TiO₂ and Co Nanoparticle-Decorated Carbon Polyhedra as Efficient Sulfur Host for High-Performance Lithium-Sulfur...

Metal organic frameworks (MOFs)-derived porous carbon is proposed as a promising candidate to develop novel, tailorable structures as polysulfides immobilizers for lithium-sulfur batteries because of their high-efficiency electron conductive networks, open ion channels, and abundant central ions that can store a large amount of sulfur and trap the easily soluble polysulfides. However, most central ions in MOFs-derived carbon framework are encapsulated in the carbon matrix so that their exposures as active sites to adsorb polysulfides are limited. To resolve this issue, highly dispersed TiO₂ nanoparticles are anchored into the cobalt-containing carbon polyhedras that are converted from ZIF-67. Such a type of TiO₂ and Co nanoparticles-decorated carbon polyhedras (CCo/TiO₂ ) provide more exposed active sites and much stronger chemical trapping for polysulfides, hence improving the sulfur utilization and enhancing reaction kinetics of sulfur-containing cathode simultaneously. The sulfur-containing carbon polyhedras decorated with TiO₂ nanoparticles (S@CCo/TiO₂ ) show a significantly improved cycling stability and rate capability, and deliver a discharge capacity of 32.9% higher than that of TiO₂ -free S@CCo cathode at 837.5 mA g^-1 after 200 cycles.