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 HPO, afford channel for proton transport, and electrostatically interact with phosphate ions of HPO 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 and a maximum power density of 10.1 kW kg. 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.