Porous Mn ₂ O ₃ @C Cathode With High Activity and Long Lifespan for Aqueous Zinc Ion Batteries

ABSTRACT Manganese‐based oxides are widely employed as cathode materials for aqueous zinc ion batteries (AZIBs) due to their low toxicity and high theoretical specific capacity. However, their inherent poor electrical conductivity, coupled with the dissolution of manganese into the electrolyte, often leads to structural degradation of the cathode. To address these challenges, Mn‐MOF was utilized as a precursor to synthesize a corncob popcorn‐like Mn 2 O 3 @C composite with high activity and long lifespan for AZIBs. This distinctive porous carbon encapsulation architecture leverages oxygen vacancies to modulate the spacing of Mn metal oxide layers and alter the valence states of metal ions, thereby enhancing both structural stability and conductivity, and reducing the Zn 2+ diffusion path. The porous structure also improves the wettability of the electrode surface and electrolyte penetration, and provides ample and rapid ion transport channels. Consequently, the fabricated corncob popcorn‐like Mn 2 O 3 @C exhibits an outstanding specific capacity of 570.5 mA h g −1 at 0.1 A g −1 and a capacity retention of over 95% after 3000 cycles at 1 A g −1 . The Zn 2+ storage mechanism was elucidated through various ex situ characterizations, revealing that the storage mechanism is governed by a mixed H + /Zn 2+ co‐insertion/de‐insertion process.