Hierarchical Defective Fe3-xC@C Hollow Microsphere Enables Fast and Long-Lasting Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries present one of the most promising energy storage systems owing to their high energy density and low cost. However, the commercialization of Li-S batteries is still hindered by several technical issues; the notorious polysulfide shuttling and sluggish sulfur conversion kinetics. In this work, unique hierarchical Fe3-xC@C hollow microspheres as an advanced sulfur immobilizer and promoter for enabling high-efficiency Li-S batteries is developed. The porous hollow architecture not only accommodates the volume variation upon the lithiation-delithiation processes, but also exposes vast active interfaces for facilitated sulfur redox reactions. Meanwhile, the mesoporous carbon coating establishes a highly conductive network for fast electron transportation. More importantly, the defective Fe3-xC nanosized subunits impose strong LiPS adsorption and catalyzation, enabling fast and durable sulfur electrochemistry. Attributed to these structural superiorities, the obtained sulfur electrodes exhibit excellent electrochemical performance, i.e., high areal capacity of 5.6 mAh cm(-2), rate capability up to 5 C, and stable cycling over 1000 cycles with a low capacity fading rate of 0.04% per cycle at 1 C, demonstrating great promise in the development of practical Li-S batteries.