Molecular Micellar Aggregate Electrolytes Enable Durable Electrochemical Proton Storage

Proton electrochemistry holds eminent potential for developing high capacity and rate energy storage devices in the post-lithium era. However, the decomposition of water in acidic aqueous electrolytes causes electrode corrosion, leading to capacity fading. Herein, we report a judicious design of molecular micellar aggregates as non-aqueous electrolytes for stable and high-voltage electrochemical proton storage. The key to our strategy lies in introducing cetyltrimethylammonium bromide (CTAB), forming micelles to improve the miscibility of acetonitrile (ACN) and H₃PO₄, afford channel for proton transport, and electrostatically interact with phosphate ions of H₃PO₄ to further promote proton transport. Such aggregates impart rapid and stable electrochemical proton storage with a widened operating voltage (1.8 V vs. 1.5 V in aqueous electrolyte). By optimizing CTAB content, proton transport can be enhanced. Asymmetric full proton battery using the optimal CTAB electrolyte achieves a maximum energy density of 102.8 Wh kg^-1 and a maximum power density of 10.1 kW kg^-1. Our simple yet robust route to micellar aggregate electrolytes enables stable proton storage, underscoring its potential for grid-scale energy storage, emergency power supplies, and portable electronics.