In-situ confining selenium within bubble - like carbon nanoshells for ultra-stable Li-Se batteries.

Abstract

Lithium-selenium (Li-Se) batteries are promising energy storage devices. However, the long-term durability and high-rate performance of the Se cathode have been limited by significant volume expansion and the troublesome shuttle effect of polyselenides during repeated charging/discharging processes. To revolutionize these issues, we applied a top-down strategy through the in-situ trapping of amorphous Se within bubble-like carbon (BLC) frameworks, which can radically minimize the presence of surface-absorbed Se while enhancing Se loading capacity. This ingenious technique successfully encapsulates all Se species within carbon nanoshells, creating a distinct half-filled core-shell structure known as Se@void@BLC. This in-situ trapping approach ensures the efficient management of Se volume changes during repeated discharge and charge cycles. Moreover, an extraordinary Se loading capacity of up to 65.6 wt% is reached. Using the Se@void@BLC as cathode for Li-Se battery, we achieve a high initial Columbic efficiency of 84.2 %, a high reversible capacity of 585 mAh g-1 , and an ultralow capacity decay of only 0.0037 % per cycle during 4000 cycles at 10 A g-1 .