Interface-Sensitive Charge Storage and Activation Behavior of Mn(1,3,5-Benzenetricarboxylic Acid (BTC))-Derived MnO/Carbon Cathodes for Aqueous Zinc-Ion Batteries.

In this study, we couple precise interface engineering via alternating current electrophoretic deposition (AC-EPD) with performance-enhancing structural transformation via annealing, enabling the development of high-performance, stable, and tunable Mn-based cathodes for aqueous zinc-ion batteries (ZIBs). Using AC-EPD to fabricate Mn(BTC) (BTC = 1,3,5-benzenetricarboxylic acid) cathodes followed by thermal annealing to synthesize MOF-derived MnO offers a synergistic approach that addresses several key challenges in aqueous ZIB systems. The MnO cathode prepared via AC-EPD from Mn(BTC) exhibited a remarkable specific capacity of up to 430 mAh/g at a current density of 200 mA/g. Interestingly, the capacity continued to increase progressively with cycling, suggesting dynamic structural or interfacial changes that improved Zn transport and utilization over time. Such capacity enhancement behavior during prolonged cycling at elevated rates has not been observed in previously reported MnO-based ZIB systems. Kinetic analysis further revealed that the charge storage process is predominantly governed by diffusion-controlled mechanisms. This behavior can be attributed to the intrinsic characteristics of the MnO phase formed from the MOF precursor, where the bulk redox reactions involving Zn insertion require ion migration into the electrode interior. Even though the electrode was processed as an ultrathin film with enhanced electrolyte contact, the charge storage remains limited by solid-state ion diffusion rather than fast surface-driven reactions, reinforcing the diffusion-dominant nature of the system.