Silver-nanoclusters boosted bifunctional hybrid catalysis for ampere-hour-scale zinc-air batteries

Rechargeable zinc-air batteries (ZABs) reveal compelling potential in energy storage systems. However, slow kinetics in oxygen reduction and oxygen evolution reactions (ORR/OER) severely constrain the practical deployment of ZABs. To overcome these issues, A heterogeneous bifunctional catalyst: Nano-silver cluster-enhanced nickel-iron-layered double hydroxide/cobalt, nitrogen-codoped carbon nano-frames structure (Ag-NiFeLDH/Co-CNF) was designed. This catalyst exhibits a half-wave potential of 0.853 V and a Tafel slope of 86.5 mV dec⁻¹ for ORR, as well as an overpotential of 310 mV at 10 mA cm⁻² and a Tafel slope of 57.62 mV dec⁻¹ for OER. Its ΔE value (0.69 V) is lower than that of commercial platinum carbon and ruthenium dioxide (0.75 V), indicating superior bifunctional activity. Electrochemical analysis, X-ray photoelectron spectroscopy, and density functional theory calculations confirm that nanosilver-clusters modulated the electronic structures of cobalt and nicle-iron-layered double hydroxide, optimized their d-band centres, and reduced reaction overpotentials. Use as a ZABs cathode, Ag-NiFeLDH/Co-CNF delivers an open-circuit voltage of 1.48 V, a peak power density of 152.82 mW cm⁻², and a specific capacity of 796.33 mAh g⁻¹. It also maintains stable cycle for over 400 cycles. Additionally, ampere-hour-scale ZABs (4.2 Ah) tested under 0.5 A and 0.5 Ah conditions demonstrate the catalyst’s scalability for practical applications.