Proton‐Coupled Chemistry Enabled p–n Conjugated Bipolar Organic Electrode for High‐Performance Aqueous Symmetric Battery

Abstract Bipolar‐type electrode materials are capable of improving the specific power and reducing the manufacturing costs for rechargeable symmetric batteries, while their development is plagued by the lack of reliable and affordable bipolar‐type materials. Here, a bipolar‐type indanthrene (IDT) with synergetic coupling effects of two redox centers of p‐type dihydrophenazines and n‐type anthraquinone in a single molecule is proposed to construct a symmetric battery. Due to the mutually affecting of n‐type and p‐type redox couples, the conjugated “p–n fusion” in the IDT material facilitates mutual electron cloud donation and withdrawal between two redox centers, thus a considerable output voltage of 0.62 V is realized in symmetric aqueous battery. Benefiting from its enriched redox centers and extended π‐conjugated structure, the symmetric battery also delivers a specific capacity of 139 mAh g⁻¹ at 0.1 A g⁻¹ and a long cycling stability with a capacity retention of 79% after 600 cycles at 2 A g⁻¹. Comprehensive ex‐situ characterizations paired with density functional theroy calculations reveal both reversible HSO₄⁻ and H⁺ uptake/removal behavior during charging/discharging process. Additionally, a symmetric cell with quasi‐solid electrolyte is established, which exhibits superior practical application capability with a capacity retention of 78% at 2 A g⁻¹ over 1000 cycles.