In Situ Coupling of Highly Dispersed Ni/Fe Metal‐NC Sites and N‐Doped 3D Carbon Fibers Toward Free‐Standing Bifunctional Cathode for Flexible Zinc‐Air Battery

Designing flexible free‐standing air‐electrode with efficient OER/ORR performance is of vital importance for the application of Zinc‐air batteries in flexible electronics. Herein, a flexible free‐standing electrode (Ni/Fe‐NC/NCF/CC) is synthesized by in‐situ coupling of binary Ni/Fe‐NC nanocubes and N‐doped carbon nanofibers (NCF) rooted on carbon cloth. The highly dispersed binary Ni/Fe‐NC sites ensure excellent ORR activity and create efficient OER active sites relative to Ni‐NC and Fe‐NC. The in‐situ coupling of Ni/Fe‐NC and NCF constructs a 3D interconnected network structure that not only provides abundant and stabilized reactive sites but also guarantees fast electron transfer and gas transportation, thus achieving efficient and fast operation of ORR/OER. Therefore, Ni/Fe‐NC/NCF/CC displays a much positive potential (0.952 V) at 4.0 mA cm −2 for ORR and a low OER overpotential (310 mV) at 50 mA cm −2 . The Zinc‐air battery with Ni/Fe‐NC/NCF/CC air‐electrode exhibits excellent battery performance with outstanding discharge/charge durability for 2150 cycles. The flexible Zn‐air batteries with foldable mechanical properties display a high power density of 105.0 mW cm −2 . This work widened the way to prepare flexible bifunctional air‐electrode by designing composition/structure and in‐situ coupling.