SiO2 nanoparticles modified polyetherimide (PEI)-based separator for lithium-sulfur batteries

The application of lithium‑sulfur batteries is restricted by issues like the shuttle of polysulfide, poor thermal stability, and low ionic conductivity, which are often thought to be solved by novel separators. Herein, a separator based on polyetherimide (PEI) with excellent electrolyte uptake was proposed by us. The mix of SiO2 nanoparticles and polyvinyl pyrrolidone (PVP) greatly improved the chemical properties of the separator. The silicon-hydroxyl group (Si-OH) on the surface of SiO2 interacts with the oxygen-containing group on the surface of PEI making the modified PEI separator possess good electrolyte affinity, lithium compatibility, low interface impedance and improved interface stability. The characterization results show that enrichment of SiO2 increases the amorphous area of the separator, decreases the crystallinity and improves the ionic conductivity and liquid absorption rate of the separator. The prepared separator (added 4 wt% SiO2) displays many merits such as high ionic conductivity (1.32 mS/cm), high liquid absorption rate (293 %), excellent thermal stability (shrinkage rate is <5 % at 180 °C for 30 min), and high initial specific capacity (498.6 mAh/g at 2C). Due to the simple preparation method, the separators prepared in this paper have a significant meaning in the research of high-safety and long-cycle lithium‑sulfur battery.