Superionic conduit of alkaline earth metals confined by two-dimensional boron–carbon layers.

This article investigates the superionic conduction properties of two-dimensional (2D) solid-state electrolytes with the formula A(BC)₂, where A represents alkaline earth metals (Be, Mg, Ca) and BC denotes graphene-like boron–carbon layers. Using first-principles molecular dynamics simulations enhanced by machine learning potentials, the study reveals that these materials exhibit superionic behavior at high temperatures (1300–1800 K), with Be(BC)₂ showing vacancy-driven ion diffusion and Mg(BC)₂ and Ca(BC)₂ displaying combined vacancy and cooperative migration mechanisms. The strong covalent B–C framework provides thermal stability, while the alkaline earth metal ions serve as mobile charge carriers with ionic conductivities significantly higher than previously reported materials, making these compounds promising candidates for high-temperature solid-state electrolytes in applications such as deep drilling and aerospace. Additionally, the presence of cation defects lowers the superionic transition temperature, further enhancing ionic mobility.