Comparative Ageing Study of CC-CV Fast Charging for Commercial 18650 Li-Ion Cells: Impact of Environmental Temperature

This work presents first results of an on-going investigation on three commercial 18650 li-ion cell references. Accelerated cycle ageing tests are performed at recommended fast charge current in commercial specifications and at three temperatures (5, 25 and 45 °C). First experimental results reveal that the impact of recommended fast charging current varies significantly between different cell reference and environmental temperature. In general, cells with higher energy density show reduced cycle life under fast charging, in contrast with high power cells. Moreover, the temperature condition at which degradation is minimal varies from one cell reference to the other. These observations suggest that optimized charging protocols and thermal management, specific to each cell reference, can better the trade-off between charging time and durability.