Abstract: Photo-assisted Li-O₂ batteries present a promising avenue for reducing overpotential and enhancing the capacity of next-generation energy storage devices. In this study, we introduce a novel photo-assisted Li-O₂ system featuring a Z-scheme In₂S₃/MnO₂/ BiOCl heterojunction as a photocathode. This innovative design significantly boosts visible light absorption and facilitates the spatial separation of photogenerated electron-hole pairs. The Z-scheme charge transfer pathway establishes efficient channels for enhancing electron transfer and charge separation, thereby fostering high photocatalytic efficiency. During illumination, photo-generated electrons traverse within the band structure, participating in the Oxygen Reduction Reaction (ORR) during discharging, while photo-induced holes in the valence band facilitate the oxidation reaction of discharge products during the charging process. Under illumination, the surface electrons of In₂S₃/MnO₂/BiOCl modify the morphology of the discharge product (Li₂O₂), leading to accelerated decomposition kinetics of Li₂O₂ during charging. Remarkably, the In₂S₃/MnO₂/ BiOCl photoelectrode exhibits a high specific capacity of 19330 mAh/g under illumination, surpassing performance in the dark by a significant margin. This results in an ultranarrow discharge/charge overpotential of 0.19/0.16 V, coupled with excellent cyclic stability and a long cycle life of 1500 h at 200 mA/g. Further surface tests on the photoelectrode demonstrate that light energy application promotes the decomposition of Li₂O₂, corroborated by density function theory (DFT) theoretical calculations. This study of Z-scheme heterostructured photocathodes sheds light on the mechanism of photo-generated charge carriers in Li-O₂ batteries, providing valuable insights into their functionality and potential for future battery technologies.

Key words: Z-scheme heterojunction, Photo-assisted, In₂S₃/MnO₂/BiOCl, Li-O₂ battery