Electrolyte systems based on diethyl carbonate

The solubility of the components of binary systems LiX-diethyl carbonate (D EC), where X = BF4- PF6-, ClO4-, in the temperature range 10-60 degreesC wa s studied by the isothermal saturation method. The compositions of the equi librium solid phases were determined by chemical analysis. In the systems L iBF4-DEC and LiPF6-DEC in the examined temperature range the following soli d phases are formed along with the nonsolvated salt: LiBF4.DEC and LiPF6.2D EC, with the melting points of 35.5 and 27.1 degreesC, respectively. The so lubility of the crystal solvates increases with temperature. The temperatur e coefficient of the solubility of LiBF4 in diethyl cabonate is negative, a nd that of LiPF6, positive. In the system LiClO4-diethyl carbonate, dependi ng on temperature, the solid phase occurring in equilibrium with the satura ted solution is either nonsolvated salt or the crystal solvate LiClO4.2DEC melting congruently at 24.8 degreesC. The temperature coefficient of the so lubility of LiClO4 in diethyl carbonate is positive. The temperature depend ence of the solubility of the crystal solvate passes through a maximum. The compositions of the crystal solvates were confirmed by chemical and thermo gravimetric analyses, and their purity was confirmed by X-ray phase analysi s and IR spectroscopy.