Designing a solubility-limited small organic molecule for aqueous zinc-organic batteries

Aiming at the issue that the organic cathode of aqueous zinc-organic batteries (AZOBs) is easy to dissolve, a solubility-limited dibenzo [a, c] dibenzo [5, 6:7, 8] quinoxalino [2, 3-i] phenazine-10, 21‑dione (TABQ-PQ) molecule is successfully designed and synthesized. The extended π-conjugated plane not only improves the π conjugation effect of TABQ-PQ but also enhances its π-π stacked interaction, resulting in low solubility and good structural stability. Furthermore, the TABQ-PQ cathode exhibits an H+-coordination charge-storage mechanism, along with high capacitance-controlling behavior, providing fast reaction kinetics. As expected, the TABQ-PQ delivers a superlong cycling life of over 30 000 cycles and a high discharge capacity of 140.7 mAh g-1 at 20 A g-1. This work sheds light on the design of solubility-limited organic electrodes for high-performance AZOBs.