Bifunctional Photoassisted Li-O2 Battery with Ultrahigh Rate-Cycling Performance Based on Siloxene Size

Directly integrating the bifunctional photoelectrode into Li-O-2 batteries has been considered an effective way to reduce the overpotential and promote electric energy saving. However, more regular investigations on various bifunctional photocatalysts have still been desired for high-performance photoassisted Li-O-2 batteries. Herein, a systematic exploration of various-sized siloxene photocatalysts affected by Li-O-2 batteries has been introduced. Compared with the utilization of larger-sized siloxene nanosheets (SNSs), the photoassisted Li-O-2 battery with a siloxene quantum dot (SQD) photoelectrode delivers a superior round-trip efficiency of 230% based on the highest discharge potential up to 3.72 V and lowest charge potential of 1.60 V and enables the maintenance of a long-term cycling life with only 13% efficiency attenuation after 200 cycles at 0.075 mA/cm(2). Furthermore, this system exhibits a record-high rate-cycling performance (162% round-trip efficiency, even at 3 mA/cm(2)) and a high discharge capacity of 2212 mAh/g at 1 mA/cm(2). These ground-breaking performances could be attributed to the synergistic effect of the photocatalytic and electrocatalytic activities of SQD photocatalysts with the ideal conduction band/valence band values, the abundant defective sites, and the stronger O-2 and lower LiO2 adsorption strengths of SQD photocatalysts. These systematic research studies highlight the significance of SQD bifunctional photocatalysts and could be extended to other photocatalysts for further high-efficiency photoelectric conversion and storage.

Automated summary

Direct integration of bifunctional photoelectrode into Li-O-2 batteries is an effective method to improve efficiency. This study explores the effects of various-sized siloxene photocatalysts in Li-O-2 batteries. Compared to larger-sized siloxene nanosheets, a photoassisted Li-O-2 battery with a siloxene quantum dot (SQD) photoelectrode demonstrates superior performance, achieving a round-trip efficiency of 230% and maintaining long-term cycling life. The outstanding performance is attributed to the synergistic effect of the photocatalytic and electrocatalytic activities of SQD photocatalysts.