Proton Capture and Relay Codesign Enables a pH-Neutral All-Organic Aqueous Proton Battery

Aqueous all-organic proton batteries promise safe, sustainable, and high-rate energy storage, but operation under near-neutral conditions is hindered by low proton activity and competition from nonproton charge carriers. Here, we report a proton capture and relay codesign strategy that enables proton-dominated charge storage without strongly acidic electrolytes. The electrode pair comprises two N-centered redox molecules with high proton affinity: an air-stable preprotonated imine cathode, DCTA-2H, and a low-potential azo anode, BCC. The electrolyte is concentrated NH₄OAc, a near-neutral proton-transfer medium in which NH₄ ⁺ forms hydrogen-bonded contacts with imine/azo sites and facilitates interfacial proton transfer rather than being stored predominantly as an intact ion. The resulting BCC||DCTA-2H full cell delivers a discharge voltage of ≈0.85 V and a capacity of 270.9 mAh g_BCC ^-1, retains 86.5% of its capacity after 3,000 cycles, and remains operable at -50°C. This work establishes coupled electrode-electrolyte design as a route to near-neutral all-organic aqueous proton batteries.