(312c) Electrode-Supported Macroporous Ceramic Membrane Separator for Lithium Ion Batteries

Lin, J. - Presenter, Arizona State University
Jin, Y., China Electric Power Research Institute
The emergence of lithium-ion batteries as the most popular energy storage system is mainly due to their high energy density and long cycle life. They find application in a wide variety of portable electronic devices as well as electric vehicles and smart grids. However, the relatively frequent occurrences of battery fires and explosions are a major cause of concern. A significant source of this flammability, along with the electrolyte, is the polymeric separator used widely in commercial lithium-ion batteries. Lithium ion batteries with inorganic separators offer advantages of safer operation. An inorganic macroporous membrane separator for lithium-ion battery was prepared by blade coating an α-Al2O3 slurry directly on the electrode followed by drying. The improved separator preparation involves a twice-coating process instead of coating the slurry all at once in order to obtain a thin (~40µm) and uniform coat. Unlike state-of-the-art polyolefin separators such as polypropylene (PP) which are selectively wettable with only certain electrolytes, the excellent wettability of α-Al2O3 allows the coated separator to function with different electrolytes. The coated α-Al2O3 separator has much higher resistance to temperature effects than polyolefin counterparts. The inorganic coated separator retains its dimensional integrity at temperatures as high as 200ºC, thus eliminating the possibility of a short circuit during thermal runaway. Lithium ion batteries half-cells and whole cells with coated α-Al2O3 separator exhibit electrochemical performance comparable with that with PP separator at room temperature. However, the coated separator shows better cycling performance than PP separator under extreme temperatures when tested over a wide temperature range of -30°C to +60°C. Therefore, the coated α-Al2O3 separator is very promising for uses in safe lithium-ion batteries for energy storage applications.