| 摘要 |
A method of operating a secondary electrochemical cell comprises the steps of (a) measuring the quantity of charge produced by the cell during discharge, (b) recharging the cell by imposing a substantially constant charging current across the cell until the cell voltage reaches a predetermined cutoff voltage, and (c) continuing to charge the cell at the predetermined cutoff voltage until the total charge returned to the cell is equal to the charge produced by the cell during the preceding discharge. The method substantially completely charges lithium ion and other similar secondary cells, under a variety of operating conditions, without causing measurable damage due to overcharge. Discharge capacity remains substantially unchanged over numerous cycles employing the technique. Charging times necessary to achieve full recharge are also shorter than for conventional, prior art techniques. The method also increases the capacity available from secondary cells operated at low temperatures. Adjusting the cutoff voltage to compensate for measured internal resistance and charging to a coulombic cutoff can be practiced separately to advantage, the combination of the two results in improved charge retention and reduction of charging time while protecting the cell from undesirable over-discharge reactions. |
