화학공학소재연구정보센터
Electrochimica Acta, Vol.45, No.19, 3127-3139, 2000
2-Methoxyethyl (methyl) carbonate-based electrolytes for Li-ion batteries
2-Methoxyethyl (methyl) carbonate (MOEMC) has been identified as a useful solvent for rechargeable Li-ion batteries. The conductivity-temperature and viscosity-temperature data for Li salt solutions in MOEMC can be fitted to the Vogel-Tammann-Fulcher (VTF) equation. The electrolytes formulated in MOEMC are characterized by the appearance of glass-transition temperatures without encountering freezing points, and this unique low-temperature behavior has allowed us to experimentally determine their glass-transition temperatures. This in turn has enabled us to experimentally demonstrate the application of the VTF theory to explain the conductivity-temperature data of these electrolytes. The results support a solvent-assisted ion conduction mechanism attributable to the strong interactions between the solvent molecules and Li ions. There appears to be no strong interaction between solvent molecules and the anions, but because of ion-pairing, the anion conduction is indirectly assisted by solvent fluctuations. Strong interactions between the solvent and Li+ have been verified by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic data. The electrolytes formulated in MOEMC have been tested for their electrochemical stability and Li cycling performance of the graphite anode and the LiCoO2 cathode, thereby demonstrating their utility for Li-ion battery development.