A dual-functional poly(vinyl alcohol)/poly(lithium acrylate)composite nanofiber separator for ionic shielding of polysulfides enables high-rate and ultra-stable Li-S batteries

摘要

Despite the high theoretical specific capacity,the main challenges of rechargeable lithium-sulfur(Li-S)batteries,including the unceasing shuttle of soluble lithium polysulfides(LiPSs)and severe Li corrosion,seriously hinder their commercial and practical applications.Herein,a bifunctional polyvinyl alcohol/poly(lithium acrylate)(C-PVA/PAA-Li)composite nanofiber separator is developed to address the main challenges in Li-S batteries by simultaneously allowing rapid lithium ion transport and ionic shielding of polysulfides.The C-PVA/PAA-Li composite nanofiber membrane is prepared via the facile electrospinning strategy,followed by thermal crosslinking and in-situ lithiation processes.Differing from the conventional Celgard-based coating methods accompanied by impaired lithium ion transport efficiency,the C-PVA/PAA-Li composite nanofiber membrane possesses well-developed porous structures and high ionic conductivity,thus synergistically reducing the charge transfer resistance and inhibiting the growth of lithium dendrites.The resulting Li-S batteries exhibit an ultra-low fading rate of 0.08%per cycle after 400 cycles at 0.2 C,and a capacity of 633 mAhg−1 at a high current density of 3 C.This study presents an inspiring and promising strategy to fabricate emerging dual-functional separators,which paves the pathway for the practical implementation of ultra-stable and reliable Li-S battery systems.