A new family of electrolytes is described. It is obtained from liquid ammoniates prepared with mixtures of three selected lithium salts, in which small amounts of amines (compounds derived from ammonia) are added. These electrolytes possess high ionic conductivities (10(-2) S cm(-1) at room temperature) even at low temperature (above 10(-3) S cm(-1) at -20 degrees C) within a large operating temperature range (-20 degrees C, + 60 degrees C) and under a low vapor pressure (below 1 bar at + 60 degrees C).