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

Abstract 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.