Formation Energy-Dominated AB-Stacking Structure Promotes Metal-Covalent Organic Frameworks for High-Performance...

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 (Cu₃) 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 Cu₃ 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.