Constructing Symmetric All-Organic Proton Battery via Scalable Flux Synthesis of Vinylene-Linked Covalent Organic Frameworks

The design and assembly of symmetric all-organic batteries, eliminating the need for distinct cathode/anode materials while maintaining comparable energy storage performance, has been a highly sought-after objective but has barely been achieved with both high capacity and long-term stability. Herein, we design and synthesize two pyrazino[2,3-<i>g</i>]quinoxaline core-based vinylene-linked covalent organic frameworks (COFs) via the flux synthesis method, featuring two-step redox reactions due to the distinct chemical environments of adjacent C═N groups, to fabricate a symmetric all-organic proton battery, which was confirmed by the mechanism study. The assembled COF-based all-organic battery exhibits excellent performance, with good specific capacity (147 mAh g^-1 at 0.1 A g^-1) and maximum energy density (87 Wh/kg) with over 5000 cycles at high current density, among the best of the reported all-organic proton batteries. The flux synthesis method facilitates the gram-scale production of COFs, enabling their successful assembly into functional pouch cells. As a result, the assembled pouch cell delivers a reversible maximum capacity of 92 mAh g^-1 at 0.1 A g^-1, corresponding to a total capacity of 0.92 Ah, approaching the theoretical design capacity. This work inspires the design of all-organic proton batteries and promotes practical application of COFs in the future.