Macroporous Multichannel Carbon Nanofibers Embedded with Co/Fe-N Electrocatalyst as the Sulfur Host for Boosting Polysulfides Conversion in Lithium-Sulfur Batteries

摘要

Lithium-sulfur batteries (LSBs) are widely recognized as promising candidates for next-generation energy storage systems, yet suffering from sluggish redox kinetics and severe shuttle effect. Herein, the macroporous multichannel carbon nanofibers (MCFs) embedded with Co/FeN active sites (Co/FeN/MCFs) were prepared by electrospinning and functionalized as the sulfur host for LSBs. The opening macropores in MCFs facilitate the storage and uniform distribution of sulfur. Meanwhile, the built-in Co/FeN sites possess double-end binding sites toward polysulfides (LiPSs), which provides an effective way for immobilization and catalytic conversion of LiPSs. The designed sulfur host with good electrical conductivity and high catalytic activity enables fast kinetics of sulfur redox reaction and reduces cell polarization. As a result, the cell equipped with the Co/FeN/MCFs/S cathode shows an initial capacity of 1523 mA h g~(-1) at 0.2 C and an ultrahigh rate performance of 891 mA h g~(-1) at 5 C, and a low decay of 0.051 % per cycle over 1000 cycles at 1 C. This work will enlighten the rational design of advanced sulfur host for practical application of LSBs.