Ultra-Large Sized Siloxene Nanosheets as Bifunctional Photocatalyst for a Li-O2 Battery with Superior Round-Trip Efficiency and Extra-Long Durability.

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O2 batteries. Herein, a novel bifunctional photo-assisted Li-O2 system is constructed by using siloxene nanosheets with ultra-large size and few-layers due to its superior light harvesting, semiconductor characteristic, and low recombination rate. An ultra-low charge potential of 1.90 V and ultra-high discharge of 3.51 V have been obtained due to the introduction of this bifunctional photocatalyst into Li-O2 batteries, and these results have realized the round-trip efficiency up to 185 %. In addition, this photo-assisted Li-O2 batteries exhibits a high rate (129 % round-trip efficiency at 1 mA cm-2 ), a prolonged cycling life with 92 % efficiency retention after 100 cycles, and the highly reversible capacity of 1170 mAh g-1 at 0.75 mA cm-2 . This work will open the vigorous opportunity for high-efficiency utilization of solar energy into electric system.