Reversible Complexing‐Enabled Coordination Networks for the Retention of Redox Species

ABSTRACT Reversible coordination between polymers and multivalent metal cations offers a potential route to reduce the dissolution and migration of mobile redox species while preserving their electrochemical accessibility. Here, we establish a reversible complexing strategy using branched polyethyleneimine (PEI) to construct coordination‐crosslinked PEI‐metal networks for retaining redox‐active species. Using Al 3+ as a model cation, the resulting PEI/Al 3+ network effectively immobilizes anthraquinone molecules while maintaining their reversible electrochemical activity. The observed capacity evolution and charge‐discharge asymmetry are consistent with a possible state‐dependent retention process, although the identity and redox state of the migrating species are not directly resolved by the present measurements. Systematic comparison shows that coordination stability depends on cation‐specific aqueous coordination chemistry, with the Zn 2+ ‐based complex exhibiting more dynamic and electrolyte‐sensitive behavior than the PEI/Al 3+ network under the tested conditions. Extending this concept, PEI‐based complexes with redox‐active cations such as Mn 2+ and Cu 2+ directly function as electrode materials with long‐term cycling stability. Moreover, the coordination structures exhibit chemically responsive dissolution under chloride‐containing conditions, enabling the release of associated species. This work presents a functional proof‐of‐concept for coupling reversible polymer‐metal complexation with the association, electrochemical utilization, and chemically responsive release of redox‐active species.