Imidazolyl ionic liquid-derived nitrogen-doped carbon layer coated Fe3O4 loaded on graphene as an advanced host for long life lithium sulfur batteries

Lithium-sulfur batteries are regarded as promising alternatives for next-generation energy storage systems. Developing high-performance lithium-sulfur battery cathode materials requires the efficient synthesis of electrocatalysts that can both anchor LiPS and catalyze their conversion. Herein, we synthesized a composite of ionic liquid-derived nitrogen-doped carbon-coated Fe 3 O 4 loaded on graphene (Fe 3 O 4 @NC/G) by utlizing the π-π interaction between [Bmim][FeCl 4 ] and graphene. Fe 3+ ions were uniformly dispersed, effectively preventing particle aggregation during the carbonization process and producing Fe 3 O 4 nanoparticles averaging 20.64 nm in size. This structure provides plentiful active sites for adsorbing and catalyzing LiPS, thereby accelerating the redox reaction. Additionally, the nitrogen-doped carbon coating not only stabilizes the Fe 3 O 4 nanoparticles and firmly anchors them to the graphene nanosheets , significantly enhancing structural integrity, but also increases the adsorption of LiPS due to the introduction of the heteroatom nitrogen. The assembled LSBs demonstrated excellent cyclic stability with a capacity fade rate of 0.35 % per cycle over 1200 cycles at 1C.