A sulfonate ligand hybrid ZIF-8 modified separator achieved high-performance Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries, as a promising high-energy-density storage system, face critical technical challenges such as lithium dendrite growth and the shuttle effect of lithium polysulfide (LiPS). This work employs a ligand hybridization strategy to develop a novel sulfonated metal–organic framework material (ZIF-8-SO₃H), which is utilized for functional modification of the Li–S battery separator. ZIF-8-SO₃H retains the original topology of ZIF-8 while achieving a uniform distribution of sulfonic acid groups within the channels. The ZIF-8-SO₃H@PP composite separator exhibits excellent Li⁺ conductivity (1.246 mS cm⁻¹) and a high Li⁺ transference number (0.82) at room temperature. A Li‖Li symmetric battery with this separator demonstrates a cycling life exceeding 2200 hours at 0.1 mA cm⁻². The Li–S battery based on the ZIF-8-SO₃H@PP separator retains a reversible capacity of 641.3 mAh g⁻¹ after 1000 cycles at 1C, and exhibits an initial discharge capacity of 836.9 mAh g⁻¹ at 2C. This work presents a universal functionalized MOF material design strategy, expanding its potential applications in advanced energy storage systems.