Suppressing the Shuttling of Polysulfide by a Self-Assembled FeOOH Separator in Li–S Batteries

Fabrication of a functional separator with physical methods such as slurry casting and vacuum filtration method is a common way to capture the dissolved polysulfide and suppress its shuttling in lithium–sulfur batteries (Li–S battery). However, most of the layers are covered on the PP separator by weak physical adhesion, and it is hard to guarantee stability during long-term cycling at high rates. Therefore, we take advantage of the strong oxidization of acidic ferrate solution and design a novel simple chemical method to tightly assemble a thin and light FeOOH layer on the PP substrate by itself. The PP@FeOOH separator can chemically immobilize the polysulfide and efficiently prohibit the shuttling. Therefore, the long-term stability of the Li–S cell is extraordinarily enhanced with this self-assembled PP@FeOOH separator. After discharging and charging for 400 cycles at 0.5 C, cycling fading is only 0.075% per cycle. This novel chemical method not only simplifies the fabrication and improves the stability of the modified layer on the PP substrate, but also offers an effective and prospective way to modify the separator with metal oxides in Li–S batteries.