Functionalized titanium nitride-based MXenes as promising host materials for lithium-sulfur batteries: A first principles study.

Abstract Searching conductive host materials to suppress the shuttle effect is a long-term goal in the development of lithium-sulfur (Li-S) batteries. In this work, first principles calculations were carried out to systematically investigate O-functionalized Ti 2 N (Ti 2 NO 2) and F-functionalized Ti 2 N (Ti 2 NF 2) monolayers as host materials to anchor the soluble Li 2 S x species. Our results demonstrate that both Ti 2 NO 2 and Ti 2 NF 2 not only possess moderate adsorption energies towards Li 2 S x species, but also achieve a good balance between adsorption energies and intactness of Li 2 S x species, which could avoid the dissolution of Li 2 S x species into electrolyte solvents and improve the utilization of active materials. In addition, after adsorption of S 8 and Li 2 S x species, the metallic character of Ti 2 NO 2 and Ti 2 NF 2 is still preserved, which benefits the redox reaction of Li 2 S x species. Given these exceptional properties, it is expected that Ti 2 NO 2 and Ti 2 NF 2 could be promising host materials for Li-S batteries with good cycling performance. [ABSTRACT FROM AUTHOR]