Lithium-Ion Battery Simulation for Greener Ford Vehicles

AUTOMOTIVE
FORD MOTOR CO., DEARBORN, MICHIGAN
motive industry. The nickel used in these
batteries is lighter than lead, helping
the battery deliver twice the power output
for the weight as lead-acid batteries.
All of Ford’s HEVs on the road today use
NiMH batteries.
“Technological advances in NiMH batteries
at the cell level are responsible for
much of the evolution of the pack design
from the Ford Escape to the Ford Fusion.
But these advances constituted the last
of the ‘low-hanging fruit’ for NiMH,” explained
Dr. Bernardi. Since automakers
already believe they have tapped most
of the potential of NiMH technology in
HEVs, they are now moving toward the
use of lithium-ion (Li-ion) technology due
to its higher energy density, higher power
density, and potential cost savings.
The Lithium-Ion Advantage
Li-ion batteries are commonplace
in the world of consumer electronics.
They’re lighter and more energy dense
than other types of batteries, making
them ideal for laptop computers, mobile
phones, and other portable devices.
For use in HEVs, Li-ion battery packs
offer a number of advantages over the
Particle Dimensionless Radial Distance
Cu foil
Negative
Sep.
Dawn Bernardi, Ph.D., is a battery research engineer
with Ford Motor Company in Dearborn, MI.
NiMH batteries that power today’s hybrid
vehicles. In general, they are 25-
30% smaller and 50% lighter, making
them easier to package in a vehicle, and
can be tuned to increase power to boost
acceleration or to increase energy to extend
all-electric driving distance. “The
hybrid-electric vehicle is the next frontier
for the lithium-ion battery. To the
Positive
Al foil
Figure 4. Simulations of lithium concentration throughout all particle locations within the positive electrode
during after 40 seconds of a 10C discharge pulse [see Figure 2]. Regions denoted “Positive,” “Sep.,”
and “Negative” correspond L neg , L sep , and L pos , respectively in Figure 1. The color scale from deep red to
deep blue is associated with highest and lowest lithium concentration. Simulation results were obtained
using COMSOL 3.5a.
user, all these advantages could translate
to better fuel economy at lower vehicle
cost,” said Dr. Bernardi.
Intensive development work is now
underway to prove-out Li-ion technology
for the auto industry, and Ford is
using its extensive experience in BEVs,
PHEVs, and HEVs to test the technology
rigorously for its critical role in highvolume
electrified vehicles of the future.
“At Ford, we believe lithium-ion batteries
have incredible potential for the next
generation of electrified vehicles, and
we’re already using lithium-ion technology
in test units for the battery-electric
vehicles that are part of our new electrification
strategy,” said Ted Miller, senior
manager of energy storage strategy and
research at Ford Motor Company. “There
are still technical challenges to make lithium-ion
technology work in high-volume
automotive applications and we are working
hard to address those.”
Modeling and Simulation
To design affordable, fuel-efficient
HEVs, manufacturers require a complete
understanding of battery life and performance
characteristics. For example, an
automobile is expected to have a 10- to
15-year lifespan, so researchers at Ford
need to ensure that new battery designs
are going to last that long as well. For
work in this arena, modeling and simulation
is invaluable.
“In order to know that the battery is
going to last the life of the vehicle, we’d
have to do at least 10-years worth of testing.
But under our accelerated product
development, we don’t have 10 years to
put out a vehicle; we have maybe 3 to
4 years,” explained Dr. Bernardi. “In a
sense, modeling and simulation allow
us to go into a time machine — fastforwarding
into the future — to help us
determine how a battery will perform after
150,000 miles based on data that we
have right now. It helps us make better
decisions with less test time.”
Batteries themselves are complex devices,
with behavior that is governed by
a multitude of interdependent physical
effects and chemical processes (see sidebar
on page 11). Batteries for automotive
propulsion are even more complicated be-
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