Electride superconductors with unique interstitial anionic electrons (IAEs) have recently attracted considerable attention. Lithium-based electride superconductors are of particular interest because of their striking electride states and superconductivity. Electrides containing Li and Bi are not yet known despite the previously reported Li-Bi binary compounds. In this study, we systematically simulated Li-rich bismuthides under compression using a state-of-the-art structure search approach combined with first-principles calculations. Strikingly, several unforeseen stable electride phases with high lithium coordination, diverse distributions of IAEs, and metallic characteristics were identified, that is, ${\mathrm{Li}}_5\mathrm{Bi}, {\mathrm{Li}}_7\mathrm{Bi}, {\mathrm{Li}}_8\mathrm{Bi}, {\mathrm{Li}}_9\mathrm{Bi}$, and ${\mathrm{Li}}_{10}\mathrm{Bi}$, where continuous phase transitions from orthorhombic Pmmn to Cmcm were observed in ${\mathrm{Li}}_5\mathrm{Bi}$, accompanied by a transformation from two-dimensional to zero-dimensional IAEs. Furthermore, superconducting property calculations revealed that ${\mathrm{Li}}_{10}\mathrm{Bi}$, featuring one-dimensional zigzag-like IAEs, had a superconducting transition temperature ($T_c$) of 4.5 K at a moderate pressure of 50 GPa, making it the highest lithium concentration electride superconductor consisting of Li and nitrogen group elements. The strong coupling between the electron states of Li $2p$ and the IAEs and Li-associated phonon modes dominates the remarkable superconductivity of ${\mathrm{Li}}_{10}\mathrm{Bi}$. This study offers valuable insights into emerging lithium-bearing electride superconductors.

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• Electronic structure
• Pressure effects
• Structural properties
• Superconductors
• Density functional calculations