Z-scheme In2S3/MnO2/BiOCl heterojunction photo-enhanced high-performance lithium-oxygen batteries

Photo-assisted Li–O 2 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–O 2 system featuring a Z-scheme In 2 S 3 /MnO 2 /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 In 2 S 3 /MnO 2 /BiOCl modify the morphology of the discharge product (Li 2 O 2 ), leading to accelerated decomposition kinetics of Li 2 O 2 during charging. Remarkably, the In 2 S 3 /MnO 2 /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 Li 2 O 2 , 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–O 2 batteries, providing valuable insights into their functionality and potential for future battery technologies.