Tantalum pentoxide (Ta 2 O 5 ) has attracted significant attention as a potential anode material for large-scale lithium-ion batteries (LIBs) due to its structural robustness and chemical stability. However, its practical electrochemical performance is limited by phase instability, a limited number of active lithium adsorption sites, and intrinsically low ionic conductivity. To address these challenges, we systematically investigated several compositions, including 10 single and 9 multi-cations and anion-substituted Ta 64 O 160 systems, denoted as TNM 1 X 1 P 1 (TN = Ta 61 Nb 1 O 159 ; M = Ti, Zr, Hf; X = Sb, Al, Ga). First-principles calculations were performed using the generalized gradient approximation with the Perdew-Burke-Ernzerhof (PBE) functional, implemented in Cambridge Sequential Total Energy Package (CASTEP) software. Structural analysis reveals that TNM 1 X 1 P 1 systems, particularly Hf-Al-P and Hf-Ga-P, exhibit enhanced stability compared to pristine Ta 64 O 160 , as indicated by lower total energies and negative formation enthalpies. Electronic structure calculations show a significant reduction in band gap upon substitution; notably, the TN-Hf-Ga-P system displays an ultra-narrow band gap of 0.03 eV, approaching metallic behavior, whereas pristine Ta 64 O 160 exhibits a wider band gap of 2.60 eV. Mechanical stability is preserved across all compositions. Lithium adsorption analysis indicates highly negative adsorption energies (-8.3 to -9.0 eV) for selected systems (Ti-Sb-P, Hf-Al-P, Hf-Ga-P), suggesting favorable Li insertion. The Li-O bond lengths (2.0-2.2Å) and significant charge transfer (0.9-1.0e) confirm strong ionic interactions without structural degradation. Among all systems, TN-Ti-Al-P delivers an average voltage of 3.4V and a calculated theoretical capacity of 67.5 mAhg -1 . This value corresponds to a DFT-based partial lithiation model in which only 8Li atoms were inserted into the TN-Ti-Ga-P supercell. Molecular dynamics simulations further confirm excellent thermal and dynamic stability.
Moin et al. (Mon,) studied this question.