Modification of glass fiber separators with a ternary V2O5/Cys/FeNi-LDH composite to enhance the performance of lithium-sulfur batteries

• A novel V 2 O 5 /Cys/FeNi-LDH composite was developed for separator modification. • The composite mitigates the polysulfide shuttle effect in Li-S batteries. • Batteries with the modified separator show a low decay rate of 0.039% per cycle. • Enhanced performance is due to synergistic effects of V 2 O 5 , Cys, and FeNi-LDH. Lithium-sulfur (Li-S) batteries are promising candidates for next-generation energy storage systems due to their high theoretical energy density and low cost. However, their practical application is hindered by the polysulfide shuttle effect, which leads to poor cycling stability and low Coulombic efficiency. To address this challenge, we developed a novel separator modifier, V 2 O 5 /Cys/FeNi-LDH (VCFN), by uniformly depositing V 2 O 5 nanoparticles onto cysteine-modified FeNi-LDH nanodisks. Electrochemical performance tests revealed that the VCFN-modified separator significantly enhanced the cycling stability and capacity retention of Li-S batteries, delivering an initial discharge capacity of 1035.2 mAh g −1 at 0.5C and maintaining 920.1 mAh g −1 after 300 cycles with a low capacity decay rate of 0.039% per cycle. High sulfur loading cells (up to 4.5 mg cm −2 ) also exhibited stable performance. The enhanced performance results from the synergistic effects of V 2 O 5 ’s catalytic properties, the high surface area of FeNi-LDH, cysteine’s function as a linker, the polysulfide adsorption ability of all three components, and the unique porous structure of VCFN, which facilitates efficient Li-ion transport. This work demonstrates that the VCFN-modified separator effectively mitigates the polysulfide shuttle effect, offering a promising approach for high-performance Li-S batteries.