SERIES-CONNECTED MULTICELL OPERATION OF LITHIUM-ION CELLS BY FLOATINGMETHOD

The resistance to damage during overcharge and overdischarge of a sing le cell and the possibility of series-connected multi-cell operation h ave been investigated using a commercialized lithium-ion cell. The sin gle cell showed sufficient cycleability in overcharge up to 4.5 V and small reversible capacity in overdischarge under 2.5 V. An overdischar ged cell below 0 V did not generate subsequent electromotive force and behaved like a resistor of an electron conductor. Multi-cell operatio ns including imbalanced cells both in a preshifted state-of-charge bet ween +30 and -5% and in various ambient temperatures were performed fo r over 1000 cycles of charge/discharge by the floating method. (C) 199 7 Published by Elsevier Science S.A.