In this work, two kinds of composite separators are prepared and used for lithium-ion batteries, which
are a PP nonwoven/PVdF-HFP/PMMA blending-type composite separator (CS) and a sandwich-like PP
nonwoven/PVdF-HFP composite separator with the introduction of PMMA nanoparticles on the surface
(nano-CS). The morphology, electrolyte uptake, ionic conductivity and electrochemical properties of the
separators are studied by SEM analysis, impedance measurements, chargeedischarge cycle and C-rate
tests, respectively. The nano-CS and CS(0.2) exhibit similar properties in electrolyte uptake (212% and
202%, respectively) and porosity (77.9% and 75.3%, respectively). Nonetheless, nano-CS shows enhanced
thermal stability and higher ionic conductivity compared with CS(0.2) and commercial PP nonwoven/
PVdF-HFP separators. Meanwhile, the LiFePO4/Li half-cell assembled with nano-CS displays the best Crate capacity and cyclability especially at the high discharge current rate, indicating that the nano-CS
separator is a kind of promising candidate for the high-performance lithium-ion batteries.