Coating of Heat-resistant Polymeric Layer to Enhance Thermal Stability of Microporous Polyethylene Separator for Lithium-ion Secondary Battery

초록

It is very important to impart enhanced thermal stability to polyolefin-based separators for the fabrication of Li-ion secondary batteries with high energy density. For this purpose, in this study, a heat-resistant polyamide-imide (PAI) polymer solution was coated onto a microporous polyethylene (PE) separator with a nano-sized coating thickness, employing a continuous slot coating process. Through attended total reflection infrared spectroscopy (ATR-FTIR) and scanning electron microscope (SEM) measurements, a thin coating of PAI inside the microporous membrane was confirmed, and the relation between the PAI coating amount and the change in pore structures on membrane surface and cross-section was clearly identified. In addition, various characteristics of the separator such as permeability, porosity, and shrinkage before and after PAI coating were systematically investigated. Based on these experimental results, it was found that the PAI coating of 1.23 g/m(2) optimally enhanced the heat resistance properties of the PE-1 separator.

키워드