π-conjugated n-heterocyclic quinone compound containing F atoms for high performance aqueous Zn-organic batteries

Abstract

2F-BPD was synthesized by introducing two -F groups to benzo[b]phenazine-6,11-dione (BPD) and used as a cathode for improving performances of aqueous Zn-organic batteries. 2F-BPD delivers high capacities of 329 mAh/g at 0.05 A/g and 161 mAh/g at 5 A/g, as well as excellent capacity retention of 82% after 10,000 cycles. The charge storage mechanism was revealed that 2F-BPD simultaneously store Zn2+ and H+ at the C = N and C = O sites. Given the synergistic effects of electron-withdrawing and induction of -F, 2F-BPD not only stabilizes its structure during the discharge/charge process, but also exhibits slightly lower solubility and faster kinetics due to an increased specific surface area, resulting in improved rate and cycling performances compared to BPD. This work suggests that introduction of -F groups can provide valuable insights for realizing enhanced performances of Zn-organic batteries.