performance of Li-S batteries has recently been highlighted. However, most of these studies focus mainly on one type of chemical interaction and effective suppression of Li 2 S x migration is still lacking. Here, we report a uniquely designed sulfur host that can immobilize Li 2 S x through a dual chemisorption mechanism. The new sulfur host is consisted of an MXene matrix and polydopamine (PDA) overcoat, where Mxene forms a strong Ti–S bonding by the Lewis acid-base mechanism while PDA withholds Li 2 S x through the polar-polar interaction. Benefited from the double chemisorption, the new cathode with a high sulfur loading of 5 mg cm −2 has been demonstrated with an initial capacity of 1001 mA h g −1 at a capacity retention of 65% over 1000 cycles at 0.2 C. Overall, this study not only presents a unique chemical mechanism to entrap Li 2 S x , but also provides a new way to rationally design a practical sulfur cathode for high-performance Li-S batteries.