Covalent Polyoxometalate-Polyimide Hybridization: Multi-Scale Molecular Engineering toward High-Performance Sodium-Ion Battery Anodes

Abstract

Organic electrodes suffer from poor active site accessibility, sluggish charge transport, and structural degradation upon cycling, limiting their practical application for energy storage. To address these challenges, this work elucidates a precise electronic and structural modulation strategy for polyimides (PI) via polyoxometalate (POM) hybridization. The key advancement lies in the multiple regulatory effects imparted by POM, enabling the construction of novel hybrid electrodes for highperformance SIBs. Specifically, the covalently anchored phosphomolybdic acid (PMo12 ) clusters disrupt π-π stacking to expose abundant active C=O sites and serve as an electron-withdrawing modulators to lower the LUMO level, thereby enhancing Na + uptake and transport kinetics. Simultaneously, they function as an electron-buffering reservoir to dissipate charge accumulation during discharge, preventing structural degradation of the PI matrix. This multi-scale synergy endows the PI-PMo 12 anode with significantly improved reversible capacity, rate capability, and cycling stability, offering a promising molecular engineering strategy for developing organic-inorganic hybrid electrodes in next-generation energy storage systems.