Dynamic Balance of Partial Charge for Small Organic Compound in Aqueous Zinc‐Organic Battery

Abstract

AbstractOrganic cathodes for aqueous zinc‐ion batteries (AZIBs) feature intrinsic flexibility and favorable kinetics, but they suffer from high solubility. Herein, a partial charge regulation strategy is deployed by designing a small organic molecule with extended π‐conjugated plane, namely benzo[i]benzo[6′,7′]quinoxalino[2′,3′:9,10]phenanthro[4,5‐abc]phenazine‐5,10,16,21‐tetraone (PTONQ). The charge equalization of active sites induced by the extended π‐conjugated plane of the PTONQ molecule combined with high aromaticity renders the molecule low solubility, fast charge transfer, and high structural stability. The fabricated Zn//PTONQ battery cycles more than 500 h at 175 mA g−1 with small capacity reduction, fast charged/discharged kinetics, and anti‐freeze performance (below ‐20°C). By a series of ex situ characterizations, it is attested that the capacity originates mainly from Zn2+ insertion/removal of PTONQ without H+ incorporation, which also accounts for the formation of Znx(CF3SO3)y(OH)2x‐y·nH2O by‐products. This result benefits the understanding of the by‐product formation mechanism of organic cathode and paves a new way to advance the aqueous Zn‐organic batteries.