Self-heating lithium-ion battery could beat the winter woes

January 20, 2016
An all-climate battery that rapidly self-heats battery materials and electrochemical interfaces in cold environments. Credit: Chao-Yang Wang, Penn State

A lithium-ion battery that self heats if the temperature is below 32 degrees Fahrenheit has multiple applications, but may have the most impact on relieving winter "range anxiety" for electric vehicle owners, according to a team of researchers from Penn State and EC Power, State College.

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

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 packs to compensate for the cold sapping of energy.

"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," said Wang. "In cold winters, range anxiety is the last thing we need."

The researchers, relying on previous patents by EC Power, developed the all-climate battery to weigh only 1.5 percent more and cost only 0.04 percent of the base battery. They also designed it to go from -4 to 32 degrees Fahrenheit within 20 seconds and from -22 to 32 degrees Fahrenheit in 30 seconds and consume only 3.8 percent and 5.5 percent of the cell's capacity. This is far less than the 40 percent loss in conventional lithium ion batteries.

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.

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

Explore further: Built in sensors make lithium-ion batteries safer

More information: Nature, DOI: 10.1038/nature16502

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21 comments

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Lord_jag
5 / 5 (7) Jan 20, 2016
Range Anxiety. What a farce. Do people really not know what a range remaining indicator is for?

Coupled with a GPS, you should never have range anxiety unless you're in a gas chugger that doesn't tell you how much more range you have or how far you have until you pull into your next free refill.

You know what gives me anxiety? Standing outside in -25C, windchill -40C for 10 minutes holding the hose of an explosive fluid while my wallet is drained for $60. That gives me anxiety every week.

Wouldn't it be nice to run a cable to the car at night from the warmth and comfort of my heated and sheltered garage?
gkam
3 / 5 (6) Jan 20, 2016
Yes, and soon you won't need to connect a cable, just set the charger to come on when the power is cheapest, and let the induction charger in/on the floor do it for you.
gkam
1.8 / 5 (5) Jan 20, 2016
Not included in the above essay is the need for heat and usually lighting when the weather is very cold, putting greater demands on batteries, and shortening the range.

Lots of room to find even more ways to improve what is already a better way to drive for short trips.
shavera
5 / 5 (6) Jan 20, 2016
Lord_jag: I have an EV, and while, in general I'd agree about the range anxiety issue, the problem becomes particularly pronounced in edge cases. During the summer, my daily commute should have 30+ miles to spare. During the winter, that number can creep to less than 10. Does my car "have" the range for my commute? Seemingly, it depends on what time of year it is. It would be nice to have a range that is more *stable* throughout the course of the year.
Eikka
2.3 / 5 (3) Jan 20, 2016
and reduction of vehicle cruise range by as much as 40 percent


Almost all of that is not because the battery is cold - because the battery still holds the same amount of charge - but because the air density and rolling resistance increases dramatically in cold and snowy conditions, and because of the use of heaters to keep the windows open from frost and fogging up.

The battery in an EV is relatively oversized to the power demand of the motor, so it can usually supply enough current without a great loss in efficiency per se. The problem is that the cycle life of a lithium battery below 0 C drops dramatically, and recharging a cold battery can be extremely stressing to the cells.

I've read some reviews of Nissan Leafs and VW electric Golfs that simply refuse to accept a quick-charge at -15 C and driving the car doesn't appreciably heat the battery either, so if you're running out of range you're basically stuck.
Eikka
3.7 / 5 (3) Jan 20, 2016
The reason why combustion engines don't see the same kind of reduction in fuel economy is because they've got a higher baseline consumption. A car that consumes 7 liters to the 100 in the summer can use 8 or 9 in the winter, where about 5 liters of fuel consumption is simply due to the inefficiency of the engine.

And because they don't use any extra fuel for heat. A car heater below -15 C has to put out 4-5 kW to keep the windows defrosted and the floor mats dry etc. etc. and still you may need to run the rear window heater wire as well or else all the vapor collects there and fogs it up.

When you flip the switch in an EV to turn on the seat heaters, the AC heater, the rear window heater... that basically draws as much power as driving the car at roughly 30 mph. It really kills your city mileage.
Lord_jag
5 / 5 (3) Jan 20, 2016
So... a 2kW heater is more than good enough for a large bedroom, but you need 4-5 kW to warm a windshield?
Eikka
2.3 / 5 (3) Jan 20, 2016
Does my car "have" the range for my commute? Seemingly, it depends on what time of year it is. It would be nice to have a range that is more *stable* throughout the course of the year.


How long have you owned the car?

The other fear is that if your winter range is already marginal with less than 10 miles to spare, a couple more years down the road and the battery capacity will drop to the point where you simply don't have enough range to go.

Though the range meters aren't actually accurate enough to 10 miles because they have to average power consumption over a number of miles. There's a "reserve tank" left over, but you're reduced to limping at a reduced speed in most models.
Lord_jag
5 / 5 (5) Jan 20, 2016
The Tesla model S has a 75kWh battery. It takes 4-5kW to drive at 30mph?

So the Tesla... a super sport EV with way larger output than any other electric can run at 30mph for 15 hours?

Cool. Thanks for those accurate number Eikka.
Eikka
3.4 / 5 (5) Jan 20, 2016
So... a 2kW heater is more than good enough for a large bedroom, but you need 4-5 kW to warm a windshield?


Yes. Your bedroom has foot-thick walls or more, and double or triple glazed windows, and carpets on the floor and a roof on top with yet more insulation.

The car windshield is constantly being blasted with 30-60 mph freezing-cold wind on the other side of a thin laminated glass. Cars have neglible thermal insulation because it would add so much weight.
Eikka
2.3 / 5 (3) Jan 20, 2016
The Tesla model S has a 75kWh battery. It takes 4-5kW to drive at 30mph?

So the Tesla... a super sport EV with way larger output than any other electric can run at 30mph for 15 hours?

Cool. Thanks for those accurate number Eikka.


Not necessarily the Tesla S. There's so much extra electronics in that car that the parasitic power use is on the order of 1-2 kW when it's running. There was a problem with the sleep modes in the computers that made some owners report 1.4 kW even when the car was "off".

4-5 kW applies to smaller lighter cars, like the Nissan Leaf, when counting just the motor power and not accessories. It's comparable to the 3-4 kW engine power of a moped, increased by the greater frontal area drag of the car.

Eikka
3 / 5 (4) Jan 20, 2016
Wouldn't it be nice to run a cable to the car at night from the warmth and comfort of my heated and sheltered garage?


Many more people don't have the luxury of garages.

A car has to be able to start and run after sitting outside in that -25 C weather. When it is -25 C outside, you have to run a 1-2 kW mains electric blower for up to an hour, because the entire interior and the frame of the car is so cold that it just sucks up all the heat. Once the interior starts to warm up, the windows start to stay clear with less power.

When you don't have a dry garage, it's hard to keep the water out because even your own breath just instantly freezes all over the interior and condensates on the windows. You need tons of hot air to dry everything out quickly while you drive, or else it just keeps accumulating.

If you don't have the heat, eventually you'll be sitting there with two little holes scrubbed in the windshield with your thumbs, trying not to crash into anything.
gkam
2.5 / 5 (8) Jan 20, 2016
Yes, . . he's right, . . why go on living?
Eikka
3 / 5 (4) Jan 21, 2016
Yes, . . he's right, . . why go on living?


If that's how you choose to take it, why indeed?

People who live with their heads in the clouds tend to stub their toes a lot.
Eikka
3.6 / 5 (5) Jan 21, 2016
What a farce. Do people really not know what a range remaining indicator is for?


Range anxiety is not just about having enough range to get where you're going right now.

It's about not having enough range to go where you might be going. Such as a surprise trip to take your kid to the hospital, or turning back half-way in to work because you left your important papers at home.

It's like living paycheck-to-paycheck with zero savings and no credit at the end of the month. If you run out, you walk. It induces stress knowing that if anything unexpected happens, all your plans and schedules are ruined because your car can't go the extra mile.

For some people that's not an issue, they just call the AA or the local towing company and order a taxi, and pay hundreds of dollars for the pleasure. For the motoring masses who don't belong to the upped-middle-class, that's a real dealbreaker.
promile
Jan 21, 2016
This comment has been removed by a moderator.
greenonions
5 / 5 (3) Jan 21, 2016
Like Lord_jag - I own a Leaf - and my experience very much supports his comment. We have 2 cars - one of them a ICE - that we can always fall back on. We are the early adopters of new technology. As Eikka points out - you have to have a certain level of wealth to be able to do that. Our joint income is around $100,000 U.S. - so we are not the super wealthy. However - we are watching the story unfold - and many smarter than me - agree that the electric car will replace the ICE. The life cost of the Leaf is very similar to driving an ICE - lower fuel/maintenance, but higher up front costs. Bolt is coming out next year with a 200 mile range - big difference. Technology moves on - and I think it is exciting times. Eikka lives under the desk - worrying about what might happen. Others of us prefer to enjoy the progress.
tear88
not rated yet Jan 21, 2016
The batteries of Tesla models are arranged in thin layer at bottom of car. Not only it does save the place, it also helps to cool the batteries, which are prone to overheating at the case of these power-hungry models. So I don't think, that the tempering of these batteries with internal resistance wire will be very energetically effective just with respect of their good cooling.

Hmm. My initial reaction to the article was "to heck with talking about it, just do it. Yesterday". But you deflated my enthusiasm. It should have been obvious to me that both extreme cold, and extreme heat (as in, the batteries catching fire) must be considered.
promile
Jan 21, 2016
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antialias_physorg
not rated yet Jan 25, 2016
Such as a surprise trip to take your kid to the hospital

I dunno how many hundreds of miles you live away from hospitals. If it's too far away do what everyone else does: call an ambulance.

or turning back half-way in to work because you left your important papers at home.

Tesla has a neat feature that tells you when to go 'fuel up'. In the above case you're going to be late anyway. So a 10 minute side trip to the power station isn't going to change the situation (could have been required with a regular car, too. They don't magically have unlimited range, you know?)

Bolt is coming out next year with a 200 mile range

I'm waiting for the Tesla Model 3. That seems to have the specs I need.

If you run out, you walk.

How is that different from other cars?

and pay hundreds of dollars for the pleasure.

They just do what every motorist does. They check the friggin' fuel gauge before/during a trip.
promile
Jan 25, 2016
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