Research On The Construction Of Ordered Ion Channels Driven By Electric Field And Their Conduction Enhancement Effect

With the rapid development of lithium ion batteries(LIBs),its better performance as the higher safety and stability were much more required.Solid polymer electrolytes have been widely studied because of its high conductivity,good mechanical properties and stable chemical properties,but the ion migration rate was significantly lower than that of traditional liquid electrolyte.The problem can be effectively solved through changing the polymer phase structure and adding conductive particlesaligned via extra filed force to formulate the dual ion channels.In this study,the electrical field was applied to control the phase structure of the blend polymer of polyethylene glycol diacrylate(PEGDA)/ polydimethylsiloxane(PDMS),so that the conductive polymer PEGDA formed polymer channels inside the matrix.On the basis of this,the well-conducting ceramic particles lithium titanium aluminum phosphate(LATP)and ionic liquid of 1-butyl-3-methylimidazolium(three trifluoroacetic sulfonyl)imide(BMIM TFSI)were added into the blend polymer.They were allowed to enter the PEGDA and align with the PEGDA to obtain a solid polymer electrolyte membrane with dual ion channels.The motion and orientation of particles in the substrate of PDMS were monitored synchronously by optical microscopy.The distribution of particles in the material section was characterized by scanning electron microscopy(SEM),energy spectrum analysis(EDS)and Raman spectroscopy.And then the ionic conductivity of the films was tested by the electrochemical workstation.In the alternative current(AC)electrical field,droplets of PEGDA connected closely and formed chains in the direction parallel to the electric field in the matrix of PDMS due to polarization.The LATP/PEGDA/PDMS membranes in which LATP oriented to form dual ion channels with three-dimensional network structure were prepared under AC of 800 V/mm and 100 Hz for 5 min.The network structure was confirmed through SEM observation,EDS element analysis and Raman spectrum analysis.The AC impedance of thin films was tested by electrochemical workstation,later the ionic conductivity was calculated using the formula.Compared with the film untreated by electric field,the oriented films showed an overall increase on ionic conductivity and it increased as the temperature rose.Similarly,droplets of BMIM TFSI formed the best structure in the polymer matrix of PEGDA/PDMS in which BMIM TFSI was oriented to be dual ion channels with three-dimensional network structure under AC of 1000 V/mm and 100 Hz for 5 min.Then BMIM TFSI /PEGDA/PDMS membranes were prepared under this condition.The network structure in the cross section was confirmed through SEM observation,EDS element analysis and Raman spectrum analysis.And the ionic conductivity was calculated using the formula after that AC impedance of thin film materials was tested by electrochemical workstation.The ionic conductivity of the oriented films was higher evidently compared with the film untreated by electric field.Meanwhile it increased as the temperature rose that conformed to Arrhenius equation.