Facile Functionalization of Separator with an Amino Acid to Boost Li–S Battery Performance

Abstract

Lithium-sulfur (Li–S) batteries are hindered by issues such as the polysulfide shuttle effect and Li dendrite formation, which leads to capacity degradation. To address these issues, a bio-strategy involving the functionalization of a commercial separator with an amino acid-polymer system, leucine-polyacrylic acid (Leu-PAA), is reported here. A simple soaking method is used in preparing the separator with the Leu-PAA, which is effective and viable for practical application. The Leu-PAA soaked separator exhibits improved wettability and thermal stability, as well as enhanced polysulfide trapping and regulated lithium ion flux. As a result, Li–S cell using the separator with Leu-PAA achieves an initial capacity of 599.9 mAh g⁻¹ at 0.5 A g⁻¹ and retains 53.5% of capacity after 500 cycles. The enhanced properties are attributed to the synergistic effects of Leu and PAA, which suppress the shuttle effect and ensure uniform ion transport, resulting in improved electrochemical performance. This work provides a promising, bio-inspired solution for improving the performance and cycle life of Li–S batteries.