Prediction of Multi-physics Behaviors of 

Large Lithium-ion Batteries 

During Internal and External Short Circuit

Gi-Heon Kim1,*, Kyu-Jin Lee1, Lawrence Chaney1, Kandler Smith1, Eric 

Darcy1,2, Ahmad Pesaran1

1National Renewable Energy Laboratory, Golden, CO, USA

2NASA Johnson Space Center, Houston, TX, USA

NREL/PR-5400-49864

Battery Safety 2010

In conjunction with 

6th Lithium Mobile Power 

Boston, MA, Nov 3rd, 2010

*: gi-heon.kim@nrel.gov

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
Performance, Durability and Safety

National Renewable Energy Laboratory 2 Innovation for Our Energy Future

Physics of Li-Ion Battery Systems in Different 

Length Scales

Li diffusion in solid phase

Interface physics

Particle deformation & fatigue

Structural stability

Charge balance and transport

Electrical network in 

composite electrodes

Li transport in electrolyte 

phase

Electronic potential &

current distribution

Heat generation and 

transfer

Electrolyte wetting

Pressure distribution

Atomic Scale

Particle Scale

Electrode Scale Cell Scale

System Scale

System operating 

conditions

Environmental conditions

Control strategy

Module Scale

Thermal/electrical

inter-cell configuration

Thermal management

Safety control

Thermodynamic properties

Lattice stability

Material-level kinetic barrier

Transport properties
Temperature Exothermic Reactions

T[K]

t[sec] t[dcsec]

Q[W]

Thermal Runaway

SEI

anode

cathode

National Renewable Energy Laboratory 3 Innovation for Our Energy Future
Modeling Thermal Runaway

 Constructed empirical reaction models using calorimetry data for 

component decompositions; Approach practiced by J. Dahn’s group

 Enhanced understanding of the interaction between heat transfer and 

exothermic abuse reaction propagation for a particular cell/module 

design, and 

 provided insight on how thermal characteristics and conditions can impact 

safety events of lithium-ion batteries.

Internal T External T

(oC)

0 20 40 (sec)

SEI decomposition positive/electrolyte negative/electrolyte

National Renewable Energy Laboratory 4 Innovation for Our Energy Future

8 20 28 40 sec

Total volumetric heat release from component reactions

4 12 16 24 32 36
SEI decomposition reaction front

0

68

Reaction Propagation

• Propagates Initially in azimuthal direction

• Forms hollow cylinder shape reaction zone

• Center axis zone starts to react

• Finally reaction goes further in outer radius cylinder zone

National Renewable Energy Laboratory 5 Innovation for Our Energy Future
Runaway Propagation

5 minutes apart between each frame

Top View

Side View

In a multi-cell module

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2 seconds apart between each frame

Closer Look at Reaction in an Individual Cell

National Renewable Energy Laboratory 7 Innovation for Our Energy Future
Fast Heat Dissipation

Temperature Heat of SEI decomposition

 Small cell module: 20 x 18650

 Highly conductive carbon matrix wetted with phase change 

materials 

National Renewable Energy Laboratory 8 Innovation for Our Energy Future
• Developed an integrated model for multi-physics internal short circuit 

of lithium-ion cells by linking and integrating NREL’s unique 

electrochemical, electro-thermal, and abuse reaction kinetics models

• Performed 3D multi-physics internal short simulation study to 

characterize an internal short and its evolution over time

Current Density

Temperature

Electro-Thermal Model

Abuse Kinetics Model Electrochemical Model

0

50

100

150

200

0

50

100

150

59.5

60

60.5

61

61.5

62

X(mm)

soc [%]

Y(mm)

Internal Short Circuit Model Study

T soc

Multi-Physics Internal Short Circuit Model

National Renewable Energy Laboratory 9 Innovation for Our Energy Future
Performed Case Study with A 20Ah Prismatic Cell

• Case Studies – 20Ah Stacked Prismatic Cell

ISC between metal (Al & Cu) current collector foils

ISC between electrode (cathode & anode) layers

Impact of short area – separator hole propagation

ISC between Al to anode – short bypassing cathode

Impact of Cell Size

Comments on Shutdown Separator

Impact of ISC location 

Cu

Cu

Cu

Al

Al

200 mm

140 mm

7.5 mm

Shorted Spot

Positive Tab

Negative Tab

To investigate impacts of various short natures and cell characteristics

National Renewable Energy Laboratory 10 Innovation for Our Energy Future
Results Agree Well with Laboratory Observations

The simulation results have reasonably reproduced the experimental 

observations from other research groups/companies including SNL, 

Exponent, Celgard, LGchem, and Sony

Sandia National Lab, Celgard

LG Chem

Exponent

SONY

National Renewable Energy Laboratory 11 Innovation for Our Energy Future
40 mm

35 mm

3 mm

Shorted Spot

Shutdown Separator for Large Cells?

Short Between Al & Cu Metal Foils

Al

Cu

• Cell Capacity: 20 Ah 0.4 Ah

Rshort ~ 10 mΩ

Ishort ~ 300 A (15 C-rate)

Rshort ~ 7 mΩ

Ishort ~ 34 A (85 C-rate)

T

Q

30 sec

T

Q

40 sec

T

Q

50 sec

T

Q

60 sec

 

 

T

Q

20 sec

0 2 4 6 8 10 12 14 16 18

0

200

400

600

800

without shutdown

shut-down functioned

National Renewable Energy Laboratory 12 Innovation for Our Energy Future

Joule heat for short Temperature @10 sec after short

800oC

25oC

surface temperature

internal temperature

100 110 120 130 140

0

0.1

0.2

100 110 120 130 140

0

0.1

0.2

110

140

120

130

100

surface temperature

temperature [oC] 

volume fraction volume fraction

Surface temperature
Shutdown Separator Limitation

Li+ eSTOP

Li+

• Thermally triggered

• Block the ion current in circuit

Large Cell

Representation

STOP

Li+

Difficult to apply in

• Large capacity system

• High voltage system

National Renewable Energy Laboratory 13 Innovation for Our Energy Future
Ceramic Reinforced Separator

Short Between Cathode and Anode Electrodes Cathode Anode 

• Shorted area: 1 mm x 1 mm

Rshort ~ 20 Ω

Ishort ~ 0.16 A (< 0.01 C-rate)

current density field 

near short

surface temperature

43.1oC

25.5oC

• Thermal signature of the short is hard to detect 

from the surface

• The short for simple separator puncture is not 

likely to lead to an immediate thermal runaway

separator hole propagation

3 cm x3 cm

Myung Hwan Kim, LG Chem, AABC08

Rshort ~ 30 mΩ

Ishort ~ 100 A (5 C)

3cm x 3cm Separator Hole

Exothermic Heat [W]

Time [sec]

Temperature at 1min after short

• Maintaining structural integrity of separator seems critical to delay short evolution 

National Renewable Energy Laboratory 14 Innovation for Our Energy Future
External Short of Multi-Cell Battery

Background

• Cell PTC device proven effective control for 

over-current hazards at Li-Ion cell and small 

battery level

• Known as ineffective in high-voltage or large 

capacity battery designs

• Need to verify if NASA’s spacesuit battery 

design (16P-5S) array could depend on cell 

PTC devices to tolerate an external short

Gasket Seal

PTC Ring

+ Top Cover

CID

Button

CID Ring

Polymer

+Tag Mounting Disk

Scored Disk Vent

Photo: NASA

National Renewable Energy Laboratory 15 Innovation for Our Energy Future
• Commercial lithium ion 18650 cells typically 

have a current-limiting PTC (positive 

temperature coefficient) device installed in 

the cell cap to limit external currents in the 

event of an external short to the cell.

• The PTC device consists of a matrix of 

crystalline polyethylene containing 

dispersed conductive particles, usually 

carbon black. The resistance of the PTC 

device increases sharply with temperature. 

• Once triggered, PTC behaves as a thermal 

regulator

• PTC device often fails to function in high 

voltage / high capacity systems

PTC Device

PTC Resistance vs. Temp

Data: SRI

National Renewable Energy Laboratory 16 Innovation for Our Energy Future
Model Development Approach

Unit Cell Model

R1(SOC,TJR)

VOCV(SOC)

C1(SOC,TJR)

Rs(SOC,TJR) RPTC(TPTC)

+

-

I(t)

V(t)

Jelly Roll PTC

5.Jelly

Bottom

4.Jelly

Middle

3.Jelly

Top 2.PTC 1.TopButton

Ambient

K45 K34 K23

K5a

K12

K4a K3a K1a

5.Jelly

Bottom

4.Jelly

Middle

3.Jelly

Top 2.PTC 1.TopButton

Ambient

5.Jelly

Bottom

4.Jelly

Middle

3.Jelly

Top 2.PTC 1.TopButton

Ambient

K45 K34 K23

K5a

K12

K4a K3a K1a

5 4 3 1

2

Multicell T&E Network Model

T10

T9

T8 T7

T6

T5

T4

T2 T3

T1

Rptc

Zjr

V0 +

-

+

-

+

-

Vmeas Rshort

Imeas

1 2 16

5-Node

Thermal 

Model

Electrical 

Model

Thermal 

Network 

Model

Electrical 

Network 

Model

electrical/thermal interaction electrical/thermal interaction

Integrated Thermal and Electrical Network Model of a Multicell Battery

for Safety Evaluation of Module Design with PTC Devices during External Short

National Renewable Energy Laboratory 17 Innovation for Our Energy Future
Unit Cell Model – Electrical

ECM including 

PTC device

R1(SOC,TJR)

VOCV(SOC)

C1(SOC,TJR)

Rs(SOC,TJR)

V1

RPTC(TPTC)

+

-

I(t)

V(t)

Jellyroll PTC

PTC Resistance vs. Temp.

Data: SRI

National Renewable Energy Laboratory 18 Innovation for Our Energy Future
Unit Cell Model – 5-node Thermal

∑ ( ) −=

j

i ij TTKQ ji

( ) dt

dT MCpTTKQ i

i

j

i ∑ ij ji +−=

Steady Form

Unsteady Form

A PTC:3.38W, Jelly:0.0093W

B PTC:3.0W, Jelly:0.0093W

C PTC:2.0W, Jelly:0.0093W

D PTC:1.0W, Jelly:0.0093W

E PTC:1.0W, Jelly:1.0W

40

60

80

100

120

140

160

temperature [oC]

Fluent

5-Node Aprox

Top buttonPTCJelly topJelly middleJelly bottom

A

B

D

C

E

40

60

80

100

120

140

160

temperature [oC]

Fluent

5-Node Aprox

Top buttonPTCJelly topJelly middleJelly bottom

A

B

D

C

E

Detailed Cell Thermal Model • Large computational requirement

• Not suitable for multicell modeling

5.Jelly

Bottom

4.Jelly

Middle

3.Jelly

Top 2.PTC 1.TopButton

Ambient

K45 K34 K23

K5a

K12

K4a K3a K1a

5.Jelly

Bottom

4.Jelly

Middle

3.Jelly

Top 2.PTC 1.TopButton

Ambient

5.Jelly

Bottom

4.Jelly

Middle

3.Jelly

Top 2.PTC 1.TopButton

Ambient

K45 K34 K23

K5a

K12

K4a K3a K1a

5 4 3 1

2

5-Node Cell Thermal Model

• Low order dynamic model

• Suitable for multicell modeling

Comparison of Detailed and 5-Node Models 

for different heat generation conditions

National Renewable Energy Laboratory 19 Innovation for Our Energy Future
Multicell Network Model − Thermal

Thermal Network Model

Thermal Mass: Identifying thermal mass at each node

Heat Generation: PTC heat, discharge/charge heat (, abuse reaction heat) 

Heat Transfer: Quantifying heat exchange among the nodes

radiationij ij connector conduction ij convection  ijj

Qtransport i ijij QQQ , Q _, Q ,

,1

, ∑ , +=−= +

≠=

 

D

d

F2 F1 F2 F3 F4

d/D

F

 

D

d

F2 F1 F2 F3 F4

d/D

F

Cell-to-Cell Irradiative Heat Transfer

Heat Conduction Through Air Gap 

Heat Transfer to Ambient

Transverse Heat Transfer Through Plates

Heat Rejection Through Wires 

Photo: NASA ISS01E5361 Photo: ABSL

 
Experimental Model Validation: 16P Bank

16P model validated against a bank short test

• 10 mΩ external short

• Peak inrush current

• PTC device trip time

• Steady-state behavior

• Temperature rise profiles for all 16 cells

I T

Test Data & Photo: SRI

National Renewable Energy Laboratory 21 Innovation for Our Energy Future
/

Simulation Results at Various Values of Rshort

• Rshort ≤ 40 mΩ: PTC-limited

• Rshort ≥ 50 mΩ: SOC-limited

• Tripped PTC device serves as 

thermal regulator

[dRPTC/dT]130 ̊C = 3 Ω / ̊C

(5 orders of magnitude > than at 25 ̊C)

• Large pre-trip heat rates are 

safe provided that they have

– Short duration

– Sufficient thermal mass

– Sufficient heat dissipation

Steady State Temp

Average Heat

Before and After Trip

PTC

Jellyroll

Post-trip

Pre-trip

Max Temp

National Renewable Energy Laboratory 22 Innovation for Our Energy Future
Extend Validated 16P Model for 16P-5S Pack 

Aluminum Plate

Nickel Bus Plate

Nickel Bus Plate

Aluminum Plate

Top Button

Jelly Roll Node 3

Jelly Roll Node 1

Jelly Roll Node 2

Glass Reinforced 

Plastic Plate

Glass Reinforced 

Plastic Plate

• 11 nodes are vertically placed at 

80 cell locations 

• Node thermal connections are 

defined considering various heat 

transfer modes

• Aluminum enclosure box is 

considered thermally lumped

• 11 x 80 + 1 = 881 node system

National Renewable Energy Laboratory 23 Innovation for Our Energy Future
ABSL experiment: Bank 3 short through external resistor

80 cell battery in 

test enclosure

10 mΩ resistor

Photo: ABSL

Model Validation for Pack External Short

Photo: ABSL

Photo: NASA

National Renewable Energy Laboratory 24 Innovation for Our Energy Future
ABSL Instrumentation

25

D

E

F

G

Brick Temperature Sensor Locations

A

B

Center-most 

cell

C

Cell Temperature Sensor Locations

Bank 3 Photos: ABSL

National Renewable Energy Laboratory Innovation for Our Energy Future
Model Validation – First 6000 seconds Temperature (

oC)

Time (s)

Symbols: ABSL test data

Lines: NREL model output

Center cell

Edge cell

GRP

Al plate-c

Al plate-p

Corner cell

Box

National Renewable Energy Laboratory 26 Innovation for Our Energy Future
Cell Temperature Distribution at 6000 seconds

Height of cylinder depicts peak 

jellyroll temperature (oC) of each 

cell as predicted by model.

National Renewable Energy Laboratory 27 Innovation for Our Energy Future
E.g., bank 3 short is caused by foreign object between banks 3 and 4*

Bank 1

+

Bank 2

-

Bank 3

+

Bank 4

-

Bank 5

+

* Requires more than two faults: Introduction of foreign object debris & penetration of Kapton/Nomex/Kapton divider between banks

Model Analysis for Pack-Internal Shorts

National Renewable Energy Laboratory 28 Innovation for Our Energy Future
4 V

8 V 16 V

12 V

.... ....

Schematic of Shorted Middle Cell Bank

• Short runs through can of cell from adjacent bank 4

• Bare walls of cells are negatively biased

• Note that 3-layer (Kapton-Nomex-Kapton) bank-to-bank insulator is omitted for clarity

Cell Bank 

3

Short

path

+

+

+

+ + +

- - - -

- -

National Renewable Energy Laboratory 29 Innovation for Our Energy Future
Bank 3 Short from 100% SOC

• Cell 42 (bank 3) participates in electrical discharge

• Cell 56 (bank 4) does not electrically discharge; its 

external can wall serves as a path for short current

• Model assumes ohmic heat of short shared equally by 

cells 42 and 56

• Internal-to-pack short more thermally severe than 

external-to-pack

• Thermal mass dominates – negligible dependence on 

Earth vs. space boundary conditions

• Runaway possibly prevented at 10 mΩ

• Runaway predicted at 20,30 mΩ with collateral damage

Bank 3

Cell 42 Cell 56

Rshort Short Condition

(SOC0 = 100%)

Cell 42 Tmax

(Bank 3)

Cell 56 Tmax

(Bank 4)

10 mΩ External-to-pack, earth 97oC @ 6000-s 75oC @ 6000-s

Internal-to-pack, earth 150oC @ 16-s 146oC @ 16-s

Internal-to-pack, space 153oC @ 16-s 147oC @ 16-s

20 mΩ Internal-to-pack, space 525oC @ 110-s 522oC @ 110-s

30 mΩ Internal-to-pack, space 595oC @ 240-s 591oC @ 240-s

National Renewable Energy Laboratory 30 Innovation for Our Energy Future
Bank 3 Short from 100% SOC: 10 mΩ vs. 20 mΩ

10 mΩ:

Bank 3 PTC devices trip quickly and 

uniformly because high inrush 

current causes PTC self-heating

Cell Current (A)

Time (s) Time (s) Cell Current (A)

20 mΩ:

Bank 3 PTC devices trip slowly at 

different times, depending upon 

bank 3 temperature distribution

Cell 42 PTC trips at 8 s

Remaining bank 3 PTC 

devices trip at 16 s

Cell 42 PTC trips at10 s

Remaining bank 3 PTC 

devices trip between 60 

s and 110 s

National Renewable Energy Laboratory 31 Innovation for Our Energy Future
Bank 3 short from 100% SOC: 10 mΩ vs. 20 mΩ

10 mΩ:

Bank 3 PTC devices trip quickly and 

uniformly due to high in-rush 

current causing PTC self-heating

Temperature (

oC)

Time (s) Time (s) Temperature (

oC)

20 mΩ:

Bank 3 PTC devices trip slowly, at 

different times dependent upon bank 3 

temperature distribution

All bank 3 PTC 

devices trip by 16 s

All bank 3 PTC 

devices trip by 110 s

Cell 42 Cell 42

Rest of bank 3 Rest of bank 3

National Renewable Energy Laboratory 32 Innovation for Our Energy Future
Bank 3 Short from 100% SOC: Cell-to-Cell Radiation

Bank 3

Cell 42

Rshort Short Condition

(SOC0 = 100%)

Cell wall 

emissivity

Cell 42 Tmax

(Bank 3)

20 mΩ Internal-to-pack, 

earth

ε = 0.3 

(Nominal)

525oC @ 110 s

ε = 0.9

(Coating)

410oC @ 102 s

(Insufficient

impact)

Design question: 

Would a high-emissivity 

coating applied to bare cell 

walls help limit thermal 

excursion?

National Renewable Energy Laboratory 33 Innovation for Our Energy Future
Bank 3 Short: SOC Dependence

Bank 3

Cell 42

Rshort Short Condition Initial SOC Initial OCV Cell 42 Tmax

(Bank 3)

20 mΩ Internal-to-pack, 

earth

1.5% 3.428 V 117oC @ 85 s

0.5% 3.346 V 83oC @ 80 s

No thermal runaway when stored at 0% SOC (3.25 OCV).

Is battery design tolerant to 

pack-internal shorts when 

stored at low SOCs?

National Renewable Energy Laboratory 34 Innovation for Our Energy Future
Summary

• NREL performed an internal short model simulation study to characterize an 

internal short and its evolution over time by linking and integrating NREL’s 

electrochemical cell, electro-thermal, and abuse reaction kinetics models.

• Initial heating pattern at short events depends on nature of short, cell 

characteristics, and system configuration.

• Temperature rise for short is localized in large capacity cells.

• Short current is carried mostly by metal collectors.

• A simple puncture in the separator is not likely to lead to an immediate 

thermal runaway of a cell.

• Maintaining the integrity of the separator seems critical to delay short 

evolution.

• PTC device is an effective thermal regulator. Maximum cell temperature 

(final state) is very similar for a variety of initial and boundary conditions.

National Renewable Energy Laboratory 35 Innovation for Our Energy Future
Summary

• 80-cell spacesuit battery electrical/thermal model 

• Captures relevant physics for cell-external shorting events, including PTC 

behavior

• Agrees well with pack-external bank 3 short experiment run by ABSL

• Predicts that design will tolerate all pack-external short resistance conditions

• Relocating short from pack-external (experimental validation) to packinternal (modeling study) causes substantial additional heating of cells 

that can lead to cell thermal runaway

• Negligible sensitivity to earth/space boundary conditions (thermal mass 

dominates)

• Large sensitivity to Rshort

• Rshort < 10 mΩ: 16P bank PTC devices trip quickly, most likely preventing runaway

• 10 mΩ < Rshort < 60 mΩ: Thermal runaway appears likely

• Nevertheless, this finding re-emphasizes the general imperative of battery pack 

assembly cleanliness

• Design is tolerant to pack-internal short when stored at 0% SOC

National Renewable Energy Laboratory 36 Innovation for Our Energy Future
Acknowledgments

Vehicle Technology Program at DOE

• Dave Howell

NASA Johnson Space Center

• NASA JSC under Interagency Agreement NNJ08HC04I

• Technical discussion: Sam Russell, Frank Davies

Symmetry Resources Inc.

• Brad Strangways

ABSL

• Craig Flora

Thank you for your attention! 

National Renewable Energy Laboratory 37 Innovation for Our Energy Future
National Renewable Energy Laboratory 38 Innovation for Our Energy Future
DOE’s New CAEBAT Program

• Will integrate the accomplishments of battery modeling 

activities in national lab programs and make them accessible 

as design tools for industry

• Will shorten time and cost for design and development of 

EDV battery systems

National Renewable Energy Laboratory 39 Innovation for Our Energy Future

CAEBAT

Program Coordinator

Task 1:

Open Architecture

Development

Task 2:

Pack Model

Development

Task 4:

Electrode/Material

Models

Task 3:

Cell Model

Development

Industry/University Participation (RFP)