Illuminating the Future: Sunlight-Powered Catalysis Unlocks Next-Generation Li–O2 Battery Performance

Abstract

Lithium–oxygen (Li–O₂) batteries have an extremely high theoretical specific energy but are hindered by the sluggish kinetics of the oxygen evolution reaction (OER). Visible-light-assisted photocatalysts can accelerate OER kinetics. However, the photoinvolved electrochemical process at the oxygen cathode remains insufficiently understood, and the interlaboratory results are not comparable and reproducible. In fact, sunlight or a xenon lamp as the light source induces a notable photothermal effect in the batteries, while its impact on reaction kinetics is always underappreciated. Here, a self-illuminating photocatalyst composed of g-C₃N₄ catalysts and Sr₂MgSi₂O₇:Eu,Dy phosphors is designed to decouple the photo and thermal effects on the reaction kinetics. Typically, the photocatalytic effects dominate at low external illumination powers, while the photothermal effects increase linearly with power. This work provides a quantitative basis for benchmarking the catalytic performance of various photocatalysts. Moreover, as a proof of concept, this study offers new insights for developing integrated photoassisted Li–O₂ batteries.