Constructing a Spider-Web Polymer Blocking Layer on Separator for the High-Loading Li-S Battery

Abstract

The cycling performance of high-loading Li−S batteries is still puzzled by the serious shuttle effect of polysulfides. Modifying the commercial separator with polysulfide anchoring materials has been demonstrated as an economical and effective approach to block the polysulfide shuttle. Herein, a cobweb-like polymer polysulfide-blocking layer has been constructed via crosslinking between lithium polysilicate (LP) inorganic oligomer and tannic acid (TA) dendritic polymer. Owing to the strongly polar Si−O and Si=O bonds in LP, the spider-web polymer possesses robust affinity towards polysulfides, indicated by the theoretical calculations. Dendritic polymer TA as the skeleton contributes to effectively exposing the abundant polar functional groups to powerfully capture the polysulfides. As a result, the cycling stability of high-loading Li−S batteries has been obviously improved. The Li−S battery with sulfur loading of 3.44 mg cm⁻² can stably cycle 100 cycles with a high capacity of 685.1 mAh g⁻¹ and columbic efficiency of 99.82 %. Even the sulfur loading increases to 7.15 mg cm⁻², the Li−S battery can still deliver a high areal capacity of 5.26 mAh cm⁻² after 50 cycles.