Bifunctional semi-closed YF3-doped 1D carbon nanofibers with 3D porous network structure including fluorinating interphases and polysulfide confinement for lithium-sulfur battery
In the study, semi-closed YF3-doped 1D carbon nanofibers with 3D porous networks (SC-YF3 doped-3D in 1D CNFs) are firstly fabricated 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 store high sulfur loading (80%). More importantly, the external semi-enclosed carbon layer maintains outstanding conductivity and further blocks polysulfide diffusion, which significantly break the limitation of traditional carbon matrix. On the other hand, the YF3 nanoparticles are beneficial for forming more uniform fluorinating electrodes interphases, achieving excellent synergistic effect of chemical and physical adsorption to polysulfide. Therefore, the assembled Li-S batteries exhibit high reversible discharge capacity of 954.2 mAh/g with a mere decay of 0.043% per cycle after 600 cycles at 1 C rate. Moreover, the discharge capacity decay can be as low as 0.029% per cycle during 800 cycles at high current density of 2 C rate. Even at a high rate of 5 C, the cells still possess a favorable capacity of 636.5 mAh/g while steadily operating 700 cycles with a mere capacity decay rate of 0.056%, implying the great potential of this stable semi-closed cathode structure for industrialization.