Point defects-induced adsorption and diffusion of lithium on monolayer titanium disulfide: A first-principles study

The impacts of point defects including single- and few-atom vacancies (V-S, V-Ti, V-S2, V-TiS3, V-TiS6) and antisites (S-Ti, T-iS) on the Li adsorption and diffusion in monolayer titanium disulfide (TiS2) are systematically investigated through first-principles calculations based on density functional theory for their underlying functions in Li-ion batteries. The calculations imply that Li adsorption and diffusion capabilities are strongly dependent on the defect types of TiS2. For example, defects V-Ti, V-TiS3 and S-Ti improve Li adsorption capability as their adsorption energies increase compared with the pristine TiS2, and V-Ti has the largest increase. V-S, V-S2 and V-Ti exhibit approximate Li diffusion energy barriers with the pristine TiS2 (0.21 eV), signifying that a neglected impact on the rate capability. More importantly, sulfur antisite S-Ti reduces Li diffusion barrier by 0.03 eV, and thus enhances diffusion rates by 3.2 times. Interestingly, S-Ti simultaneously enhances Li adsorption and diffusion capabilities in monolayer TiS2 to some degree, and V-Ti considerably favors Li adsorption without compromising diffusion rates, suggesting that the introduction of defects S-Ti and V-Ti in TiS2 displays excellent properties for energy storage systems. This study benefits for comprehending the impacts of point defects and designing high-performance electrode materials for rechargeable batteries.

Automated summary

First-principles calculations based on density functional theory were used to systematically investigate the impacts of point defects, including vacancies and antisites, on the Li adsorption and diffusion in monolayer titanium disulfide (TiS2). The results show that defect types strongly influence Li adsorption and diffusion capabilities, with certain defects enhancing adsorption and diffusion rates significantly. This study provides insights for designing high-performance electrode materials for rechargeable batteries.