Search

Rechargeable lithium‐oxygen (Li‐O2) 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‐O2 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‐O2 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‐O2 batteries. [ABSTRACT FROM AUTHOR]

Although biomass‐derived carbon (biochar) has been widely used in the energy field, the relation between the carbonization condition and the physical/chemical property of the product remains elusive. Here, we revealed the carbonization condition's effect on the morphology, surface property, and electrochemical performance of the obtained carbon. An open slit pore structure with shower‐puff‐like nanoparticles can be obtained by finely tuning the carbonization temperature, and its unique pore structure and surface properties enable the Li–O2 battery with cycling longevity (221 cycles with 99.8% Coulombic efficiency at 0.2 mA cm−2 and controlled discharge–charge depths of 500 mAh g−1) and high capacity (16,334 mAh g−1 at 0.02 mA cm−2). This work provides a greater understanding of the mechanism of the biochar carbonization procedure under various pyrolysis conditions, paving the way for future study of energy storage devices. [ABSTRACT FROM AUTHOR]