Efficient Bifunctional Catalytic Electrodes with Uniformly Distributed NiN2 Active Sites and Channels for Long-Lasting Rechargeable Zinc-Air Batteries

Abstract

Freestanding bifunctional electrodes with outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties are of great significance for zinc-air batteries, attributed to the avoided use of organic binder and strong adhesion with substrates. Herein, a strategy is developed to fabricate freestanding bifunctional electrodes from the predeposited nickel nanoparticles (Ni-NCNT) on carbon fiber paper. The steric effect of monodispersed SiO₂ nanospheres limits the configuration of carbon atoms forming 3D interconnected nanotubes with uniformly distributed NiN₂ active sites. The bifunctional electrodes (Ni-NCNT) demonstrate ideal ORR and OER properties. The zinc-air batteries assembled with Ni-NCNT directly exhibit extremely outstanding long term stability (2250 cycles with 10 mA cm^-2 charge/discharge current density) along with high power density of 120 mV cm^-2 and specific capacity of 834.1 mA h g^-1 . This work provides a new view to optimize the distribution of active sites and the electrode structure.

Keywords: NiN 2 active sites; carbon nanotubes; electrocatalysis; freestanding air electrodes; zinc-air batteries.