Development of reliability models for batteries in zero-emission powertrain

Environmental climate change has encouraged countries across the world to develop policies aimed to the reduction of energy consumption and greenhouse gas emissions. The introduction of Zero-emission Vehicles based on electrical powertrains, could reduce the emission of environmental pollutants, the noise levels and could increase the liveability of urban areas. Although in recent years research on batteries has brought several benefits to electric vehicle performance, key barriers to their adoption are still cost, autonomy, long charging times and the leak of a suitable network of charging stations. Substantial improvements in electric vehicles performance are expected with the development of new Li-ion batteries, thanks to some notable advantages over other types of batteries, such as: high energy density, high power density, long cycle life and long calendar life. In this PhD thesis work is first present a reliability assessment procedure based on an ageing model able to estimate from datasheet information the lifetime of Lithium-ion batteries for electric vehicles, the residual capacity and reliability margins under different driving cycles, taking also into account the battery calendar ageing. The manuscript subsequently 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.