A donor-acceptor conjugated bipolar polymer with multielectron redox sites for long-cycle-life and high-rate aqueous zinc dual-ion batteries

Aqueous zinc-ion batteries（AZIBs） have hugely latent advantages in large-scale energy storage due to its innate safety,reasonable price,and sustainability.However,most AZIB cathode materials suffer from short cycling life and poor rate performance.Herein,a bipolar donor-acceptor（D-A） conjugated microporous polymer（PTZ-BDTB）,consisting of electron-withdrawing benzo[1,2-b:4,5-b']dithiophene-4,8-dio ne（BDTB） units and electron-donating phenothiazine（PTZ） units,is developed as the cathode material of aqueous zinc dual-ion batteries（AZDIBs）.The D-A type structure design could reduce the band gap,thus promoting electron transfer in the polymer framework.Therefore,the PTZ-BDTB cathode in a30 mol/kg（m） ZnCl2 water-in-salt electrolyte exhibits a high reversible capacity of 202 mA h g-1 at0.05 A g-1 with excellent rate performance(109 mA h g-1 at 15 A g-1),which is far superior to its counterpart polymers PPTZ and PB-BDTB.Impressively,PTZ-BDTB shows ultra-stable cycle performance with capacity retention ratios of 76.2% after 460 cycles at 0.05 A g-1 and 96% after 27000 cycles at 5 A g-1.PTZBDTB also exhibits a low self-discharge ability with capacity retention about 76.4% after resting the battery for 28 days.These results demonstrate that D-A type structural design is a promising strategy for constructing high performance cathode materials for AZDIBs.