Anhydrous Fast Proton Transport Boosted by the Hydrogen Bond Network in a Dense Oxide-Ion Array of α-MoO 3 .

Developing high-power battery chemistry is an urgent task to buffer fluctuating renewable energies and achieve a sustainable and flexible power supply. Owing to the small size of the proton and its ultrahigh mobility in water via the Grotthuss mechanism, aqueous proton batteries are an attractive candidate for high-power energy storage devices. Grotthuss proton transfer is ultrafast owing to the hydrogen-bonded networks of water molecules. In this work, similar continuous hydrogen bond networks in a dense oxide-ion array of solid α-MoO 3 are discovered, which facilitate the anhydrous proton transport even without structural water. The fast proton transfer and accumulation that occurs during (de)intercalation in α-MoO 3 is unveiled using both experiments and first-principles calculations. Coupled with a zinc anode and a superconcentrated Zn 2+ /H + electrolyte, the proton-transport mechanism in anhydrous hydrogen-bonded networks realizes an aqueous MoO 3 -Zn battery with large capacity, long life, and fast charge-discharge abilities.