A method of maintaining the performance level of an electrochemical cell is described. The cell usually includes a negative electrode that includes an alkali metal; a positive electrode that includes at least one transition metal halide; a molten salt electrolyte based on an alkali metal haloaluminate; and a sodium ion-conducting solid electrolyte partitioning the positive electrode from the negative electrode. The method is based on a treatment regimen that includes the step of applying a series of electrical cycles to the cell, wherein the series includes at least one deep discharge of the cell. Each discharge of the cell is usually followed by recharging the cell to its available capacity.