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.

Rational design of a cobalt sulfide nanoparticle-embedded flexible carbon nanofiber membrane electrocatalyst for advanced lithium-sulfur batteries.

Both the sluggish redox kinetics and severe polysulfide shuttling behavior hinders the commercialization of lithium-sulfur (Li-S) battery. To solve these obstacles, we design a cobalt sulfide nanoparticle-embedded flexible carbon nanofiber membrane (denoted as CoS2@NCF) as sulfiphilic functional interlayer materials. The hierarchically porous structure of carbon nanofiber is conducive to immobilizing sulfur species and facilitating lithium-ion penetration. Moreover, electrocatalytic CoS2nanoparticles can significantly enhance the catalytic effect, achieving favorable adsorption-diffusion-conversion interface of polysulfide. Combined with these synergistic features, the assembled Li-S cell with CoS2@NCF interlayer exhibited a great discharge capacity of 950.9 mAh g-1with prolonged cycle lifespan at 1 C (maintained 648.1 mAh g-1over 500 cycles). This multifunctional interlayer material used in this contribution provides an advanced route for developing high-energy-density Li-S battery.