An evaluation of the use of ethylene carbonate as a solvent for high‐energy nonaqueous batteries has been performed. The results are compared with those obtained for propylene carbonate. A solution has higher conductivity, lower viscosity, and lower influence on the polarization of Li, , and electrodes than an analogous solution. Discharge curves at 1.0 and 2.4 mA/cm2, obtained under the same conditions in and PC solutions for and cells, gave better results when EC was used. A test cell , capable of providing about 200 Whr/kg (outside casing excluded) when discharged at 1.0 mA/cm2 at 30°C, has been fabricated.