Isoreticular Covalent Organic Frameworks with Complementary Redox Cores Enable High-Voltage All-COF Sodium Dual-Ion...

Covalent organic frameworks (COFs) have emerged as promising electrode materials for sodium-ion batteries, combining molecular-level tunability with crystalline porous architectures and structural robustness. However, high-voltage all-COF batteries remain rare, as constructing complementary low-potential anodes and high-potential cathodes remains challenging. Herein, an isoreticular redox-core tailoring strategy is employed to construct complementary n-type and p-type COF electrodes for sodium dual-ion batteries. Two highly crystalline two-dimensional COFs with closely related architectures were synthesized using electron-deficient triazine and electron-rich triphenylamine redox cores, respectively. Triazine-based Trz-COF functions as a low-potential n-type anode that predominantly operates within 0.01-1.4 V vs. Na+/Na, whereas triphenylamine-based TPA-COF serves as a high-potential p-type cathode that predominantly operates within 3.4-4.2 V vs. Na+/Na for reversible PF6- storage. In situ spectroscopic analyses and theoretical calculations reveal that variation of the redox-active core dictates the charge-storage behavior and electrode potential, while the preserved framework architecture maintains efficient ion transport. Pairing these COFs yields a high-voltage all-COF sodium dual-ion battery operating over 2.0-4.2 V with an average discharge voltage of 3.40 V, delivering 116 mAh g-1 and retaining 76 mAh g-1 after 1000 cycles at 0.5 A g-1. This study establishes redox-core tailoring within an isoreticular COF family as a molecular design strategy for regulating electrochemical function in crystalline organic frameworks and demonstrates its application to high-voltage all-COF sodium dual-ion batteries.