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. [ABSTRACT FROM AUTHOR]