Oxygen vacancies in MnOx regulating reaction kinetics for aqueous zinc-ion batteries

MnO 2 cathode materials have presented challenges due to their poor conductivity, unstable structure, and sluggish diffusion kinetics for aqueous zinc-ion batteries (AZIBs). In this study, a nanostructured MnO x cathode material was synthesized using an acid etching method, Which introduced abundant Mn(III) sites, resulting in the formation of numerous oxygen vacancies . Comprehensive characterizations revealed that these oxygen vacancies facilitated the reversible adsorption/desorption of Zn 2+ ions and promoted efficient electron transfer . In addition, the designed mesoporous structure offered ample active sites and shortened the diffusion path for Zn 2+ and H + ions. Consequently, the nanosized MnO x cathode exhibited enhanced reaction kinetics, achieving a considerable reversible specific capacity of 388.7 mAh/g at 0.1 A/g and superior durability with 72.0% capacity retention over 2000 cycles at 3.0 A/g. The material delivered a maximum energy density of 639.7 Wh kg −1 at 159.94 W kg −1 . Furthermore, a systematic analysis of the zinc storage mechanism was performed. This work demonstrates that engineering oxygen vacancies with nanostructure regulation provides valuable insights into optimizing MnO 2 cathode materials for AZIBs.