Natural Polyphenol‐Reinforced Ion‐Selective Separators for High‐Performance Lithium‐Sulfur Batteries with High Sulfur Loading and Lean Electrolyte

Abstract Ion‐selective separators are promising to inhibit soluble intermediates shuttle in practical lithium‐sulfur (Li−S) batteries. However, designing and fabricating such high‐performance ion‐selective separators using cost‐effective, eco‐friendly, and versatile methods remains a formidable challenge. Here we present ion‐selective separators fabricated via the spontaneous deposition of green tea‐derived polyphenols onto a polypropylene separator, aimed at enhancing the stability of Li−S batteries. The resulting natural polyphenol‐reinforced ion‐selective (NPRIS24) separators exhibit rapid Li ion transport and high soluble intermediates inhibition capability with an ultralow shuttle rate of 0.67 % for Li 2 S 4 , 0.19 % for Li 2 S 6 and 0.10 % for Li 2 S 8 . This superior ion‐selectivity arises from the high electronegativity and strong lithiophilic nature of the phenolic compounds. Consequently, we have achieved high‐performance Li−S batteries that are steadily cyclable under the challenging conditions of an S loading of 5.7 mg cm −2 , an electrolyte‐to‐S ratio of 5.1 μL mg −1 , and a 50 μm Li foil anode. Furthermore, the NPRIS24 separator enhances the performance of other Li metal batteries utilizing commercial LiFePO 4 (5.3 mg cm −2 ) and LiNi 0.5 Co 0.2 Mn 0.3 O 2 (9.9 mg cm −2 ) cathodes. This work underscores the potential of utilizing natural polyphenols for the design of advanced ion‐selective separators in energy storage systems.