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CMU study suggests difficulties in reaching targeted low price points for Li-ion batteries

11 December 2016

A new study by a team at Carnegie Mellon University examining the costs for varied cell dimensions, electrode thicknesses, chemistries, and production volumes of cylindrical and prismatic Li-ion batteries finds that although further cost savings are possible from increasing cell dimensions and electrode thicknesses, economies of scale have already been reached, and future cost reductions from increased production volumes are likely to be minimal.

Their findings suggest that prismatic cells, which are able to further capitalize on the cost reduction from larger formats, can offer further reductions than those possible for cylindrical cells. However, none of these changes are sufficient to reach the DOE energy storage target of $125 kWh by 2020, the study found. Even in the most optimistic scenario, when the cells are the largest (20720), electrodes the thickest (100 mm), and the production volume is 8 GWh per year, the cost per kWh for LMO cells is well above the DOE target. NCA cells are $206 kWh-1 and NMC cells are $180 kWh-1. Their paper is published in the Journal of Power Sources.

Ciez1
Historical prices and future cost predictions for lithium-ion batteries. Estimates include both cell- and pack-level cost assessments, which is reflected in the significant variability in the cost estimates. The DOE target (advanced to 2020) and represented by the blue horizontal line, is $125/kWh. Ciez and Whitacre. Click to enlarge.

Engineering and Public Policy (EPP) Ph.D. student Rebecca Ciez and Materials Science and Engineering (MSE) and EPP Professor Jay Whitacre—who earlier this year published a paper concluding that lithium market fluctuations are unlikely to impact Li-ion battery prices significantly (earlier post)—developed a process-based cost model tailored to the cylindrical lithium-ion cells currently used in the EV market.

They noted that due to current sales trends, three lithium-ion chemistries account for nearly all of the storage capacity, and half of the cells are cylindrical. However, no specific model has existed to examine the costs of manufacturing these cylindrical cells.

The number of vehicles sold and the storage capacity of these vehicles varies significantly. The Tesla Model S, one of the most popular electric vehicles, has a battery pack that varies between 75 and 90 kWh, much larger than the 10.5 kWh average pack size for PHEVs and double the 42 kWh average for BEVs. These packs also use cylindrical lithium-ion cells, a departure from the prismatic cells examined in previous models.

Electric vehicle sales and pack sizes also impact the most commonly used lithium-ion chemistries. Lithium Nickel Cobalt Aluminum Oxide (NCA) is the most common chemistry, accounting for half of the storage capacity on the road today, and Lithium Manganese Oxide (LMO) and Lithium Nickel Manganese Cobalt Oxide (NMC) account for approximately a quarter each. Other chemistries have been used in niche applications (predominantly in California compliance cars and early electric vehicle models), but have largely been phased out.… Also as a result of these sales trends, on a per kWh basis, the majority of lithium-ion batteries on the road in the US today are cylindrical.

To date, manufacturing process research and cost models have focused exclusively on prismatic cells, and there is no specific model to address the costs of manufacturing cylindrical cells. To address the disparity between the current EV battery market and research, we present a process-based cost model specifically adapted for manufacturing cylindrical lithium-ion cells.

—Ciez and Whitacre

Further cost reductions are possible if manufacturers can avoid markups on cathode precursor materials, and by increasing the size of the cells. In this regard, prismatic cells have a slight advantage over cylindrical cells, because they can use thicker electrodes and have a higher storage capacity per cell. However, even with these changes, none of the cells considered reached the Department of Energy cost target of $125 per kWh.

Ciez
Cost per kWh for lithium ion batteries made in two different configurations: cylindrical and prismatic. Even at full scale, where all economic advantages are realized, no approach is near the $125 per kWh target. Source: CMU. Click to enlarge.

While initial cost savings are possible from increased production volumes, the potential for cost reductions from scale alone past 1 GWh of annual production—a level large battery manufacturers have already surpassed—is minimal, they found. At these higher production volumes, materials play a significant role in the $/kWh cost, accounting for roughly half of overall expenses.

Cathode material costs can be reduced by producing them from precursors in-house instead of purchasing them from suppliers. LMO is subject to the highest markup, at almost 200%, but the markup for NCA and NMC have substantial impacts on the cost per kWh as well. Like prismatic cells, lithium prices play a small role in the cost of NMC and NCA cylindrical cells. A more than 200% increase in the price of lithium carbonate leads to a less than 10% increase in the cost per kWh for each of the cell configurations considered.

—Ciez and Whitacre

Cell hardware is also a significant contributor to overall cost; with their greater design flexibility, prismatic cells can be larger, requiring less hardware per kWh and thereby reducing cost. The study found that LMO prismatic cells can be manufactured for less than half the cost of cylindrical LMO cells. Although there is potential for reducing costs using prismatic formats for NCA snd NMC cells, those cells are more rate-limited than their LMO counterparts, the study found.

Many of these materials are already highly commoditized, and unlikely to see significant cost reductions. While we are open to the idea that very low-cost lithium-ion batteries can be produced, our comprehensive analysis does not show a clear pathway to this based on what we know today.

—Rebecca Ciez

This work was supported by a National Science Foundation Graduate Research Fellowship.

Resources

  • Rebecca E. Ciez, J.F. Whitacre (2016) “Comparison between cylindrical and prismatic lithium-ion cell costs using a process based cost model,” Journal of Power Sources, Volume 340, Pages 273-281 doi: 10.1016/j.jpowsour.2016.11.054.

December 11, 2016 in Batteries, Manufacturing | Permalink | Comments (38)

Comments

Researchers making statements about costs that they have no reliable information about are no good. Tesla has the lowest cost and the highest energy density cells in the world. The range of their cars proves it. Earlier this year Tesla confirmed they were below 190 USD per kwh at the pack level meaning their battery cells are below 150 USD per kwh. Tesla uses about 80 USD worth of raw materials currently per kwh. Musk believe a production markup of only 20 USD per kwh in mass production on the cost of raw materials are possible. So 100 USD per kwh with current battery tech in super mass production at the cell level. Future battery cells like the 2170 cell that Tesla will make at their Nevada 150 GWh per year factory may even cost less because its higher energy density uses fewer raw materials per kwh.

https://electrek.co/2016/11/02/tesla-panasonic-2170-battery-cell-highest-energy-density-cell-world-cheapest-elon-musk/

That said Tesla’s new self-driving tech is going to sell Tesla’s cars much better and faster than better battry tech that takes many year to evolve. Driverless cars are already here and will start transporting passengers on the Tesla Network in 2018 on a massive scale.

And here is the rub for large battery BEVs.

Costs simply have not reduced as fast and far as hoped for.

Tesla claims should be treated as Tesla claims.

A company which is repeatedly pulled by the SEC for inaccurate and misleading accounting in financial figures for which it has legal liability is not to be taken accorded open ended credence for what is says on costs for which it has no liability, and where costs can be compiled on all sorts of bases,

More credible is GMs $145 KWH at the cell level for their purchases of NMC prismatics from LG Chem, but that is at the cell level, not the battery level and is not in very substantial disagreement with the figures laid out here.

GM uses pouch cells in the Bolt not prismatic.

Hi Janner.
I believe they call them pouch prismatic.

It looks as this is the beginning to the end for EVs. Cost will be lowest around 2025, and market penetration will peak, but later, the lack of raw materials will increase prices and customers will turn their interest to something else.

Davemart Tesla’s latest quarterly account the one that had a positive earnings for the first time in a long period was adjusted in accordance to SEC recommendations that Tesla stopped reporting non-GAAP figures. Tesla only reported the non-GAAP because they better represented their dealings with leases that previously were done mostly by Tesla. Now that this is outsourced to third party financial companies the justification for reporting non-GAAP figures is no longer as strong. So Tesla changed it. Tesla did not hide anything and reported both figures previously not have they broken any law. See more here https://electrek.co/2016/11/28/tesla-tsla-sec-accounting-method/

Tesla’s less than 190 USD per kwh at the pack level and GM’s statement of 145 USD per kwh at the cell level tells me that this is where we are currently at the battery cost level in mass production. However, GM warns that their Bolt battery pack can degrade by up to 40% after 100,000 miles which does not sound like a very good battery to me. I have never heard of a Tesla that lost 40% of its capacity after 100,000 miles. GM also only gives a warranty of 100,000 miles unlike Tesla’s warranty that is unlimited on miles or 8 years.

https://electrek.co/?s=bolt+40%25

That prismatic cells should be better than cylindrical cells is BS. There is no evidence to support that. All we know that the best BEVs in their price segment namely the Bolt and the Model S and X all use cylindrical cells.

Actually I found a link that suggests the bolt uses prismatic cells. It is quite elaborate so I believe it is true. See http://www.mychevybolt.com/forum/viewtopic.php?t=119

It also says the 60kwh battery is 960 pound. Tesla can do 90kwh with only 1200 pound.

Choosing a bev over a gas serial hybrid is silly. The nissan e-note, a serial hybrid cost only 19 000$ and make a profit for nissan amd the chevy bolt cost 35 000$ offer few range and gm lose 9 000$ WE have to have sustainable car on the market without costly subsidies. Trump and rex tillerson and pruitt will cut these silly subsidies of the climate change scam and thus eradicate bevs.

If one looks at the individual points on the chart its and compare values for each individual year, the strongest conclusion I come back with is that the experts (blue circle) are usually wrong.

I stick my neck out to predict that the low cost battery (less than $100/kWh) of whatever other chemistries than those of current batteries will not be forthcoming. However, extended range BEVs will enter the market place in the next 5 years with around 20 kWh battery pack sizes plus range extenders (PEM or solid oxide fuel cell/metal air battery/gas turbine/opposed piston engine) that will cost much less than a 60-80 kWh battery pack. It will provide affordable vehicles of unlimited operating ranges at very low or zero emission levels.

See page 4 here for the usage prismatic (pouch)
http://www.manufacturing.gatech.edu/sites/default/files/uploads/nsf/201101NSFEnergyManufacturingHu.pdf

Also note that the 25% of batteries given as NMC in the article are obviously LG Chem's batteries, whatever they are designated as.

As for the Tesla financials, I have been following them for a great deal longer than one quarter, so figures stuffed up by suddenly counting all their ZEV credits don't impress me.

I don't intend to go into the gruesome financials of Tesla on a site more interested in technical issues, but they are hardly such as to inspire confidence in anything else they claim.

You cannot sell the Commoner on ion battery chemistries and cost/size/kWh. You can sell the Commoner on Vehicle bling, size, price, fueling time and miles between fueling. The Commoner believes modern day vehicles are clean because he doesn't smell anything bad. Place some Mercaptan in the fuel (e.g. our NG supply) and the Commoner may change his mind.

In the future, a BEV will be "tagged" as a city car. The Commoner will not perceive the tag in a negative way. It is plain and simple.

Seriously? You guys are going to fall for yet another study that assumes current technology will determine future costs and limitations? LMMFAO!!!

Davemart, you're still hurting that everyone, even Toyota, is finally admitting that HFCVs are a joke. But I expected better from you than to keep taking it out on doom and gloom predictions for BEVs.

DaveD:

You seem to have allowed your prejudices to entirely warp your perceptions.

I have at no stage said that these are ultimate limits for batteries, but that these appear to be serious issues for the present chemistry of them.

Nor have Toyota changed their policy.

They have aways said that they would produce electified cars as and when suitable batteries became available.

They discontinued the IQ EV as the batteries were not good enough at the time in their view.

They are now producing the Prius Prime and will introduce other PHEVs as they have now developed batteries good enough for that application.

They have also said that on a relaxed time schedule they will produce BEV by around 2020 with a 300 km on the Japanese scale range, which is around 110 miles on the EPA.

Kerp your fantasies and your ill manners to yourself, then you might be able to read and understand what is written, instead of substituting your obsessions for the facts.

I think PHEVs are a better use of expensive batteries than BEVs. I think HEVs are a better use than PHEVs. You can make 60-100 HEVs that get 40% better mileage rather than ONE BEV.

For years, you've been on here claiming that FCVs were more practical and wanted us to all stop and acknowledge how right you were and your predictions just a few months ago.

Now Toyota has even pulled back and put their CEO personally in charge of the new EV division. It must be painful for you now so I can understand your frustrations.

Your predictions about the eventual winner were clearly wrong and that must be hard to deal with.

By 2021, there will be batteries for under $100/kWh at the cell level. These studies are as pathetic as the ones that said it was over $1,000/kWh back in 2011 and would be $450/kWh in 2016.

Stupid is stupid is stupid. This is like watching a bunch of people at a Trump rally claim that Trump cares about them even though they're poor. LOL

SJC,
You're making a false assumption that we have to choose one over the other. Trump will not be able to slow momentum because automakers still have to deal with CARB and other countries that will not change their standards.

So it will take all of these strategies to hit the numbers they need in 5 years on their fleet average.

DaveD said:

'For years, you've been on here claiming that FCVs were more practical and wanted us to all stop and acknowledge how right you were and your predictions just a few months ago.'

I have made no such prediction.
If you want to claim that, go and find and like the exact quote, or withdraw your fabrications.

What I have said is that it is absurd to dismiss fuel cell cars, but repeatedly said that I do not know what the balance between fuel cell vehicles and battery electric cars would be, nor is it possible for anyone else to know as the relative progress of the technologies is unknowable.

I have also said that it is very difficult to have a society using a lot of renewables without hydrogen or other chemical storage, but if my own preference for a lot of nuclear were followed then there would be less need for FCEVs.

So stop lying about what I have said, and learn to read.

CMU study suggests difficulties in reaching targeted low price

Difficulties folks, it said "difficulties" not 'impossibilities.' What's the old adage? "It takes 20% of the effort to reach 80% of the way and 80% of the effort to get the last 20%"

Where's the surprise here?

I should add that welcoming advances in fuel cells and hydrogen production does not mean that I would not welcome advances in batteries, for instance perhaps lithium sulphur or magnesium sulphur.

Why would I not welcome it?

I have advocated low emission transport for years, and am not prescriptive about how it is done.

That is the province of ideologues with their one, sole, and only solutions, a notion which is based on ignorance, arrogance and narrow mindedness.

Batteries and fuel cells work great together, and enable each other.

The more either improve or both the more I will be pleased.

Batteries are agnostic, How is a fuel cell of concern? Batteries are not the answer either. Batteries are heavy and do not work well in cold climates. In general, electricity to charge batteries is dirty, and was delivered to the target at great loss.

CAFE is relevant and important. CARB is only relevant to followers of the biased CARB community.

We can build HEV, PHEV and EV but when batteries are scarce and expensive I would rather have 100 HEVs get 40% better mileage than 1 in a 100 be a BEV and get 1% better mileage.

SJC. Amen brother.

Doc Strange Love,

I couldn't care less about CARB as they're a bunch of hydrogen morons. However, they're relevant because they control a huge market for cars in California and other blue states follow their lead. But most importantly, they were established and running their mandates before the EPA so they're grandfathered in.

So Trump and his morons can't effect them. THAT is why they're important. The CARB members are as crooked and biased as they come so I'm no fan. They are nothing more than a convenient firewall against Trump.

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