Nanopore separator of cross-linked poly(propylene glycol)-co-pentaerythritol triacrylate for effectively suppressing polysulfide shuttling in Li–S batteries

Lithium–sulfur (Li–S) batteries have attracted tremendous attention as the next generation of lithium batteries. In the battery construction, a nanopore separator can improve the performance of the Li–S battery by working as a nanofiltration film, inhibiting the migration of soluble polysulfide ions between the electrodes. Herein, a new strategy to synthesize a nanopore separator of poly(propylene glycol)-co-pentaerythritol triacrylate (PPG-co-PETA) particles to suppress polysulfide shuttling has been proposed. The PPG-co-PETA cross-linked particles were easily obtained by a facile approach of UV-induced monomer polymerization while implementing molecular cross-linking for nanopore control. The characteristic nanopore size of the PPG-co-PETA separator ranged from ∼1.24 nm to ∼1.86 nm upon changing the type of photo-initiator and content of cross-linking agent. The results showed that the optimized separator for a Li–S battery could possess an electrolyte uptake of 350% with excellent thermal, mechanical and electrochemical properties. Notably, the Li–S battery using such a new type of nanopore separator exhibits superior retention discharge capacity (>200 cycles). It is believed that the nanopore separator of cross-linked PPG-co-PETA is a potential alternative to the commercial Celgard separator for effectively blocking polysulfide shuttling in Li–S batteries.