Transcript Innovation, Implementation & Impact

Modeling battery electrode
properties
Presentation to:
Math Problems in Industry workshop
David Clatterbuck
Jacqueline Ashmore
6/16/08
TIAX LLC
15 Acorn Park
Cambridge, MA
02140-2390
www.TIAXLLC.com
Reference No.:
© 2006 TIAX LLC
Overview
Introduction to TIAX
Batteries & electrodes
MPI workshop project description
MPI workshop, WPI, 2008
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Overview
Introduction to TIAX
Batteries & electrodes
MPI workshop project description
MPI workshop, WPI, 2008
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Introduction to TIAX
Focus
TIAX implements innovations, accelerating the transformation of ideas and
technologies into significant and sustainable business growth for our clients.
Ideas & Technologies
Market Impact
Implementation
Focus
Hospitals
Universities
Company A
National Labs
Company B
Reach of Research
Corporate R&D
Reach of Companies
End
Start
Inventors
Start-ups
Company C
Company …
•
•
•
•
Internal laboratories
Development tools
150+ technologists
Surround technologies
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Introduction to TIAX
Approach
We incorporate several important elements into our approach, making TIAX
unique in its ability to create value for our clients.
Implementation
Focus
Approach:
IP Blending
Collaboration
Leveraging investments by accessing and incorporating the
most appropriate IP from all available sources
Creating a team that really works—reliably accelerating
development while building capabilities
Linked Diversity
Integrating deep technical expertise within a multidisciplinary
business context
Context Shifting
Adapting proven solutions and insights from one industry to
resolve issues and create opportunities in another
Hands-On
Delivering tangible results using our people, tools, and
infrastructure
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Introduction to TIAX
Overview
TIAX is a new, independent company that builds on the 116-year legacy of
Arthur D. Little, Inc.
• Founded in May 2002 by Dr. Kenan Sahin
• Acquired assets of the ADL Technology & Innovation
business
• Dr. Charles Vest, MIT President Emeritus, chairs our
Advisory Board
• More than 150 scientists, engineers, and technicians,
with PhD and MS degrees from top universities
• More than 40,000ft2 of laboratory space
• Extensive ties to research and industry
• Headquartered in Cambridge, MA, with a West Coast
presence in Silicon Valley, CA
• An ISO 9001-registered and secure facility
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Introduction to TIAX
History
TIAX advances a century-long track record of breakthrough innovation.
Nonflammable motion
picture film (sold to Eastman
Kodak)
Commercialized scroll
technology for
automotive applications
Sent five
experiments on first
moon mission
Pioneered commercial
cryogenics applications,
founded HELIX
Patented
technology
leads to
development MIT Holds
of Fiberglas Controlling Interest
Non-CFC aerosol
device
Commercialized
& patented
synthetic
penicillin
Griffin &
Little
established
1886
Heat-pump
water heater
has 60%
more efficiency
TIAX LLC founded (May 2002)
Flavor Profile
method
First iso-octane
(later adopted as
antiknock gas
standard)
Developed
reformer
technology—
enabling fuel-cell
vehicles to use gasoline
& alternative fuels
Non-toxic foam neutralizes
chemical & biological agents
Developed SABRE
with IBM
Formulated
Slim Fast
line of
drinks
Advanced protective
clothing used by
industrial & agricultural
workers
New line of cooking
appliances for
SubZero/Wolf
APTAC chemical reactor
measures process risk
Developed and sold advanced
lithium ion battery technology
to major Japanese firm
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Introduction to TIAX
Mission
TIAX’s mission is to help clients create an impact in the market and a difference
in people’s lives across four interconnected themes:
Health &
Wellness
Lifestyle
Comfort &
Convenience
New ways to deliver care
as well as improve
wellness through the air we
breath, our food and
personal care products
Enabling people be more
effective in daily chores
and make their time more
enjoyable, satisfying and
fulfilling
Enhancing people’s safety
and security at rest or
while performing functions
and missions
Delivering energy/power
efficiently, subject to cost
effective resource and
environmental constraints
Human
Safety &
Security
Energy
Efficiency &
Sustainability
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Overview
Introduction to TIAX
Batteries & electrodes
MPI workshop project description
MPI workshop, WPI, 2008
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Batteries & electrodes
Li-ion batteries Applications
Advanced Li-ion battery technology is one of TIAX’s key market areas
TIAX has the largest independent Li-ion battery research group in the US
Our research spans the Li-ion field:
 cathode, anode, electrolyte, separator, battery safety
 modeling, material synthesis, characterization, performance testing
Applications:
Portable electronics
Power Tools
Laptops
Hybrid electric vehicles
(HEVs) – Toyota Prius
Plug-in hybrid electric vehicles
(PHEVs) – Chevy Volt
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Batteries & electrodes
Modeling
We use a wide range of linked models which span the range from atomistic
calculations, to cost models for entire systems.
New Products &
Processes
Customer
Model
Value - in Use Model
C3H8
Ef
Quantum
Chemistry
O
M
C3H7 H
O
Market Model
M
Microkinetics
Transport phenomena
–$
Battery engineering
¥€
Device engineering
Cost model
Examples
Quantum Chemistry: Designing new cathode materials with improved cycle life (stability).
Battery Engineering: Determining the role of internal short circuits in battery safety incidents.
Cost Modeling: Evaluating the impact of different cathode materials on the cost of PHEV
battery systems.
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Batteries & electrodes
Key Battery Attributes
Li–ion batteries must meet a range of performance criteria which vary in
importance depending on the application.
Key Battery Attributes
• Energy Density: Total amount of energy that can be stored per unit mass or
volume. How long will your laptop run before it must be recharged?
• Power Density: Maximum rate of energy discharge per unit mass or volume. Low
power: laptop, i-pod. High power: power tools.
• Low-Temperature Energy Density: The amount of energy that can be recovered
decreases at low temperatures due to slower charge and mass transfer.
• Safety: At high temperatures, certain battery components will breakdown and can
undergo exothermic reactions.
• Life: Stability of energy density and power density with repeated cycling is needed
for the long life required in many applications.
• Cost: Must compete with other energy storage technologies.
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Batteries & electrodes
Li-ion battery chemistry/physics
A Li-ion battery is a electrochemical device which converts stored chemical
energy directly into electricity.
To a large extent, the cathode material limits the
performance of current Li-ion batteries
V
Separator
+
-
Cathode
Li Li Li Li Li Li
LiMO2
Anode
Li Li Li Li Li Li
Graphite
• During charging an external voltage
source pulls electrons from the
cathode through an external circuit to
the anode and causes Li-ions to move
from the cathode to the anode by
transport through an liquid electrolyte.
• During discharge the processes are
reversed. Li-ions move from the anode
to the cathode through the electrolyte
while electrons flow through the
external circuit from the anode to the
cathode and produce power.
Non-aqueous electrolyte
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Batteries & electrodes
Anode Current Collector
Li-ion battery chemistry/physics
More details on the transport of Li-ions.
• Both the anode and cathode are made from a collection
of powder particles which are bonded together into a
3-D porous body (electrode).
• During discharge, ion transport in the electrode occurs as
follows (green line)
1. Li-ion starts in the bulk of a cathode particle.
2. It undergoes solid state diffusion in the particle.
3. At the surface it disassociates from the e- and enters
the electrolyte which occupies the pores of the
electrode.
4. The ion is transported through the electrolyte (liquid
phase diffusion) to the anode.
5. In enters the anode.
6. It undergoes solid state diffusion in the anode.
• At the same time, the electron must pass through the
collection of solid particles to a metal current collector
where it can be extracted from the cell and used to power
a device (red line). It can not travel in the electrolyte.
6
5
4
4
Electrolyte
4
3 1
2
Cathode
Current
Collector
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WPI,
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Batteries & electrodes
Battery Electrodes
Real electrodes are more complex.
• Electrodes typically contain high surface area carbon to increase the
electrical conductivity between particles.
• A small amount of polymer binder is used to hold the particles in place.
• Typical particle size ~10um.
• Typical electrode thickness 50-75um.
Cathode Current
Collector
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Batteries & electrodes
Particle size distribution
Real powder particles can have different morphologies and surface roughness.
10mm
1mm
10mm
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Batteries & electrodes
Impact of electrode structure
The internal structure of the electrode plays an important role in the
performance of a battery.
Energy vs. Power
• For a given battery chemistry, the energy stored in the battery is proportional to
the amount of active materials (i.e. anode + cathode powder).
– For a cell of a given size, the higher the packing fraction of the powders, the
more energy the battery can store and the longer your device can run before it
needs recharging.
• The power (rate of energy delivery) depends on having sufficient mass and
electrical transport throughout the electrodes. In theory, higher power can be
achieved with:
– smaller particles
– higher surface area
– larger fraction of porosity (i.e. more electrolyte)
– thinner electrodes
• Careful design of electrodes is required in order to produce electrodes with the
desired balance between high power and high energy.
• Commercial electrode design is currently dominated by empirical
experimental approaches.
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Batteries & electrodes
Property trade-offs
For a given cathode material, you can vary the electrode morphology to gain
power at the expense of energy density.
Different applications require different combinations of properties (laptop vs. cordless drill).
Specific Power / W kg
-1
Power and energy from a high-power cell design
6500
5500
4500
CAM-7
3500
LiFePO4
NCA
NCM
LiMn2O4
2500
1500
100
120
140
160
180
Energy Density of High Power Cell / Wh kg-1
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Batteries & electrodes
Impact of electrode structure
The internal structure of the electrode plays an important role in the
performance of a battery.
Electrodes for cathodes with slow solid state diffusion
• Some cathode materials suffer from poor kinetics (slow solid state diffusion)
• Some success has been achieved by using very small cathode particles
(~100nm) because the average diffusion distance a Li-ion must travel in the
particle is much smaller.
• However, these nano-powders typically have a low tap density and are difficult
to tightly pack due to surface effects. This causes the batteries to have lower
energy densities.
• Selecting a the best particle size will involve a trade-off between energy
density and rate behavior.
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Overview
Introduction to TIAX
Batteries & electrodes
MPI workshop project description
MPI workshop, WPI, 2008
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MPI workshop problem description
Overview
TIAX would benefit from algorithms, methods, models, scaling relations, or
frameworks to analyze the effect of different particle characteristics on
electrode properties.
• Knowledge of qualitative and/or quantitative relationships between electrode
structure and performance will be useful in:
– Isolating which features of current electrode structures are critical in
achieving good performance,
– Predicting improvements to current empirically determined relationships,
– Identifying tradeoffs in structural features and performance.
• The inputs for the problem for the MPI workshop are particle properties; the
outputs are electrode properties.
• TIAX can link the predicted electrode properties to key parameters quantifying
electrode performance, such as energy density.
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MPI workshop problem description
Input variables
The inputs for the problem for this workshop are particle properties.
(Zamponi, Nature, 2008)
• Some particle characteristics to consider might include:
– Size of monodisperse spheres
– Roughness of monodisperse spheres
– Radii of bidisperse spheres
– Particle sizes with more realistic distributions of sizes (i.e. Gaussian distribution)
– Deviations from sphericity, e.g., ellipsoidal particles
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MPI workshop problem description
Output variables
The outputs for the problem for this workshop are electrode properties.
• Some electrode properties of interest include:
– Packing fraction or void volume
– Total surface area
– Average path lengths for transport through the individual solid particles to
the particle surface
– Average path length for diffusion through the void volume from the surface
of a particle to the surface of a collection of particles (electrode) of a
certain thickness.
– Effective cross-sectional area for this type of mass transport.
– Average path length to travel through the collection of particles of a certain
thickness, if you must travel only through the particles (passing from
particle to particle only at points where they meet). Effective crosssectional area for this type of transport.
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MPI workshop problem description
Problem scope
Determining all of the electrode properties for all possible combinations of
particle characteristics is probably not a manageable task!
• It may be useful to consider some of the more complex electrode properties
for the case of simple particle size distributions (i.e., monodisperse spheres).
• For more complex particles, determining the packing fraction may be a
sufficiently challenging problem.
http://www.physics.nyu.edu/~pc86/
packing.html
• We would also like to increase our understanding of the literature in this area;
any information you can provide on relevant references will be useful.
Finally, experiments
involving M&Ms may
contribute to
understanding the
packing fraction of
different shaped
particles.
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MPI workshop problem description
Contact information
David and Jacquie will be a “tag team” at the workshop part-time.
• When we are not here you can reach either of us in the following way:
– Jacquie
mobile tel. 617 899-8935
– David
office tel. 617 498-6088 (mobile tel. 510 290-0982)
• We look forward to seeing the results, and thank you in advance for your
efforts!
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