Lithium-sulfur batteries (LiSBs) are promising next-generation batteries because of their low cost and high theoretical energy densities. Despite remarkable advances over the decades, polysulfide (PS) shuttling during battery cycling remains a challenge in the development of commercial LiSBs and is accelerated under practical conditions. Herein, we report a permselective ionic shield between the electrodes that blocks PS shuttles and passes Li ions to high-performance LiSBs. This shield is easily built onto the separator by ionic complexation and intermolecular bonding of functional polymers, thereby improving the battery performance and safety. The LiSB with the developed shield delivers a remarkable discharge capacity of 917 mAh g-1 after 1000 cycles at 2 C. In addition, the behavior of LiSBs under practical conditions that can realize a high energy density is investigated to achieve the optimal balance in this system. This study provides new insights into the imminent development of separators for practical LiSBs.
Keywords: functional polymers; layer-by-layer; lithium−sulfur batteries; permselective ionic shield.