Designing Advanced LiTiXY (X, Y = O, S, Se, and Te) via DFT Engineering: Chalcogen Substitution Incorporation

The advancement of lithium-ion battery (LIB) technologies hinges on the development of cathode materials with superior voltage profiles, rate capability, and structural stability. In this study, we conduct a comprehensive first-principles investigation of LiTiXY compounds (X, Y = O, S, Se, Te), focusing on the influence of chalcogen substitution on the electronic structure, voltage behavior, and electrical transport mechanisms. Using DFT calculations with GGA and GGA + U functionals, we evaluate the band gaps, density of states (DOS), and reaction voltages using both internal energy and Fermi-level-based approaches. A novel semi-quantitative model is employed to analyze electrical rate capability, incorporating both energy-level mismatch (ΔCB/ΔVB) and band continuity across lithiated-delithiated interfaces (CCTB model). Results reveal that compounds such as LiTiTeS and LiTiSeTe exhibit metallic or near-metallic character in their delithiated states, enabling efficient electron transport and low activation barriers. Meanwhile, structural analysis demonstrates that moderate volume changes upon delithiation particularly in Se- and Te-containing systems correlate with favorable cycling stability. Our findings offer a clear design pathway for engineering high-performance LIB cathodes through targeted anion substitution strategies.