2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Lithium-ion Batteries development of Coated Microporous Separators experiment

S.H. Kim, C.G. Hwang, J.H. Oh, J.H. Noh, B. Yoo
Nano Practical Application Center, KR

Keywords:
separtor, microporous, batteries

Abstract:
Secondary battery consists of mainly positive electrode materials and plates, negative electrode materials and plates, electrolytes (electrolytic fluid and organic solvent), membrane (separators), and packaging materials. Membrane or separator: It will electrically insulate between cathode and anode, minimize separating distance, and is made up of very stable polymer membrane mainly PE, PP materials. It is very important to develop the commercial high power separators, especially in the rapidly growing high-power battery markets for electric vehicles, This study according to the industrial and technical requirements, in this study, we have focused on developing an advanced high-power and high-energy density separators with enhanced stability by using the conventional separator materials. Research objective: Coating techniques of high-power and high-capacity separators for secondary batteries have been studied and developed for the purpose of the longer service life performance and electrode plates regarding higher loading density. Experimental methodology: To minimize thermal property changes of the PE separator by enhancing thermal capabilities, the microporous layers have been controlled by using solvent/non-solvent ratios and systematical silica coatings. The thermal conductivities of PVDF and inorganic materials are better than that of PE material (0.5 W/mK) and therefore they are selected as coating materials on PE separator with a blade (or bar) coating equipment. Dry and wet coatings have been performed by using active materials (Polymer(PVDF-HFP)+Inorganic additives) and solvent system (Solvent 90 % + Non-solvent 10 %). Results: According to the tensile test results of the functional separators measured by UTM equipment, there are small increments but not much different in the tensile strengths and ductility between the experimental coated-PE separator and a conventional PE separator. Thermal shrinkage tests were performed to characterize the thermal properties of PE separator at initial temperature of 100 with 10 increments in each step and kept them for one week in each step. Test results show that functional coated-PE separator has been improved in the thermal shrinkages as compared to the conventional PE separator, especially the wet coated PE separator shows much enhanced thermal stability. After keeping them at 130 for 1 hour, conventional PE separator was melted and completely deformed, but wet coated-PE separator kept in their shape even after melt down index.


Nanotech 2008 Conference Program Abstract