Novel Porous Separator based on PVdF and PE Nonwoven for Rechargeable Lithium Batteries

Abstract

The novel porous separator based on PVdF (poly(vinylidene fluoride)) and a PE (polyethylene) non-woven matrix is prepared by coating PVdF/NMP solution on the matrix (NMP: N-methyl-2-pyrrolidone). The pore structure is generated in the PVdF region by phase inversion of the polymer solution. The PE non-woven matrix imparts mechanical strength and a thermal shut-down property to the separator, while the PVdF component provides a hydrophilic ionic conducting phase. The physical properties of the separator, such as morphology, pore size and its distribution, porosity and mechanical strength, are measured. The ionic conductivity of the separator is 8.9 × 10−4 S cm−1 at 25 °C. The capacity at the C/2 rate is maintained at about 86% of the initial value on the 100th cycle at the room temperature. The electrolyte is stable up to 4.5 V in the presence of the novel separator.