Emergence of One-Dimensional Interstitial Anionic Superconductivity in Li–F System under High Pressure

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Inspired by lithium-based electrides with pressure-induced superconductivity (e.g., Li 8 Au, Li 6 P, and Li 6 As), we performed first-principles calculations on Li n F m ( n = 1–11, m = 1–3). By incorporating zero-point energy (ZPE) and van der Waals (vdW) interactions, we obtained convex hulls distinct from previous reports and identified four phases with 1D interstitial anionic electrons (IAEs): stable P 1̅-Li 9 F at 50 GPa; metastable C 2-Li 6 F at 50 GPa, P 2 1 / c -Li 5 F 2 at 100 GPa, and P 1̅-Li 10 F at 50 GPa. All four compounds are predicted to be high-pressure, phonon-mediated superconductors, albeit with distinct origins of the superconducting carriers. Among them, Li 10 F exhibits the strongest electron–phonon coupling (EPC) constant λ = 0.873 and the highest superconducting critical temperature ( T c ≈ 10 K). More remarkablely, our study indicates that Li-associated IAEs play a significant role in the superconductivity of Li 10 F. Our work not only predicts the first example of superconductivity in lithium halides but also highlights the crucial role of IAEs in influencing superconductivity.