Electrides represent a unique class of materials in which excess electrons are confined to interstitial sites within the crystal lattice rather than being bound to atomic nuclei. Here, we present ScAl—an existing metallic compound—as a three-dimensional electride with a nontrivial topological electronic structure. Via first-principles calculations, we demonstrate that ScAl qualifies as a zero-dimensional electride, with excess electrons occupying the $3d$ Wyckoff position in its lattice. Notably, the electronic bands near the Fermi level mainly originate from these excess electrons. A band inversion occurs among the bands near the Fermi level, leading to the formation of a nodal loop characterized by a drumhead surface state. We establish the effective model to characterize the nodal loop, revealing the symmetry protection mechanism. Due to the relatively weak spin-orbital coupling (SOC) in the excess electrons, the inclusion of SOC introduces a small gap at the nodal loop. Moreover, the topological and electride characteristics of ScAl are robust against external perturbations, such as strain and doping. Our findings expand the family of inorganic electrides and highlight the intricate interplay between electride chemistry and band topology, offering different avenues for exploration in this field.

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• Alloys
• Topological materials
• Density functional theory
• First-principles calculations