Self-standing sulfur cathodes enabled by a single Fe site decorated fibrous membrane for durable lithium–sulfur batteries

Abstract

Rational design of sulfur host materials to synergize the retention and catalysis of lithium polysulfides (LiPSs) is of great significance to accomplish efficient sulfur electrochemistry for lithium–sulfur (Li–S) batteries. Herein, we have elaborately designed Fe single atom decorated porous carbon nanofibers (FeSA-PCNF) through electrospinning to construct self-standing and binder-free cathodes for Li–S batteries. The unique architecture of FeSA-PCNF with interconnected fibrous networks and hierarchical porous structures guarantees rapid charge transfer kinetics as well as abundant active interfaces for LiPS conversions. Moreover, the highly active FeN₄ moieties with surrounding graphitic N dopants embedded in the porous carbon nanofibers ensure strong chemisorption and superior electrocatalytic conversion towards LiPSs. As a consequence, the Li–S batteries assembled with FeSA-PCNF demonstrate superior electrochemical performances with a high rate capability of 791 mA h g⁻¹ at 5C and a low capacity decay rate of 0.048% per cycle after 500 cycles at 2C. More encouragingly, a high areal capacity of 11.1 mA h cm⁻² is achieved after 50 cycles with an ultrahigh sulfur loading of 17 mg cm⁻² and a low electrolyte/sulfur ratio of 5 μl mg⁻¹. This work presents a promising strategy for rational design of self-standing and binder-free cathodes for practically feasible and high-performance Li–S batteries.