Organic Zinc‐Ion Battery: Planar, π‐Conjugated Quinone‐Based Polymer Endows Ultrafast Ion Diffusion Kinetics

Abstract A novel poly(phenazine‐alt‐pyromellitic anhydride) (PPPA) has been successfully designed and synthesized via a condensation polymerization strategy as promising cathode material in organic zinc‐ion batteries. Electrochemical quartz crystal microbalance (EQCM), FTIR and XPS characterizations verify a reversible Zn 2+ ‐coordination mechanism in our PPPA cathode. Intriguingly, an ultrahigh Zn 2+ diffusion coefficient of 1.2×10 −7 cm 2 s −1 was found in this large π‐conjugated system, which is the highest one among all organic cathode materials for zinc‐ion batteries. Theoretical calculations reveal the extended π‐conjugated plane in our PPPA sample results in a significant reduction on energy gap, effectively accelerating intramolecular electron transfer during charge/discharge process. Our finding provides insights to achieve high zinc‐ion transport kinetics by a design strategy on planar polymer system.