Reinforced PEI/PVdF Multicore-Shell Structure Composite Membranes by Phase Prediction on a Ternary Solution

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrochemistry

Background:

• Polyvinylidene fluoride (PVdF) membranes are widely used in lithium-ion batteries.
• Enhancing the mechanical and thermal properties of PVdF separators is crucial for battery safety and performance.
• Polyetherimide (PEI) is a high-performance polymer with excellent thermal and mechanical properties.

Purpose of the Study:

• To develop a novel polyetherimide (PEI)-reinforced polyvinylidene fluoride (PVdF) composite membrane with a multicore-shell structure.
• To investigate the effect of PEI content and electrospinning parameters on membrane morphology and properties.
• To evaluate the suitability of the developed membranes for lithium-ion battery applications.

Main Methods:

• Ternary solution preparation and single-nozzle electrospinning.
• Theoretical prediction of phase separation.
• Characterization of membrane morphology, fiber diameter, tensile strength, modulus, and thermal stability (shrinkage).

Main Results:

• Successfully fabricated PEI/PVdF composite membranes with a multicore-shell structure.
• Optimized PEI ratio and spinning time to control fiber and fibril diameters.
• Achieved significant improvements in tensile strength (48 MPa) and modulus (1.5 GPa).
• Demonstrated excellent thermal stability with only 6.6% shrinkage at 180 °C, outperforming commercial separators.

Conclusions:

• The multicore-shell morphology, featuring oriented PEI nanofibrils, is key to the enhanced properties.
• PEI/PVdF composite membranes offer a promising alternative for lithium-ion battery separators due to superior mechanical and thermal performance.
• Controllable textural properties allow for tailored membrane design for specific battery requirements.