A Polymer Network Layer Containing Dually Anchored Ionic Liquids for Stable Lithium–Sulfur Batteries

Abstract Lithium–sulfur (Li–S) batteries with high sulfur utilization, long‐cycle life, and dendrite‐free features hold great promise for the development of next‐generation energy storage devices of high energy density. Considerable efforts have been committed to solving the polysulfide shuttle problem toward highly stable Li–S batteries. Here, a unique polymer network containing dually anchored ionic liquids (DA‐PIL) is devolped to improve the cycling performance and coulombic efficiency of Li–S batteries. This DA‐PIL electrolyte incorporates the amphiphilicity of both the polysulfides anion and lithium cation, creating an ionic function layer on polypropylene separator. Noteworthily, the DA‐PIL network is “clean” in the sense that no free ionic specifies are introduced to the electrolyte system. The DA‐PIL layer not only enables strong supression against polysulfide shuttling but simultaneously allows fast lithium transportation owing to cooperate electrostatic interaction among anchored cations and anions. The DA‐PIL layer functionalized on a polypropylene separator can boost excellent stability of Li–S battery with >1600 h cycling test at 0.25 mA cm−2. The Li–S cell with DA‐PIL layer delivers a higher discharge capacity of 827.4 mAh g−1 at 1C. A discharge capacity of 630.6 mAh g−1 is retained after 1000 cycles.