Sandwiched aramid nanofiber/Al2O3-coated polyolefin separators for advanced lithium–sulfur batteries

Abstract

Separators have a significant impact on the safety and performance of Lithium-sulfur (Li–S) batteries. However, the current microporous polyolefin separators often suffer from inferior thermostability and electrolyte wettability. Here, a sandwiched separator based on aramid nanofibers (ANFs) and Al2O3 nanoparticles was exploited on the base of a polyolefin separator through a facile coating process. The thin coating layer involves an entangled ANF network and Al2O3 NPs combine high strength, toughness, desirable nanoscale porosity, excellent thermostability, and wettability, which are conducive to improving the pristine polyolefin separators. Notably, the hybrid coating layer and sandwiched construction endow the separator with the capabilities of reducing the shuttle effect and improving the electrochemical performance. The Li–S battery equipped with the obtained Al2O3/ANFs@PP separator delivers an enhanced first-cycle discharge capacity of 1233 mAh g-1 and 99.83% Coulombic Efficiency after 200 cycles at 0.5C. The mechanically robust, heat-resistant, wettable, and nano-porous separator could shed fresh insights into the development of advanced separators for polysulfide shuttle-free and long-life Li–S batteries.