Formation Energy‐Dominated AB‐Stacking Structure Promotes Metal‐Covalent Organic Frameworks for High‐Performance Dual‐Ion Storage Potassium‐Ion Batteries

Abstract

ABSTRACT The long‐range AA‐stacking structures present in most covalent organic frameworks (COFs) result in poor utilization of redox‐active sites and suboptimal electrochemical performance. Herein, we report a metallized COF (Cu@MCOF‐D) by pre‐synthesizing cyclic trinuclear copper clusters (Cu 3 ) and integrating them with 2,6‐diaminoanthraquinone (DAAQ). Formation energy calculations confirm that the material possesses a thermodynamically stable AB‐stacking structure, which effectively alleviates interlayer K + adsorption shielding and optimizes the interlayer K + diffusion kinetics. Results from ex situ transmission electron microscopy analyses under different charge/discharge states indicate that Cu 3 exhibits strong adsorption capability toward FSI − , while the ‒C═O/‒C═N‒ groups chemically bind K + , and together they synergistically enable dual‐ion storage. When applied as potassium‐ion battery (PIB) anode, the reduced diffusion barrier allows a high reversible capacity of 153.8 mAh g −1 at 20.0 A g −1 , and delivers 96.8% capacity retention after 6500 cycles at 5.0 A g −1 , demonstrating exceptional long‐term K + storage stability. In PIB full cells using potassium iron hexacyanoferrate as the cathode, a high energy density of up to 197.5 Wh kg −1 is achieved. Furthermore, by employing 3,4,9,10‐perylenetetracarboxylic dianhydride heat‐treated at 450°C as the cathode, outstanding cycling stability is realized, with a capacity retention of 93.2% after 2000 cycles.