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

Abstract

ABSTRACT 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 NH 4 OAc, a near‐neutral proton‐transfer medium in which NH 4 + 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.