Based on the considerations above and the relevant studies, the
objective of this work is to propose a bicomponent crosselectrospinning method to prepare nanofiber membrane. The crosselectrospinning apparatus was equipped with four needles, two of
which were fed with PVdF-HFP solution and the rest with PI solution,
arrayed in line alternately. Comparing with traditional mono component membrane and composite membrane, the membrane
prepared with this method not only combines the advantages of both
polymers, but also maintains thefibrous morphology of PVdF-HFP and
PI separately, sufficiently keeping their respective roles in the nanofiber composite membrane. On the one hand, the mechanical property
of composite membrane was dramatically improved due to higher
cohesion among the electrospun nanofibers resultant from the thermal calendering process where the PVdF-HFP component with lower
melting point served as bondingfiber, providing with shutdown
property at relatively low temperatures around its melting point. On
the other hand, the separator consisting of heat resistant polyimide
component could be imparted with excellent property of thermal
stability, preventing from thermal runaway at temperatures lower
than its melting temperature. All these properties obtained simultaneously by means of bicomponent cross-electrospinning would be
beneficial for enhancing the safety performance of lithium ion battery