Characteristics of lithium ion battery with aluminum oxide-coated polyolefin separators employing water-processable terpolymer binder

초록

Here we report a water-soluble terpolymer, poly[(2-acrylamido-2-methyl-1-propanesulfonic acid)-co-(sodium 4-vinylbenzenesulfonate)-co-acrylonitrile] (PASA), which was synthesized via aqueous solution-based radical polymerization of three comonomers, and its application as a binder for ceramic particles coated on the separator films of lithium ion battery (LIB). The synthesized PASA polymer exhibited a high glass transition temperature higher than ca. 100 degrees C and an initial thermal degradation at 196 degrees C. The PASA polymer as a binder was added to the aqueous slurry of alumina microparticles by varying its content (0-20 wt%), which was then coated on both sides of the polyolefin (PO) separator films. The resulting alumina/PASA (AmPASA)-coated separator films showed high dimensional stability even at ca. 150 degrees C compared to a drastic deformation of the pristine separator films at 150 degrees C. The specific capacity of LIB coin cells was enhanced from 44.6 mAh/g to 49.3 mAh/g by applying the AmPASA-coated PO-separator films (PASA = 2 wt%). The LIBs with the AmPASA-coated PO-separator films (PASA = 2 wt%) showed a well-kept capacity even after cycling for 30 times (0.2-0.4 % reduction only) and normal charging/discharging performances under various C-rates (0.1 C-5 C).

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