Effect of WLTP CLASS 3B Driving Cycle on Lithium-Ion Battery for Electric Vehicles

Abstract

Capacity loss over time is a critical issue for lithium-ion batteries powering battery electric vehicles (BEVs) because it affects vehicle range and performance. Driving cycles have a major impact on the ageing of these devices because they are subjected to high stresses in certain uses that cause degradation phenomena directly related to vehicle use. Calendar capacity also impacts the battery pack for most of its lifetime with a capacity degradation. The manuscript describes experimental tests on a lithium-ion battery for electric vehicles with up to 10% capacity loss in the WLTP CLASS 3B driving cycle. The lithium-ion battery considered consists of an LMO-NMC cathode and a graphite anode with a capacity of 63 Ah for automotive applications. An internal impedance variation was observed compared to the typical full charge/discharge profile. Incremental capacitance (IC) and differential voltage (DV) analysis were performed in different states of cell health. A lifetime model is described to compute the total capacity loss for cycling and calendar ageing exploiting real data under some different scenarios of vehicle usage.