In a lithium-ion battery, the lithium is stored in metallic (uncharged) form inside the particles of a graphic electrode. During discharge the lithium comes to the electrode’s surface, where it is ionized, creating a current that travels to the cathode. At the cathode, typically a lithium-based alloy, the ions are neutralized and enter electrode particles as metallic lithium. The battery is recharged by forcing a current to flow in the opposite direction, moving the lithium back into the anode. Credit: MAPLE Lab/WUSTL
U.S. Dept. of Energy (DOE) announced Aug. 2 that a team of engineers at
Washington University in St. Louis will receive $2 million to design a
battery management system for lithium-ion batteries that will guarantee
their longevity, safety and performance. This is a particularly
challenging project because the electrochemical reactions inside the
battery are not easily captured in mathematical form.
project is one of 12 that won funding from the DOE’s Advanced Research
Projects Agency-Energy (ARPA-E) under the new AMPED program that focuses
on innovations in battery management and storage to advance electric
vehicle technologies and to help improve the efficiency and reliability
of the electrical grid.
latest round of ARPA-E projects seek to address the remaining
challenges in energy storage technologies, which could revolutionize the
way Americans store and use energy in electric vehicles, the grid and
beyond, while also potentially improving the access to energy for the
U.S. military at forward operating bases in remote areas,” says
Secretary of Energy Steven Chu.
cutting-edge projects could transform our energy infrastructure,
dramatically reduce our reliance on imported oil and increase American
energy security,” Chu says.
initiative is part of a broader effort to strengthen the university’s
expertise in energy-related technologies,” says Pratim Biswas, PhD,
chair of the Department of Energy, Environmental & Chemical
Engineering in the School of Engineering & Applied Science.
this grant targets car batteries,” he says, “the technology is also
directly applicable to intermittent sources of energy such as solar that
produce energy that may need to be buffered rather than plugged
directly into electrical grid.”
department has also recently won a large grant in solar technology and
plans to launch an effort called Solar Energy and Energy Storage, or
AMPED award goes to the Modeling, Analysis and Process-control
Laboratory for Electrochemical systems (MAPLE) in the Department of
Energy, Environmental & Chemical Engineering, led by Venkat
Subramanian, PhD, associate professor.
want to give credit to my doctoral students,” Subramanian says.
“Without their efforts, we wouldn’t have been able to submit a proposal.
The solicitation came and we had two weeks to respond after the team
was formed, and then we got a review and we had to respond over the
addition to Subramanian, the team includes doctoral students
Venkatasailanathan Ramadesigan, Paul Northrop, Sumitava De, Bharatkumar
Suthar and Matthew Lawder.
batteries are what are called secondary cells, because the
electrochemical reactions that create a current are reversible and the
battery can be recharged. The more familiar primary cells, in contrast
are used once and thrown away.
lithium is stored in metallic (uncharged) form inside the particles of a
graphic electrode, explains Subramanian. During discharge the lithium
comes to the electrode’s surface, where it is ionized, creating a
current that travels to the cathode. At the cathode, typically a
lithium-based alloy, the ions are neutralized and enter electrode
particles as metallic lithium.
The battery is recharged by forcing a current to flow in the opposite direction, moving the lithium back into the anode.
batteries hold great promise for applications such as electric vehicles
because they have high energy density (energy stored per unit volume)
and lose charge very slowly when not in use.
battery is perfect and lithium-ion batteries, like all batteries, have
drawbacks. If the batteries are charged too fast, they can heat up and
may explode. To avoid catastrophic failure, manufacturers overdesign the
batteries and use only part of their energy capacity per cycle,
goal of the AMPED program is to push the current technology to
100-percent efficiency, while making sure battery lifetime is not
compromised,” Subramanian says. This would ultimately reduce the weight
of the car and improve its energy efficiency.
Revving up the models
you can predict what will happen inside the battery, you can push the
battery to do more per cycle,” Subramanian says. “Currently empirical
(experience based) models that have no predictive capability are used to
manage the batteries. This is why manufacturers over-stack the
material; they have no idea what’s happening inside.”
are physics-based models of lithium-ion batteries but they are
computationally intensive and can’t be solved in real time by the usual
is where the MAPLE lab comes in. The engineers plan to use a class of
simulation techniques called spectral methods aided by mathematical
analysis to solve a physics-based model’s differential equations.
Spectral methods should allow them to cut down on the model’s
computational demands so that it runs faster.
Battery Management System (BMS), MAPLE lab develop will keep the
battery operating optimally, enabling maximum utilization of energy at
general,” Subramanian says, “people write mathematical models and then
plug them into commercial software to solve them. We relish solving the
models ourselves to see if we can find more elegant ways to do it.
That’s the overarching theme of our work.
are also interested in re-examining predictive models of importance for
medicine, such as those used in medical imaging, to see if we can solve
them faster but with the same accuracy so that they can be used in
real-time sensing and control,” he says.
on the Defense Advanced Projects Agency (DARPA), famous for its daring
funding decisions, ARPA-E was launched in 2009 to seek out breakthrough
technologies that are too risky for private-sector investment but have
the potential to energy technology, form the foundation for entirely new
industries, and have large commercial impacts.