High-throughput screening of 2D transition metal hexaaminobenzene coordination polymers as anode materials for sodium-ion batteries.

Sodium-ion batteries (SIBs) hold tremendous promise for next-generation large-scale energy storage; however, their practical viability is heavily bottlenecked by the lack of robust anode materials capable of accommodating the large sodium ions without severe structural degradation. Herein, we perform a systematic high-throughput screening of two-dimensional transition metal hexaaminobenzene coordination polymers (2D TM-HAB-CPs) as high-capacity SIB anodes. By rationally evaluating a broad pool of 38 transition metal candidates, we identify Zn-HAB-CP as the most optimal host material. Distinct from early transition metals that form highly localized polar bonds, the fully filled 3d10 configuration of the Zn2+ center establishes a highly delocalized covalent network with the π-conjugated HAB ligands. This unique electronic architecture effectively buffers local electrostatic repulsion, enabling Zn-HAB-CP to achieve the strongest global thermodynamic adsorption energy (-2.713 eV) while simultaneously maintaining the most viable Na migration kinetics (0.926 eV) among the investigated candidates. Furthermore, ab initio molecular dynamics simulations confirm the thermodynamic stability of the sodiated 2D lattice at room temperature. Sequential multi-ion adsorption calculations further reveal that Zn-HAB-CP can accommodate a high density of sodium ions, delivering an impressive theoretical specific capacity of 617.90 mAh g-1. This work not only highlights the superiority of MOF based materials as SIB anode materials, but also provides profound fundamental insights into the π-d conjugated engineering of 2D energy storage materials.