Beyond Electrostatics: Anion‐π ⁺ Orbital Hybridization Underpins High‐Performance Chloride Storage in Poly(arylamine) Organic Cathodes

The interactions between ionic charge carriers and host framework critically govern electrochemical reactions and ion‐storing performance, serving as a pivotal design consideration for energy storage devices. However, the fundamental understanding of the covalent‐ionic interactions between anion and oxidized π + ‐framework remains limited thus far. Here we reveal the covalent‐ionic nature of anion‐π + interactions between poly(arylamine)s (PAAs) and Cl − anions. Cl − ‐π + complexes bearing rigid polymeric aryl‐substituted dihydrophenazine (PDPZ) exhibit both electrostatic interaction and distinct Cl − →π + charge‐transfer orbital contribution, confirming the underlying hybrid covalent‐ionic nature of Cl − ‐π + interaction. The synergistic effect of Cl − ‐π + interaction and high electron delocalization capability of PDPZ x+ framework enables reversible Cl − intercalation/deintercalation during multi‐electron redox, achieving a high anion storage capacity of 236 mAh g −1 and remarkable energy densities of 175 Wh kg −1 (Zn||PDPZ cell, in 30 m ZnCl 2 ), alongside long calendar life as cathodes for Cl − ‐based dual‐ion batteries (Cl‐DIBs). Spectroscopic evidence reveals dynamic evolution of vibrational modes and electronic structures from PDPZ to PDPZ x+ ·xCl − complexes, demonstrating the entire π + ‐framework participation and anion‐to‐π + charge transfer during chloride storage. Our mechanistic insights into anion‐π + interactions in Cl‐DIBs provide theoretical guidance for designing advanced anion‐storage organic cathodes and advance anion coordination chemistry.