Thermal Management of Electric Vehicle Battery Packs

This dissertation discusses the thermal management needs of electric vehicle battery packs and the appropriate techniques to improve their performance. It covers the working of lithium-ion batteries, heat problems, operating range, and the need for battery thermal management systems. Various cooling techniques such as air cooling, liquid cooling, direct refrigerant cooling, and phase change material are evaluated, and a combined solution is proposed. The dissertation is submitted in partial fulfillment for the degree of in at .

To analyze & quantify the thermal (Heat) management needs of Electric Vehicle battery packs &
apply appropriate thermal management techniques
<Author name>
<Guide name>
<Month name yyyy>
Dissertation submitted in partial fulfilment for the
degree of
<Degree name> in <insert your degree title>
<Faculty name>
<University name>

Abstract
Electric vehicles are becoming more and more popular because they used electricity as the
source of energy, which does not emit any hydrocarbons or greenhouse gas. They are
efficient, fast to meet the requirements of the masses. However, there are certain factors that
limits their development. Some of them are cost, safety and life of the battery. Therefore, the
study of this management needed in order to accomplish the maximum power improving the
performance under any condition.
The battery thermal management system (BTMS) plays a very important role to regulate the
heat exchange in the batteries. Some of the BTMS technologies are, air cooling system, liquid
cooling system, director refrigerant cooling system and phase change material (PCM). This
evaluated on the basis of their size, cost, reliability and many other factors and based on that
a combined solution is evolved that could solve the issues of thermal management and
increasing the performance to a great level compared to the before systems.
i

Acknowledgment
The support from my teachers needs to be acknowledged because without their support it
would not have been possible for me to finish this project. They guided me throughout the
project which was precious. Apart from them I would also like to acknowledge staff members
and my friends who encouraged me to take this project as a challenge that would help me to
learn and grow.
A special thanks to me parents who helped me in my research for the sources. They have
always inspired me. Last but never the least I would like to acknowledge god almighty who
have always filled me with positive energy, not just in this project but throughout my life.
ii

Table of Contents
Abstract.......................................................................................................................................i
Acknowledgment.......................................................................................................................ii
Table of Contents......................................................................................................................iii
1 Introduction.........................................................................................................................1
1.1 Background..................................................................................................................1
1.2 Objectives....................................................................................................................1
1.3 Overview.....................................................................................................................1
2 Lithium-ion Batteries..........................................................................................................2
2.1 Working.......................................................................................................................2
2.2 Heat problems..............................................................................................................4
2.3 Operating range...........................................................................................................5
3 Battery Thermal Management Systems (BTMS)...............................................................7
3.1 Needs...........................................................................................................................7
3.2 Some of the cooling techniques...................................................................................7
3.2.1 Air systems...........................................................................................................7
3.3 Liquid systems.............................................................................................................9
3.4 Direct refrigerant systems..........................................................................................11
3.5 Phase Change Materials............................................................................................12
4 Appropriate Thermal Management Solution...................................................................14
4.1 Combined liquid cooling system (CLS) + PCM.......................................................15
5 Conclusion........................................................................................................................19
References.................................................................................................................................iv
iii

1 Introduction
1.1 Background
As the time is changing, the technology is also changing. The electric vehicles are becoming
more and more advanced. Different types of batteries are employed for the purpose is to
optimise everything. The batteries operate by generating energy through electrochemical
reactions which are highly temperature dependent. In order to maintain proper working
environment of temperature, a battery thermal management system is employed. Therefore
the correct knowledge of the system, its application and implementation is very much
required. Also note that as the time is changing everything is become compact, and so is the
battery but as the batteries are becoming smaller and smaller, its capacity and power
requirements are increasing. Therefore the energy consumption is another important aspect in
BTMS. Thus increasing the life of the battery.
1.2 Objectives
The goal of this report propose a model for balancing the temperature of a battery so that its
performance is increased. For this every aspect of a battery is discussed starting from the
basic model of a lithium-ion battery. Many systems for heating and cooling are discussed in
detail and at last a combined solution is provided that includes the best systems, ideal for
implementing in the electric vehicles today.
1.3 Overview
This report discusses some acceptable and popular techniques to manage the temperature and
heat. The correct balancing between them is discussed in order to increase the performance.
At first the basic working of a lithium-ion batteries discussed because the fundamentals play
an important role in understanding the whole scenario. The temperature dependency is
discussed in a lithium-ion battery along with the operating temperature range required. Next
some of the common BTMS solutions are discussed. The mechanism, functions, advantages
and disadvantages are discussed. At last a new method is proposed combining the already
discussed models in order to increase the performance.
1

2 Lithium-ion Batteries
2.1 Working
A lithium-ion battery is very popular among the electric vehicles (EVs) as well as the hybrid
electric vehicles (HEVs). It constitutes two electrodes, electrolyte and the separator as shown
in figure 1. The anode is made up of graphite or carbon, the cathode is made up of lithium
metal oxide and electrolyte is an organic solvent in which the thieves also dissolved. During
discharging, the goal of the anode is to throw the electrons out to the external circuit. Thus,
the anode undergoes oxidation. Whereas, the cathode receives all the electrons from the
external circuit that are thrown away by the anode (Techopedia, n.d.). Thus, a cathode
undergoes reduction process. An electrolyte is a substance that contains both the electrodes
debris inside it and it makes it possible to exchange irons between cathode and anode. The
separator helps to act as a boundary between the two electrodes and hence preventing their
short circuit. The solid electrolyte interface (SEI) is formed outside the anode during the first.
It decreases the rate of the reaction and hence the current (Woodford, 2018). One of the
biggest advantage with the lithium-ion batteries is that it can be charged again and again. This
means that the electrochemical reactions can be reversed (Poole, n.d.). The lithium ions travel
from the negative electrode to the positive electrode during discharging while, it travels from
the positive electrode to the negative electrode (Troiano, 2013). The reaction for the lithium-
cobalt batt is given as,
Figure 1 (Electropaedia, n.d.)
Reaction at cathode is shown in the figure 2:
2

Figure 2 (Electropaedia, n.d.)
Reaction at anode is shown in the figure 3:
Figure 3 (Electropaedia, n.d.)
There are a variety of lithium batteries available in the market which varies in terms of the
material used as the cathode. For example Lithium Cobalt Oxide, Lithium Manganese Oxide,
Lithium Iron Phosphate and many more. In the table 1, many types of cathode substances
along with its description is mentioned.
Chemical name Material Short form Description
Lithium Cobalt
Oxide
LiCoO2 Li-cobalt The capacity is large
and ideal for cell
phone, camera and
laptop batteries.
Lithium Manganese
Oxide
LiMn2O4 Li-manganese Very safe, although
there capacity is low
as compared to the
lithium cobalt oxide
but the power is
specific and runs
longer. There are
used in electric bikes,
medical apparatus
and EV.
Lithium Iron
Phosphate
LiFePO4 Li-phosphate
Lithium Nickel
Manganese Cobalt
Oxide
LiNiMnCoO2 NMC
Lithium Nickel
Cobalt Aluminium
Oxide
LiNiCoAlO2 NCA There are becoming
popular in electrical
power trains and
3

grids.Lithium titanate Li4Ti5O12 Li-titanate
Table 1 (Battery University, 2018)
As per the table 1, three cathode materials are best suited for EVs, li-phosphate, li-manganese
and NMC (Evans, n.d.), (Energy Storage Association, n.d.).
2.2 Heat problems
The performance of the lithium ion batteries are dependent on the operating voltage and the
temperature. If it doesn’t operate within the range than it can be damaged permanently. First
of all we analyse in terms of operating voltage. If the battery is charged at a voltage higher
than the acceptable voltage, then the amount of current increases in the circuit. It creates two
issues, when the currents are high, more number of lithium ions are deposited at the anode as
lithium. This process is called as lithium plating. Due to this process the number of free
lithium irons decreases also there is a loss of the capacity of the battery. There are two kinds
of lithium plating, heterogeneous and homogeneously lithium plating. It occurs in the form of
branch that is the layers of lithium increases subsequently over time and ultimately if the
overvoltage situation persists then a time comes when both electrodes gets short-circuited. In
the case of under voltage during discharging, the copper current collector of the anode breaks
down. The rate of discharge is increased and so the voltage of the battery. The copyrights that
are broken down gets deposited as copper metal (Electropaedia, n.d.). This was is not
reversible. If the control the situation persists longer, time comes when both electrodes gets
short-circuited. It damages the battery permanently as well as it is dangerous. Another plus is
also happens. The metallic oxide, either cobalt oxide or manganese oxide, gets reduced by
depleting oxygen. This results in further loss of capacity.
The temperature also plays a very important role. The rate of the reaction is linearly
dependent upon the temperature. The capacity is directly proportional to the reaction rate. In
the case of low temperature, the reaction rate is decreased and therefore the current carrying
ions also decreases. In the case of higher operating temperature, the temperature of the
battery is increased. The rate of dissipation is less than the heat generated. Hence, the overall
temperature is high and hence it will damage the battery in the long run. The resultant in a
thermal runaway. Thermal runaway constitutes many stages such that each would make the
situation worse.
4

Around 80° the SEI layer dissolves in the electrolyte. Due to this and exothermic reaction
occurs between the anode and the electrolyte. This increases the temperature further. Now, at
around 110°C the organic solvents begins to disintegrate in this release is hydrocarbon gases.
The pressure increases inside the battery due to the gas but they do not burn because there is
insufficient oxygen to enable conversion. At this point the temperature is so much that the
separator also gets dissolved and the anode and cathode gets short-circuited. The temperature
happens to be around 135°C. Finally around 200°C, the metal oxide also gets disintegrated.
This releases oxygen which allows the hydrocarbon gas to burn. This process is also
exothermic and increases the temperature as well as the pressure further.
Another problem is the unequal distribution of temperature in the battery. This is due to the
huge temperature, fluctuating current, positioning of positive and negative terminals and
many more. It results in thermal runaway and hence the life of the battery decreases.
2.3 Operating range
In order to avoid the issues mentioned above, the temperature of the battery should be
maintained in the optimum range of operation. This would not only increase the life of the
battery but also increase its performance and energy consumption which is highly needed in
an EV. The temperature distribution should be even. Thus, the battery thermal management
system is very important for a battery.
Figure 4 shows a graph between the operating temperature and the power. When the
temperature of the battery is between 20° and 40°, it attains the maximum power. The cycle
life of the battery drops below 10°C due to the lithium plating. Also it drops after 60° because
of the breakdown of the materials of electrodes as shown in the figure 5. Thus, the operating
temperature of the battery should be controlled in such a manner that it lies between 20° and
40° so that the maximum power and performance is achieved. The even destruction of the
temperature can be controlled under 5K in order to ensure safety and increase the life of the
battery. The ventilation of the battery should be proper so that heat is dissipated properly.
5

Figure 4 (Electropaedia, n.d.)
Figure 5 (Electropaedia, n.d.)
6

3 Battery Thermal Management Systems (BTMS)
3.1 Needs
The safety of the battery pack along with its performance in terms of power and capacity has
to be ensured. The electric vehicles have a limited power supply therefore it should be stored
and controlled in such a way that the thermal runaway is prevented thus increasing its life.
The BPMS has to accomplish the following functionality is in order to enhance the battery
usability.
1. Cooling: during the operation of the battery, heat is generated. This heat is in the form
of an energy loss which cannot be prevented but it can be minimised by taking proper
measures. When the temperature of the battery increases beyond the optimal range, it
should be managed to bring it back to the required temperature range. A cooling
system can serve this purpose in BTMS.
2. Heating: the temperature of the battery may become less than the optimum range if it
is operating in a cold climate. Therefore, to bring it back to the optimal range, IET
mechanism can be employed such as a PTC heater quickly.
3. Insulation: there occurs a wide range of temperature difference between the outside
and inside environment of the battery when it is either kept too hot or too cold
conditions. This difference is not like when it is kept under normal conditions and
therefore the temperature of the battery falls arises very quickly outside the optimum
range. This is a major issue that affects the performance of the battery and to avoid
this proper insulation should be ensured.
4. Ventilation: ventilation is very much important in order to exhaust all those gases
which are harmful. These are generated due to the electrochemical reactions of the
battery. This function is combined with the cooling and heating functions in case of
certain BTMS systems.
7

3.2 Some of the cooling techniques
3.2.1 Air systems
Air is used as a medium to transfer the heat around the battery system. The air that is taken in
for cooling and heating purpose can be either atmospheric or from a system that could be a
4

heating or cooling. In the case of cooling it can be an air conditioner system that supplies are
conditioned air or a heater. The air passes through the evaporator in case of air conditioning.
If there is taken directly it is called as passive while if it is taken directly it is called as active.
Active systems can provide more amount of heating or cooling as compared to the present
systems by offering about thousands of watts cooling or heating whereas a passive system
offering to around hundreds. Both systems are called as forced air systems because the air is
supplied with the help of a blower. Figure 6 shows a passive and active systems (Chen, et al.,
2017), (Lu, et al., 2016).
Figure 6 (Lu, et al., 2016)
Both systems of full functionalities of heating and cooling as well as ventilation. The
ventilation systems in built and there is no need to add an external system. In the case of
forced air system with a recovery, the heat can be recovered from the exhaust gases with the
help of the heat recovery system such as air to air heat exchanger. This saves the extra energy
in the heating purpose as the waste exhausts is used to offer the heat. The system mentioned
above is shown in the form of a block diagram in figure 7. The forced air system is highly
reliable as well as requires very less maintenance. Although it provides a poor management
of heat yet due to economical nature it is used in low ends. If the temperature exceeds the
optimal range then it will result in thermal runaway.
8

Figure 7 (Lu, et al., 2016)
When the temperature is above 30°, the inside temperature of the battery surpasses 55° which
is greater than the optimum range of operation and hence thermal runaway occurs. The
distribution of the heat is on even due to degradation and life cycle. If the optimum range is
neglected, a difference of 2°C between the cells occurs with the discharge current rate of 2C
and a difference of 4.8 is a great when the discharge current is 6.67C. The fluid affects the
conformity of the temperature. With an increase in the flow rate, the measured temperature
difference of the cells also increases. It can be as high as 5K. This results in the degradation
and the number of battery cycles also. If anyone cell fails, the thermal runaway spreads. The
table 2 depicts that the volume of air is much larger than that of water at the same rate while
the coefficient of heat in the case of water is larger than that in the case of a. Therefore in the
case of air cooling in order to dissipate heat same as what are cooling, it needs larger volume
and create. This means that more power and space are required. Hence we can say that air
cooling is not efficient.
Volumetric flow rate (L/s) Average heat transfer
coefficient (W/m^2K)
Air 43 25
Mineral oil 0.057 57
Water 0.049 390
Table 2 (Lu, et al., 2016)
3.3 Liquid systems
Apart from air, water is a great source of heat transfer. There are two types of liquid that are
used for thermal management system. The first one is the direct liquid while the second is
conducting liquid. The dielectric liquids are in direct contact with the batteries and it includes
mineral oils. The conducting liquids has an indirect contact. It includes a mixture of ethylene
9

glycol and water. In the case of direct contact liquids, the battery cells are submerged in that
while in the case of conducting liquids a jacket is formed around the batteries through which
the conducting liquid flows, where the battery modules are placed on the cooling or the
heating plate. Comparing with the two approaches, the indirect systems are an edge because
there is a better isolation between the environment and the battery module (Avidtp, n.d.),
(Dincer & Rosen, 2018). This gives the system safe (SAE International, 2018). There are
many heat sinks used for cooling. Just like the air cooling systems, the liquid crystals can also
be categorised into active and passive systems. Radiators is used as a heat sink in passive
liquid systems. Figure 8 shows the block diagram of the passive ecosystem (BOYD
Corporation, n.d.). The pipe helps to circulate the liquid. This liquid absorbs the heat and the
radiator release it from the battery. Fans can help the radiators to dissipate the heat faster and
thus increasing the performance. If the difference between the ambient air and the battery
temperature is very low or if the battery temperature is lower than the ambient air, the system
fails (Hareyan, 2018), (Zhoujian, et al., 2017).
Figure 8 (Zhoujian, et al., 2017)
Figure 9 shows an active liquid cooling system. It can be seen that there are two loops, the
upper one being the primary while the lower one being the secondary. In the primary loop the
fluid circulates through the pipe and exchange the heat, the secondary loop in the air
conditioning loop. During cooling operation, the upper heat exchanger works as an
evaporator (EVAP) instead of the radiator while during heating, it works as condenser
(COND). This is achieved through a 4 way valve. The ambient temperature affects the
10

passive cooling system since the dissipation of the heat depends on the radiator. It dissipates
heat by the difference in
4

temperature between the ambient temperature and the liquid. Normally, there is no issue but
when there is high ambient temperature it is unsuitable. Compared to this the active cooling
system has a great thermal performance which will keep the optimum temperature intact and
the even distribution of the temperature is also maintained because the coolant has a high
coefficient of heat. But due to many moving parts they are complicated and thus difficult to
maintain enabling leaking out also (Rao, et al., 2017), (Zhao, et al., 2015).
Figure 9 (Zhoujian, et al., 2017)
3.4 Direct refrigerant systems
It is similar to the active liquid cooling system as mentioned above but in the place of fluid,
direct refrigerant is used for the exchange of heat from the battery. The block diagram of a
direct refrigerant system (DRS) is shown in figure 10. DRS is more efficient as compared to
the previous systems because the refrigerant is used directly as a coolant instead of cooling
the coolant first with the help of the refrigerant and then cooling the system. The only
problem with this system is that it is complicated and hence their maintenance is not easy.
11

Figure 10 (Zhoujian, et al., 2017)
3.5 Phase Change Materials
PCM or the phase changing materials stores and releases heat at a fixed point during melting
and solidification due to high fusion heat. The figure 11 is a graph plotted between the energy
storage and the temperature change. PCM is solid when the temperature is lower than the
melting point. As the temperature increases the heat is stored in the form of sensible heat
after absorbing. At the melting point the heat is stored as the latent heat after absorbing and
reaches a maximum point. Simultaneously the PCM changes its state to liquid. Further
increase in temperature makes the PCM becomes liquid and absorbs the heat and stores it in
the form of sensible heat back again. At the melting point since it absorbs the heat and
reaches its maximum value in the form of latent heat, it delays the temperature rise. Due to
this reason it is used as a buffer in BTMS. A PCM system is many times used along with an
air cooling and a liquid cooling system to improve the thermal management. When the
temperature increases beyond the working temperature of the battery that is from 40° to 50°,
the system works well because of high latent heat and thermal conductance, the inside
temperature of the cell is below 55°. Table 3 denotes the characteristics of PCM. In the case
of hardship situations for example when the current discharge rate is 6.67C with an ambient
temperature of 45°, the surpassing above 0.5K is not allowed in the maximum temperature
difference of the cell. In the normal conditions this defence is negligible (Global Greenhouse
Warming, n.d.). Because the PCM graphite Patrick’s absorbs and distributes heat fast, the
prima donna is prevented in the case when one cell fails.
12

Figure 11 (Global Greenhouse Warming, n.d.)
Although PCM is good yet there is a big disadvantage that it should be employed in cool
environment as well as spacious. It as ritual of the PCM is lower than that of the battery pack
which is released when the PCM melting point is higher than the ambient temperature, to the
battery module (Microtek, 2018), (Souayfane, et al., 2016).
Density (g/cm^3) Latent heat (J/g) Heat conductivity
(W/(m K))
PCM(L) 0.79 173.6/266 0.167
PCM(S) 0.916 0.346
Table 3 (Global Greenhouse Warming, n.d.)
13

4 Appropriate Thermal Management Solution
Figure 12 shows the comparison of the BTMS systems described above. The energy
consumption, caused, reliability, size, weight, safety and the performance and analysed
whose numerical values are evaluated in the table 4. Based upon the results, a new and
innovative BTMS system can be constructed which consists of a combined liquid cooling
system and a PCM system.
Figure 12
Items Performance Safety Weight Size Reliability Cost Energy
consumption
Sum
Weighing
factor
X12 X5 X3 X3 X11 X4 X4
Active air
system
1 1 3 1 3 3 1 78
Passive
liquid
system
2 1 2 2 2 2 3 83
Active
liquid
system
3 3 1 3 1 1 2 86
14

Combined
liquid
system
3 3 1 3 1 1 3 90
Direct
refrigerant
system
3 2 2 3 1 1 3 88
PCM 3 3 2 3 1 1 3 93
Table 4
4.1 Combined liquid cooling system (CLS) + PCM
The liquid cooling system works on four modes namely: heater working with bypass, heater
working without bypass, passive cooling system and active cooling system. One big
advantage of using a cooling system is that it has both passive and active systems. Advantage
of the passive cooling system is that it is simple and it dissipates heat in the normal situations
with very low power consumption whereas during high conditions, the active cooling system
comes into play which has a better thermal management in order to keep the temperature of
the battery in the required range. The PCM has an advantage of a very good performance in
terms of thermal management while the CLS removes the limited range of operation of PCM.
The block diagram is shown in the figure 13.
Figure 13
15

Four figures are discussed that demonstrates the temperature, the consumption of energy, he
transferred and the overview. Figure 14 shows the change in temperature over time. The blue
line depicts the temperature of the battery while the green depicts the inlet temperature of the
coolant before the battery and the red depicts the coolant is outright temperature of the
battery. Figure 15 shows the consumption of energy of the different sections. In the case of
passive cooling system, the consumption is very less for a radiator only the pump energy is
taken into consideration. Figure 16 shows the transfer of the heat between the fluid and the
battery. The red curve depicts the heating, cyan depicts the passive cooling and the blue
depicts the active cooling. Here, the heating or the cooling power of the battery. Figure 17
gives the overview of the complete operation. It constitutes many important information such
as the rate of heat generation, temperature of the battery, BTMS state and the rate of flow of
the pump. The PCM employs latent heat in order to deduct the consumption of energy and
introduce a delay in the temperature rise.
Figure 14
16

Figure 15
Figure 16
17

Figure 17
18

5 Conclusion
This report highlights the importance of the battery management in EV vehicles. It operates
under different weather conditions as well as situations. Because the battery is a source of
power so proper techniques has to be evolved so that is increased because the source is
limited. The air cooling system dissipates heat much less than a water cooling system. To
compensate and to match the latter, it needs to become more complicated and spatial also the
energy consumption of increases. Moreover with the increase of the flow rate, the maximum
temperature difference between the cells can exceed so much that if any one cell fails, the
thermal runaway will spread over the entire battery which will degrade it slowly. Liquid
cooling systems have the much better thermal performance that can help the battery to lie in
the operating range of temperature but the structure is complicated and hence very difficult to
maintain. It may also leak out. The issues mentioned above are solved by direct coolant
systems but it is also bulky. PCM on the other hand has the best thermal maintenance
capabilities but it lacks in the temperature boundary. Observing the strengths and weaknesses
of each system, a combined system of the liquid and PCM is involved that removes the flaws
of thermal management through PCM while the maximum range is increased by liquid
system. Improvements can be made in the management of the heat. A warning signal could
be generated to warn when the system is in danger. Energy saving should be increased. This
can be implemented by applying many control strategies. These strategies would increase the
charging rate as well as ensure the safety.
19

References
Avidtp (n.d) What is the Best Electric Vehicle Battery Cooling System? [Online]. Available
from: https://avidtp.com/what-is-the-best-cooling-system-for-electric-vehicle-battery-packs/
[Accessed 25 October 2018].
Battery University (2018) Types of Lithium-ion [Online]. Available from:
https://batteryuniversity.com/index.php/learn/article/types_of_lithium_ion [Accessed 25
October 2018].
BOYD Corporation (n.d) Air vs Liquid Cooling: Advancements in Thermal Management for
Power Electronics [Online]. Available from: https://www.boydcorp.com/resources/technical-
papers/air-vs-liquid-cooling-advancements-in-thermal-management.html [Accessed 25
October 2018].
Chen, K., Wang, S., Song, M. & Chen , L. (2017). International Journal of Heat and Mass
Transfer. Structure optimization of parallel air-cooled battery thermal management system,
Volume 111, pp. 943-952.
Dincer, I. & Rosen, M. A. (2018). Numerical Heat Transfer. Heat transfer modeling of a
novel battery thermal management system, 73(5), pp. 277-290.
Electropaedia (n.d) Lithium Battery Failures [Online]. Available from:
https://www.mpoweruk.com/lithium_failures.htm [Accessed 25 October 2018].
Energy Storage Association (n.d) Lithium Ion (LI-ION) Batteries [Online]. Available from:
http://energystorage.org/energy-storage/technologies/lithium-ion-li-ion-batteries [Accessed
25 October 2018].
Evans, J. L. (n.d). The Good, the Bad and the Ugly How Safe are Lithium-Ion Batteries?.
[Online]. Available from: https://www.batterypoweronline.com/markets/testingservices/the-
good-the-bad-and-the-ugly-how-safe-are-lithium-ion-batteries/ [Accessed 25 October 2018].
Global Greenhouse Warming (n.d) Phase Change Material [Online]. Available from:
https://www.global-greenhouse-warming.com/phase-change-material.html [Accessed 25
October 2018].
Hareyan, A. (2018). Chevy Volt's Liquid Cooled Battery vs Nissan Leaf's Air Cooled Battery:
2 Systems. [Online]. Available from: https://www.torquenews.com/1/chevy-volts-liquid-
cooled-battery-vs-nissan-leafs-air-cooled-battery-2-systems [Accessed 25 October 2018].
Lu, Z. et al. (2016). Energy Procedia. Thermal Management of Densely-packed EV Battery
with Forced Air Cooling Strategies, Volume 88, pp. 682-688.
v

Microtek (2018) How do PCMs work? [Online]. Available from:
http://microteklabs.com/how-do-pcms-work.html [Accessed 25 October 2018].
Poole, I. (n.d). Li-ion Lithium Ion Battery Technology. [Online]. Available from:
https://www.radio-electronics.com/info/power-management/battery-technology/li-ion-
lithium-ion.php [Accessed 25 October 2018].
Rao, Z., Qian, Z., Kuang, Y. & Li, Y. (2017). Applied Thermal Engineeering. Thermal
performance of liquid cooling based thermal management system for cylindrical lithium-ion
battery module with variable contact surface, Volume 123, pp. 1514-1522.
SAE International (2018) Integrated Cooling System for Underfloor High Voltage Devices in
PHEV [Online]. Available from:
https://www.sae.org/publications/technical-papers/content/2018-01-1184/ [Accessed 25
October 2018].
Souayfane, F., Fardoun, F. & Biwole, P. H. (2016) Energy and Buildings. Phase change
materials (PCM) for cooling applications in buildings: A review, Volume 129, pp. 396-431.
Techopedia (n.d) Lithium-Ion Battery (LIB). [Online]. Available from:
https://www.techopedia.com/definition/2653/lithium-ion-battery-lib [Accessed 25 October
2018].
Troiano, J. (2013). How do Lithium Ion Batteries Work? A Nanotechnology Explainer.
[Online]. Available from: http://sustainable-nano.com/2013/10/15/how-do-lithium-ion-
batteries-work/ [Accessed 25 October 2018].
Woodford, C. (2018). Lithium-ion batteries. [Online]. Available from:
https://www.explainthatstuff.com/how-lithium-ion-batteries-work.html [Accessed 25 October
2018].
Zhao, J., Rao, Z. & Li, Y. (2015). Energy Conversion and Management. Thermal
performance of mini-channel liquid cooled cylinder based battery thermal management for
cylindrical lithium-ion power battery, Volume 103, pp. 157-165.
Zhoujian, A. et al. (2017) A review on lithium-ion power battery thermal management
technologies and thermal safety. A review on lithium-ion power battery thermal management
technologies and thermal safety, 26(5), pp. 391-412.
15