The Study On Preparations And Modifications Of The New Gel Polymer Electrolyte Membranes For Lithium Ion Batteries

The gel polymer electrolyte?GPE?was studied and concerned widely because of higher ionic conductivities and its good mechanical properties as well as safety.Now,the preparation of GPE with good performance is the main research direction,The good performances include good compatibility with the electrolytic solution,the ideal microstructure and high room temperature ionic conductivity as well as good mechanical strength and thermodynamic stability,This paper prepared gel polymer elecrolyte with best comprehensive properties by blending different materials.GO was prepared by the modified Hummers,and GO was placed in a furnace preheated to 1050? with N₂,after ten minutes,GO was splitted into individual sheets because of the evolution of CO₂ and H₂O.Graphite,GOand GN were characterized by FTIR,SEM,XRD Test.the surface of GO is rich in founctional groups,such as C=O,C-OH,-COOH,C-O-C et al.so interlayer spacing of GO?d001=8.327 A?is obviously greater than Natural flake graphite?d002=3.361A?;the structure of Graphene is not exactly single layer,but Several single overlay.some structure of graphite was maintained in grapheme.PAN-MA/PVDF,PAN-MA/GO,PAN-MA/PVDF/GN based GPE matrix film was prepared by three step method including solution copolymerization,solution blending and solvent evaporation.After three matrix films absorbing electrolytic solution,the GPE membranes was prepared,the change of the structures and properties of the GPE membranes with different content of PVDF,GO,GN was studied and characterized by FTIR,DSC,SEM,Mechanical Test,AC Impedance Plot Test.The results show GPE membranes with nano-meter and micro-meter holes and better swelling properties after absorbing electrolytic solution.Porous structure is good for absorption of the electrolyte.The ionic conductivity is proportional with liquid holdup.the structures of graphite oxide and graphene are layers with large specific surface area,so,the porosity of the membrane increases.The polymer membranes have the advantages of stable mechanical properties and high conductivity by adding an appropriate content of blending materials.When the content of PVDF is 25%,the maximum liquid holdup of PAN-MA/PVDF GPE is 27%and the the maximum conductivity is 1.580 × 10^-4 S/cm at room temperature.When the content of GO is 5%,the maximum liquid holdup of PAN-MA/GO GPE is 39.5%,the maximum conductivity is 2.444 × 10^-4 S/cm at room temperature,when the content of GO is 5%,the maximum liquid holdup of PAN-MA/PVDF/GN GPE is 50.1%,the maximum conductivity is 3.354 × 10^-4 S/cm.their performance are meeting the requirements of lithium ion batteries.Graphite oxide and graphene materials are expected to be widely used in the field of lithium ion batteries.