Study On The System Structure And Spectral Properties Of Electric Double Layer Organic Electrolyte

In this paper, DMF/LiNO₃and DMC/LiClO₄was studied through the change ofsolution system’s internal structure and the charcter of infrared and fluorescencespectrum, using the N,N-dimethyl formamide（DMF） and dimethyl carbonate（DMC） assolvent. The reaserch result was verified by simulating as follows:1、 In solution systems, different concentrations correspond to differentconductivity theory: low concentration met with the ion-solvent conductivity theory,ion and solvent molecules were affected by the electrophoretic effect and relaxationeffect that the conductivity is increased with the increasment of concentrationslowly; high concentration met with the ion association conductance theory, theDMF molecules which were affected by Li⁺strongly oriented arrangement andformed the solvation layer. The blocked impact of the DMF molecules around Li⁺were reduced to Li⁺so as to the increasment of the Li⁺and the surrounding solventmolecules’ move rate and the conductivity.2、As the solute added, the DMF and DMC molecules and cations have beensolvated,then calculated solution’s solvation number and confirmed the ion andsolvent interaction possibilities theoretically through infrared spectroscopy by thechange of N-C=O and C=O stretching vibration.Solution ion formation of free ionpair and contact ion pair, the calculated solution association equilibrium constantsof the trend for the first decreases and then increases.3、It showed that nitrogen atom and chlorine atom which are from NO₃^-andClO₄–protonated that n�'π transite reducely and leading to the solution of thefluorescence intensity decreases by comparing the fluorescence spectra. On the lowconcentration LiClO₄/DMC solution fluorescence spectrum for Gauss isdecomposed into5elementary peak, ion association constants affect Gauss elementpeak half width, that is the broadening of spectral lines is greater, more significanteffect in solution with ion association.4、C-N and C=O from [Li（DMF）_n]⁺clusters vibration band happened red shift,thus determine that C-N and C=O bond property have been changed and N-C=Oformed localized bond in the solution. With the increase of the number of DMF, thenumber of positive charge of Li⁺from [Li（DMF）_n]⁺cluster was gradually reduced,and the ability to electronics was also reduced. The drawing capacity of oxygen atoms from N-C=O groups has been decreased on Li⁺partly, so as to shorten thelength of the keys of O-Li. Compared with each cluster of the component of thefrontier molecular orbital in [Li（DMF）_n]⁺, it is found that the absorption spectrumare from the HOMO oxygen atoms and the nitrogen atoms to LUMO lithium atomelectron transition.