Rational design of a bismuth oxide micro petal-anchored graphitic nanofiber-modified separator for high-performance lithium-sulfur batteries

초록

Lithium-sulfur (Li-S) batteries are regarded as promising next-generation energy storage systems owing to their high theoretical capacity (1675 mAh/g), low cost and environmental compatibility. However, their practical application is hindered by the dissolution and migration of lithium polysulfide species (LiPSs), known as the shuttle effect, and the sluggish solid-solid conversion from Li2S4 to Li2S. In this study, two-dimensional (2D) bismuth oxide micro petals anchored on graphitic nanofibers (Bi/GNF) are synthesized via a facile hydrothermal approach and are employed as a functional interlayer for Li-S batteries. The 2D-Bi/GNF@PP modified separator considerably improves the electrochemical performance, delivering a specific capacity of 1157 mAh/g at 0.1 C. The cell retains a reversible capacity of 594 mAh/g at 0.2 C with a low decay rate of 0.08% per cycle over 500 cycles. This enhanced performance is attributed to the excellent electrical conductivity of the 2D-Bi/GNF structure, which promotes strong chemical interactions with LiPSs, suppresses the shuttle effect and facilitates improved sulfur utilization and redox kinetics. This study demonstrates that integrating catalytic materials within a modified separator is an effective strategy for improving the performance and practical feasibility of Li-S batteries.

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