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GM Exploring Supercap Li-Ion Combination for Next Generation Energy Storage for EREVs

GM is exploring combining supercapacitors for power with high-energy lithium-ion batteries for a next-generation energy storage system for the E-Flex EREVs. Click to enlarge.

General Motors is actively exploring the concept of combining supercapacitors and lithium-ion batteries in a next-generation energy storage system (ESS) for its E-Flex series of extended range electric vehicles (EREVs).

Although the primary objective of the project is to explore using supercapacitors for peak shaving the power capacity requirements of the lithium-ion battery pack, such a combination of ESS technologies also has the benefit of addressing the low-temperature performance issues of lithium-ion batteries, said Dr. Mark Verbrugge, Director, Material and Process Labs at GM’s Tech Center, during a presentation at the Advanced Automotive Battery Conference (AABC) this week in Tampa, FL.

The concept is especially suited for the EREV vehicles—such as the Volt—because of the combined requirement for high energy and high power. This is not for the coming Volt in 2010, Verbrugge stressed, “but we’re thinking beyond.”

Some initial results of the supercap-Li-ion combo (in green) compared to two conventional Li-ion chemistries. The upper grouping is plotted against the left vertical axis; the bottom three against the right vertical axis. Click to enlarge.

To keep the system complexity down, they are eliminating the DC/DC converter. The initial system being explored, partly as a way of developing and validating the method for subsequent work—consists of 6 100F Nesscap supercapacitors and two Kokum high-energy lithium-ion batteries.

Initial results show augmented power delivery for the ESS, at lower battery surface temperatures, with a slight sacrifice in energy density. GM has not yet evaluated the effect of the lower battery temperature on cycle life (higher battery temperatures degrade the performance of the cells)—a potential positive trade-off against the decreased energy density.

We’re running the Volt power versus time profile through this combination with and without the supercaps.  We wanted to show it [the early work], perhaps it will be compelling to those who want to provide ESS to the automotive industry.

—Mark Verbrugge

Supercapacitor manufacturer Maxwell Technologies and Argonne National Laboratory are investigating the potential of combinations of the two types of storage technologies for hybrid and plug-in hybrid vehicles as well. (Earlier post.)



In the article, "Kokum Lithium Ion Batteries" should read,
"Kokam Lithium Ion Batteries", for people that don't want to install East Indian fruit where their battery pack
should be.

Harvey D


GM, Ford and Chrysler have disappointed so many people for so long that it has become an acquired behavior to berate them no matter what they do.

However, one must admit that they deserved the scoldings most of the time.

Are the persistence reduction in sales of their vehicles a sign of more to come?

Will the Big 3 change their ways quickly enough to regain customers' trust?

If not, they may become the Mid-3 sooner than they think.


stas peterson,

Interestingly enough, one country critical for European trade will end up forcing the equivalent of Tier 2 Bin 5 emissions rules for diesel engines in Europe: Switzerland. This country suffers from SERIOUS air pollution problems from diesel trucks in the winter (the combination of high altitude and narrow mountain valleys makes it worse because it literally traps in the pollutants) and they want diesel vehicles to be much cleaner than the current Euro 4 standard.


Jim: The Apera may be legally registered as a motorcycle but they have worked exceptions to this rule so that you don't need a helmet.

Duh, the supercaps + battery is a good idea. Until someone can come up with a cap that operates better than a battery with respect to energy density(I keep forgetting which a cap is worse at, energy density or power) But, I know that everyone I have talked to are tired of the political inertia to get anything done in the US and, as a subset, major manufacturers. Yes I know the difference between the two and for the most part market forces MUST be involved if we are going to get well built, usable vehicles on the road that are also environmentally friendly and economical.


Hasn't this already been done? What are we waiting for... Here is a company that is trying to work with the big automakers and isn't getting any traction.
Check it out.


They have put this combination in a car and drove it across the country.

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