Calendar life performance of pouch lithium-ion cells

An accelerated method was used to determine the effect of temperature, end-of-charge voltage and the type of storage condition over the performance pouch lithium-ion cells. The cells were studied for 4.0 V and 4.2 V end-of-charge voltages (EOCV) both at 5 degrees C and 35 degrees C. The irreversible capacity loss of the cell was analyzed every month using a capacity measurement protocol. The results indicated that higher temperature and voltage accelerates the degradation of the cells. The open circuit voltage (OCV) decay of the cells stored under open circuit conditions was also analyzed. The reasons for the irreversible capacity loss, energy loss, OCV decay and the increase in the internal resistance of the cell are discussed in detail. The most detrimental storage condition and the most mild storage condition are identified and discussed in detail. (c) 2004 Elsevier B.V.. All rights reserved.