The highly dispersed Co-based nanoparticles encapsulated into porous N-doping carbon polyhedral with the low content of Ru modification as a promising cathode catalyst for long-life Li-O₂ batteries

Lithium (Li)-O₂ batteries have triggered worldwide interest due to their ultrahigh theoretical energy density. However, it is a long shot for the grand-scale applications of Li-O₂ battery at current stage owing to its significant polarization, inferior cycling life, and irreversible decomposition of Li₂O₂. Herein, a facile way of preparing the highly dispersed Co-based nanoparticles encapsulated into porous N-doping carbon polyhedral with the low content of Ru modification (LRu@HDCo-NC) is explored through the pyrolysis of Co/Zn based zeolitic imidazole frameworks (ZIFs) containing Ru-based ligands. Even with the very small amount of Ru introduction (1.8%), LRu@HDCo-NC still exhibits the superior oxygen evolution reaction/oxygen reduction reaction (OER/ORR) performance and also inhibits side reactions in Li-O₂ battery because of the abundant pores, plentiful surface N heteroatoms, and highly dispersed metal-based sites which are induced by the volatilization of Zn, and conductive/stable carbon skeleton derived from ZIFs. When applied in Li-O₂ batteries, LRu@HDCo-NC cathode delivers a high discharge capacity of 15,973 mAh·g⁻¹ at 200 mA·g⁻¹, good capacity retention at higher rate (12,362 mAh·g⁻¹ at 500 mA·g⁻¹) and outstanding stability for > 300 cycles with low voltage polarization of < 2.3 V under a cut-off capacity of 1,000 mAh·g ⁻¹ at 500 mA·g⁻¹. More critically, a series of ex situ and in situ characterization technologies disclose that the LRu@HDCo-NC cathodes can effectively promote the reversible reactions in Li-O₂ batteries.