Application of Sydnones to Lithium Battery Electrolytes

Abstract

The sydnone compounds are well known as typical mesoionic compounds. A number of sydnones have been synthesized, and their structures, reactions and various physicochemical properties have been mainly studied in the field of medicine and pharmacology because they have varied types of biological activities. Some alkylsydnones are liquids at room temperature, and have high dielectric constants and large dipole moments. This paper focuses on the characteristics of the 3alkylsydnones to lithium battery electrolytes. Figure 1 shows the conventional structure of alkylsydnones. Fig. 1 Structure of 3-alkylsydnones. 3-MSD 3-ESD 3-PSD 3-i-PSD 3-BSD 3-s-BSD 3-PESD 3-BMSD H H H H H CHa CH~CH2 CH~ In Table 1, physical properties of 3-alkylsydnones at various temperatures are investigated by dielectric constant( f ), viscosity( 7)) and density( p) measurements. These 3-alkylsydnones have high dielectric constants and large viscosities compared with those of other polar solvents. Figure 2 shows the variation in specific conductivity( "' ) of 3-alkylsydnone - 1 ,2-dimethoxyethane (DME) binary mixed solutions. The higher dielectric constant solvent exhibits the higher conductivity in the solution. The 3-alkylsydnone-based binary systems are preferable to 3alkylsydnones alone because of their high conductivities. The enhancement of specific conductivity upon addition ofDME is due to the lower viscosity of the mixture, which increases the ionic mobility. With a larger mole fraction of DME, the conductivities decrease mainly due to the increase in ion pair formation upon addition ofDME with low dielectric constant.