Engineering nanostructured Ag doped α-MnO2 electrocatalyst for highly efficient rechargeable zinc-air batteries.

Engineering of highly active, and non-precious electrocatalysts are vital to enhance the air-electrodes of rechargeable zinc-air batteries (ZABs). We report a facile co-precipitation technique to develop Ag doped α-MnO2 nanoparticles (NPs) and investigate their application as cathode materials for ZABs. The electrochemical and physical characteristics of α-MnO2 and Ag doped α-MnO2 NPs were compared and examined via CP, CV, TGA/DTA, FT-IR, EIS, and XRD analysis. CV result displayed higher potential and current for ORR in Ag doped α-MnO2 NPs than α-MnO2; but, ORR performance decreased when the Ag doping was raised from 7.5 to10 mmol. Moreover, α-MnO2 and Ag doped α-MnO2 NPs showed 2.1 and 3.8 electron transfer pathway, respectively, showing Ag doped α-MnO2 performance to act as an active ORR electrocatalyst for ZABs. The EIS investigation exhibited that charge-transfer resistance for Ag doped α-MnO2 was extremely lower associated to the MnO2 demonstrating that the successful loading of Ag in α-MnO2. A homemade ZAB based on Ag-MnO2-7.5 showed a high open circuit potential, low ohmic resistances, and excellent discharge profile at a constant current density of 1 mA/g. Moreover, Ag-MnO2-7.5 show a specific capacity of 795 mA h g-1 with corresponding high energy density ∼875 Wh kg-1 at 1 mA cm-2 discharging conditions.