Anthraquinone porous polymers with different linking patterns for high performance Zinc-Organic battery

Anthraquinone have desirable redox property, high specific capacity, and structural diversity, making them standing out as candidate cathode materials. However, they are still restricted in long cycling life for aqueous Zn-ion batteries (ZIBs) due to the structural instability and dissolution during the repeated H⁺/Zn²⁺ co-intercalation commonly leads to a fast capacity fading. Herein, two completely new isomeric porous polymers PTA-O26 and PTA-O14 with triazine have been designed and synthesized. The impact of the location of anthraquinone units on the redox potentials, Zn²⁺/H⁺ co-insertion behavior, and battery performance of polymer electrodes has been systematically studied. Experimental and DFT calculations studies clearly reveal the outstanding structural symmetry and highly reversible redox reaction for PTA-O26 cathode, which can effectively tackle the bottleneck problems for ZIBs on aspects of structural stability and Zn²⁺/H⁺ co-insertion dynamics. Naturally, PTA-O26 displays a specific capacity of 296 mAh g^-1 after 250 cycles with a high-capacity retention of 92.2 %.Moreover, the flexible soft-packaged battery by using PTA-O26 as cathode coupled with Zn foil as counter electrode manifests good stability under different bending conditions. The study provides a new insight about how to tune the structures for high performance batteries.