Double-Layered Modified Separators as Shuttle Suppressing Interlayers for Lithium–Sulfur Batteries

The shuttling phenomena in lithium–sulfur batteries lead to drastic attenuation of the capacity. This can be suppressed effectively by modifying the separator. Herein, a double-layered separator composed of a macroporous polypropylene (PP) matrix layer and an arrayed poly­(methyl methacrylate) (PMMA) microsphere retarding layer is designed as the separator for lithium–sulfur batteries. A sulfur positive electrode with the PP/PMMA separator exhibits a high initial capacity of 1100.10 mAh g^–1 at a current density of 0.1 mA cm^–2 along with a high Coulombic efficiency, which is higher than the corresponding first discharge capacity results obtained using the standard PP separator (948.60 mAh g^–1). In the double-layered separator, the arrayed PMMA microspheres can inhibit the diffusion of polysulfides through physical and chemical adsorption, thereby improving the electrochemical performance of lithium–sulfur batteries. In addition, the PMMA microspheres enhance the affinity of the separator to the electrolyte, which will increase the adsorption of the electrolyte to the separator and accelerate the diffusion rate of lithium ions.