Zirconia-supported cobalt nanoparticles as high-performance sulfur cathode for lithium-sulfur batteries

Lithium-sulfur (Li-S) battery is now a promising technology for energy storage. However, rapid capacity decay due to sulfur dissolution and shutting effect severely limit its commercial development. In this work, a NH₂-UIO-66 metal organic framework-derived porous composite (Co-ZrO₂@NC) consists of nitrogen-doped carbon (NC) and zirconium oxide (ZrO₂) loaded with cobalt nanoparticles was prepared. The porous NC component not only increases the accommodation of sulfur in the cathode, but also benefits the charge transfer in sulfur electrochemistry. The Co and ZrO₂would act as active centers to enhance the adsorption/conversion of lithium polysulfide and improve its electrochemical utilization. When used in sulfur cathode, the Co-ZrO₂@NC electrode shows excellent electrochemical performance with an initial specific capacity of 1073 mAh g^-1at a rate of 0.2 C and a reversible capacity of 1015 mAh g^-1after 100 cycles, corresponding to a capacity retention of 94.6%. Furthermore, after 300 cycles at 1.0 C, corresponding to a capacity retention of 75.4%. Moreover, the cell also exhibits good rate performance (640 mAh g^-1at 3.0 C). Even at high sulfur loading of 4.0 mg cm^-2, the S/Co-ZrO₂@NC cathode is able to deliver an areal specific capacity of 4.8 mAh cm^-2.