Three-Gap High- <i>T</i> _c Topological Superconductivity in Lithium-Doped Bilayer Borophenes

Realizing topological superconductors (TSCs) with high transition temperatures (high-<i>T</i>_c) remains a central challenge in the development of fault-tolerant quantum computation. Here, we propose a route for realizing high-<i>T</i>_c TSCs by integrating multigap superconductivity with nontrivial band topology in lithium-doped bilayer borophene. Extensive structural searches and high-throughput screening of over 4000 Li_1-<i>x</i>B_<i>x</i> nanosheets identify eight promising multigap TSC candidates. Among them, the LiB₁₂ nanosheet is identified as a prototypical three-gap superconductor and simultaneously a topological metal with a symmetry-protected Dirac nodal loop. Fully anisotropic Migdal-Eliashberg calculations reveal cooperative couplings between σ↔in-plane and π↔out-of-plane phonon, which markedly enhance electron-phonon interactions and drive a high-<i>T</i>_c of 57 K. These findings underscore the potential of metal-doped bilayer borophenes as a cutting-edge material platform for achieving high-<i>T</i>_c multigap TSCs.