Multiple Protophilic Redox-Active Sites in Reticular Organic Skeletons for Superior Proton Storage.

Protons (H+) with the smallest size and fastest redox kinetics are regarded as competitive charge carriers in the booming Zn-organic batteries (ZOBs). Developing new H+-storage organic cathode materials with multiple ultralow-energy-barrier protophilic sites and super electron delocalization routes to propel superior ZOBs is crucial but still challenging. Here we design multiple protophilic redox-active reticular organic skeletons (ROSs) for activating better proton storage, triggered by intermolecular H-bonding and π-π stacking interactions between 2,6-diaminoanthraquinone and 2,4,6-triformylphloroglucinol nanofibrous polymer. ROSs expose reticular electron delocalization geometries to fully access build-in protophilic carbonyl sites and promote ultrarapid H+ migration with an ultralow activation energy (0.13 vs. 0.29 eV of Zn2+ ions), thus delivering high capacity (359 mAh g-1) and large-current survivability (100 A g-1). Moreover, the extended interconnected reticular structures strengthen the anti-dissolution of ROSs in aqueous electrolytes, affording long-lasting proton-storage activity in ZOBs to a superior level (60,000 cycles at 20 A g-1). Systematic studies identify the source of excellent charge storage as high-kinetics H+-coupled five-electron redox process of carbonyl motifs in superstable ROSs. These findings can be of importance for evoking superior proton activity in multiple redox organics to build advanced Zn-organic batteries.