Fluoride-samarium(III) doped hierarchically porous carbon nanofibers as thin separator coating layer with excellent adsorption and outstanding catalysis of lithium polysulfide for lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries are promising for next-generation energy storage due to their high energy density and low cost. However, challenges such as the “shuttle effect,” slow reaction kinetics, and lithium dendrite growth hinder their performance. In this study, we developed fluoride-samarium(III) doped hierarchically porous carbon nanofibers (SmF3-PCNFs) and coated them onto separators. These three-dimensional porous carbon networks confined LiPSs, while polar SmF3 nanoparticles acted as efficient chemical anchors and catalysts. Simultaneously, the polar fluoride interfaces between the SmF3-PCNFs and cathode also can accelerate the transport of lithium ions and enhance the adhesion between them, enabling them to accommodate the huge volume changes of the sulfur cathode during cycling and improve long-cycle stability. Moreover, the modified separator with excellent lithium affinity also enables uniform lithium deposition to reduce lithium dendrite growth. Combining these advantages, the assembled Li-S battery with SmF3-PCNFs modified separator exhibits a high initial discharge specific capacity of 1068.2 mAh g−1 and retains a capacity of 655.3 mAh g−1 after 750 cycles (with a decay rate of only 0.05 % per cycle), and the Coulombic efficiency remains above 93 %. This work will pave a new design path for the preparation of modified separators in high-performance Li-S batteries.