Conjugation Extended Redox Oligomer Integrated Freestanding Cathodes for High‐Capacity Stable Zinc‐Ion Batteries

Abstract Organic cathodes as promising alternatives for aqueous zinc‐ion batteries (AZIBs) face challenges of limited capacity and low cycling stability. To address these concerns, a conjugation extended quinone oligomer, i.e., 2,2′‐(9,10‐dioxo‐9,10‐dihydrophenanthrene‐2,7‐diyl)bis(cyclohexa‐2,5‐diene‐1,4‐dione) (PB), is developed herein for integrating with the framework of 2D MXene nanosheets covalently bonded single‐walled carbon nanotube (MXSC) as freestanding film cathodes for high‐capacity stable AZIBs. The sufficient exposure of redox‐active sites in hierarchical architecture enables synergistically enhanced conductivity, suppressed dissolution in electrolytes, and efficient ion/electron transfer for charge storage. The optimal PB@MXSC cathode contributes a highest specific capacity of 202 mAh g −1 at 1 A g −1 and 160 mAh g −1 at 10 A g −1 , together with an exceptional 81.2% capacity retention after 12 000‐cycle cycling at 10 A g −1 , rivaling the‐state‐of‐the‐art organic cathodes in the literature. Featuring three‐fold higher tensile strength than pristine MXene, the cathodes are endowed with unparalleled mechanical durability and a retention of 87.6% capacity over 1 000 bending cycles. The experimental and theoretical analyses reveal the Zn 2+ and H + dual‐ion co‐storage mechanism. This work pioneers a universal design paradigm for high‐performance flexible energy storage devices, bridging molecular engineering with advanced materials and sustainable electrochemistry.