Zn 3 V 3 O 8 nanorods with outstanding electrochemical kinetics as novel anode for aqueous ammonium‐ion batteries

Abstract Aqueous ammonium‐ion batteries (AAIBs) showed great potential in large‐scale energy storage systems due to their low‐cost, ultrafast kinetics, plentiful resources, inherent security and environmental friendliness. Herein, the well‐dispersed Zn 3 V 3 O 8 nanorods and agglomerated MnV 2 O 4 nanoparticles were prepared and firstly used as anodes for AAIBs. The ultrafast reaction kinetics and NH 4 + diffusion kinetics of Zn 3 V 3 O 8 were confirmed by systematically contrasting with MnV 2 O 4 . Specifically, Zn 3 V 3 O 8 delivered perfect cyclic performances with 82.6% capacity retention after 500 cycles. When coupled with the β‐MnO 2 cathode, the β‐MnO 2 //Zn 3 V 3 O 8 full batteries submitted a maximum energy density of 86 Wh·kg −1 and a maximum power density of 677 W·kg −1 . The phase transformation from Zn 3 V 3 O 8 to Zn 3 (OH) 2 V 2 O 7 ·2H 2 O during the first charge process and the reversible building/breaking behaviors of hydrogen bonds during the NH 4 + insertion/extraction processes were discussed by ex situ technology analyses. Thus, the fresh perceptions on the phase transformation laws and the hydrogen bonds evolution mechanisms could enrich the fundamental understanding of the NH 4 + storage mechanism, and promote the development of the practical applications for Zn 3 V 3 O 8 in aqueous ammonium‐ion batteries.