Rational design of ultrafine cobalt free electrospun nanofibers as efficient and durable binfunctional oxygen electrocatalysts for rechargeable zinc-air battery

Rational design of efficient and stable bifunctional oxygen electrocatalyst is of significant importance for research and progress of rechargeable zinc-air battery (ZAB). Herein, ultrafine cobalt free perovskite type oxide Sr2Fe1.5Mo0.5O6-δ nanofibers (SFM NF) and SFM nanoparticles (SFM NP) have been prepared via the electrospinning technique and combustion technique, respectively, and their electrochemical behaviors in the field of ZAB have been studied. Our study demonstrates that SFM NF catalyst has better bifunctional electrocatalytic activities and more durable charge–discharge cycling stability than SFM NP catalyst. When used as cathode catalysts for ZABs, SFM NF electrode exhibits a higher peak power density of 137 mW cm−2 than 107.9 mW cm−2 for SFM NP electrode. In addition, SFM NF electrode presents a lower galvanostatic charge–discharge voltage gap (ΔE) of 0.94 V than 1.13 V for SFM NP electrode when operated at 10 mA cm−2, which can be explained by the enhanced bifunctional electrocatalytic activities. More importantly, SFM NF electrode presents a significantly low ΔE degradation rate of 0.01 V/100 h during the 300-hour operation, indicating its excellent change-discharge stability. Our findings indicate that SFM NF catalyst is a greatly promising cathode candidate of efficient and durable rechargeable ZAB, and the electrospinning technique is an effective strategy to prepare efficient electrocatalysts for energy storage and conversion application.