Construction of Porous hetero structured materials defluorinated carbon nanotubes@SiO2-ZnO modified separator for safety and high performance lithium-sulfur batteries

Lithium-sulfur batteries have received widespread attention as an energy storage device. Low cycle life due to the shuttle effect, Slow polysulfide oxidative reduction dynamics, and battery safety issues such as lithium dendrites have hindered the commercial progress of lithium-sulfur batteries. Here we propose Three-layer porous tubular structure material (DCNT@SNT-ZnO) based on defluorinated carbon nanotubes (DCNT) with silica nanotubes (SNT) in the middle layer and zinc oxide (ZnO) in the outermost layer was prepared. The zinc oxide on the surface of this three layer tubular structure material effectively anchors the polysulfides, which are then further catalytically converted by the silica inside through the micropores. At the same time, the porous structure formed after defluorination is more conducive to the penetration of the electrolyte and the diffusion of lithium ions. Through the synergistic effect between the above materials, the lithium-sulfur battery exhibits excellent electrochemical performance. After 400 cycles at 1C current density, it still maintains the specific capacity of 643 mAh g(-1), and has good multiplication capacity of 896 mAh g(-1) at high current density of 4C. The CV curves with different scan rates and first-principle calculations demonstrated that the DCNT@SNT-ZnO modified separator effectively enhanced the diffusion of lithium ions.