Analysis of Li-Ion Battery Joining Technologies*
Wayne Cai, Ph.D.Manufacturing Systems Research Laboratory
General Motors Global R&D CenterWarren, MI, USA
International Battery Seminar and ExhibitMarch 21, 2017
* W. Cai, B. Kang, and S.J. Hu, (2017), Ultrasonic Welding of Lithium-Ion Batteries, ASME Press* W. Cai, (2016), Lithium-ion Battery Manufacturing for Electric Vehicles: A Contemporary Overview, in Advances in Battery Manufacturing, Service, and Management Systems (eds J. Li, S. Zhou and Y. Han), John Wiley & Sons, Inc., Hoboken, NJ, USA.
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Outline
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1. BATTERY ELECTRIC VEHICLES2. LI-ION BATTERY CELLS, MODULES AND PACKS
1) Formats of Li-ion Battery Cells2) Battery Modules and Pack
3. JOINING TECHNOLOGIES FOR BATTERIES 1) Ultrasonic Metal Welding2) Resistance Welding3) Laser Beam Welding4) Wire-bonding5) Mechanical Joining
4. BATTERY MANUFACTURING: THE INDUSTRIAL LANDSCAPE1) Cell Manufacturing2) Module Assembly (Cell-to-Cell)3) Pack Assembly (Module-to-Module)
5. CONCLUSIONS
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1. Battery Electrical Vehicle Landscape
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Updated 3/30/2015
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1. Battery Electrical Vehicles
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Chevy Volt
Source: Google images
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Hierarchy of Battery Pack Manufacturing
Electrodes-to-Tab
Joining Processes of Battery Pack
Cell Level
Module-to-Module
Module Level Pack Level
Case(Sealing) Cell-to-Cell
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2. LI-ION BATTERY CELLS, MODULES & PACKS
Cylindrical Cells(1) The cylindrical cells are known to be less volumetric efficient than prismatic cells, but were the first format of li-ion cells
(2) 18650 cylindrical cells are used in Tesla’s electric vehicles
(3) PTC, or Positive Temperature Coefficient, is a type of material that demonstrates significantly high electrical resistivity at high temperatures so as to melt the PTC itself to break the circuit at higher electrical current.
(4) CID, or Current Interrupt Device, is another passive device that breaks when the pressure inside a cell reaches high levels. Normally, when the cell is overheated, such as in a thermal-away, the pressure increases to a level to break the CID and thereof the circuit.
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2. LI-ION BATTERY CELLS, MODULES & PACKS
Prismatic Cells
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2. LI-ION BATTERY CELLS, MODULES & PACKS
Pouch Cells
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highly conductive materials
thin, multi-layer materials
dissimilarmaterials
100% reliability
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3. JOINING TECHNOLOGIES FOR BATTERIES
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3. JOINING TECHNOLOGIES FOR BATTERIES
Ultrasonic Welding
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3. JOINING TECHNOLOGIES FOR BATTERIES
Ultrasonic Welding
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3. JOINING TECHNOLOGIES FOR BATTERIES
Ultrasonic Welding
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3. JOINING TECHNOLOGIES FOR BATTERIES
The Ultrasonic Bonding Mechanisms
A combination of the following four mechanisms may attribute to the bonding: (a) micro-melting (e.g., a few microns of thin interface layer melting), (b) metal interlocking (due to plastic deformation, particularly the severe
deformation caused by sonotrode knurls), (c) atomic diffusion, and (d) metallic bonding
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Chevy Volt Ultrasonic Welding:between battery tabs and the interconnect bus bar
15http://insideevs.com/2013-chevy-volt-battery-
pack-and-drivetrain-disassembly-video/
B.S. Kang, W. Cai, and C.A. Tan, “Dynamic Stress Analysis of Battery Tabs under Ultrasonic
Welding,” ASME Journal of Manufacturing Science & Engineering, 136(4), 041011 (May 21, 2014).
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3. JOINING TECHNOLOGIES FOR BATTERIES
Ultrasonic Welding Quality Prediction #1: Temperatures and Bonding Quality
The finding: preheating enhances the bonding quality
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3. JOINING TECHNOLOGIES FOR BATTERIES
Ultrasonic Welding Quality Prediction #2: Fracture
Fractures of the top layers should be avoided
Simulated deformation as compared with the experimental results
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3. JOINING TECHNOLOGIES FOR BATTERIES
Ultrasonic Welding Quality Prediction #3: Vibration
Cautions should be exercised to void damage from vibrations
GM Confidential
Interconnect (Cu)
Tab 3 (Cu) Tab 2
Tab 1Tab 4
Tab 5Tab 6 (Al)
existing welds Anvil
Active welds
Sonotrode
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3. JOINING TECHNOLOGIES FOR BATTERIES
Resistance Spot Welding
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3. JOINING TECHNOLOGIES FOR BATTERIES
Laser Beam Welding
Laser Braze-Welding
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BMW i3: Laser Welding
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3. JOINING TECHNOLOGIES FOR BATTERIES
Wire-bonding
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3. JOINING TECHNOLOGIES FOR BATTERIES
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3. JOINING TECHNOLOGIES FOR BATTERIES
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4. BATTERY MANUFACTURING: THE INDUSTRIAL LANDSCAPE
Cell Manufacturing
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4. BATTERY MANUFACTURING: THE INDUSTRIAL LANDSCAPE
List of battery cell components requiring joining
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4. BATTERY MANUFACTURING: THE INDUSTRIAL LANDSCAPE
Welding occurs for the following four scenarios in a battery cell
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4. BATTERY MANUFACTURING: THE INDUSTRIAL LANDSCAPE
Module Assembly (Cell-to-Cell)
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Conclusions
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Thank You!
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