Multidentate Chelation Enables High‐Efficiency Mn2+ Storage in Polyimide Covalent Organic Framework for Aqueous All Mn‐Ion Battery.

Aqueous divalent manganese ions (Mn2+) have recently emerged as a promising candidate for the development of multivalent ion rechargeable batteries. Here, a multidentate chelation strategy is demonstrated for high‐efficiency Mn2+ storage in a polyimide covalent organic framework (PI‐COF) anode based on the understanding of Mn2+ coordination chemistry. In contrast to other multivalent cations, Mn2+ can bond with two adjacent enolized carbonyl groups and the triazine ring to form a novel multidentate chelation configuration in charged PI‐COF lattice. As such, a large Mn2+ storage capacity of 120 mAh g−1 at 0.2 A g−1 along with great cycling stability can be achieved in PI‐COF. Ex situ characterization and first‐principles calculations further identify the occurrence of polydentate Mn2+ coordination and its critical role in stabilizing the enolized PI‐COF intermediates. Notably, an all Mn‐ion prototype cell assembly is demonstrated by coupling a PI‐COF/Mn2+ anode with a high‐voltage cathode based on MnO2/Mn2+ conversion reaction. The well‐designed cell exhibits a stable discharge plateau of 1.28 V and an impressive capacity of 115 mAh g−1 at the current density of 0.2 A g−1. This work highlights the utility of coordination chemistry for achieving highly efficient energy storage by optimizing the matching between energy‐carrying ions and organic host materials. [ABSTRACT FROM AUTHOR]