Synergistic physical and chemical polysulfide immobilization via laser-induced graphene separator in Li-S batteries

The commercialization of lithium–sulfur (Li-S) batteries is limited by the dissolution and migration of lithium polysulfides, which cause rapid capacity decay and poor cycling stability. Here, we introduce laser-induced graphene (LIG) as a multifunctional separator coating to mitigate these issues. LIG, produced via direct laser scribing of polyimide, forms a three-dimensional, porous graphenic network with high conductivity and tunable heteroatom functionality. Its hierarchical structure of few-layer graphene nanosheets provides abundant sites for physical confinement of polysulfides while enabling rapid electron transport. Electrochemical tests show that LIG-coated separators significantly enhance sulfur utilization, suppress the shuttle effect, and deliver stable reversible capacities of ∼950 mAh g⁻¹ after 400 cycles under high sulfur loading, with excellent rate performance. Density-of-states analysis confirms that defect-rich regions in LIG strengthen sulfur binding and facilitate charge transfer. In-situ SEM and EDS mapping demonstrate the structural resilience of LIG, maintaining morphological integrity after prolonged cycling. These findings establish LIG-coated separators as a scalable and effective strategy for high-performance, durable Li-S batteries.