FeNi decorated nitrogen-doped hollow carbon spheres as ultra-stable bifunctional oxygen electrocatalyst for rechargeable zinc-air battery with 2.7% decay after 300 hours cycling

Research on non-noble metal bifunctional electrocatalysts with high efficiency and long-lasting stability is crucial for many energy storage devices such as zinc-air batteries. In this report, nitrogen-doped porous hollow carbon spheres with a size of about 300 nm were fabricated using a modified Stöber method and decorated with an FeNi alloy through a pyrolytic reduction process, resulting in a promising bifunctional electrocatalyst for both the oxygen evolution reaction and oxygen reduction reaction. The as-prepared FeNi@NHCS electrocatalyst exhibits excellent bifunctional activity in KOH electrolyte, attributed to its mesoporous structure, large specific surface area, and the strong coupling between the FeNi nanoalloy and nitrogen-doped carbon carriers. The electrocatalyst demonstrates excellent ORR performance with E 1/2 = 0.828 V and OER activity with E j =10 mA = 1.51 V. A zinc-air battery using FeNi@NHCS as the air electrode achieves an open-circuit voltage of 1.432 V and a maximum power density of 181.8 mW cm −2 . After 300 h of galvanostatic charge-discharge cycles, the charge-discharge voltage gap (Δ U ) of the battery had only decayed by 2.7%, demonstrating superior cycling stability. The Zn-air battery assembled by the bifunctional FeNi@HMCS electrocatalyst displayed a maximum power density of 181.8 mW cm −2 and superior stability for over 300 hours.