Bifunctional semi-closed YF3-doped 1D carbon nanofibers with 3D porous network structure including fluorinating interphases and polysulfide confinement for lithium–sulfur batteries

Abstract

In this study, semi-closed YF₃-doped 1D carbon nanofibers with 3D porous networks (SC-YF₃-doped 3D in 1D CNFs) are fabricated for the first time via electro-blown spinning technology. The internal 3D porous networks not only offer a stable 3D electrode structure to accommodate the volume expansion, but also enable a high sulfur loading (80%). More importantly, the external semi-enclosed carbon layer maintains outstanding conductivity and further blocks polysulfide diffusion, which significantly breaks the limitation of a traditional carbon matrix. On the other hand, the YF₃ nanoparticles are beneficial for forming more uniform fluorinating electrode interphases, achieving the excellent synergistic effect of chemical and physical adsorption to polysulfide. Therefore, the assembled Li–S batteries exhibit a high reversible discharge capacity of 954.2 mA h g⁻¹ with a decay of merely 0.043% per cycle after 600 cycles at 1C rate. Moreover, the discharge capacity decay can be as low as 0.029% per cycle during 800 cycles at a high current density of 2C rate. Even at a high rate of 5C, the cells still possess a favorable capacity of 636.5 mA h g⁻¹ while steadily operating for 700 cycles with a capacity decay rate of merely 0.056%, implying the great potential of this stable semi-closed cathode structure for industrialization.