thermal study of a stthermal study of a · pdf filethermal study of a superior lithium ion...

THERMAL STUDY OF A SUPERIOR LITHIUM ION POLYMER BATTERY

Buletinul AGIR nr. 3/2012 ● iunie-august 1

THERMAL STUDY OF A STHERMAL STUDY OF A STHERMAL STUDY OF A STHERMAL STUDY OF A SUPERIOR LITHIUM ION UPERIOR LITHIUM ION UPERIOR LITHIUM ION UPERIOR LITHIUM ION POLYMER POLYMER POLYMER POLYMER BATTERY BATTERY BATTERY BATTERY

Eng. Andrei PRUTEANU, PhD Student1,.Eng. Vlad-Andrei SCARLATACHE PhD Student

1,

Prof. Eng. Romeo Cristian CIOBANU PhD2, Eng. Georgiana VIZITEU PhD Student

1

1 Gheorghe Asachi Technical University of Iaşi

2S.C. Comfrac R&D Project Expert S.R.L. Bucharest

REZUMAT. REZUMAT. REZUMAT. REZUMAT. Această lucrare prezintă o analiză a comportamentului termic a unei baterii litium ionAceastă lucrare prezintă o analiză a comportamentului termic a unei baterii litium ionAceastă lucrare prezintă o analiză a comportamentului termic a unei baterii litium ionAceastă lucrare prezintă o analiză a comportamentului termic a unei baterii litium ion----polimer, baterie polimer, baterie polimer, baterie polimer, baterie cececece este este este este mai des utilizată în domeniul auto datorită densitămai des utilizată în domeniul auto datorită densitămai des utilizată în domeniul auto datorită densitămai des utilizată în domeniul auto datorită densităţţţţii sale ridicate de enerii sale ridicate de enerii sale ridicate de enerii sale ridicate de energie precum gie precum gie precum gie precum şşşşi a densităi a densităi a densităi a densităţţţţii de putere. ii de putere. ii de putere. ii de putere. Comportamentul termic al bateriei constă în descrierea distribuţiei temperaturii utilizând diverse configuraţii ale Comportamentul termic al bateriei constă în descrierea distribuţiei temperaturii utilizând diverse configuraţii ale Comportamentul termic al bateriei constă în descrierea distribuţiei temperaturii utilizând diverse configuraţii ale Comportamentul termic al bateriei constă în descrierea distribuţiei temperaturii utilizând diverse configuraţii ale termocuplurilor şi o analiză termografică. A fost demonstrat că termocuplurilor şi o analiză termografică. A fost demonstrat că termocuplurilor şi o analiză termografică. A fost demonstrat că termocuplurilor şi o analiză termografică. A fost demonstrat că utilizândutilizândutilizândutilizând diverse configuraţii ale terdiverse configuraţii ale terdiverse configuraţii ale terdiverse configuraţii ale termocuplurilor mocuplurilor mocuplurilor mocuplurilor se poate se poate se poate se poate obobobobţţţţineineineine distribuţidistribuţidistribuţidistribuţia a a a temperaturii temperaturii temperaturii temperaturii pe suprafape suprafape suprafape suprafaţţţţaaaa baterieibaterieibaterieibateriei, precum , precum , precum , precum şi influenţele şi influenţele şi influenţele şi influenţele temperaturiitemperaturiitemperaturiitemperaturii asupra performanţei bateriei.asupra performanţei bateriei.asupra performanţei bateriei.asupra performanţei bateriei. Cuvinte cheie:Cuvinte cheie:Cuvinte cheie:Cuvinte cheie: comportament termic, Li-Ion polimer, distribuţia temperaturii ABSTRACT. ABSTRACT. ABSTRACT. ABSTRACT. This paper presents a thThis paper presents a thThis paper presents a thThis paper presents a thermal behavior analysis of a Liermal behavior analysis of a Liermal behavior analysis of a Liermal behavior analysis of a Li----ion polymer batteryion polymer batteryion polymer batteryion polymer battery that is more often used in that is more often used in that is more often used in that is more often used in automotive domain due to its high energy and power density. The thermal behavior of battery consists in describing the automotive domain due to its high energy and power density. The thermal behavior of battery consists in describing the automotive domain due to its high energy and power density. The thermal behavior of battery consists in describing the automotive domain due to its high energy and power density. The thermal behavior of battery consists in describing the temperature distribution using different configuratiotemperature distribution using different configuratiotemperature distribution using different configuratiotemperature distribution using different configuration of n of n of n of thermocouples and a thermothermocouples and a thermothermocouples and a thermothermocouples and a thermographic analysis. It was shown that graphic analysis. It was shown that graphic analysis. It was shown that graphic analysis. It was shown that using different configuration of thermocouples reveals the distribution of battery temperature and the influence which this using different configuration of thermocouples reveals the distribution of battery temperature and the influence which this using different configuration of thermocouples reveals the distribution of battery temperature and the influence which this using different configuration of thermocouples reveals the distribution of battery temperature and the influence which this may have on its performance.may have on its performance.may have on its performance.may have on its performance. Keywords:Keywords:Keywords:Keywords: thermal behavior, Li-Ion polymer, temperature distribution.

1. INTRODUCTION

The need to reduce the vehicle emissions combined

with the decreasing oil resources has made automotive

industry to find pure electric vehicles (EVs) in order to

solve these global demands [1]. Electric vehicles

depend on the batteries type [2] and improving the their

life-time will reduce the runtime and the costs for the

vehicle. Also, it is very important to know and manage

the battery status, for achieving a better level of

reliability and safety. Taking into consideration these

aspects, it can be said that the battery performance, cost

and life affect directly the life and performance of the

electric vehicles. Therefore, the need to extend the

battery lifetime and to use it at their full capacity, is of

the most importance.

The most significant parameters of the battery

technology for EVs are the power density and energy

density. Power density is the amount of energy that can

be provided in a time interval and energy density

represents the capacity to store the energy. In Figure 1

are presented various storage devices with different

energy and power. Thus, due to their high energy

density, high voltage, good stability and slow loss of

charge when are not used, Li-Ion polymer batteries are

quiqly becoming the most used technologies for the

next generation of EVs industry. Also, these cells are

very good for the high rate-of-discharge applications

such as acceleration of EVs. Despite these positive

aspects, which justify the recent spread of this

technology, it is important to notice that during

operation, Li-Ion polymer batteries must be carefully

monitored and managed (electrically and thermally) for

avoiding problems related to safety (inflammability)

and performance [3].

The main parameter, the temperature, has also a

Fig. 1. Ragone chart comparing different storage devises incuding

supercapacitors

Buletinul AGIR nr. 3/2012 ● iunie-august_____________________________________________________________________________________

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WORLD ENERGY SYSTEM CONFERENCE – WESC 2012


important influence on the battery which can affect both

the time life and energy of the battery, and automotive

drive-ability and fuel economy. For these reasons the

battery temperature should be within a temperature

range which is considered optimum to achieve good

performance and long life, for both use and storage.

This temperature range differs between technologies

and manufacturer. In Figure 2 is shown the impact of

different temperatures on battery capacity.

Usually, batteries are grouped in packs when are

used for EVs, so an uneven temperature distribution in

a pack should be taking into account. This temperature

deviation in a pack could drive to various

charge/discharge behavior. Also, storing pack in a too

hot or cold climate can affect them and cause a decrease

in their total capacity shortening their shelf-life [4].

As it was described above, the battery temperature

distribution is an important parameter for effective

operation in all environments. Thus, many study have

been made over the last years for the thermal

management of battery for the EVs to find better active

and passive, air and liquid cooling. For example in [5] it

is examined a passive thermal management for EVs

battery, consisting of embedded phase change material

(PCM) which dissolves during an operation to absorb

the heat obtained from the battery. In [6] is evaluate the

thermal loss of a Li-ion battery for EVs based on

electric parameters and experiments. In [7] a thermal

management of a Li-ion battery pack is realized in order

to observe the link between battery thermal

comportment and design parameters.

This paper presents a thermal behavior analysis of a

Li-ion polymer battery, which consists in describing the

temperature distribution using different configuration of

thermocouples and a thermographic analysis.

2. DESCRIPTION OF THE THERMAL ANALYSIS TEST PROCEDURE

In order to study the battery temperature

distribution, a thermal analysis was performed.

The test bench used for the thermal analysis of the

Li-ion polymer battery consists in the following

devices: a power supply, an electronic load, data

acquisition and a environmental chamber. The first

three devices are represented in a block diagram shown

in Figure 3. The power supply is used to provide

electricity for the entire test system. The electronic load

is a device used to absorb the power produced and the

acquisition system measures the parameters of interest

(ex. temperature) and converts it into an electrical

signal and also provides data storage (DAQ). All these

components are linked together through GPIB interface

(General Purpose Interface Bus) that allows the

communication with a computer for their programming

and control.

Fig. 3. The block diagram used for the experimental results.

Fig. 2. The various characteristics of capacity affected by the

temperature variation.

Fig. 4. Inside of environmental chamber during testing to an

Li-ion polymer battery

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_____________________________________________________________________________________WORLD ENERGY SYSTEM CONFERENCE - WESC



For thermal conditioning it is use the environmental

chamber, which is a device that simulates an

environment with different temperature and humidity as

shown in Figure 4 The device allows running tests for

temperatures ranging between -40˚C to +100˚C with a

humidity gamma modification from 15% to 98%. In

general, these chambers are used in the industries

domain and mostly useful for testing of electronic

components to see how they perform in different kinds

of conditions and to identify manufacturing flaws and

weaknesses.

All the devices described above (Figure 3), are

connected to a computer for both control and

management and for data storing and processing. The

software used to make this connection is the LabVIEW

program, provided by National Instruments.

The battery technical specifications used for the

experimental tests in this paper are listed in the Table 1.

The battery has a specific shape, also named pouch cell

with a capacity of 41 Ah, a rated voltage of 3,7 V with

an approximate weight of 1030g. It can be observed

that the thickness of the battery is approximately twenty

times less than the other dimensions (length and width).

For the thermal analysis, different configurations

with several thermocouples were placed on both battery

outer surfaces and also on the contacts and supply

cables, in order to determine their temperature

distribution.

The configuration presented in Figure 5 shows the

first arrangement of thermocouples on the battery. This

configuration with a large number of sensors, has

allowed the evaluation of the temperature difference

along the battery outer surfaces.

Table 1

Technical specification of the battery

For this arrangement it was observed that the most

significant heat peaks occur at higher values of

discharge current.

In order to find the optimal number of sensors

(thermocouples) that can be placed on the battery which

can provide significant results and can reveal the hottest

zones of the battery considering also external contacts

and power cables a new configuration (case I) was

realized as shown in Figure 6.

This arrangement provides different results, for the

sensors placed in the same area, similar to the one from

Figure 5.

In Figure 7 is presented the evolution of the

discharge current of the battery for Case I. The most

important change in this case refers to the power cables

heating, at which were placed sensors T6 and T12 and

to the external contacts warming, where sensors T2 and

T14 were attach. It was seen that even if the external

contacts are metallic and heat up rapidly, their warming

does not have a major influence over the temperature of

the battery body as shown in Figure 8.

It was notice that it would be better to positioned the

external contacts on both opposite sides of the battery,

Parameters Values

Cell Dimension

Length: Max. 223 mm

Width: Max. 213mm

Thickness: Max. 10,6mm

Weight Max. 1030 g

Capacity Tip. 41 Ah, Min. 40 Ah

Voltage 3,7 V

Upper limit voltage 4,16 ± 0,03 V

Lower limit voltage 3 V

Operation Temperature Range Charge: 11 ÷ 45 °C

Discharge: -21 ÷ 56 °C

Max. Cont. Discharge Current 320 A

Max. Cont. Charge Current 120 A

Fig. 5. Distribution of thermocouples on faces of the cell:front

side respectively, back side.

Fig. 6. First arrangement of thermocuples distribution including

power cables (Case I).


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in order to make more uniform the battery temperature

level.

The second arrangement for power cables (Case II)

is realized by placing sensors only on the most

significant thermal zones like in Figure 9. Due to this

simplified configuration, in Figure 10 are presented the

temperature evolution and the current characteristics

and it can be observed that the discharge current is

increased until it reaches the value of 320 A.

Then, for the same discharge current (120 A), for

both Case I and Case II, it was observed that for the

Case I the T14 indicates a maximum temperature of

37,5 °C and for Case II, T2 indicates only approx. 30°C.

For Case I, the high temperature of T14, occurs due to

the power cables warming and in Case II, the power

cables warming influence less the external contacts of

the battery. The both thermocouples T14 and T2,

mentioned above, are positioned on the positive battery

contact. At a high value of discharge current (320 A), it

can be observed (Figure 10) that the T2 reaches a

temperature value more than 80 °C. Thus, for a better

temperature distribution it is indicated to increase the

number of power cables at the battery positive external

contact.

In Figure 11 it is shown the temperature distribution

for the entirely surface of the battery where it can be

seen better that the highest heating zone appears near

the battery positive contact.

3. DESCRIPTION OF THERMOGRAPHIC ANALYSIS

The thermographic analysis, made through the use

of thermal cameras, detects the radiation in the infrared

range of the electromagnetic spectrum (from 9 to 14

nanometers), producing images that are called

thermograms. Because infrared radiation is emitted by

all objects in environment conditions, according to the

blackbody emission law, thermographs allows to see

Fig. 11. Temperature distribution on the outer surface of the Li ion

polymer battery

Fig. 8. Temperature evolution depending by the second

arrangement of thermocouples

Fig. 9. Second arrangement of thermocuples distribution

including power cables (Case II).

Fig. 10. Evolution of discharge current (max. 320A) and

temperature of the battery in third configuration.

Fig. 7. Evolution of the discharge current of the battery.

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these radiation which otherwise, will be invisible to the

human eye. The amount of radiation emitted by an

object increases with temperature.

Emissivity is the ability of an object to emit thermal

radiation. Mainly, the range variation of emissivity is

from 0 (complete absence of emission) to 1 (complete

emission). This property varies according to the

variation of the temperature, making it very difficult to

identify a value for the complex objects and varied as a

battery.

In the tests conducted it has been supposed an

emissivity with a value of 0.5 for the battery. Referring

to Figure 12 is important to note that, since it is possible

to setup the instrument to a single value of emissivity at

a time, only the temperatures that refer to the surface of

the battery are significant, therefore the color scale

refers only to these. The observed values for the black

background, electrodes and cables, are not significant,

because they are objects with different emissivity

values. Based on the data obtained experimental, in

Figure 13 it is shown the temperature evolution, which

refers to the temperature at the center of the surface of

the battery. It is possible to say that there is similarity

with the values obtained with the other measurement

techniques (using thermocouple T8), that confirm the

emissivity value chosen is reasonably close to real.

4. CONCLUSIONS

This paper presents a thermal behavior analysis of a

Li-ion polymer battery where the main concern its

represented by the difference of temperature

distribution along the outer surface of the battery.

The results obtained regarding the heat distribution

on the outer surface of the battery indicates a several

concerns related to construction of cells, especially the

positioning of the external contacts. Therefore, from the

thermal point of view, it was notice that it would be

better to positioned the external contacts on both

opposite sides of the battery, in order to make more

uniform the battery temperature level.

A study regarding the heating module-level of the

battery pack should be performed for further

investigations, due to the fact that usually, when are

used for electric vehicle the batteries are used being

connected in series/parallel.

ACKNOWLEDGMENT

This work was supported by:

-EURODOC “Doctoral Scholarships for research

performance at European level” project, financed by the

European Social Found and Romanian Government.

- Project MNT-ERA.NET 2011 with acronym CarPolCap.

BIBLIOGRAPHY

[1] Teratani, Tatsuo, et al. Energy-saving Technologies for

Automobiles. s.l. : Wiley InterScience, 2007

[2] Sun Kai, Shu Qifang, Overview of the types of battery

models, Control conference (CCC), 2011

[3] Yinjiao Xing, Qiang Miao, K. L. Tsui, M. Pecht, Prognostics

and health monitoring for lithium-ion battery, IEEE Intelligence

and Security Informatics, 2011

[4] Lewis, Richard. Sax's Dangerous Properties of Industrial

Materials, John Wiley & Sons, 2004

[5] M. Y. Ramandi, I. Dincer, G.F. Naterer, Heat transfer and

thermal management of electric vehicle batteries with phase

change materials, Heat Mass Transfer, 2011

[6] C. Mi, Li Ben, D. Buck, N. Ota, Advanced Electro-thermal

Modeling of Lithium-Ion Battery System for Hybrid Electric

Vehicle Applications, Vehicle Power and Propulsion Conference

IEEE, 2008

[7] G. Karimi, X. Li, Thermal management of lithium-ion batteries for

electric vehicles, International Journal of Energy Research, 2012

Fig. 13. Temperature evolution during the life cycle, based on the

detection of the thermocamera

Fig. 12. Capture of a thermogram of the Li-ion polymer

battery


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About the authors

Eng. Andrei PRUTEANU,

Gheorghe Asachi" Technical University of Iasi

email:[email protected]

Was born in Iasi, Romania in 1985. He received B.Sc. in 2009 and M.Sc. degrees in Information Systems for Environment

Monitoring in 2010 both from the Faculty of Electrical Engineering from the „Gheorghe Asachi” Technical University of

Iasi. Since October 2009 he is a PhD Student at „Gheorghe Asachi” Technical University of Iasi, Faculty of Electrical

Engineering at Department of Electrical Measurements and Materials. His main research is related to new energy

materials for batteries, supercapacitors and dielectric analysis.

Eng. Vlad-Andrei SCARLATACHE,



Was born in Bîrlad, Vaslui, Romania in 1985. He received B.Sc. in Electrical Engineering Specialization from the

Technical University “Gheorghe Asachi” of Iasi in 2009, and M.Sc. studies in Information Systems for Environment

Monitoring from the Technical University “Gheorghe Asachi” of Iasi in 2010. Since October 2009 he is a PhD Student at

Technical University “Gheorghe Asachi” of Iasi, Faculty of Electrical Engineering, Department of Electrical

Measurements and Materials.

Prof. Eng. Romeo Cristian CIOBANU, PhD,

S.C. Comfrac R&D Project Expert S.R.L. Bucharest


Was born in Piatra-Neamt, Romania, in 1961. He received a PhD degree in Electrical Engineering from the University

Politehnica of Bucharest and a PhD degree in Chemistry from the Technical University of Iasi. He is currently a Professor

at the Technical University of Iasi, Electrical Engineering Department. His research focuses on Industrial Diagnosis,

Dielectric Measurements, Quality and Maintenance, Composite Technologies.

Eng. Georgiana VIZITEU,



Was born in Vaslui, Romania in 1985. She received B.Sc. in Electrical Engineering Specialization from the Technical

University “Gheorghe Asachi” of Iasi in 2009, and M.Sc. studies in Energy Management Systems from the Technical

University “Gheorghe Asachi” of Iasi in 2010. Since October 2010 she is a PhD Student at Technical University

“Gheorghe Asachi” of Iasi, Faculty of Electrical Engineering, Department of Electrical Measurements and Materials.

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