Spin Effect-Induced layer spacing Adaptation in vanadium bronze cathodes for Fast Zinc-Ion storage

Abstract

The cathode material of aqueous zinc-ion batteries is a critical constraint on their further application due to the poor structure stability. Consequently, understanding their charge–discharge mechanisms and developing high-performance materials are key to promoting their use. This study investigates the effect of dopant atoms, particularly manganese (Mn), on the properties of vanadium bronze (MVO). Mn, with its larger ionic radius and higher d-electron count, enhanced the electrochemical properties of MVO: the specific capacity is up to 370 mAh/g @100 mA/g and has good rate performance, with a capacity of about 300 mAh/g at 1000 mA/g, a capacity retention rate of 92 % after 2000 cycles and showed the excellent capacity and stability. Mn was present in both the interlayers and within the vanadium bronze structure, promoting the self-adaptive and a more pronounced electron transfer with the metal–oxygen bonds in the structure. This enhanced the covalent character of the metal–oxygen bonds and improved the intrinsic conductivity. The results of in-situ Raman and SQUID measurements revealed changes in Mn–O bond lengths on molecular and atom level and the intrinsic nature of the “pillar effect”. These findings provide new insights into ion-doping strategies for enhancing electrochemical performance in zinc-ion batteries.