Composite melt-blown nonwoven fabrics with large pore size as Li-ion battery separator

A kind of composite melt-blown nonwoven fabric with larger pore size compared to commercial microporous polyolefin-based separators was prepared in order to improve the cell performance and safety of Li-ion batteries at high C-rate. Heavy-weight melt-blown nonwoven fabrics were directly assembled into coin-type Li-ion batteries. Then light-weight melt-blown nonwoven fabrics were chosen as the substrate and the coating process with a series of concentrations of nano-SiO2 and polyvinylidene fluoride (PVDF) was studied. The pore size and distribution, porosity, electrolyte absorption capacity, wettability and thermal dimensional stability of the composite melt-blown nonwoven fabrics were measured. Finally, the cell performances of Li-ion batteries assembled with composite nonwoven fabrics were tested in comparison with the microporous polyolefin-based separator. It is found that the composite nonwoven fabrics had higher electrolyte absorption capacity, better wettability and thermal dimensional stability than the polyolefin separator. The composite nonwoven fabrics demonstrated higher discharging capacities and better cycling performance. In addition, Li-ion batteries assembled with composite nonwoven fabrics showed better C-rate performance than that of the polyolefin separator.