Lithium-intercalation-induced structural evolution and superconductivity modulation in 2H-Li_xTaSe₂

We systematically investigated the structural and superconducting properties of polycrystalline 2H-Li_xTaSe₂ (0.1 ≤ x ≤ 1.0) synthesized via a high-temperature solid-state reaction. Lithium (Li) intercalation induces an expansion along the c-axis and intralayer distortions within the Ta–Se coordination network. The superconducting transition temperature (T_c) is increased to 2.95 K at x = 0.1 driven by the synergistic enhancement of the electronic density of states at the Fermi level, N(E_F), and strengthened electron–phonon coupling. With further Li doping, although N(E_F) continues to increase, lattice stiffening and pronounced distortions in the Ta–Se coordination polyhedra weaken the electron–phonon interaction, ultimately suppressing superconductivity. These findings highlight the critical role of intralayer structural modulation in governing structure-tunable superconductivity in layered materials.