Study On The Preparation And Characterization Of Composite Separator Modified By Nano Particles For Lithium-ion Batteries

In the Lithium ion battery system,the separator is one of the key materials,which build the battery electrolyte system together with the electrolyte.It plays an important role on the electrochemical performance and safety performance of the battery.In this paper,two kinds of nano particles?nano-TiO₂ and nano-BaSO₄?were prepared by the methods of in-situ polymerization and surface modification,and composite separators were prepared by using the methods of solvent evaporation and liquid phase precipitation.The main research contents and results were showed as follows:?1?The composite electrolyte separator was prepared by coating nano-TiO₂ particles upon the surface of aramid membrane with PVDF-HFP copolymer as binder.The test results of scanning electron microscopy?SEM?,transmission electron microscope?TEM?,thermo gravimetric analysis?TGA?,thermal shrinkage,electrochemical impedance spectroscopy,and battery performance test showed that the properties of composite separators enhanced significantly by the addition of nano-TiO₂ particles.The results showed that the composite separator had excellent thermal stability that the shrinkage was 0 % at 150 ?.The porosity,electrolyte uptake and ionic conductivity of the composite separator were 45 %,214 % and 1.34 mS/cm.Meanwhile,the battery performance demonstrated that the cycling performance and c-rate performance of the composite separator containing nano-TiO₂ particles were much better than those of composite separator without nano-TiO₂ particles.?2?The composite electrolyte separator was prepared by coating nano-BaSO₄ particles upon the surface of aramid membrane with PVDF-HFP copolymer as binder.The test results of scanning electron microscopy?SEM?,thermo gravimetric analysis?TGA?,thermal shrinkage,electrochemical impedance spectroscopy,and battery performance test showed that the properties of composite separators enhanced significantly by the addition of nano-BaSO₄ particles.The results showed that the composite separator had excellent thermal stability that the shrinkage was 0 % at 200 ?.The porosity,electrolyte uptake and ionic conductivity of the composite separator were 58.4 %,134 % and 0.83 mS/cm.Meanwhile,the battery performance demonstrated that the cycling performance and c-rate performance of the composite separator containing nano-BaSO₄ particles were much better than those of composite separator without nano-BaSO₄ particles.