With increasing research on lithium batteries, the technology of electric vehicles equipped with lithium battery packs as the main energy storage system has become more and more mature, and the design and testing of lithium ion battery packs are becoming extremely important. As the battery system becomes more complex, it is necessary to optimize its structural design and to monitor its dynamic performance accurately. This research considers two related topics. The first is the design of a battery submodule made up of cylindrical lithium cells. The objective of this design is to improve its energy density and optimize the heat dissipation performance according to the installation position and space constraints in Ford Focus EV 2013, and, produce a submodule prototype based on this design; The second objective is to derive and verify an equivalent circuit model for a prismatic lithium battery cell of high energy capacity based on experimental results. In terms of mechanical structure, the basic structure of a battery pack is determined by the desired performance as well as cell characteristics. In this research, the Samsung 35E 18650 cylindrical cells are chosen. 20 battery cells are connected in parallel to form a battery submodule, and 13 battery submodules are connected in series to form a battery pack. The battery pack design process mainly includes positioning and connection of battery cells, heat dissipation mechanism, cabling and inside the pack. The above considerations were applied to prototype battery submodule with an energy density of 216.87 Wh/kg. Some key considerations in the design of the battery pack include checking the conductivity and the welding connection. Chemistry of lithium-ion batteries are constantly evolving with industrial demands which call for higher energy storage capacity. Therefore, this research selected a new high-capacity prismatic cell to establish an equivalent circuit model using characterization and experiments, followed by verification. A 280 Ah Lithium Iron Phosphate (LFP) prismatic battery cell was selected and characterized by testing under various operating conditions for validation, the Urban Dynamometer Driving Schedule (UDDS) was used. / Thesis / Master of Applied Science (MASc) / This thesis introduces how to design a battery pack using cylindrical battery cells, also shows how to conduct characterization tests and build a equivalent circuit battery model.

The field of energy storage has improved drastically within the last two decades. Batteries of various chemistries have been relied on to provide energy for numerous portable electronic devices. Lithium-ion cells, when compared to other chemistries have been known to provide outstanding energy-to-weight ratios and exhibit low self-discharge when not in use [1]. The aforementioned benefits in conjunction with decreasing costs have made lithium-ion cells an exceptional choice for use in electrical vehicles (EVs). Battery Management Systems (BMS) in EVs are responsible for providing estimates for values that are indicative of the battery pack’s present operating condition. The current operating condition could be described by State of Charge, power fade, capacity fade and various other parameters [2]. Importantly, it is essential for the estimation technique to adjust to fluctuating cell characteristics as the cell ages, in pursuance of having available accurate estimates for the life time of the pack. In order for the estimation technique to properly estimate the desired quantities, a mathematical model capable of capturing cell dynamics is desired. There are various proposed methods recommended for mathematically modeling a cell, namely equivalent Circuit modeling, electro-chemical modeling and impedance spectroscopy. Consequently, in order to ensure mathematical models are accurate and further to have the ability to compare the proposed models, it is essential to have available data gathered from a given cell at specific operating conditions. This Master’s thesis outlines the development of a lithium-ion cell tester that is capable of controlling, monitoring and recording parameters such as current, voltage and temperature. The Dual capability of obtaining data from standardized cell tests as well as high frequency cell tests is fascinating and intriguing. As this capability holds the possibility of reducing cost otherwise spent on man hours and equipment which are both paramount in any industrially automated process. / Thesis / Master of Applied Science (MASc)

This thesis consists of three main objectives: fundamental and literature review of EV batteries, experimental development, and validation of two liquid cooling battery modules, thermal modeling and comparison of the inter-cell cooling battery module. / The traditional vehicles with internal combustion engine have resulted in severe environmental pollution, which motivates the development of electric vehicles and hybrid electric vehicles. Due to a low energy density and long refueling time of the battery pack, it is still hard for electric vehicles and hybrid electric vehicles to be widely accepted by the consumers. As the batteries with a better ultra-fast charging capability are massively produced, the range anxiety issue is somewhat alleviated. During a charging with large current magnitude, the battery generally has a great amount of heat generation and evident temperature rise. Therefore, a thermal management system is necessary to effectively dissipate the battery loss and minimize the degradation mechanisms caused by extreme temperature. The motivation of this thesis is to study the discipline of the battery thermal management system as an application for electric vehicles. The design methodologies are presented in both experiment test and numerical simulation. For the comparative study between active liquid cooling methods for a lithium-ion battery module using experimental techniques, two battery modules with three Kokam Nickel Manganese Cobalt battery cells connected in parallel are developed. One has liquid coolant flowing along the edge of the model, and another with liquid coolant flowing between the cells. Several characterization tests, including thermal resistance tests, fast charging tests up to 5C, and drive cycle tests are designed and performed on the battery module. The inter-cell cooling module has a lower peak temperature rise and faster thermal response compared to the edge cooling module, i.e., 4.1⁰C peak temperature rise under 5C charging for inter-cell cooling method and 14.2⁰C for edge cooling method. The thermal models built in ANSYS represent the numerical simulation of the inter-cell cooling module as a comparison with the experiment. A cell loss model is developed to calculate the battery heat generation rate under ultra-fast charging tests and a road trip test, which are further adopted as the inputs to the thermal models. The simulation of the 5C ultra-fast charging test gives the peak temperature rise just 0.47⁰C lower than the experimental measurement, it indicates that the FEA thermal models can provide an accurate temperature prediction of the battery module. / Thesis / Master of Applied Science (MASc) / With a demanding market of electric vehicles, battery technologies have grown rapidly in recent years. Among all the battery research topics, the development of ultra-fast charging, that can fully charge the battery pack within 15 minutes, is the most promising direction to address the range anxiety and improve the social acceptance of electric vehicles. Nevertheless, the application of ultra-fast charging has many challenges. In particular, an efficient thermal management system is significant to guarantee the safety and prolong the service life of the battery pack. This thesis contributes to study the fundamentals of the battery field, and design liquid cooling systems to observe the thermal behavior of a battery prototype module under fast charging and general use. FEA thermal modeling of the battery module is developed to provide a guide for further test validation.

Ultra-fast charging of electric vehicles will soon be available to charge the batteries in less than 15 minutes to 80% state of charge. However, very few studies of batteries under these conditions exist. To design a battery pack with ultra-fast charging in mind, more information about batteries is needed, both electrically and thermally. In this thesis, the performance of three specific commercial lithium-ion batteries during ultra-fast charging is investigated and their thermal behaviour is simulated for use in the battery pack design process. The cells are charged at 1C to 6C current rates, or as high as 10C, and the surface temperature of each cell is measured. The loss calculated from the charging tests are used in a thermal analysis of the three batteries using finite element analysis. The batteries are modeled in a simple cooling apparatus to determine their thermal management requirements in a pack, i.e., how effectively must the heat be removed from the cells to obtain a specific temperature in a pack. Test results show that ultra-fast charging is possible with very little loss; but, it is dependent on the battery. The analysis illustrates important trade-offs between the battery type, charge rate, and the thermal management system. This thesis presents a holistic view to the study of the batteries for eventual use in the design of a battery pack. The thermal performance of the batteries is equally important as their electrical (charge) performance. It also attempts to justify the observed behaviour of the batteries by their underlying chemical behaviour. The work here can be used as a jumping-off point for further work on the ultra-fast charging of batteries or the design of a battery pack. / Thesis / Master of Applied Science (MASc) / Ultra-fast charging of electric vehicles, i.e., fully charging the vehicle in less than 15 minutes, will soon be more available. However, literature on the ultra-fast charging of the batteries used in these vehicles is limited. It is not widely known whether the batteries can effectively achieve ultra-fast charging or how the batteries behave under these conditions. Charging batteries this fast means that the battery cells will heat up. The temperature of the cell greatly impacts its longevity and safety. The thesis attempts to address these questions by studying three commercial lithium-ion batteries, selected for specific characteristics, that show potential for ultra-fast charging. The batteries are charged at different rates to ultra-fast charging levels and the charge performance at each rate is determined. The temperature of the batteries is simulated with different cooling systems to determine how effectively must heat be removed from the batteries to maintain the cells at a specific temperature.

With increasing costs of fossil fuels and intensified environmental awareness, low carbon vehicles, including hybrid electric vehicles (HEVs), are becoming more popular for car buyers due to their lower running costs. HEVs are sensitive to the driving conditions under which they are used however, and real-world driving can be very different to the legislative test cycles. On the road there are higher speeds, faster accelerations and more changes in speed, plus additional factors that are not taken into account in laboratory tests, all leading to poorer fuel economy. Future trends in the automotive industry are predicted to include a large focus on increased hybridisation of passenger cars in the coming years, so this is an important current research area. The aims of this project were to determine the energy consumption of a HEV in real-world driving, and investigate the differences in this compared to other standard drive cycles, and also compared to testing in laboratory conditions. A second generation Toyota Prius equipped with a GPS (Global Positioning System) data logging system collected driving data while in use by Loughborough University Security over a period of 9 months. The journey data was used for the development of a drive cycle, the Loughborough University Urban Drive Cycle 2 (LUUDC2), representing urban driving around the university campus and local town roads. It will also have a likeness to other similar driving routines. Vehicle testing was carried out on a chassis dynamometer on the real-world LUUDC2 and other existing drive cycles for comparison, including ECE-15, UDDS (Urban Dynamometer Driving Schedule) and Artemis Urban. Comparisons were made between real-world driving test results and chassis dynamometer real-world cycle test results. Comparison was also made with a pure electric vehicle (EV) that was tested in a similar way. To verify the test results and investigate the energy consumption inside the system, a Prius model in Autonomie vehicle simulation software was used. There were two main areas of results outcomes; the first of which was higher fuel consumption on the LUUDC2 compared to other cycles due to cycle effects, with the former having greater accelerations and a more transient speed profile. In a drive cycle acceleration effect study, for the cycle with 80% higher average acceleration than the other the difference in fuel consumption was about 32%, of which around half of this was discovered to be as a result of an increased average acceleration and deceleration rate. Compared to the standard ECE-15 urban drive cycle, fuel consumption was 20% higher on the LUUDC2. The second main area of outcomes is the factors that give greater energy consumption in real-world driving compared to in a laboratory and in simulations being determined and quantified. There was found to be a significant difference in fuel consumption for the HEV of over a third between on-road real-world driving and chassis dynamometer testing on the developed real-world cycle. Contributors to the difference were identified and explored further to quantify their impact. Firstly, validation of the drive cycle accuracy by statistical comparison to the original dataset using acceleration magnitude distributions highlighted that the cycle could be better matched. Chassis dynamometer testing of a new refined cycle showed that this had a significant impact, contributing approximately 16% of the difference to the real-world driving, bringing this gap down to 21%. This showed how important accurate cycle production from the data set is to give a representative and meaningful output. Road gradient was investigated as a possible contributor to the difference. The Prius was driven on repeated circuits of the campus to produce a simplified real-world driving cycle that could be directly linked with the corresponding gradients, which were obtained by surveying the land. This cycle was run on the chassis dynamometer and Autonomie was also used to simulate driving this cycle with and without its gradients. This study showed that gradient had a negligible contribution to fuel consumption of the HEV in the case of a circular route where returning to the start point. A main factor in the difference to real-world driving was found to be the use of climate control auxiliaries with associated ambient temperature. Investigation found this element is estimated to contribute over 15% to the difference in real-world fuel consumption, by running the heater in low temperatures and the air conditioning in high temperatures. This leaves a 6% remainder made up of a collection of other small real-world factors. Equivalent tests carried out in simulations to those carried out on the chassis dynamometer gave 20% lower fuel consumption. This is accounted for by degradation of the test vehicle at approximately 7%, and the other part by inaccuracy of the simulation model. Laboratory testing of the high voltage battery pack found it constituted around 2% of the vehicle degradation factor, plus an additional 5% due to imbalance of the battery cell voltages, on top of the 7% stated above. From this investigation it can be concluded that the driving cycle and environment have a substantial impact of the energy use of a HEV. Therefore they could be better designed by incorporating real-world driving into the development process, for example by basing control strategies on real-world drive cycles. Vehicles would also benefit from being developed for use in a particular application to improve their fuel consumption. Alternatively, factors for each of the contributing elements of real-world driving could be included in published fuel economy figures to give prospective users more representative values.

Advancements in batteries, microprocessors as well as an extra emphasis being put on the environment has pushed electric vehicles to the forefront of today. Despite the many benefits of electric vehicles, range anxiety and long charge times are hurdles to overcome. These shortfalls are a result of the current battery technology regardless of the many breakthroughs over the last decade. Lithium-ion Batteries and other modern chemistries pose a number of challenges in testing and research when compared to the traditional lead acid batteries. Current test systems fall short in providing a complete testing solution with. The focus of this thesis is to develop a complete software framework for battery characterization: testing, modelling and characterization to accompany battery testing hardware developed by D&V Electronics. The first step in battery characterization, involves battery testing in order to obtain data. This required development of the test software and a number of battery tests, including: Charge and discharge, state of charge vs. open circuit voltage curve generation, Electro-Impedance Spectroscopy, and capacity test. Research was done in order to ensure developed test procedures lined up with that of other publications. All data from the testing data is logged to a central database, allowing for the second major development, the model framework. The model framework is composed of seven different battery models that can be parameterized with the touch of a button, using data collected from the tester. It is a software framework that is meant to be expandable by abstracting the details of a model from the tester. This allows for new models and parameterization techniques to be integrated into the software without the need of new software development. Lastly, all development was used to do a battery characterization of a prismatic battery cell. All tests were conducted on a battery over two hundred cycles, followed by battery parameterization using the mode framework. The battery models were then used to simulate a US06 drive profile and compared to the same profile with measurements taken from the tester. With an average root mean square error of 8 millivolts, the battery characterization using the framework proved to be a success. / Thesis / Master of Applied Science (MASc)

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Litiumjon-batterier har blivit väldigt populära för tillämpning i fordon. Den här teknologin har fler olika kemier att erbjuda som kontinuerligt förbättras. Litium-titanat-oxid-batterier använder (LTO) LTO som anod och erbjuder långt cyklingsliv samt minskar risk för SEI-bildning och litiumplätering.  Det här examensarbetet siktade på att undersöka om LTO-batterier kan användas som startbatterier i kommersiella fordon. Metodologin inkluderade två motorstart försök med en kommersiell 12s1p LTO-modul, laddnings/urladdningtester med en kommersiell LTO-cell med nominell spänning 2.3V samt överurladdningstester med byggda pouchceller. Materialet för pouchceller extraherades från en kommersiell LTO-cell och sedan studerades med SEM-EDX före och efter överurladdningstesterna. Resultatet visade att LTO-batterier kan användas som startbatterier i en diesel V8 motor även vid 39%SoC. Dessutom visade simuleringar att LTO-batterier kan användas inom Kinetic Energy Recovery System (KERS) tillämpning och behålla 60% SoC efter 500 laddning/urladdnings cykler. Resultaten från både KERS och motorstarterna visade att LTO är en lovande kandidat för ersättning av blybatterier. Laddnings/urladdnings tester visade att en kommersiell 12s1p LTO modul kan maximalt uppnå 73%SoC när den laddas med fordon-liknande strömmar. Däremot var SoC oberoende av laddningsström. Överurladdningstester med pouchceller visade att det är relativt ofarligt att urladda LTO 0.4V under spänningsgränsen utan stora ökningar i impedans eller stor kapacitetsförlust. Största förluster kopplades till åldring av NMC-baserade positiva elektroden. / Lithium ion batteries have become quite popular in vehicle applications in the past few decades. This technology offers multiple chemistries to choose from, that are continuously studied and improved. Lithium-titanate-oxide (LTO) batteries use LTO material as an anode, providing long cycling life, as well as essentially eliminating risk for SEI formation and lithium plating.  This Master thesis project aimed to investigate how well LTO-based lithium-ion batteries can perform in Start Ignition Lighting (SLI) application in commercial vehicles. The methodology included two engine crank tests with a commercial 12s1p LTO module, charge/discharge tests on a commercial LTO cell with nominal voltage 2.3V, as well as overdischarge cycling tests on assembled pouch cells. The materials for the pouch cells were extracted from a commercial LTO cell and later analysed with SEM-EDX before and after overdischarge tests. The results demonstrated that LTO-based Li-ion batteries can be successfully start a diesel V8 engine even at 39% SoC. Furthermore, when simulating an urban vehicle with an implemented Kinetic Energy Recovery System (KERS) application, a commercial cell LTO cell achieved and retained around 60\%SoC throughout 500 charge/discharge cycles. Combined results from KERS and engine start tests imply that LTO is a strong candidate for replacing lead-acid in these applications. Charge/discharge tests showed that commercial 12s1p LTO cell can maximum reach around 73%SoC when charged in a vehicle-like way. However, this maximum SoC limit was more or less independent of applied charging current. Furthermore, electrochemical overdischarge tests on the pouch cells demonstrated that it is relatively safe to overdischarge the cell 0.4V below the specified safety limit without significant rise in impedance or capacity fade. Major performance losses were attributed to the aging of the NMC-based positive electrode.