Highly Dispersed Ru-Co Nanoparticles Interfaced With Nitrogen-Doped Carbon Polyhedron for High Efficiency Reversible Li-O2 Battery.

Abstract

The lithium-oxygen (Li-O2 ) battery with high energy density of 3860Wh kg-1 represents one of the most promising new secondary batteries for future electric vehicles and mobile electronic devices. However, slow oxygen reduction/oxygen evolution (ORR/OER) reaction efficiency and unstable cycling performance restrain the practical applications of the Li-O2 battery. Herein, Ru-modified nitrogen-doped porous carbon-encapsulated Co nanoparticles (Ru/Co@CoNx -C) are synthesized through reduction of Ru on metal-organic framework (MOFs) pyrolyzed derivatives strategies. Porous carbon polyhedra provide channels for reactive species and stable structure ensures the cyclic stability of the catalyst; abundant Co-Nx sites and high specific surface area (353 m2 g-1 ) provide more catalytically active sites and deposition sites for reaction products. Theoretical calculations further verify that Ru/Co@CoNx -C can regulate the growth of Li2 O2 to improve reversibility of Li-O2 batteries. Li-O2 batteries with Ru/Co@CoNx -C as cathode catalyst achieve small voltage gaps of 1.08V, exhibit excellent cycle stability (205 cycles), and deliver high discharge specific capacity (17050 mAh g-1 ). Furthermore, pouch-type Li-O2 batteries that maintain stable electrochemical performance output even under conditions of bending deformation and corner cutting are successfully assembled. This study demonstrates Ru/Co@CoNx -C catalyst's great application potential in Li-O2 batteries.