Fabrication and application of TiO2-modified PMIA separators with strong mechanical properties in lithium-ion batteries

A TiO2/PMIA composite separator was prepared using poly(m-phenylene isophthalamide) (PMIA) as the base separator and polyacrylonitrile (PAN) as the binder to load TiO2 particles on its surface. The tensile strength of the TiO2/PMIA composite separator (37 MPa) was found to be greater than that of the pure PMIA separator (22 MPa) (increment of 68.2%), whereas the elongation at break of the TiO2/PMIA composite separator increased by 40%. TiO2 is a semiconductor material with a high dielectric constant which is also beneficial to improve electrochemical performance of PMIA seperator. The button cell assembled by the TiO2/PMIA composite separator had the best cycle performance (113.6 mAh/g), and its specific capacity was still 85.5 mAh/g at 2 C. Therefore, TiO2/PMIA composite separators with high mechanical properties can be used as promising lithium-ion battery separators in a wide range of applications.