Pastor-Fernández, Carlos (2019) Degradation diagnostics of lithium-ion batteries for automotive applications. EngD thesis, University of Warwick.

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Abstract

Motivated by political, social and economic factors, automotive original equipment manufacturers have adopted vehicle electrification as a technology to either reduce or eliminate tailpipe emissions. However, the design and development of Battery Electric Vehicles (BEVs) are facing significant challenges to achieving full market penetration. Some of these challenges are to ensure specific battery performance, range, safety, charging time and lifetime. Battery degradation affects each of these factors negatively. To mitigate this negative impact, researchers agree that battery degradation needs to be better understood. For this, it is essential to develop non-invasive battery health diagnostic techniques that can be applied in real-world operating conditions. This Innovation Report presents the findings from an International Engineering Doctorate (EngD (Int.)).

This Innovation Report investigates factors influencing the degradation of Lithium-ion Batteries (LIB) in BEV applications. The contribution of this research is to provide the underpinning knowledge that allows manufacturers to improve the durability and performance of Electric Vehicle battery assemblies concerning degradation.

This contribution has been achieved through four related studies within two primary areas of investigation. Firstly, the research focuses on evaluating Cell-to-Cell Variabilities (CtCV) in LIB packs in Study 1 and their implications for the monitoring of the State of Health (SoH) in Study 2. Study 1 proposes a systematic procedure to quantify the amount and the origin of CtCV in battery packs. Study 2 quantifies CtCV experimentally with respect to SoH for a scenario equivalent to a typical BEV life (10 years) or customer mileage (100,000 miles). Further, Study 2 suggests a non-invasive methodology to monitor SoH in a vehicle. These results can be employed by academics and engineers to quantify battery degradation in imbalance scenarios. The second avenue of investigation was to improve the current SoH definition employed in the automotive industry. After conducting a critical and extensive review of the most pertinent literature in Study 3, Study 4 suggests a step-by-step methodology to quantify the most pertinent degradation modes. This non-invasive diagnosis methodology can be applied in the context of on-board and on-board vehicle applications. The application of this methodology can be further used by academia and industry to improve lifetime control strategies and future battery designs.

In conclusion, the impact of this thesis is to define diagnosis techniques that can be further employed by engineers to reduce the negative consequences of battery degradation into battery performance, autonomy and lifetime.

Item Type:	Thesis or Dissertation (EngD)
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering T Technology > TL Motor vehicles. Aeronautics. Astronautics
Library of Congress Subject Headings (LCSH):	Electric vehicles -- Batteries, Lithium ion batteries, Lithium ion batteries -- Deterioration
Official Date:	April 2019
Dates:	Date Event April 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Warwick Manufacturing Group
Thesis Type:	EngD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Widanage, Widanalage Dhammika ; Marco, James
Sponsors:	Jaguar Land Rover (Firm) ; Engineering and Physical Sciences Research Council
Format of File:	pdf
Extent:	xxvii, 245 leaves : illustrations, charts
Language:	eng

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