Thermal Modeling and Analysis of a Pouch Type Li-Polymer ... · Thermal Modeling and Analysis of a...

Meng Xiao, [email protected] 1 Copying this presentation is strictly forbidden.

Thermal Modeling and Analysis of a Pouch Type

Li-Polymer Battery

Meng Xiao, Auburn University


Overview

• Literature review

• Heat sources analysis

• Heat generation measurement using infrared camera

• Heat generation measurement using calorimeter

• Simulation using electrochemical thermal model


Literature review

• In 2003, K. Thomas and J. Newman proposed heat of mixing in Li-ion battery

electrodes. [1]

• In 2008, X. Zhang etc. in U of Michigan claim the heat of mixing is negligible

compare to other heat source terms. [2]

[1] K.Thomas, J. Newman, J. Power Sources, Vol. 119-121, 2003, pp. 844-849

[2] X. Zhang etc. J. Electrochemical Soc. Vol.155(7) , 2008, pp. A542-A552

* Data provided by 3M company, 2011

-4-2024

Heat generation test of a coin cell *

Curr

ent, A

3.6

3.8

Voltage, V

1000 2000 3000 4000 5000 6000 70000

0.2

Time, s

Heat flow

, m

W

• Researcher in 3M company

observed heat generation rate

decayed slowly after current

interruption, (lasts 1000s) in coin

cell.


Heat source terms

• Reversible heat generation: Change of entropy

• Irreversible heat generation: Joule heating

in electrode

in electrolyte

by overpotential

in current collector

• Total sum of the heat generation: qg=qrev+qirr=qrev+qs+qe+qact+qcc

T

ETjq Li

rev

2

lq seff

s

Generate heat qrev

Generate heat qirr

Discharge

qrev Generate

heat qirr

Charge

Absorb heat

ll

c

lq eeeff

Deeff

e

ln2

Li

act jq 22

yxq cc

cccc

cccc


Interpretation of the Heat of mixing

• Electrode with different

stoichiometry number has

large chemical potential

difference

• Lithium ions in electrodes

are not uniform distributed

at charging or discharging

• The process of lithium ion

moving from high potential

part to low potential part

result in heat of mixing

Concentration of Li ion in solid @ 5C discharge

00.5

1

0

0.5

1

0.4

0.6

0.8

r (radius)

15s

l (thickness)

Cs/C

s.m

ax

00.5

1

0

0.5

1

0.4

0.6

0.8

r (radius)

100s

l (thickness)

Cs/C

s.m

ax

00.5

1

0

0.5

1

0

0.5

1

r (radius)

200s

l (thickness)

Cs/C

s.m

ax

00.5

1

0

0.5

1

0

0.5

1

r (radius)

600s

l (thickness)

Cs/C

s.m

ax

0 0.2 0.4 0.6 0.8 1

Sep

arat

or

Curr

ent

coll

ecto

r (C

u)

Curr

ent

coll

ecto

r (A

l)

Positive

electrode

area

Negative

electrode

area

L

Electrode

particle

Ion flux

Different

chemical

potential


Infrared camera approach

• Anti-glare spray on the battery surface

• FLIR SC655 infrared camera Frame rate: 50 Hz

Resolution: 640*480 pixels

Thermal sensitivity - <0.05°C @30°C/50mK

Focus distance – 24.6 mm

Object temperature range – -20°C to 150°C

• Multiple digital filters employed to reduce noise

• Differentiate temperature to calculate heat generation


IR camera approach

0 50 100 150-20

0

20

40

60

80

100

Time, sec

He

at

Ge

ne

ratio

n R

ate

, W

att

simulation

experiment

heat generation comparison of 110A cycle test

7C charge

rest

7C discharge

rest

• Temperature differentiate method based on the temperature profile measured

from IR camera

• 7C cycle because of noises


Design of Calorimeter

Thermal

couples

TEMs

Battery

TEM controller Tref

battery

temperature

Qestimate

Heat pump

estimator Load profile

• Battery

LiMn2O4/Carbon pouch type power cell

15.7Ah, 15cm*20cm*5mm

Voltage range 2.5V~4.15V

• Thermal-electric module (TEM) * 2

24V, 160W

• Labview implementation

Measurement of temperature at center and

terminals

PI controller

Overpotential heat generation estimation

Heat transfer from terminal tabs estimated

Goal: fast response and small error


1 1.5 2 2.5 3 3.5 4

x 10-3

0

0.5

1

1.5

2

2.5

3

3.5x 10

-3 Battery EIS

Calorimeter calibration – AC current

1.9e-3 Ohm @ 1Hz

• Battery is pure resistive if applied 1Hz AC current.

• Joule heating dominants the overall heat generation at this frequency

• Impedance at certain frequency is independent to current amplitude

-100 -50 0 50 100

3.3

3.4

3.5

3.6

3.7

Battery current, A

Term

inal voltage, V

Battery response to 1Hz AC current

73.9A

54.4A

40.0A

23.3A

8.13A


Calorimeter calibration – AC current

• PI controller

• Apply AC current to the battery

• Temperature control error < 0.02 ºC

• Heat transfer through terminal tab

0 500 1000 1500 2000 2500-150

-100

-50

0

50

100

150

Time, s

Battery

curr

ent, A

Battery IRMS

=68.5A, 1Hz (Ip-p

=193.7A)

0 500 1000 1500 2000 250022

22.2

22.4

22.6

22.8

23

Time, s

Battery

tem

pera

ture

, oC

Battery IRMS

=68.5A, 1Hz (Ip-p

=193.7A)

0 2 4 6 8 100

0.05

0.1

0.15

0.2

Battery heat generation, W

TE

M c

urr

ent, A

• The heat pump coefficient = 52.6W/A

• Heat transfer through each terminal tab = 0.315W/K

• The clear step of TEM current is observed


5C discharge (consider TEM effect)

400 600 800 1000 1200 1400

0

20

40

60

80

Time, s

Heat genera

tion ,W

5.1C (80A) discharge

Measured Qg

Battery QOP

400 600 800 1000 1200 1400

0

20

40

60

80

Time, s

Heat genera

tion ,W

5.1C (80A) charge

Measured Qg

Battery QOP

•Heat generation rate is almost same amount as overpotential heating

with slightly phase delay

• In 5C charge and discharge at room temperature, heat generation after

current interrupt will quickly decay to zero within no more than 60s


Model setup for pouch type cell

• Micro cell has current collector / separator / electrode layers

• Electrode is mixture of electrode particles and electrolyte

• Chemical reaction occur at surface of particles

• Lithium ion de-intercalate from one electrode, travel through electrolyte and intecalate

to the other electrode

• A pouch type cell is assumed to consist of microcells that have multiple layers in the L

direction, so that the microcell is simplified with one dimensinal model.

• ce

• Φe

• Φs

• ηSEI

• cs

• T

Sep

arat

or

LixC6 LiyMO2

Curr

ent

coll

ecto

r (C

u)

Curr

ent

coll

ecto

r (A

l)

Electrolyte

Positive

electrode

area

Negative

electrode

area

Electrode

particle

L

X

Y


Dynamic modeling

Micro cell model Micro cell model

•Energy conservation

•Heat transfer

•Charge conservation

Temperature

distribution

Parameters:

•Battery geometry

•Maximum capacity

•Concentration

•Activity coefficient

•Diffusion

coefficient

•Change of enthalpy

•Conductivity

etc.

•Cell voltage

•Temp. distribution

•SOC

•Overpotentials

•Reaction rate

•Concentration

•Efficiency

•Butler-Volmer

Mass balance

•In electrolyte

•In solid

Reaction rate

Current

Overpotential

Concentration

Nernst

equ.

Standard

potential

Micro cell model

Initial conditions:

•Initial SOC

•Load profile

•Initial temperature

distribution

•Ambient

temperature

Single cell model

Potential

distribution

Heat source


Simulation result

400 600 800 1000 1200 1400

0

20

40

60

80

Time, s

Heat genera

tion, W

80A discharge validation

simulation

experiment

400 600 800 1000 1200 1400

0

20

40

60

80

Time, s

Heat genera

tion, W

80A charge validation

simulation

experiment

Both simulation and experiment result show the heat generation after current

interrupt is very small and rapid decay to zero at the given LIPB cells.

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