High-Entropy Alloy Self-Supporting Bifunctional Electrocatalysts with Exceptional Performance for Flexible Zinc-Air Batteries

The development of efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) bifunctional catalyst with high activity and stability is highly demanded for flexible rechargeable zinc-air batteries (ZABs). Herein, we proposed high-entropy alloy (HEA) FeCoNiCrCu nanoparticles assembled on carbon nanofibers (FeCoNiCrCu/CNFs) as bifunctional catalyst for ZABs by electrospinning in-situ growth method, which exhibited an overpotential of 240 mV and a 50.3 mV dec−1 Tafel slope at a current density of 10 mA cm−2, much higher than that of the RuO2 basedstandard commercial catalysts. Also, superior ORR performance was observed for FeCoNiCrCu/CNFs with a half-wave potential of 0.78 V. The potential difference between the OER overpotential and the ORR half-wave potential is only 0.69 V for FeCoNiCrCu/CNFs, exceeding that of most of the catalysts reported so far. Using FeCoNiCrCu/CNFs as air cathode, the assembled flexible ZABs exhibited an open circuit potential of 1.371 V, a peak power density of 87 mW cm−2, a specific capacity of 820 mAh gZn−1, and excellent stability over 75 hours of continuous charge and discharge cycles at different bending angles. The rational design of FeCoNiCrCu/CNFs paves a new avenue to the commercialization of bifunctional oxygen catalysts in ZABs.