Li₁₀Bi: A lithium-rich electride with coexisting superconductivity and solid-state lithium-ion conductivity

Electrides, characterized by interstitial quasi-atoms (ISQs) where electrons occupy lattice voids instead of atomic orbitals, provide a unique platform for discovering novel superconductors and mixed-conduction materials. Here, using crystal structure prediction combined with first-principles calculations, we systematically explore lithium-rich Li–Bi compounds under high pressure. Several new Li-rich stoichiometries, LiBi, Li₁₁Bi₂, Li₉Bi, and Li₁₀Bi, are identified as thermodynamically stable. Among them, the C2/m phase of Li₁₀Bi features one-dimensional ISQ networks, exhibiting both metallic and electride characteristics. Electron–phonon coupling analysis reveals a dome-shaped evolution of superconducting transition temperature (T_c), reaching a maximum value of 9.9 K at 35 GPa, where the superconductivity is primarily driven by strong Li-derived phonon modes. Ab initio molecular dynamics simulations further reveal a temperature-induced superionic transition above 700 K, where Li⁺ ions diffuse freely while Bi atoms remain fixed within the lattice. This coexistence of superconductivity and superionicity within a single crystalline framework highlights Li₁₀Bi as a prototype dual-functional electride, bridging the gap between quantum superconductors and solid-state lithium-ion conductors. These findings open a new route for designing multifunctional materials that integrate electronic and ionic transport for next-generation energy and quantum applications.