Simcal Project: Calendar Aging Results Obtained On a Panel of 6 Commercial Li-Ion Cells

Battery performances degrade over time, not only due to their charge/discharge profile, commonly called ‘cycling aging’, but also at rest, commonly called ‘calendar aging’. This second type of aging is much less studied than the first one, probably due to the fact that the purpose of a battery is precisely to be charged / discharged. Many efforts have thus been made by battery manufacturers to improve aging in cycling. Moreover, we intuitively expect a greater impact on aging of cycling compared to rest time. However, time spent at rest can be prominent in many applications. This is the case of vehicles (including electric vehicles) which stay at rest approximately 90% of their time (in parking mode). This is why the SIMCAL Project, conducted by 14 French partners, focused on the study of calendar aging during 3 years. This communication establishes a synthesis of performances obtained, and describes the main aging mechanism understood thanks to post-mortem analyses.