Synergistic co-reaction of Zn2+ and H+ with carbonyl groups towards stable aqueous zinc–organic batteries

Aqueous Zn–organic batteries are attracting extensive attention because of the green and sustainable nature. However, most of organic cathodes suffer from limited stability (<3000 cycles) and low potential (∼0.8 V vs. Zn/Zn2+). Herein, we propose a novel polymer, poly (2-chloro-3,5,6-trisulfide-1,4-benzoquinone) (PCTB), as cathode for zinc battery, and demonstrate that the bent molecular chain and the electron-withdrawing group of PCTB facilitate Zn2+-storage. This polymer shows robust cycle stability (9000 cycles) with an increased potential of 1.02 V (vs. Zn/Zn2+). Such performance can be retained even with a high mass loading cathode (8 mgPCTB cm–2). Interestingly, the charge storage of PCTB depends on the synergistic Zn2+/H+ co-coordination reaction with carbonyl groups. Both DFT calculations and experiments demonstrate that the Zn2+ coordination dominates the capacity contribution, but which must be energized by a trace of H+ coordination. This might guide the design of the organic electrode materials.