Preparation And Properties Of PAMPS-based Lithium Ion Polymer Electrolyte Membranes

Polymer electrolytes membrane is key material to determine the performance of lithium batteries.There are also a series of the problems in application for polymer electrolytes membrane,such as the low ionic conductivity,the poor dimensional stability and the safety problems with electrolyte solutions.In order to solve the above problem,based on 2-acrylamido-2-methylpropanesulfonic acid（AMPS）,a series of sulfonic acids were synthesized by the strong ion activity of sulfonic acid groups and the polymerization of carbon-carbon double bonds.The copolymer of the group was modified by the method of blending modification,and the compatibility of the polymer electrolyte membrane was investigated by cosolvent method,viscosity method and EDS spectrum analysis.Further research on the structure and properties of the polymer electrolyte membrane is carried out to optimize the performance of the polymer electrolyte membrane.The specific research content is as follows:A polymer containing a sulfonic acid group and an amide group has good hydrophilicity,electrical conductivity,and thermal stability,but a single polymer electrolyte membrane has poor film forming properties,and a polymer containing a fluorocarbon structure can Further improve the mechanical properties and ionic conductivity of the polymer.In this paper,the free radical polymerization of 2-acrylamido-2-methylpropanesulfonic acid（AMPS）monomer was carried out by solution polymerization using potassium persulfate-sodium bisulfite as initiator and aqueous solution as dispersion medium.Copolymerization of acrylamido-2-methylpropanesulfonic acid/trifluoroethyl methacrylate（AMPS/TFEMA）,respectively,to obtain a clear and transparent viscous polymer PAMPS solution at a concentration of20%after 8 hours of reaction.The copolymer of P（AMPS-TFEMA）,which is a blue-green viscous copolymer,was characterized by infrared spectroscopy,nuclear magnetic resonance,XRD and XPS,and the thermal stability was tested.Experiments show that the analysis of the characteristic peaks of the copolymer by IR and ¹H NMR,as well as the further characterization of XRD and XPS,found that AMPS monomer,AMPS and TFEMA have successfully polymerized separately to form polymer PAMPS and copolymer P（AMPS-TFEMA）.After thermogravimetric analysis,it was found that both the polymer PAMPS and the copolymer P（AMPS-TFEMA）have good thermal stability.The blending compatibility of polymer PAMPS,P（AMPS-TFEMA）and PVDF was studied by cosolvent method,viscosity method and EDS spectrum analysis.The results showed that the PAMPS/PVDF showed good compatibility when the ratio of PAMPS was 10%-40%by cosolvent method and viscosity method.When PPEGS-PEG was 20-30%,the content of PEG was 20-30%.（PAMPS-PEG）/PVDF has good compatibility;when P（AMPS-TFEMA）ratio is 10%-40%,P（AMPS-TFEMA）/PVDF shows good compatibility.The EDS spectrum analysis further confirmed that the copolymer and PVDF have a good compatibility in a certain ratio.P（AMPS-TFEMA）/PVDF,PAMPS/PVDF and（PAMPS-PEG）/PVDF blend membranes were prepared by immersion precipitation phase inversion.The surface structure of the film was observed by infrared spectroscopy and SEM,and the properties of the film were tested.It was found that as the polymer content increased,the electrolyte membrane exhibited more and more uniform pores.Combining the properties of the three polymer membranes,the most mechanically effective membrane is（PAMPS-PEG）/PVDF,which can withstand a maximum force of 17.99N;the conductivity of P（AMPS-TFEMA）/PVDF membrane is 2.6×10^-3S.cm^-1,the electrochemical window is 3.5V,P（AMPS-TFEMA）/PVDF blend membrane thermal decomposition temperature is 350°C,and the change in swelling ratio is 3.06%.