Durable Organic Anode Material With High Mass‐Loading for Proton Batteries

ABSTRACT Organic materials are highly compelling candidates for next‐generation electrodes. However, low mass‐loading and poor cycle stability in aqueous electrolyte during repetitive charge‐discharge process significantly undermine its practical deployment. Here, indanthrone (IDT), characterized with extended conjugated π‐system and rigid planar structure, was developed as a high‐performance proton‐storage material. Electrochemical analyses and theoretical calculations identify two carbonyl (C=O) and two imine (C = N) groups as the active proton‐hosting sites. Importantly, two additional carbonyls flanking the imines remain inactive owing to intramolecular hydrogen bonds, which enhance the chemical and electrochemical robustness of IDT and underpin extended cycling. As a result, a full MnO 2 @GF//IDT cell delivers ultra‐stable operation for over 20,000 cycles at a high mass loading of 8 mg cm −2 , demonstrating durable performance and practical relevance. These results establish a structure‐function blueprint for organic proton batteries and highlight IDT as a promising, scalable proton‐storage material.