Enabling High-Rate and Long-Cycling Zinc–Air Batteries with a ΔE = 0.56 V Bifunctional Oxygen Electrocatalyst

Abstract

Zn–air batteries (ZABs) are promising next-generation energy storage devices due to their low cost, intrinsic safety, and environmental benignity. However, the sluggish kinetics of the cathodic reactions severely limits the ZAB performances in practical use, calling for high-efficiency bifunctional oxygen reduction and evolution electrocatalysts. Herein, an ultrahigh-active bifunctional electrocatalyst is developed with a record-low ΔE of 0.56 V, significantly outperforming the noble-metal-based benchmark (Pt/C+Ir/C, ΔE = 0.77 V) and many other reported bifunctional electrocatalysts (mostly ΔE ≥ 0.60 V). The nanoscale composite of Fe-based single-atom sites and nanosized layered double hydroxides endows the bifunctional electrocatalyst with high conductivity and a large active surface that afford strengthened electron conduction and ion transport pathways. Furthermore, a remarkable improvement in stability is realized following the current division principle. ZABs with the bifunctional electrocatalyst deliver a high peak power density of 198 mW cm⁻² and excellent cycling durability for over 6000 cycles. Moreover, ampere-hour-scale ZABs are constructed and cycled under 1.0 A and 1.0 Ah conditions. This work breaks the activity record for bifunctional oxygen electrocatalysis and expands the potential of ZABs for sustainable energy storage.