Orbital Engineering of π-d Conjugation in One-Dimensional Metal-Organic Materials for Lithium-Ion Batteries: A DFT Study.

Understanding and tuning π-d conjugation is essential for advancing metal-organic materials in metal-ion batteries. Here, we applied density functional theory (DFT) to systematically investigate π-d conjugation in metal-organic systems. Using a Ni-based metal-organic polymer as the model system, our results show that strong π-d conjugation originates from effective hybridization between Ni 3d orbitals and ligand π orbitals mediated by bridging groups. Among the three bridging groups (─O, ─S, and ─NH), S provides the strongest coupling due to favorable orbital overlap. Ligand functionalization further modulates this interaction via energy level alignment, where electron-withdrawing groups enhance π-d hybridization and charge delocalization, while electron-donating groups weaken it. These factors collectively influence Li adsorption and electrochemical performance. This study establishes a unified design strategy combining bridge atom selection and functional group tuning to optimize π-d conjugation for high- performance metal-organic electrode materials.