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.