GRA
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Re: All "Future" battery technology thread

Sat May 13, 2017 12:31 pm

Brad Berman via plugincars.com:
Tesla Makes Progress in Pursuit of a Battery Breakthrough
http://www.plugincars.com/tesla-makes-p ... 32868.html

I generally treat most announcements of battery breakthroughs as so much hot air, but this is more of an announcement of continuing gradual improvement, and it's from Jeff Dahn, who has more credibility than the average startup promoter trolling for investors (which isn't to say that hype is impossible).

researcher working for Tesla said this week that the life of electric car batteries could be extended to 20 years of use. Jeff Dahn of Dalhousie University, based in Nova Scotia, said that battery life—the capability of cells to maintain their energy and power capacity over time—is one of his four critical interrelated research goals. The other three are lower costs, increased energy density and improved safety.

“Doubling the lifetime of the cells was exceeded in round one,” said Dahn in a presentation at the Massachusetts Institute of Technology. The use of an aluminum coating appeared to be helpful in extending the longevity of cells. “We have another four years to go,” said Dahn. “So we’re going to go as far as we can.”

Panasonic is Tesla’s battery partner. “We think the existing technology can extend the energy density of lithium-ion batteries by 20 to 30 percent,” said Kazuhiro Tsuga, Panasonic’s president, as reported last month by Japan’s Nikkei. Increased energy density and reduced costs are the keys to offering long-range electric cars at an affordable price. . . .

Dahn’s research project with Tesla is only one year into a five-year effort—and is already being utilized in “2170” cells being produced in Tesla’s Nevada-based Gigafactory.

IMO, the two out of four which are most important at the moment are reduced cost/kWh and increased longevity. The former will directly lower battery prices for a given capacity, while the latter will reduce the need to oversize battery capacity to give it an adequate range at its end of life, while reducing battery weight and space and contributing to knock-on weight reductions, and indirectly reduce cost even if $/kWh remains the same. It will also reduce/eliminate any concerns about having to find the money for a replacement at some nebulous point int he future. The closer a battery's life comes to equaling the life of the car, the more acceptable and better value for money it will be for the general public (assuming it's affordable in the first place).

Increased energy density is always nice, but cost is the pacing factor to mass adoption right now. Safety seems to be adequate among currently available batteries, but it never hurts to improve it.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

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RegGuheert
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Re: All "Future" battery technology thread

Sat May 13, 2017 1:25 pm

Thanks, GRA! Great find! I've been unsuccessfully trying to locate Dr. Dahn's recent presentation at the 34th Annual International Battery Seminar. No matter, the news you found gives us an idea where things are going.

Of course, since this is Dr. Dahn's NMC technology that they are discussing, Tesla (or their customers if they give them the option) will have the option to trade some or all of the additional life against capacity by simply adjusting the upper cutoff voltage. From the Electrek article which was quoted in the article in International Business Times which PlugInCars was quoting:
Electrek quoting Dr. Jeff Dahn wrote:“In the description of the [Tesla] project that we sent to NSERC (Natural Sciences and Engineering Research Council of Canada) to get matching funds from the government for the project, I wrote down the goal of doubling the lifetime of the cells used in the Tesla products at the same upper cutoff voltage. We exceeded that in round one. OK? So that was the goal of the project and it has already been exceeded. We are not going to stop – obviously – we have another four years to go. We are going to go as far as we can.”
Here is another interesting quote:
Electrek wrote:In the second half of the talk, he explained how their new testing methods led them to discover that a certain aluminum coating outperformed any other material. The cells tested showed barely any degradation under high numbers of cycles at moderate temperature and only little degradation even in difficult conditions.
I wonder what is getting coated in aluminum.

Unfortunately, MIT pulled the video of the session which Electrek linked to in their article.
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

JRP3
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Re: All "Future" battery technology thread

Sat May 13, 2017 1:45 pm

GRA wrote:IMO, the two out of four which are most important at the moment are reduced cost/kWh and increased longevity. The former will directly lower battery prices for a given capacity, while the latter will reduce the need to oversize battery capacity to give it an adequate range at its end of life,...


Except no one is really doing that. Tesla didn't make a 100kWh pack to provide extra range at the end of the vehicle life, they did it because people want more range now. Tesla packs are showing very good capacity retention. Tesla reserves maybe 10% of capacity total, more of at the low end, because extreme DOD is harmful to the pack, and I've not seen any evidence that Dahn's work would change that. Longer cycle life is good but at this point cost and energy density are still the highest priority, with improved safety coming in third. Cycle life would be fourth on that list for automotive, though a higher priority for grid storage packs.

GRA
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Re: All "Future" battery technology thread

Sat May 13, 2017 2:01 pm

JRP3 wrote:
GRA wrote:IMO, the two out of four which are most important at the moment are reduced cost/kWh and increased longevity. The former will directly lower battery prices for a given capacity, while the latter will reduce the need to oversize battery capacity to give it an adequate range at its end of life,...

Except no one is really doing that. Tesla didn't make a 100kWh pack to provide extra range at the end of the vehicle life, they did it because people want more range now. Tesla packs are showing very good capacity retention. Tesla reserves maybe 10% of capacity total, more of at the low end, because extreme DOD is harmful to the pack, and I've not seen any evidence that Dahn's work would change that. Longer cycle life is good but at this point cost and energy density are still the highest priority, with improved safety coming in third. Cycle life would be fourth on that list for automotive, though a higher priority for grid storage packs.

I agree that people want more range, but the question is what are they willing to pay for. Tesla buyers don't much care about the cost, but everyone else does. The Bolt can probably meet commute/errand needs for a decade or more pretty much regardless of climate, but it's a very expensive way to achieve that. The general public would be far more willing to accept even two-passenger commute cars with adequate range, if they cost $15k and they knew the battery would last for 15 years.

So sure, we'd all like to see a miracle battery with a lot higher specific energy and energy density, but until longevity is increased the car will cost far more (and be far heavier) than it should be to give it long range over time, compared to an ICE.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

JRP3
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Re: All "Future" battery technology thread

Sat May 13, 2017 2:07 pm

Cost is directly tied to specific energy. The more kWh you get from the same amount of material the lower the cost. Longevity has no impact on cost at this point.

GRA
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Re: All "Future" battery technology thread

Sat May 13, 2017 3:46 pm

JRP3 wrote:Cost is directly tied to specific energy. The more kWh you get from the same amount of material the lower the cost. Longevity has no impact on cost at this point.
Cost can be tied to specific energy either way. If you have to use more expensive materials (i.e. different chemistry) to boost the specific energy, or your quality control has to be tighter, then it can cost more. Just as a for instance, LFP is probably slightly cheaper in raw materials costs than NMC or most of the others, and also has better cycle life, heat tolerance and safety, but lower energy densities. LTO same re life, lowest cost but lowest specific energy, on the anode side.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

JRP3
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Re: All "Future" battery technology thread

Sat May 13, 2017 4:24 pm

NCA is more than twice the density of LiFePO4 so on a per kWh basis it is in fact cheaper. It is a prime example of why cycle life does not improve costs, as is LTO, which is the most expensive lithium based chemistry yet has the longest cycle life, the exact opposite of your claims. As I keep saying, longer cycle life does not positively impact vehicle purchase costs.

GRA
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Re: All "Future" battery technology thread

Sat May 13, 2017 4:47 pm

JRP3 wrote:NCA is more than twice the density of LiFePO4 so on a per kWh basis it is in fact cheaper
Yo have cost breakdowns?

JRP3 wrote:It is a prime example of why cycle life does not improve costs, as is LTO, which is the most expensive lithium based chemistry yet has the longest cycle life, the exact opposite of your claims. As I keep saying, longer cycle life does not positively impact vehicle purchase costs.

It seems our sources differ, as the one (admittedly, simplistic) I consulted shows LTO as having the lowest cost (which surprised me): http://batteryuniversity.com/learn/article/types_of_lithium_ion

What source(s) were you using?
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

JRP3
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Re: All "Future" battery technology thread

Sat May 13, 2017 5:39 pm

Battery University isn't always an up to date resource, but even they show NCA as lower cost than LiFePO4, and though their graph shows LiTiO as least expensive, further down in their summary table they say the following:

Long life, fast charge, wide temperature range but low specific energy and expensive.

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RegGuheert
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Re: All "Future" battery technology thread

Sat May 13, 2017 6:00 pm

JRP3 wrote:Battery University isn't always an up to date resource,...
It's no wonder when it comes to Li-ion considering how quickly things are changing. They list LFP as having a cycle life of 1000-2000 cycles, but you can purchase LFP batteries with a similar capacity, but that can handle 12,000 cycles.

The work that Dr. Jeff Dahn is doing to eliminate the corrosion of the NMC cathode at high voltages is very critical, as it will allow significantly more capacity by allowing the termination voltage to be increased to 4.5V. If he can pull that off, it will put NMC far ahead of other technologies for vehicle applications. He recently identified the key cause of the corrosion and is working to find other chemistries that will work better.
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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