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.

2011 DOE Vehicle Technologies Program Review

Numerical and Experimental Investigation 

of Internal Short Circuits in a Li-ion Cell

This presentation does not contain any proprietary, confidential, or otherwise restricted information Project ID: ES109 

PI: Matthew Keyser, Gi-Heon Kim

Presenter: Gi-Heon Kim

Energy Storage Task Lead: Ahmad Pesaran

Contributors:

Matthew Keyser, Dirk Long, John Ireland, YoonSeok Jung, 

Kyu-Jin Lee, Kandler Smith, Shriram Santhanagopalan 

National Renewable Energy Laboratory

Eric Darcy

National Renewable Energy Laboratory (Jan-Sep, 2010)

NASA-JSC

NREL/PR-5400-50917
NATIONAL RENEWABLE ENERGY LABORATORY

Overview

Timeline

2

Budget

Barriers

Partners

• Li-ion abuse tolerance and reliability

• Li-ion performance

• NASA-JSC

• Dow Kokam

• Battery Safety Consulting Inc.

• Battery Design LLC

• Sandia National Laboratories (SNL)

• U.S. Navy

Overview

• Project Start: 2009

• Project End : 2014

• Ongoing

• FY10: $500K

• FY11: Anticipated $500K

Funded by Dave Howell, Energy Storage R&D

Vehicle Technology Program, U.S. Department of Energy
NATIONAL RENEWABLE ENERGY LABORATORY

Background

3

Relevance

• Because of its high specific energy and power density, the Li-ion battery (LIB) is a 

promising candidate to date for electric energy storage in electric drive vehicles

(EDVs)

• Safety concerns regarding violent failure of the LIB system are a major obstacle 

to overcome for fast market acceptance of EDV technologies

• Thermal instability and flammability of the LIB components make them prone to 

catastrophic thermal runaway under some rare ISC conditions

• Many safety incidents that take place in the field are due to an ISC that is not 

detectable or predictable at the point of manufacture

Internal Short Circuit (ISC), a Major Concern
NATIONAL RENEWABLE ENERGY LABORATORY

Motivation

4

Relevance

• Evolving during Life: Latent defect gradually evolves to create an ISC while the 

battery is in use; inadequate design and/or off-limit operation causes Li plating, 

stressing separator

• Difficulty of Early Detection: Electrical and thermal signals of early stage ISCs 

are not easily detected in large-capacity LIB systems

• Complex Physics with Numerous Sensitive Factors: Behavior of a LIB with an 

ISC depends on various factors, including nature of the short; cell characteristics 

such as capacity, chemistry, electrical and configuration; and attributes of the 

pack where the cell is integrated

• Poor Reproducibility: To date, no reliable and practical method exists to create 

an on-demand ISC in Li-ion cells that produces a response that is relevant to the 

ones produced by field failures

Barriers for Addressing Failures Due to ISC
NATIONAL RENEWABLE ENERGY LABORATORY

Objectives

5

Relevance

1. Model Investigation: Enhance knowledge of the complex physics of 

evolution and development of an ISC and subsequent cell responses 

using NREL’s multiphysics ISC model 

2. Test Method Development: Establish a relevant ISC test method by 

developing an on-demand short activation device to produce 

representative and reproducible ISCs in a active cell and relevant cell 

responses

3. Model+Test: Perform a synergistic study with combination of modeling 

and experimental approaches 
NATIONAL RENEWABLE ENERGY LABORATORY

Milestones

6

Milestones

• Matthew Keyser, Dirk Long, Ahmad 

Pesaran, “NREL Internal Short Circuit 

Simulator Development Summary”

FY10 Milestone Report

• “Li-Ion Abuse Response Modeling and Internal Short Circuit Simulation”

FY11 Milestone Report – Due in September 2011
NATIONAL RENEWABLE ENERGY LABORATORY

Approach

7

Approach

Model Validation

• Confirm Model Assumptions

• Provide Model Input

• Identify Critical Parameters

• Provide Complete Data Set for 

Non-Measurable Quantities

• Multiphysics ISC modeling

• Understanding cell behaviors

• Develop relevant ISC in active 

cell

• Provide consistent and 

reproducible results

Lead Investigator: Gi-Heon Kim

Lead Investigator: Matthew Keyser

Focus of Testing Study 

Focus of Modeling Study

Experiment Design

Photo Credits: Dow Kokam – Ben McCarthy

Photo Credits: 

NREL– Dirk Long
NATIONAL RENEWABLE ENERGY LABORATORY 8

• Perform multiphysics ISC model study using NREL’s electrochemical, electrothermal, 

and abuse reaction kinetics models

• Predict cell responses and onset of thermal runaway corresponding to the nature of the 

short and cell characteristics 

 Internal Short Circuit Modeling

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 Model Study

soc

Current Density

Temperature

Electrothermal Model

Abuse Kinetics Model

T

Cases for Short Path

• ISC between metal (Al & Cu) current collector foils

• ISC between electrode (cathode & anode) layers

• ISC between Al to anode – short bypassing cathode

• Impact of cell size

• Impact of ISC location 

Cathode Anode 

Al

Cu

Al

Anode 

Approach – Modeling

Approach
NATIONAL RENEWABLE ENERGY LABORATORY 9

• Small, low-profile and implantable into Li-ion cells, preferably during assembly

• Consistent and repeatable activation of internal short

• Electrolyte-compatible phase change material (PCM) for key component

• Triggered by heating the cell above PCM melting temperature



Approach – Testing

Approach

Internal Short Circuit Instigator Device Development

Spiral wound battery shown – can also be applied to prismatic batteries
NATIONAL RENEWABLE ENERGY LABORATORY

Previous Accomplishments

10

Technical Accomplishments

8 20 28 40 sec

Total Volumetric Heat Release from Component Reactions

4 12 16 24 32 36

• Three-dimensional LIB abuse kinetics model was developed in support of 

DOE’s ATD program, and the development was continued in the DOE’s ABR 

program

• Previous study

 Focused on understanding the interaction between heat transfer and 

exothermic abuse reaction propagation for a particular cell/module 

design

 Provided insight on how thermal characteristics and conditions can 

impact safety events of LIBs

Internal T External T (°C)

0 20 40 (sec)

Note: Since NREL did not participate in 2010 AMR, this poster presentation 

include some of the project accomplishments done before May, 2010.
NATIONAL RENEWABLE ENERGY LABORATORY

Accomplishments

11

Technical Accomplishments

ISC Model Investigation
NATIONAL RENEWABLE ENERGY LABORATORY

Impact of Cell Capacity

12

Technical Accomplishments

Initial cell heating pattern under ISC varies with cell capacity

• Shorted area: 1 mm x 1 mm

• Rshort ~ 10 mΩ

• Ishort ~ 300 A (15 C-rate)

Temperature at 10 sec after short

800°C

25°C

surface temperature

internal temperature

• Short between Al and Cu foils

20 Ah cell 0.4 Ah cell • Rshort ~ 7 mΩ

• Ishort ~ 34 A (85 C-rate)

100 110 120 130 140

0

0.1

0.2

100 110 120 130 140

0

0.1

0.2

temperature [°C] 

volume fraction volume fraction

100°C

140°C

Temperature

at 7 sec after short

Temperature

at 8 sec after short

0 10 20 30 40 50 60

0

2

4

6

8

10

12

Exothermic Reaction Heat [kW]

Time [sec]

10 sec 20 sec

30 sec

50 sec

40 sec

60 sec

Temperature evolving with time

200 mm

140 mm

7.5 mm

Shorted Spot

Positive Tab

Negative Tab 40 mm

35 mm

3 mm

Shorted Spot

• A small-capacity cell is heated globally

• ISC heating in a large cell is likely local 

• Thermally triggered “shut-down separator” 

may function effectively in a small cell
NATIONAL RENEWABLE ENERGY LABORATORY

Impact of Separator Integrity

13

Technical Accomplishments

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

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

43.1°C

25.5°C

• 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

Shorted area: 3 cm x3 cm

• Rshort ~ 30 mΩ

• Ishort ~ 100 A (5 C)

3cm x 3cm Separator Hole

Exothermic Heat [W]

Time [sec]

Temperature at 1min after short

1cm x 1cm Separator Hole

Joule heat @ cathode layer

Joule heat @ foils

• Short between anode to cathode • 20 Ah capacity cell
NATIONAL RENEWABLE ENERGY LABORATORY

Impact of Short Paths

14

Technical Accomplishments

Electrical resistance of ISC varies with short path across electrodes

• 20 Ah capacity cell

Short between

Al & Cu foils

Short between

anode and cathode

Short between

anode and Al foil

• Rshort ~ 10 mΩ

• Ishort ~ 300 A (15 C-rate)

Temperatures at 10 sec after short

800°C

25°C

surface temperature

internal temperature

• Rshort ~ 20 Ω

• Ishort ~ 0.16 A (<0.01 C-rate)

Temperatures at 20 min after short

43.1°C

25.5°C

internal temperature

Temperatures at 1 hr after short

surface temperatures

internal temperatures

250°C

37°C

• Rshort ~ 2 Ω

• Ishort ~ 1.8 A (<0.1 C-rate)

• ISC bypassing cathode is likely to evolve into a hard short in relatively brief time
NATIONAL RENEWABLE ENERGY LABORATORY

Impact of Short Location

15

Technical Accomplishments

Cell response varies with short location and cell electrical configuration

Surface Temperatures

• 20-Ah capacity stacked cell ISC Far from Tab

0 10 20 30 40 50 60

0

2

4

6

8

10

12

Exothermic Reaction Heat [kW]

Time [sec]

50°C 900°C

ISC Near Tab 

ISC far from tab 

Rshort ~ 10 mΩ

Ishort ~ 300 A (15 C-rate)

 

 

Electric Potential at Shorting Layers

 

 

Rshort ~ 4.7 mΩ

Ishort ~ 520 A (26 C-rate)

 

300oC

30oC

Internal Temperatures

• For low-resistance ISC, near-tab ISC results in a smaller resistance because of 

shorter short-current path through shorting layers

• Pattern of local heating for convergence of short-current varies with location of short 

and internal electrical configuration of a cell

Surface Temperatures

ISC Near Tab 
NATIONAL RENEWABLE ENERGY LABORATORY

Accomplishments

16

Technical Accomplishments

ISC Test Method Development
NATIONAL RENEWABLE ENERGY LABORATORY

NREL ISC Device

17

Technical Accomplishments

NREL developed an on-demand activation device creating representative ISC

Separator

Positive current collector (Al)

Cathode electrode

ISC device

Negative current collector (Cu)

Anode electrode

Activated short with PCM wicked

by battery separator

Photo Credit: Dirk Long, NREL

• Triggered by heating the cell above PCM melting temperature (presently 40°C – 60°C)

• Initial device design focus is on anode-to-cathode active material short 

• Improved device design focus is on anode-to-Al short

 NREL’s ISC instigator design

Wax

• Anode to Cathode ISC • Anode to Al ISC

This device is applied for patent
NATIONAL RENEWABLE ENERGY LABORATORY

Characterizing the ISC Device 

18

Technical Accomplishments

Model helps to understand characteristics of ISC device and short triggered

Axis symmetry geometry Current 

Boundary Condition

Ground 

Boundary Condition

Property Al pad Cu pad Cu piece

Positive 

current 

collector

Negative

current 

collector

Cathode 

electrode

Anode 

electrode Separator

Electric 

conductivity [S/m] 3.541x107 5.8x107 5.8x107 3.541x107 5.8x107 5 58 1x10-15

Assuming no interface contact 

resistance between components

Electric potential contour

Current density norm contour

Graphic not drawn to scale

• Cathode layer is the most 

resistive part in the short 

current path

• Short current is mostly 

carried by metal foils

separator
NATIONAL RENEWABLE ENERGY LABORATORY

ISC Device Function Test

19

Technical Accomplishments

NREL ISC device consistently activated a short in laboratory testing

0

50

100

150

200

250

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 20 40 60 80 100 120 140

Current (Amps), Temperature (oC)

Voltage Drop Across Platens (Volts) 

Time (Seconds)

Voltage Current Temperature

Consistent Short Impedance ~ 0.5 mΩ

• Impedance test • Coin cell test

0

5

10

15

20

25

30

35

40

45

50

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 5 10 15 20 25 30 35 40

Copper Platen Temperature (oC)

Coin Cell Voltage (Volts)

Time (Minutes)

Voltage Temperature

Reliable ISC Trigger in Coin Cells – 100% Success Rate

• In laboratory testing, the activated device can handle currents in excess of 200 A to simulate hard shorts 

(<5mΩ).

• Phase change from non-conducting to conducting has been 100% successful during trigger tests.

• Separator is an excellent wick for melted PCM.

• Nine of nine coin cells shorted with new ISC device design, shown here using a 42°C – 44°C melting PCM.

Photo Credit: Dirk Long, NREL
NATIONAL RENEWABLE ENERGY LABORATORY

ISC Device Implantation in a Large Cell 

20

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

0 20 40 60 80 100 120 140

Voltage (Volts)

Time (Minutes)

Cell 11 Cell 12 Cell 13

4-amp discharge voltage curves from initial cycle data

Dow Kokam 8-Ah pouch cells with anode-Al ISC device

Device has negligible impact on cell performance.

Cell 11 capacity = 7.862 Ah

Cell 12 capacity = 7.864 Ah

Cell 13 capacity = 7.789 Ah

Technical Accomplishments

Implantation of NREL ISC device does not impact electrochemical performance 

of 8-Ah Dow Kokam cells
NATIONAL RENEWABLE ENERGY LABORATORY

Implanting Anode-to-Cathode ISC in 8-Ah cells

21

Technical Accomplishments

ISC was consistently activated in 8-Ah stacked cells using NREL’s ISC device 

Implantation of ISC Device 

for Anode to Cathode short

Anode electrode

Cathode electrode

ISC device 

Cu side

Voltage Response to ISC 

Shown here implanted inside 

a Dow Kokam 8-Ah pouch cell 

ISC device 

Al side

• Thermal runway was not observed due to high 

impedance of the ISC between anode-tocathode electrode surfaces 

Photo Credits: Dow Kokam – Ben McCarthy
NATIONAL RENEWABLE ENERGY LABORATORY

Implanting Anode-to-Al ISC in 8-Ah cells

22

Technical Accomplishments

Anode-to-Al ISC implanted yielded lower impedance shorts in a 8-Ah cell

Dow Kokam lightly glued the custom ISC 

device to the modified cathode, lined up the 

separator hole with a template to center the 

separator hole, and then allowed stacking to 

proceed.

Implantation of ISC Device for 

Anode-to-Aluminum short

removed 

cathode coating

ISC device 

Cu side

stacking

0

20

40

60

80

100

120

3.85

3.9

3.95

4

4.05

4.1

4.15

0 5 10 15 20 25 30 35 40 45 50

Temperature (oC)

Voltage (Volts)

Time, Minutes

Voltage, Temperature Response to ISC

Detected a 55°C temperature rise in 80 seconds

Cell temperature on side of 

ISC device

OCV

Hot plate temperature

turned off here

On demand ISC – anode-to-Al trigger device

DK 8-Ah pouch cell

Isoc = 100%, 57°C ISC trigger temperature

• NREL’s ISC device was easily implanted during the 

manufacturing process on DK’s automated production line

Photo Credits: Dow Kokam – Ben McCarthy

OCV: Open Circuit Voltage
NATIONAL RENEWABLE ENERGY LABORATORY 23

Destructive Physical Analysis of Triggered Cell

Technical Accomplishments

Severe heat-affected zones were observed near the implanted short, 

subsequently creating separator holes in the adjacent layers 

Photos courtesy of Ben McCarthy, Dow Kokam

Unfolding the cell after the anode-to-Al short 

• Severe heat-affected zones in eight electrode layers in vicinity 

of ISC device and on inside of pouch laminate side near short.

• Tabs stayed intact.

• Anode and cathode sandwiching the ISC were not yet 

separated to prevent damage.

Inside pouch Anode electrode Damaged separator

Photo Credit: Dow Kokam – Ben McCarthy
NATIONAL RENEWABLE ENERGY LABORATORY

Collaborations

24

Collaborations with Other Institutions

Dow Kokam

• Dow Kokam assembled ISC-implanted cells and tested them to evaluate 

NREL’s ISC instigator device

NASA Johnson Space Center

• Eric Darcy of NASA-JSC, awarded by NASA’s Innovation Ambassador 

Program, joined NREL’s energy storage team (Jan ~ Sep 2010) and 

participated in the invention of NREL’s ISC instigator device 

• NASA-JSC also tested the ISC device at its facilities in Houston, Texas

Battery Safety Consulting, Inc.

• Dr. Daniel Doughty of Battery Safety Consulting, Inc. was subcontracted 

to submit a recommendation of Li-ion “Safety Roadmap” to DOE

• This document analyzes battery safety and failure modes of state-of-theart cells and batteries and makes recommendations on future 

investments that would support DOE’s mission
NATIONAL RENEWABLE ENERGY LABORATORY

Collaborations

25

Collaborations with Other Institutions

Battery Design LLC

• NREL researchers are collaborating with Robert Spotnitz of Battery 

Design LLC to expand NREL’s exothermic kinetics (empirical) model 

inventory

Sandia National Laboratories

• NREL researchers continue to discuss using SNL’s test data for NREL’s 

model development and validation with Christopher Orendorff of SNL 

U.S. Navy

• NREL researchers continue to discuss using Naval Surface Warfare 

Center (NSWC) test data for NREL’s model development and validation 

with Clint Winchester of NSWC’s Carderock division 
NATIONAL RENEWABLE ENERGY LABORATORY

Future Work

26

Future Work / Deployment Strategy

 NREL ISC Device

– Test cathode-to-Cu and Al-Cu collector shorts in stacked cells 

– Implant and test ISC device in 18650 cylindrical cell designs (with 

NASA)

– Test the effectiveness of battery management systems in preventing 

collateral damage to cells neighboring the cell with an ISC

– Partner with cell manufacturers and auto industry to help them design 

safer LIB systems, which appears critical to realizing technologies for 

green mobility

I

Time

 ISC Evolution Study

– Understand initial evolution of an ISC using a 

controllable test fixture

– Investigate factors and conditions affecting the time 

scale for ISC development

– Quantify the sensitivity of the factors 
NATIONAL RENEWABLE ENERGY LABORATORY

Future Work

27

Future Work / Deployment Strategy

 Pressure Model 

– Predict pressure evolving inside a battery 

container during thermal runway

– Understand cell venting mechanism

– Based on empirical correlations between 

temperature and volume of gas evolved 

from abuse reactions ARC chamber pressure evolution 

C. Orendorff, SNL

 Modeling Overcharge Mechanism

– Cathode Instability: Changes in the composition and lattice structure of 

the cathode host matrix during overcharge will be simulated

– Electrolyte Decomposition: The electrolyte decomposes due to the high 

voltage. The reactions taking place during this process will be included 

in the safety model

– Lithium Deposition: Lithium deposition during overcharge is usually 

assumed to take place when the anode voltage goes below 0V vs. 

lithium, whereas in this work we will explore the factors leading to the 

drop in the anode voltage
NATIONAL RENEWABLE ENERGY LABORATORY

Summary – Model Investigation

• The multiphysics ISC model study was performed using NREL’s 

electrochemical, electrothermal, and abuse reaction kinetics models

• Initial cell heating pattern under ISC varies with cell capacity

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

• The short for simple separator puncture is not likely to lead to an immediate 

thermal runaway

• Electrical resistance of ISC varies with short path across electrodes

• ISC bypassing cathode is likely to evolve into a hard short in relatively short 

time

• Cell thermal runaway response varies with short location and cell electrical 

configuration

• For low-resistance ISC, near-tab ISC results in a smaller resistance in a 

stacked cell because of shorter short-current path through shorting layers

• Pattern of local heating for convergence of short current varies with the 

location of the short and the internal electrical configuration of the cell

28

Summary
NATIONAL RENEWABLE ENERGY LABORATORY

Summary – Test Method Development

• NREL has developed a small, low profile device for simulating ISCs in 

active Li-Ion cells (applied for a patent)

• The ISC device was proven to activate a short consistently and repeatedly 

in laboratory tests

• To date, anode-cathode and anode-Al short-circuit cases have been tested 

in Li-ion coin and stacked pouch cells

• Implantation of NREL ISC device does not impact electrochemical 

performance of 8-Ah Dow Kokam cells

• The ISC device has shown great potential to produce results relevant to 

field failures caused by internal cell defects

– Evaluation of ISC response of a cell no longer has to rely on lessrelevant crush tests

– Results show promise to guide and focus cell production line defect 

and contamination mitigation measures

– Comparison of the abuse tolerance of various cell designs will be 

possible

29

Summary
NATIONAL RENEWABLE ENERGY LABORATORY

Publications and Presentations

30

1. G.-H. Kim, L. Chaney, K. Smith, A. Pesaran, E. Darcy, “Thermal Analysis of the 

Vulnerability of the Spacesuit Battery Design to Short-Circuit Conditions,” 2010 Space 

Power Workshop, Manhattan Beach, CA, April 22, 2010.

2. G.-H. Kim, K. Smith, K.-J. Lee, A. Pesaran, “Integrated Lithium-Ion Battery Model 

Encompassing Physics in Varied Length Scales,” The 3rd International Conference on 

Advanced Lithium Batteries for Automobile Application, Seoul, Korea, September 8–10, 

2010. 

3. G.-H. Kim, K.-J. Lee, L. Chaney, K. Smith, E. Darcy, A. Pesaran, “Numerical Analysis on 

Multi-physics Behaviors of Lithium-ion Batteries for Internal and External Short,” 218th ECS 

Meeting, Las Vegas, NV, October 10–15, 2010.

4. G.-H. Kim, K.-J. Lee, L. Chaney, K. Smith, E. Darcy, A. Pesaran, “Prediction of Multiphysics Behaviors of Large Lithium-ion Batteries at Internal and External Short Circuit,” 

Battery Safety 2010 in conjunction with 6th Lithium Mobile Power, Boston, MA, November 

3, 2010.

5. E. Darcy, M. Keyser, D. Long, Y.S. Jung, G.-H. Kim, A. Pesaran, B. McCarty, “On-Demand 

Internal Short Circuit Device,” 2010 NASA Aerospace Battery Workshop, Huntsville, AL, 

November 17, 2010.

6. M. Keyser, D. Long, Y.S. Jung, A. Pesaran, E. Darcy, B. McCarthy, L. Patrick, C. Kruger, 

“Development of a Novel Test Method for On-Demand Internal Short Circuit in a Li-Ion 

Cell,” Large Lithium Ion Battery Technology and Application Symposium in conjunction with 

Advanced Automotive Battery Conference 2011, Pasadena, CA, January, 24–28, 2010.

7. E. Darcy, M. Keyser, D. Long, Y.S. Jung, A. Pesaran, B. McCarthy, “On-Demand Internal 

Short Circuit Device,” 83rd Li Battery Technical/Safety Group Meeting, Key West, FL, 

February 16–17, 2011.
NATIONAL RENEWABLE ENERGY LABORATORY

Technical Back-up Slides

31
NATIONAL RENEWABLE ENERGY LABORATORY

Current abuse test methods may not be 

relevant to field failures

32

Penetration and Crush Tests Methods 

• Army/Navy/FBI use nail/bullet penetration tests.1

• NASA uses a crush test with a rounded rod.2

• Underwriters Laboratory (UL) uses a blunt nail crush test.3

• Motorola/Oak Ridge National Laboratory use a pinch (crush) test 

on pouch cells.4

Reliable, but not representative of field failures

1. Lyman, P., and Klimek, P., 69th Lithium Battery Technical/Safety Meeting, Myrtle Beach 2004.

2. Jeevarajan, J., 2008 NASA Aerospace Battery Workshop, Huntsville, AL.

3. Chapin, T., and Wu, A., 2009 NASA Aerospace Battery Workshop, Huntsville, AL.

4. Maleki, H., and Howard, J.N., J. Power Sources, 2008.
NATIONAL RENEWABLE ENERGY LABORATORY

Current abuse test methods may not be 

relevant to field failures

33

Contamination Test Methods 

• BAJ5 and Celgard6 retrofitted a Ni particle into the jellyroll of a cell 

and triggered the event using a crush test.

• Sandia National Laboratories has tried several methods7,8,9:

• Building cells with Ni particle contamination and combined with sonication, 

thermal ramp, or overcharge to trigger the short

• Implanting low-melting indium (In) alloy in the separator combined with heat 

trigger.

• TIAX retrofitted a metallic particle into the jellyroll of a cell and 

triggered the event by repeated charge/discharge cycling.10

More relevant, but with reliability and reproducibility challenges

5. Battery Association of Japan, Nov 11, 2008, presentation on web.

6. S. Santhanagopalan et al., J. Power Sources, 194 (2009) 550-557.

7. Orendorff, C., et al., ECS Meeting, May 2009.

8. Orendorff, C., and Roth, E.P., USABC TT Meeting, Feb 2009.

9. Orendorff, C., et al., ECS Meeting, Oct 2010.

10. Barnett, B., et al., 2010 Power Sources Conference.
NATIONAL RENEWABLE ENERGY LABORATORY

Hot Plate

34

Electrical Insulation

+

Mass

Internal short circuit 

simulator

-

Power cables to a 

battery cycler

Copper buss bars

Acrylic guide tube

Thermal/Elec. Insulation

Varying mass yields pressures

between 1 and 15 psi

Photo Credit: Dirk Long, NREL

Laboratory Test Fixture 
NATIONAL RENEWABLE ENERGY LABORATORY

Test Setup for Triggering ISC Implanted in a Cell

• Cell is charged to the 

appropriate state of charge.

• Hot plate provides the heating 

source.

• Cell is placed under 

compression (~1.6 psi).

• Al plate between hot plate and 

cell has an embedded 

thermocouple (TC).

• Thermocouple placed cell side 

opposite hot plate.

• Thin foam pad and Lexan plate 

placed between cell top and 25-

lb weight.

• Thin particulate bag 

encapsulates cell and its top TC 

(not shown for clarity).

Hot plate

Aluminum plate with embedded TC

Cell with ISC device

Thin rubber foam liner

Lexan sheet

25 lbs

TC

Graphic is not to scale

and for illustration only

TC

35
NATIONAL RENEWABLE ENERGY LABORATORY

Al layer of ISC device

Improving Interface Contact Resistance

• Cathode active material contact 

resistance with the pure Al foil 

pad of our ISC is on the order of 

~1 Ω and is driving the 

resistance of the anode-tocathode short.

– A metallic contaminant pressed into 

the cathode material during 

manufacturing would have much 

better contact resistance, as field 

failures have demonstrated

• Looking at advanced materials 

for improving contact 

resistances

– Carbon/polyvinylidenefluoride 

(PVDF) deposited on Al (pictured)

– High-conductivity micro-carbon 

fibers (pictured)

• Bonding Al disc onto the 

cathode active material during 

electrode coating. Photo courtesy of ESLI

Cathode layer

Cathode layer

Al

Carbon/PVDF 

Photo Credit: Bobby To, NREL

36