The high performances of SiO2/Al2O3-coated electrospun polyimide fibrous separator for lithium-ion battery

A SiO2/Al2O3-coated electrospun PI membrane was prepared by means of simple dip coating of Al2O3 and SiO2 mixture onto electrospun PI membrane. The electrochemical performance of the membrane was tested as a separator in the lithium-ion batteries and compared with those of PI membrane, Al2O3-coated PI membrane, SiO2-coated PI membrane, trilayer SiO2/Al2O3-coated PI membraneand Celgard 2400 separators. The SiO2/Al2O3-coated electrospun PI membrane exhibits the best electrochemical performance, including the cycling performance and rate capability. The optical mass ratio of SiO2/Al2O3 was 2:1. The SiO2 component on the interface decrease the interface resistance. Meanwhile, Al2O3 component increase the ionic conductivity. Owing to the intrinsic thermal stability of ceramic materials and PI, the composite membrane doesn't have the thermal shrinkage problem of commercial separators.