Steric hindrance modulation of hexaazatribenzanthraquinone isomers for high-capacity and wide-temperature-range aqueous proton battery

Abstract

Organic materials with rich active sites are good candidates of high-capacity anodes in aqueous batteries, but commonly low utilization of active sites limits their capacity. Herein, two isomers, symmetric hexaazatribenzanthraquinone (s-HATBAQ) and asymmetric one (a-HATBAQ), with rich active sites have been synthesized in a controllable manner. It is the first time to reveal that sulfuric acid catalyst can facilitate the stereoselective formation of s-HATBAQ. Attributed to the reduced steric hindrance in favor of proton insertion as well as the amorphous structure conducive to electrochemical dynamics, s-HATBAQ exhibits 1.5 times larger specific capacity than a-HATBAQ. Consequently, the electrode of s-HATBAQ with 50% reduced graphene oxide (s-HATBAQ-50%rGO) delivers a record high specific capacity of 405 mAh g−1 in H2SO4 electrolyte. Moreover, the assembled MnO2//s-HATBAQ-50%rGO aqueous proton full batteries show an exceptional cycling stability at 25°C and can maintain ∼92% capacity retention after 1000 cycles at 0.5 A g−1 at −80°C. This work demonstrates the controllable synthesis of isomers, showcases a wide-temperature-range prototype proton battery and highlights the significance of precise molecular structure modulation in the organic energy storage.

Unveiling Organic Electrode Materials in Aqueous Zinc-Ion Batteries: From Structural Design to Electrochemical Performance

“…As shown in Fig. 1 b, the exposure of active sites in organic small molecules has promoted the higher utilization of active functional groups, leading to fast kinetics and higher initial specific capacity [ 52 , 53 ]. However, the intrinsic dissolving problem of organic small molecules and their discharge products in water has hindered their practical applications.…”