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Enhancement of meltdown temperature of the polyethylene lithium-ion battery separator via surface coating with polymers having high thermal resistance / Y. S. Chung in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4346–4351 Titre : Enhancement of meltdown temperature of the polyethylene lithium-ion battery separator via surface coating with polymers having high thermal resistance Type de document : texte imprimé Auteurs : Y. S. Chung, Auteur ; S. H. Yoo, Auteur ; C. K. Kim, Auteur Année de publication : 2009 Article en page(s) : pp. 4346–4351 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Lithium-ion  battery  Polyethylene  separators  Thermal  runaway  reactions Résumé : When a lithium-ion battery is overcharged, it starts to self-heat because of exothermic reactions occurring within the components of the cell. Separator shutdown is a useful safety feature for preventing thermal runaway reactions in lithium-ion batteries. The polyethylene (PE) separators used here had shutdown temperatures of around 135 °C. Because the cell temperature continues to increase before actually beginning to cool even after shutdown, the separator should have a higher meltdown temperature than the shutdown temperature to work as an insulator even above the shutdown temperature. To enhance the meltdown temperature of the separator, in this study, a PE separator was coated with polymers synthesized from various ethylene glycol dimethacrylate monomers. When the separator was coated with polymer synthesized from diethylene glycol dimethacrylate (DEGDMA), its shutdown temperature and meltdown temperature were increased to 142 and 155 °C, respectively. Furthermore, a slight increase in the air permeability of the separator was observed when the separator was coated with polymer synthesized from an ethanol solution containing the proper amount of DEGDMA. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900096z [article] Enhancement of meltdown temperature of the polyethylene lithium-ion battery separator via surface coating with polymers having high thermal resistance [texte imprimé] / Y. S. Chung, Auteur ; S. H. Yoo, Auteur ; C. K. Kim, Auteur . - 2009 . - pp. 4346–4351. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4346–4351 Mots-clés : Lithium-ion  battery  Polyethylene  separators  Thermal  runaway  reactions Résumé : When a lithium-ion battery is overcharged, it starts to self-heat because of exothermic reactions occurring within the components of the cell. Separator shutdown is a useful safety feature for preventing thermal runaway reactions in lithium-ion batteries. The polyethylene (PE) separators used here had shutdown temperatures of around 135 °C. Because the cell temperature continues to increase before actually beginning to cool even after shutdown, the separator should have a higher meltdown temperature than the shutdown temperature to work as an insulator even above the shutdown temperature. To enhance the meltdown temperature of the separator, in this study, a PE separator was coated with polymers synthesized from various ethylene glycol dimethacrylate monomers. When the separator was coated with polymer synthesized from diethylene glycol dimethacrylate (DEGDMA), its shutdown temperature and meltdown temperature were increased to 142 and 155 °C, respectively. Furthermore, a slight increase in the air permeability of the separator was observed when the separator was coated with polymer synthesized from an ethanol solution containing the proper amount of DEGDMA. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900096z

Performance changes of surface coated red phosphors with silica nanoparticles and silica nanocomposites / Y. S. Chung in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 740–748 Titre : Performance changes of surface coated red phosphors with silica nanoparticles and silica nanocomposites Type de document : texte imprimé Auteurs : Y. S. Chung, Auteur ; M. Y. Jeon, Auteur Année de publication : 2009 Article en page(s) : p. 740–748 Note générale : chemical engenireeng Langues : Anglais (eng) Mots-clés : Phosphors Résumé : To improve the photoluminescence and long-term stability of the Y2O2S:Eu3+ phosphor, surface coatings with silica nanoparticles and poly(methyl methacrylate) (PMMA)-silica nanocomposites were performed via four different techniques. Phosphors were coated with nearly monodispersed silica nanoparticles (5 nm) by a dip-coating method and a sol−gel method (Stöber method). To fabricate the silica nanopariticles used for the phosphor coating, hydrolysis and condensation reactions for the formation of silica nanoparticles, and radical polymerization for the formation of poly(1-vinyl-2-pyrrolidone) were performed simultaneously. Phosphors were coated with PMMA-silica nanocomposites by using two different methods: by reacting silica nanoparticles and methyl methacrylate (MMA) monomer and by reacting mixtures containing MMA and tetraethylorthosilicate. Between these methods, the latter method exhibited the greatest enhancement of photoluminescence and long-term stability of the phosphors. When phosphors were coated with PMMA-silica nanocomposite by the second method, the PL intensity of Y2O2S:Eu3+ was enhanced approximately 5% over that of the uncoated phosphors. In contrast to a decrease in cathode luminescence (CL) intensity with increasing bombardment time for uncoated phosphor, a nearly constant CL intensity was observed for the phosphors coated with PMMA-silica nanocomposite by the latter method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007488 [article] Performance changes of surface coated red phosphors with silica nanoparticles and silica nanocomposites [texte imprimé] / Y. S. Chung, Auteur ; M. Y. Jeon, Auteur . - 2009 . - p. 740–748. chemical engenireeng Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 740–748 Mots-clés : Phosphors Résumé : To improve the photoluminescence and long-term stability of the Y2O2S:Eu3+ phosphor, surface coatings with silica nanoparticles and poly(methyl methacrylate) (PMMA)-silica nanocomposites were performed via four different techniques. Phosphors were coated with nearly monodispersed silica nanoparticles (5 nm) by a dip-coating method and a sol−gel method (Stöber method). To fabricate the silica nanopariticles used for the phosphor coating, hydrolysis and condensation reactions for the formation of silica nanoparticles, and radical polymerization for the formation of poly(1-vinyl-2-pyrrolidone) were performed simultaneously. Phosphors were coated with PMMA-silica nanocomposites by using two different methods: by reacting silica nanoparticles and methyl methacrylate (MMA) monomer and by reacting mixtures containing MMA and tetraethylorthosilicate. Between these methods, the latter method exhibited the greatest enhancement of photoluminescence and long-term stability of the phosphors. When phosphors were coated with PMMA-silica nanocomposite by the second method, the PL intensity of Y2O2S:Eu3+ was enhanced approximately 5% over that of the uncoated phosphors. In contrast to a decrease in cathode luminescence (CL) intensity with increasing bombardment time for uncoated phosphor, a nearly constant CL intensity was observed for the phosphors coated with PMMA-silica nanocomposite by the latter method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007488