Near‐Theoretical Redox‐Site Utilization and Fast Zn ²⁺ Storage in a Polyimide‐CNT Cathode

ABSTRACT

Achieving high utilization efficiency together with fast electrochemical transport remains a central challenge for organic cathodes in aqueous zinc‐ion batteries. Herein, a π‐conjugated imide‐linked polyimide based on pyrene‐4,5,9,10‐tetraone and pyromellitic dianhydride (PMDA–PTO) is reported, where a carbonyl‐rich conjugated polyimide framework is integrated with a conductive carbon nanotube (CNT) network to promote electronic percolation and facilitate efficient utilization of redox‐active sites together with fast and durable Zn‐ion storage. The PMDA–PTO–CNT composite delivers a discharge capacity of 328 mAh g ⁻¹ at 0.05 A g ⁻¹ , corresponding to ∼98% utilization of its theoretical capacity, and maintains 316 mAh g ⁻¹ at 20 A g ⁻¹ , while sustaining stable electrochemical operation over 10 000 cycles at 5 A g ⁻¹ . Electrochemical analyses reveal reduced polarization, enhanced pseudocapacitive behavior, and improved electrochemical transport within the CNT‐containing electrode architecture. Ex situ Fourier transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), and Grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) measurements support a reversible carbonyl‐centered cation‐storage mechanism within a structurally disordered polymer framework that retains only short‐range organization during cycling, while density functional theory (DFT) calculations corroborate the multistep delocalized redox behavior of the conjugated backbone. Collectively, these findings provide insight into structure–transport relationships in quinone‐based polymer cathodes and highlight how electronic percolation and redox‐site accessibility enable high utilization, fast kinetics, and long‐term stability in aqueous Zn‐ion batteries.