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Showa Denko starts full-swing marketing of Poly-N-vinylacetamide (PNVA(TM)) optimized for use as a binder to form heat-resisting ceramic layer in separators to be used in lithium-ion batteries (LIBs), under the trade name of "GE191 Series."
PNVA is a water-soluble polymer synthesized through polymerization of N-vinylacetamide, and SDK is the only company in the world which produce N-vinylacetamide on a commercial basis. PNVA is designed to have many hydrogen bonds. It has heat-resisting property, and can make oxided-metal particles disperse uniformly and stably. "GE191 Series" is a grade of PNVA that fulfills requirements for use as heat-resisting ceramic layer, and contributes to improvement in heat-resisting property and thinness of the layer. Thus GE191 Series is acclaimed as additive for separators in LIBs that can improve safety and durability of LIBs through improvement in heat-resisting property of coating layers in separators, and adopted for use in onboard LIBs.
Conventional separator of LIB consists of thin films of polyethylene, polypropylene and other materials. If an LIB generates heat abnormally and its temperature rises, crystals in separators melt, separating films shrink, electrodes contact each other and short-circuit, and there may be a serious accident such as fire. If separator of LIB is coated with heat-resisting ceramic layer to which SDK's "GE191 series" is added, GE191 Series gives heat-resisting property to the separator. In addition, inorganic particles in the heat-resisting layer including alumina and boehmite and particles of GE191 Series are bonded strongly through hydrogen bonding. This heat-resisting layer protects the shape of separator against abnormal heat, and reduces risk of contact and short-circuiting between electrodes.
Furthermore, GE191 Series has high-hydrophilicity and high-viscosity-thickening property (high rheological property), keeps high viscosity of coating materials even under low stress due to uniform disperse of ceramic particles, and has excellent thixotropic property (the property of becoming less viscous when subjected to an applied stress). Therefore, use of GE191 Series as binder for separator gives high-storage-durability (sedimentation-resisting property) to heat-resisting ceramic layer, and enable LIB manufacturers to coat separators and electrodes speedily and improve efficiency of coating process, thereby contributing to cost reduction through cutting in loss of coating materials.
Global LIB market is expected to continue rapid growth due to the progress in 5G telecommunication technology and CASE (connected, autonomous/automated, shared, electric) related automotive technologies. SDK has many products that improve performance of LIBs including PNVA, aqueous binder resin "POLYSOL(TM)," pouch-type LIB packaging material "SPALF(TM)," and additive for anode and cathode "VGCF(TM)." Making the most of these products, SDK will aim to expand its LIB material business further through provision of optimum solutions that respond to the demands of customers.