Dual Redox Mediators Assisted Hierarchically Porous Hollow Carbon Shell Cathode for Enhanced Performance Li-O2 Battery

Rechargeable lithium-oxygen (Li-O-2) batteries with high theoretical energy density are regarded as a promising candidate for the booming electric vehicle manufacturing industry, whereas their commercial application is hindered due to poor cyclic stability caused by the sluggish kinetics and inevitable cathode passivation. Herein, a synergistic working mechanism of Li-O-2 battery is initiated by implementing well-designed hollow carbon shells with hierarchically porous hollow structure (HCS) assisted by dual redox mediators (RMs) simultaneously, so as to systemically address issues of diminished discharge capacity and reaction kinetics. The hierarchically porous structure of HCS constructs more space to accommodate Li2O2, increases the accessibility of active sites, and enhances discharge capacity. More importantly, the dual RMs regulate the growth mechanism of Li2O2 in surface-mediated mode, resulting in an easily decomposed film-like Li2O2 with higher electron transport capacity and improving the reaction kinetics. As a result of the synergistic effort, an HCS-based Li-O(2 )battery with dual RMs manifests a total discharge capacity of 24580 mA h g(-1) and a prolonged cycle life of 2500 h at the current density of 100 mA g(-1). This design philosophy will open up a new way to optimize and upgrade the cathode materials of Li-O-2 batteries.