An unusual overcharge tolerance phenomenon was observed in Electrochem's polymer lithium ion cells. The cells could be overcharged up to several times of the nominal capacity without a significant increase in cell potential. Experimental studies were carried out to understand this phenomenon. Cyclic voltammograms on gelled solid polymer electrolytes indicated that this phenomenon was not originated from oxidation-reduction shuttle mechanism. A correlation between the apparent overcharge tolerance capability and anode to cathode capacity ratios was found. This observation suggested that a portion of the overcharge current was bypassed by a weak electronic conducting path associated with non-dendritic lithium deposition on carbon anode surfaces during overcharge.
展开▼
