A Conductive/Ferroelectric Hybrid Interlayer for Highly Improved Trapping of Polysulfides in Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are catching intensive worldwide attention for the outstanding energy density, low-cost, and nontoxic nature of sulfur. However, the very limited lifespan and rate performance of Li-S systems originating from dissolution and diffusion of long-chain polysulfides in liquid electrolytes, as well as the intrinsic poor conductivity of sulfur, severely hinder their practical application. Herein, an electrospinning and subsequent dipping and drying method is developed here to fabricate a duplex architecture consisting of reduced graphene oxide (rGO) layer and BaTiO3 (BTO)-decorated carbon nanofibers (BTO@CNFs), and it is used as a multifunctional interlayer for Li-S batteries. The 3D interwoven CNFs with conductive pathways for both electrons and ions can enhance the contact between polysulfides with BTO nanoparticles and promote the reuse of inactivated sulfur. Additionally, the ferroelectric BTO nanoparticles adhered on CNFs can realize a highly robust trapping to polysulfides via the extremely polar interaction. Moreover, the surface rGO layer can act as a textural barrier to intercept the shuttling polysulfides. Consequently, the modified Li-S batteries with the rGO/BTO@CNF interlayer deliver superior electrochemical performance of 865 mAh g(-1) after 200 cycles at 0.3 C and a rate capability of 672 mAh g(-1) at 3 C.