Publication

Abstract : Manganese‐based cathode materials have attracted significant interest in zinc‐ion batteries (ZIBs) due to their high theoretical capacity, affordability, and environmentally friendly nature. Recently, Na 2 Mn 3 O 7 (NMO) has emerged as a promising electrode material for ZIBs owing to its unique triclinic crystal structure, which consists of infinite parallel [Mn 3 O 7 ] 2 ⁻ layers. This layered framework includes a vacancy at one of the seven Mn sites, which plays a crucial role in facilitating the insertion and accommodation of incoming Zn 2+ ions. This structural feature allows for efficient zinc intercalation, transforming NMO into a Zn–Mn‐based system electrochemically. In this study, the focus is on investigating the mechanism of self‐ion exchange occurring in NMO, utilizing an electrolyte composed of 2 M ZnSO 4 and 0.1 M MnSO 4 , exhibiting a reversible capacity of ∼240 mAh g −1 at a C/10 rate with a Coulombic efficiency of ∼99%. The self‐ion exchange mechanism and structural changes during the battery operation were investigated using ex‐situ x‐ray diffraction and x‐ray photoelectron spectroscopy analysis. The reversible phase transformations between hydrated and partially dehydrated states suggest a robust mechanism for Zn 2+ ion insertion and extraction, contributing to the stability and performance of the Zn–Mn electrode material in ZIB applications.