Testing and characterisation of large high-energy lithium-ion batteries for electric and hybrid electric vehicles

This thesis considers the drivetrain and battery system requirements of Hybrid Electric Vehicles. The data herein proves that a series hybrid electric drivetrain with Lithium-ion batteries and plug-in recharge promises to be viable and sustainable. However, for mass production of series HEVs comprehensive performance characteristics and prediction of ageing behaviour of Lithium-ion batteries is essential but currently not available.<br/>The main part of the thesis, following a graphical comparison of different energy storage solutions, is a detailed treatise on large Li-ion batteries. Construction and Li-ion working principles are summarised, together with several effects such as Peukert and memory effects, ageing of Li-ion cells, their temperature dependence and safety, and limits of charging/discharging.<br/>Preliminary performance tests on 50 and 100 Ah Li-ion cells showed the necessity for a careful investigation of suitable reference conditions in order to achieve reproducibly precise results from repeated discharge/charge cycles. Then the main tests result in detailed graphs and tables of the discharge and charge characteristics. These main tests include effects of rate of discharge, energy-efficiency, temperature, resting time between test-cycles, hysteresis, ageing, and degradation. A new testing method that is based on the step response technique is suggested and investigated to whether it gives a meaningful but rapid measure of open circuit voltage and equivalent circuit models of the battery. Statistically significant theoretical models, equations and graphs are included.<br/>The Appendix gives summaries of the author's seven main publications and presentations dealing with Systems Approach and five publications on Large Li-ion batteries, followed by most of these in full.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2007

Author dc:creator

• Doerffel, Dennis