Vanadate ion promoting the transformation of α-phase molybdenum trioxide (α-MoO3) to h-phase MoO3 (h-MoO3) for boosted Zn-ion storage

Molybdenum trioxide (MoO 3 ) has been widely studied in the energy storage field due to its various phase states and unique structural advantages. Among them, lamellar α -phase MoO 3 ( α -MoO 3 ) and tunnel-like h -phase MoO 3 ( h- MoO 3 ) have attracted much attention. In this study, we demonstrate that vanadate ion (VO 3 - ) can transform α -MoO 3 (a thermodynamically stable phase) to h -MoO 3 (a metastable phase) by altering the connection of [MoO 6 ] octahedra configurations. h -MoO 3 with VO 3 - inserted (referred to as h -MoO 3 -V) as the cathode material for aqueous zinc ion batteries (AZIBs) exhibits excellent Zn 2+ storage performances. The improvement in electrochemical properties is attributed to the open tunneling structure of the h -MoO 3 -V, which offers more active sites for Zn 2+ (de)intercalation and diffusion. As expected, the Zn// h -MoO 3 -V battery delivers specific capacity of 250 mAh·g −1 at 0.1 A·g −1 and rate capability (73% retention from 0.1 to 1 A·g −1 , 80 cycles), well exceeding those of Zn// h -MoO 3 and Zn// α -MoO 3 batteries. This study demonstrates that the tunneling structure of h -MoO 3 can be modulated by VO 3 - to enhance the electrochemical properties for AZIBs. Furthermore, it provides valuable insights for the synthesis, development and future applications of h -MoO 3 .