Battery Separators Consisting Of Polyphenylene Sulfide Nonwovens Modified By Silicone Or Silica Ceramic Slurry

At present,lithium-ion battery has been developed into the mobile vehicles,energy storage systems and other fields,which requires the battery with high energy density and power density.However,the development of high-performance batteries must focus on the two major challenges associated with: security problems and battery performance problems.As a part of lithium-ion battery,the separator plays the isolation of cathode materials and anode materials,which prevents the electrons from passing through.Although the separator does not participate in any battery reaction,but its structure and performance of the battery have an important impact on the charge and discharge performance and safety performance.Therefore,in order to achieve the successful development of high-energy-density lithium-ion battery,it is necessary to develop high-performance separator with matching.Polyolefin porous membranes such as PE or PP have many advantages and have an absolute dominance in commercial lithium ion batteries.However,the polyolefin separator temperature resistance is limited,and has a relatively low porosity and poor electrolyte infiltration,which will seriously limit the safety performance of the battery and charge and discharge performance.The nonwoven separator has the characteristics of low processing cost and high porosity,and it is possible to get rid of the defects of single material selection of polyolefin porous separator due to the wide range of nonwoven material selection.Thus,the use of high temperature polymer nonwovens to prepare high-performance diaphragm has become an important development direction today.Polyphenylene sulfide?PPS?has a good high temperature thermal stability,chemical resistance,flame retardant,insulation and so on.Therefore,the use of non-woven fabric prepared as a diaphragm in the large-capacity lithium-ion battery has great potential for application and industrialization prospects.Based on this advantage,this project will be a high-performance meltblown polyphenylene sulfide non-woven fabric as the substrate,through its surface modification method,the preparation of polyphenylene sulfide-based composite separator.And the basic physical properties,electrochemical performance and battery performance of the separator were characterized.The specific research contents are as follows:?1?A composite separator?VSR/PPS?having a porous structure was obtained by physically coating the vinyl silicone resin?VSR?on the surface of the polyphenylene sulfide?PPS?nonwoven.The basic physical properties,electrochemical properties and battery properties of the composite separators were characterized by suitable means.It has been found that the composite separator has good wettability compared with the commercial separator,which is mainly related to the pore structure of the composite separator and its composition.The composite separator has a higher discharge specific capacity,which is mainly due to the excellent wettability of the composite separator and the higher porosity of the separator,which can provide a higher ionic conductivity and a lower interface impedance for the separator.In addition,we also found that the composite separator at high temperature dimensional stability is much better than the commercial diaphragm.?2?The composite separator?SiO₂@PVDF/PPS?with porous structure was obtained by physically coating nano-SiO₂ and PVDF on the surface of polyphenylene sulfide?PPS?nonwoven.The basic physical properties,electrochemical properties and battery properties of the composite separators were characterized by suitable means.It has been found that the composite separator has good wettability compared with the commercial separator,which is due to the development of composite separator height pore structure,coated with high specific surface area of nano-SiO₂,with liquid-like groups of PVDF and composition of the material polarity,which enhanced the absorption of the composite membrane on the electrolyte.The composite has a higher discharge specific capacity,which is mainly due to the excellent wettability of the composite separator and the higher porosity of the separator,which can provide a higher ionic conductivity and a lower interface impedance for the separator.In addition,the composite separator at high temperature dimensional stability is much better than commercial separator,which is mainly due to the excellent thermal stability of the polyphenylene sulfide nonwoven itself,and the surface of the composite membrane is coated with nano-SiO₂ with excellent heat resistance,which provides security for the battery working under the condition of high temperature environment.