A sandwich-like composite nonwoven separator for Li-ion batteries

In this paper, the background, current research status and problems of separators for Li-ion batteries were reviewed first. Then a novel sandwich-like type of composite nonwoven separators was prepared to improve the performance of composite nonwoven Li-ion battery separators by combining SiO2/PVDF-HFP membranes with PVDF-HFP dipped PP nonwoven fabric. The physical and electrochemical properties of the composite separators were measured and analyzed. It is found that the mean pore size of the composite separators was in the range of 100 to 300 nm with maximum pore size less than 2 μm. The composite nonwoven-based separators possessed higher electrolyte uptake, stronger thermal stability, better wettability and lower interfacial resistance than the commercial PE separator. The batteries assembled with composite nonwoven separators showed stable cycling performance and improved rate performance. The composite nonwoven separators are expected to be a promising alternative to commercial PE separator.