Hydroquinone versus Pyrocatechol Pendants Twisted Conjugated Polymer Cathodes for High‐Performance and Robust Aqueous Zinc‐Ion Batteries

Abstract

AbstractAqueous zinc‐ion batteries (ZIBs) have emerged as a cost‐effective and safe energy storage technology but have remained a challenge in developing efficient Zn2+ hosting materials for large‐scale applications. The authors have herein designed a ladder‐type dithieno[3,2‐b:2′,3′‐d]pyrrole core twisting hydroquinone or pyrocatechol redox pendants as redox conducting polymer cathodes for highly‐efficient and robust aqueous ZIBs. The impact of pendant configuration on the energy level, Zn2+ hosting behavior, and battery performance of these polymer electrodes are systematically investigated. Experimental and theoretical studies clearly reveal the outstanding molecular planarity and highly reversible redox reaction for hydroquinone‐derived PDpBQ cathode, which can effectively tackle the bottleneck problems for ZIBs on aspects of structural stability and Zn2+ insertion/extraction dynamics. Steady capacity output upon 120 mAh g−1 is achieved with considerable rate performance (52.5% of capacity retention at 5 A g−1), while pyrocatechol‐derived polymer PDoBQ exhibits a sharply fading redox responsiveness (over 45%) due to restricted charge transfer and unselective zinc‐ion capturing nature. This molecular design of highly conductive backbone twisting redox pendants with planar molecular plane and specific Zn2+ hosting as polymer cathodes demonstrates an effective strategy for high‐performance and robust ZIBs.