Cobalt Nanoparticles Embedded Nitrogen-Doped Carbon Nanotubes as Bifunctional Catalysts for Flexible Solid-State Zn-Air Battery

Reasonable designing bifunctional catalyst based on non-precious metal materials for the durable oxygen reduction reaction/oxygen evolution reaction (ORR/OER) with high efficiency and sustainable economy is an attractive research topic toward flexible and rechargeable solid-state Zn-air batteries. In this paper, a novel one-dimensional cobalt nanoparticles embedded nitrogen-doped carbon nanotubes nanocomposite (Co-NC CNTs) was successfully prepared via a simple and inexpensive method to achieve the electrocatalyst containing Co nanoparticles with abundant reaction activated sites. The Co-NC CNTs directly function as a bifunctional and flexible catalyst with a remarkable electrochemical performance, including the relatively positive half-wave potential (0.82 V vs RHE) compared to the commercial platinum carbon (Pt/C) (0.84 V vs RHE) for ORR and the lower overpotential (0.46 V) compared to ruthenium oxide (RuO2) (0.4 V) for OER. Impressively, the assembled liquid rechargeable Zn-air batteries (ZABs) attain a peak power density of 115 mW cm(-2) at the current density 194 mA cm(-2) and a large special capacity (786.7 mAh g(-1)) as well as a better cycling stability of 150 cycles/50 h at 10 mA cm(-2). A flexible solid-state Zn-air battery produced from Co-NC CNTs catalyst demonstrates the superior flexibility under bent condition at any angle and maintains the excellent stability. (C) 2020 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.