Mangano-philic surface formation aided by alkaline-earth metal element for long lasting manganese based zinc aqueous batteries

Abstract

In this study, we investigated the performance characteristics of MnO2 in aqueous zinc-ion batteries (ZIBs) through the deposition/dissolution process. The focus is on the gold-coated (Au/CC) carbon cloth substrates for MnO2 deposition. Modification with mangano-philic nanosized Au layers improved the electrode performance for MnO2 deposition during charge and its dissolution into Mn2+ on discharge. Additionally, we introduced alkaline-earth metal hydroxides as pH buffer agents within the electrode system, noting significant improvements in the cell capacity and stability when coated with barium hydroxide (Ba(OH)2). This approach mitigated the pH fluctuations that are typically detrimental to the cell performance with the help of local pH buffering derived from alkaline-earth metal hydroxides on the surface of electrode. Cycling tests under different current densities highlighted the stable cyclability of the B-Au/CC electrodes, maintaining high Coulombic efficiency and capacity over extended cycles. Furthermore, in-depth electrochemical and spectroscopic analysis revealed the intricate processes of MnO2 deposition and dissolution and vice versa. These findings indicate the potential of using Mn-based materials and advanced electrode designs to enhance the capacity, energy density, and cyclability of aqueous ZIBs.