B4 Cluster-Based 3D Porous Topological Metal as an Anode Material for Both Li- and Na-Ion Batteries with a Superhigh Capacity.

The high rate performance of a battery requires the anode to be conductive not just ionically but also electronically. This criterion has significantly stimulated the study on 3D porous topological metals composed of nonmetal atoms with a light mass. Many carbon-based 3D topological metals for batteries have been reported, while similar work for 3D boron remains missing. Here, we report the first study of a 3D boron topological metal as an anode material for Li or Na ions. Based on systematic calculations, we found that the reported 3D topological metal H-boron composed of B4 cluster shows a low mass density (0.91 g/cm3) with multiple adsorption sites for Li and Na ions due to the electron-deficient feature of boron, leading to an ultrahigh specific capacity of 930 mAh/g for Li and Na ions with a small migration barrier of 0.15 and 0.22 eV, respectively, and small volume changes of 0.6% and 9.8%. These intriguing features demonstrate that B-based 3D topological quantum porous materials are worthy of further study for batteries.