Dynamic release electrolyte design for stable proton batteries

Aqueous proton batteries (APBs) have recently demonstrated unprecedented advantages in the fields of ultralow temperature and high‐power energy applications due to kinetically favorable proton chemistry. Proton acids (e.g. H2SO4, H3PO4) as the common proton‐conducting electrolyte, however, seriously corrode electrode materials and current collectors, resulting in limited cycle life of APBs. Here we reported protonated amine as a feasible proton transport mediator and releasing source for APBs based on its dynamic chemical dissociation equilibrium. Free protons in the electrolyte are limited to a quite low level. Consequently, the optimized electrolyte with a nearly neutral pH value significantly suppresses corrosion and broadens material selection option for APBs. The CuFe‐TBA electrode exhibited a long cycle performance over 40000 cycles with only ~0.0004% attenuation rate per cycle in the optimized electrolyte. The WO3 and VO2(B) electrode also displayed high cycling stability. Benefiting from enhanced electrode stability in the optimized electrolyte, the resultant CuFe‐TBA/WO3 and CuFe‐TBA/VO2(B) full batteries display impressive long‐term cycling performance with high‐capacity retention. Our work presents a proton dynamic‐release electrolyte for durable APBs which is highly promising for scalable energy systems.