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

Abstract

Nonmetallic ammonium (NH<inf>4</inf> ⁺) ions are applied as charge carriers for aqueous batteries, where hexagonal MoO<inf>3</inf> is initially investigated as an anode candidate for NH<inf>4</inf> ⁺ storage. From experimental and first-principle calculated results, the battery chemistry proceeds with reversible building–breaking behaviors of hydrogen bonds between NH<inf>4</inf> ⁺ and tunneled MoO<inf>3</inf> electrode frameworks, where the ammoniation/deammoniation mechanism is dominated by nondiffusion-controlled pseudocapacitive behavior. Outstanding electrochemical performance of MoO<inf>3</inf> for NH<inf>4</inf> ⁺ 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.