Abstract:

In order to obtain a better lithium-ion battery separator with good performance, the first layer of the membrane was prepared by electrospinning poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer solutions, then alumina and zirconia microparticles were deposited on the surface by electrostatic  electrostatic spraying, and a novel sandwiched composite membrane was formed followed by fabricate the other P(VDF-HFP) nanofibrous layer by  electrospinning. The single-layer P(VDF-HFP) separator was prepared as a comparison by electrospun at the same time. The physical performance, including morphology, permeability, liquid electrolyte uptake and thermal stability, and electrochemical properties such as ionic conductivities of membranes at room temperature, electrochemical stability, and cycling performance of the two kinds of separators were investigated. The results demonstrate that electrolyte uptake of the composite membrane is 420%, while the Gurley value and thermal shrinkage are0.117S/(100mL?cm²) , and 20.25%, respectively. Good electrolyte uptake contributes to the ionic conductivity which is up to 2.31 mS/cm at room temperature, electrochemical stabilivity window is 5.4 V, and initial cycle charge and discharge capacity of the prepared battery is 138.6 mA?h/g. Except for the small weakness in permeability, all the other properties of the composite membrane are improved. It’s found that the performance of the composite membrane is better than that of the single-layer electrospun P(VDF-HFP) separator under the same test conditions.

Key words: electrospun, nanofiber, electrostatic spraying deposition, lithium-ion battery, separator elecrochemical propety