Monitoramento da condutividade e dos espectros vibracionais de eletrólitos à base de Mg(II) e híbridos contendo Mg(II) e Li(I): informações de interesse à área de baterias de metais multivalentes

Abstract

Ion conductivity and vibrational spectra measurements were carried out for the Mg(CF3SO3)2 tetrahydrofuran(THF)/N,N-dimethylformamide (DMF) and Mg(CF3SO3)2:LiClTHF/DMF electrolytes and the data are in excellent agreement. Solvent-separated ion pairs (SSIPs) are the major species in both systems and are characterized by a band at 754 cm-1 (δs(CF3) mode of triflate). Ion associations taking place in minor proportion are described by a band at 758 cm-1 , which is assigned to Mg2+:CF3SO3 - type contact ion pairs (CIPs), in the former electrolyte, and Cl-:Mg2+:CF3SO3 - and Li+ :CF3SO3 - kind CIPs in the second system. Spectral changes are also observed for the vibrational modes of THF and DMF coordinated to the cations. At the region of the ether (ν(CO+CC)), the Raman spectra of the electrolytes show the same asymmetry at 895 cm-1 , which is better resolved from the IR ones. Bands at 687 and 672 cm-1 are observed and attributed to the δs(OCN) vibrations of DMF bound to Mg(II) and Li(I), respectively. The findings reported here are certainly of interest to Mg battery community.