Al2O3/poly(ethylene terephthalate) composite separator for high-safety lithium-ion batteries

Separators have garnered substantial attention from researchers and developers in regard to their crucial role in the safety of lithium-ion batteries. In this study, a composite separator was prepared by coating cubic Al2O3 nanoparticles on non-woven poly(ethylene terephthalate) (PET) via a simple dip-coating process. The basic properties of the Al2O3-coated PET non-woven composite separator were characterized by scanning electron microscopy and other specific measurements in respect to its morphology, porosity, electrolyte wettability, and thermal shrinkage as well as its application in lithium-ion batteries. We found that the composite separator has outstanding thermostability, which may improve battery safety. Additionally, by comparison against the commercial Celgard 2500 separator, the proposed composite separator exhibits higher porosity, superior electrolyte wettability, and higher ionic conductivity. More importantly, the lithium-ion battery assembled with this composite separator shows better electrochemical performance (e.g., cycling and discharge C-rate capability) compared to that with the Celgard 2500 separator. The results of this study represent a simple approach to preparing high-performance separators that can be used to enhance the safety of lithium-ion batteries.