Initiating Hexagonal MoO₃ for Superb-Stable and Fast NH₄ ⁺ Storage Based on Hydrogen Bond Chemistry

Nonmetallic ammonium (NH₄ ⁺ ) ions are applied as charge carriers for aqueous batteries, where hexagonal MoO₃ is initially investigated as an anode candidate for NH₄ ⁺ storage. From experimental and first-principle calculated results, the battery chemistry proceeds with reversible building-breaking behaviors of hydrogen bonds between NH₄ ⁺ and tunneled MoO₃ electrode frameworks, where the ammoniation/deammoniation mechanism is dominated by nondiffusion-controlled pseudocapacitive behavior. Outstanding electrochemical performance of MoO₃ for NH₄ ⁺ storage is delivered with 115 mAh g^-1 at 1 C and can retain 32 mAh g^-1 at 150 C. Furthermore, it remarkably exhibits ultralong and stable cyclic performance up to 100 000 cycle with 94% capacity retention and high power density of 4170 W kg^-1 at 150 C. When coupled with CuFe prussian blue analogous (PBA) cathode, the full ammonium battery can deliver decent energy density 21.3 Wh kg^-1 and the resultant flexible ammonium batteries at device level are also pioneeringly developed for potential realistic applications.