Co nanoparticles embedded into leaf-like porous carbon as a promising cathode catalyst for Li-O2 batteries

Abstract

Rechargeable Li-O₂ batteries show great potential due to their superior high energy density. However, the practical application is still limited by the sluggish kinetics, resulting in poor cycling performance and high overpotentials. Herein, highly dispersed Co nanoparticles embedded into porous N-doped carbon matrix (DCo-NC) with carbon nanotubes is explored through the pyrolysis of a bimetallic leaf-shaped ZnCo-ZIFs. The evaporation of Zn species and porous carbon matrix derived from ZIFs prevents the Co nanoparticles aggregation, exposes more Co-N active sites and provides abundant pores. They facilitate Li⁺ and electron transfer, prevent Co nanoparticles from deactivation and provide enough space for Li₂O₂, thereby accelerating oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) kinetics. Accordingly, the Li-O₂ batteries with DCo-NC cathode exhibit reduced overpotential, high discharge capacity (10,490 mA h g⁻¹ at 100 mA g⁻¹ current density) and improved cycling performance (258 cycles at 500 mA g⁻¹ with a limited capacity of 500 mA h g⁻¹, 103 cycles at 500 mA g⁻¹ with a limited capacity of 1000 mA h g⁻¹).