Theoretical investigation on the strain engineering control of TiC as tunable high-efficiency bifunctional cathode materials for Lithium–Sulfur batteries

Abstract

Developing efficient cathode materials and strategies to suppress the shuttle effect and promote the reaction kinetics were the key scientific issues for the development of high performance lithium–sulfur (Li–S) batteries. Modify the properties of a material through strain engineering is an effective strategy to enhance the performance of adsorption and catalysis ability for special species. In this paper, first-principles calculations were carried out to investigate the anchoring effect and electrochemical performance of TiC (001) subjected to biaxial symmetric mechanical (compressive and tensile) strains. The results demonstrate that the adsorption energies of the lithium polysulfides (LiPSs) were enhanced monotonically and the metallic properties were also remaining along with the strain from compressive to tensile . In addition, an appropriate strain could reduce the migration barrier of Li ions, the dissociation barrier of Li2S and the Gibbs free energy of the sulfur reduction reaction (SRR) to realize the rapid charge/discharge processes. Especially, the p-band center of carbon atoms in TiC was proposed as an effective descriptor to identify the adsorption and catalysis ability of the anchoring materials under biaxial strain. Our results indicate that strain engineering is a promising strategy to improve the comprehensive performance of anchoring materials in Li − S batteries.