A Bifunctional Iron-Nickel Oxygen Reduction / Oxygen Evolution Catalyst for High-Performance Rechargeable Zinc-Air Batteries

Efficient and robust electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for developing high-performance rechargeable zinc-air batteries (ZABs). Here, we report a highly stable, efficient bifunctional OER/ORR electrocatalyst and demonstrate its integration and robust performance in an aqueous ZAB. The catalyst is based on dual iron/nickel sites which are atomically dispersed on porous nitrogen-doped carbon particles and wrapped in electrically conductive multi-walled carbon nanotubes. Comprehensive experimental analyses and complementary density functional theory (DFT)-level computations provide in-depth understanding of the physical and electronic structure of the catalyst. Electrocatalytic analyses show high performance as OER and ORR catalyst (OER/ORR voltage difference = 0.71 V (at j = 10 mA cm-2). Catalyst integration in a ZAB results in excellent performance metrics: open circuit voltage 1.44 V, specific capacity (782 mAh g-1 at j = 15 mA cm−2, peak power density 218 mW cm−2 at j = 260 mA cm−2) and long-term durability over 600 charge/discharge cycles. This work highlights how high-performance bifunctional OER/ORR catalysts based on atomically dispersed non-critical metals can be designed and deployed in advanced energy storage systems.