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evnow
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 11:45 am

drees wrote:Is it really a 45Ah cell when it drops to 35Ah after a dozen cycles? That's nearly a 25% loss in capacity. Better to call it a 35Ah battery which is still impressive.

After 400-500 80% cycles it's down to 25Ah - 30% down from 35Ah and only about half of it's fresh capacity. By this point it's only nominally better than today's tech.

If they can get the anode to hold up better it'd be a lot more impressive.
Yes - thats what I was thinking too. It is much better to call it a 35Ah cell (300 Wh/kg) cell.

This is what the Envision guy wrote in MT. I don't know enough about battery research to say whether his claim (that some more engr work will improve cycle life) is true or not.
Please note that the cells have cycled 400 times in our labs and are still cycling. Cells have also been sent to NSWC for cycle tests. The important thing is to first reach the energy density and then continue to improve cycle life. If cycle life was less then 20 cycles, one could make an argument that there is a science issue. At this point, having cycled over 400 times and still cycling – engineering work will be needed to increase cycle life.

Also note, number of cycles as cited in USABC manual for electric cars is a 1000 cycles. For a 300 mile car, if you cycle all the way 1000 times, you get 300 * 1000 = 300,000 miles.
Read more: http://blogs.motortrend.com/cost-cuttin ... z1nboBBen0" onclick="window.open(this.href);return false;

I think even a 500 cycle, 80 kWh battery @300Wh/kg that comes in at $15k, 500 pounds of cells (close to Leaf battery) in 2015 will be very compelling to a large % of population. That will give about 250 miles of range when new. It will be 3 times better than the Leaf battery in terms of density.

Ofcourse, the cost isn't proven yet. But the cost is probably good because they aren't using expensive materials like Cobalt. Some Chinese manufacturers already offer cells in the $200/kWh range.
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batzman
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 2:12 pm

Very interesting article... and mentions the leaf as well for comparison...

http://www.greencarreports.com/news/107 ... the-masses" onclick="window.open(this.href);return false;

New Battery Promises To Bring 300-Mile Electric Cars To The Masses
BY NIKKI GORDON-BLOOMFIELD
2012 Leaf Brilliant Silver SL
Member 100 mile club & 200 km club
Schneider Electric L2 EVSE 30A charger
9.45 kW PV Solar System

Herm
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 3:58 pm

It may be that this same cell derated to 300Wh/kg and 80% SOC becomes a 1000 cycle cell.. and that is pretty darned good. Very practical for everyday 40 mile driving if your pack can do 200 miles all out.

Desertstraw
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 4:50 pm

Envia, the future battery may be here.
http://www.scientificamerican.com/article" onclick="window.open(this.href);return false;.
cfm?id=new-energy-dense-battery-could-enable-long-distance-electric-cars

"Looking for signs that the automotive landscape may be changing sooner than most people realize? Here's one. Envia Systems, a start-up battery company that counts General Motors as a significant investor, has announced it has produced a cell with an energy density of 400 watt-hours per kilogram (Wh/kg). It also claims they will be priced somewhere in the $125 per kilowatt-hour neighborhood."

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Re: All "Future" battery technology thread

Mon Feb 27, 2012 5:19 pm

evnow wrote:
Bassman wrote:I read an article on this last year. They basically replace the spent electrolyte in the battery with a charged one. So it's like filling your small tank (batteries) at a gas station but with battery fluid instead of gasoline. :)
No it isn't. That is completely different.
I was talking about the MIT article. So it was the same battery I was talking about!
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SanDust
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 5:21 pm

It's interesting when something becomes "news". Envia uses the NMC technology developed by Argonne Labs. GM and LG Chem have also licensed this technology and an early form of that chemistry is already in the Volt battery. In addition, Nissan announced over two years ago that its next generation battery would double the specific energy using NMC technology.

That said, 400 wh/kg is impressive. That number has always been said to represent the point at which EVs can seriously compete with ICE vehicles. I wouldn't worry overly much about the 400 cycles. That's a decent number of cycles and cycle life can always be improved. However, expecting these on the road in a year or two is a big stretch. More like four or five years would be a better guess.

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Re: All "Future" battery technology thread

Mon Feb 27, 2012 5:49 pm

In a couple of years this thread will have grown to a couple hundred pages and cover about 20 different battery news releases.. what fun! :)

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evnow
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 6:56 pm

drees wrote:Is it really a 45Ah cell when it drops to 35Ah after a dozen cycles? That's nearly a 25% loss in capacity. Better to call it a 35Ah battery which is still impressive.
This is what the Envion guy is writing in GCR. The "drop" in capacity is because after 3 cycles they are just charging to 80% DOD. Definitely that graph presenatation needs to be improved.
The capacity drops off in the first three cycles because the first 3 cycles were done at 100% DoD (C/20, C/10 and C/3 rates respectively). Cycles 4-400 were conducted at 80% DoD at C/3 which are typical charge/discharge profiles in automotive EV applications. By definition you'd get 80% of the original capacity. Hope this helps.
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evnow
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Re: All "Future" battery technology thread

Mon Feb 27, 2012 6:57 pm

SanDust wrote:It's interesting when something becomes "news". Envia uses the NMC technology developed by Argonne Labs. GM and LG Chem have also licensed this technology and an early form of that chemistry is already in the Volt battery. In addition, Nissan announced over two years ago that its next generation battery would double the specific energy using NMC technology.
This is not NMC. They are using Si-C anode and High Density Manganese Rich cathod. They get good price by not using Cobalt which is expensive.

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Re: All "Future" battery technology thread

Mon Feb 27, 2012 10:19 pm

evnow wrote:This is what the Envion guy is writing in GCR. The "drop" in capacity is because after 3 cycles they are just charging to 80% DOD. Definitely that graph presenatation needs to be improved.
That makes a lot more sense and cycle life looks halfway decent, then. Still have some work to do on cycle life - good lithium cells will do close to 100% DoD and last 400-500 cycles before losing 20% capacity.

I wonder how calendar life affects it?

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