Self-Heating Lithium-Ion Battery Overcomes Range Loss Issues In Cold Temperatures

FEB 7 2016 BY MARK KANE 23

World's First Fast Rechargeable Battery at Low Temperature

World’s First Fast Rechargeable Battery at Low Temperature

Penn State and Penn State spin-off EC Power presented a solution to overcome the decline in performance of cold lithium-ion batteries.

Their idea is to create self-heating cells called All-Climate Battery, which rely on use of a nickel foil inside cells combined with a temperature sensor attached to a switch. If the battery pack is needed and temperature is below 0˚C (32˚F), the circuit will be closed and the nickel foil will work as heater:

“The all-climate battery uses a nickel foil of 50-micrometer thickness with one end attached to the negative terminal and the other extending outside the cell to create a third terminal.  A temperature sensor attached to a switch causes electrons to flow through the nickel foil to complete the circuit.  This rapidly heats up the nickel foil through resistance heating and warms the inside of the battery.  Once the battery is at 32 degrees Fahrenheit, the switch turns off and the electric current flows in the normal manner.

While other materials could also serve as a resistance-heating element, nickel is low cost and works well.”

According to Penn State, the results are very encouraging, while the prototype cells were only 1.5% heavier and cost was only 0.04% higher.

The team claims capability to heat battery cells from -4 to 32˚F (from -20˚C  to 0˚C) within 20 seconds using 3.8% of cell capacity. Heating from -22 to 32˚F (from -30˚C  to 0˚C) took 30 seconds and uses 5.5% of the available energy.

Why is heating batteries important? Well, cell performances (charging capability, efficiency) are much better at higher temperatures:

“Conventional batteries at below freezing temperatures suffer severe power loss, which leads to slow charging in cold weather, restricted regenerative breaking and reduction of vehicle cruise range by as much as 40 percent, the researchers said in today’s (Jan. 20) issue of Nature.  These problems require larger and more expensive battery packs to compensate for the cold sapping of energy.”

We doubt whether 40% loss of range comes directly from a cold battery, because most of the range loss comes from driving conditions in the winter and heating (up to several kW of additional usage).

Chao-Yang Wang, William E. Diefenderfer Chair of mechanical engineering, professor of chemical engineering and professor of materials science and engineering and director, Electrochemical Engine Center said:

“It is a long standing problem that batteries do not perform well at subzero temperatures. This may not be an issue for phones and laptops, but is a huge barrier for electric vehicles, drones, outdoor robots and space applications.”

“We don’t want electric cars to lose 40 to 50 percent of their cruise range in frigid weather as reported by the American Automobile Association and we don’t want the cold weather to exacerbate range anxiety. In cold winters, range anxiety is the last thing we need.”

“Next we would like to broaden the work to a new paradigm called SmartBattery. We think we can use similar structures or principles to actively regulate the battery’s safety, performance and life.”

More details can be found in this article: “Lithium-ion battery structure that self-heats at low temperatures“.

EC Power also presented a set of prismatic and pouch cells in 10 to 20 Ah capacity that were manufactured to demonstrate viability and to enable tests in vehicles.

All-Climate Battery Cells

All-Climate Battery Cells

Source: Penn State via Green Car Congress

Categories: Battery Tech


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23 Comments on "Self-Heating Lithium-Ion Battery Overcomes Range Loss Issues In Cold Temperatures"

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It would make it impossible to keep the cells balanced or the same temps.
Outside cells will use much more than inside module cells making it even worse.
Just circulating warm, cool air works far better.

… warm, cool air …


Er. . .

, is the new OR. , hadn’t you heard?

Then write it like this: warm, cool, air. With two commas, or: Just circulating either warm or cool air…etc
Nick was correct in calling that out, as it is confusing.

I guess some people are easily confused. It is fairly obvious to most. The rest are too dumb to matter.

, (for the uninitiated, we all know a comma, means or.)

Since it is only being used to raise the temp to 32F, and it happens in a matter of seconds, I don’t see this as being an issue.

Kdawg, that would only mean you have little knowledge of how to make lithium batteries have a long life.

I don’t think you understand what they are doing.

Most batteries are inherently self heating to some degree during operation. There is plenty of heat from the controller and motor to keep batteries and passengers warm.

I’m no battery specialist but what I can say is that is a welcome feature that should have been done firsthand.
Subzero cold battery cut regeneration to zero, energy capacity by 15% and some chemical efficiency is also loss in those condition.
So if it’s that fast to heat it up, you would still have a battery with less energy if it has been charge cold.
So you would only gain more regeneration and marginal efficiency in the power chain, but if it could be use to heat up your battery before top it up and balance the cell at proper time before departure it would help a lot.
That would be a “Get ready” feature.
40% is pretty optimistic, but 20-25% gain would be achievable and welcome.

It definitely wouldn’t make cell balancing impossible, just more challenging. It would need nondissipative BMS with relatively high balancing current.

While not technically impossible, it is likely that any benefit from cell level heating versus pack level heating could be overshadowed by the cost and complication of the BMS system it would require.

But if they made the heating centrally controlled and simultaneous for all cells, it woudn’t cause any issue with balancing.

Maybe you should call Penn State research and let them know they don’t know what they are doing. Then let us know what they said.

How does the efficiency compare to warming the batteries with a liquid heating system?

I assume there would be less losses, but didn’t see any numbers.

That’s the crux of the matter. There will be energy loss either way, but perhaps this could be more efficient in using battery power, and thus less range loss.

Is 32F a critical temperature for a typical EV battery of the future, or is this sensor mis-selected/mis-configured?

I’ve seen claims that 20° F is the critical temperature, but there may be practical reasons for activating the heating at the freezing point of water.

Upon further reflection, perhaps I shouldn’t have used the term “critical temperature”. It’s not like batteries suddenly quit working all at once, like water freezing at 32° F.

As I understand it, there is a gradual loss of li-ion battery performance starting at about 40° F, altho that may vary a bit depending on the exact chemistry. But as I said, the loss in performance is gradual.

Perhaps 20° is the temperature at which the loss becomes really noticeable when driving an EV, altho I would expect that to vary somewhat between different EV models, since they don’t all use the same method of maintaining battery temperature.

Yes, it is gradual and there really is no starting temperature. Even at 60° F the battery has measurable capacity loss compared to 70° F. But it’s not practically significant loss.

Depends on type of the batttery, but typical li-ion batteries still have over 90% capacity at 32° F, but closer to 80% at 20° F. Considering the trade-off between the energy lost for heating and the capacity loss in cold, I’d say 32° F seems like reasonable set point.

Thanks for the elucidation.

Have they stuck these self-heating cells into a pack large enough for a 200+ mile BEV and put into climate simulators yet?

I would think before Penn State or EC Power expound on their new battery technology, they would have some statistics to back up their theories.

Thanks Mark, for sharing this information and relaying that it is hypothetical at this stage.

To think that so many people are involved in deeply trying to improve the performance and reliability of lithium cells as referred to in the article, that they would further want to prove their theory backed up with hard data.

I’ll shelve this in the “?” file for now, as it’s just one of so many claims as to groups that are on the brink of a breakthrough to greatly improve lithium performance. If true, and even at a 15-25% improvement in cold weather performance, it would be highly significant.

As far as I know BMW have incorporated in the i3 a “Get ready at XX hr” that pre heat the cabin and the battery and it seems a valuable feature for cold climate users.
It does give more range both ways, saving on heating the cabin and more potent battery, but you need 7 hours before departure to allow time to heat the battery.
So quick heating would help a lot!
Don’t know about the % of benefit thought.