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ZENN and EEStor What has happened PDF Print E-mail
Written by Greg Allen   
Monday, 29 October 2007
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ZENN and EEStor What has happened
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Let's catch up on what has happened:

ZENN Motor Company paid ultracapacitor developer EEStor $2.5 million for a 3.8 percent equity. This deal means that ZENN gets an exclusive opportunity for EEStor's ultra-capacitor batteries for small to medium sized vehicles.It is said that EEStor is using the 2.5 million to fund the next stages of testing for their ultracapacitors by an independent third party lab. If the much talked about capacitors meet the requirements laid out in the ZENN agreement, then ZENN will get another option to invest another $5 million dollars under the same terms as the initial 2.5 investment.

EEStor CEO recently said that commercial production within 10 months away.  The ZENN Motors CEO had said the exact same thing a day or so before. Really, the EEStor technology is the giant unknown right now. If they can do what they claim they can, than every other battery manufacturer in the world will rethink their business. ZENN Cars

Ok.. so imagine a ultracapacitor driven Electric Vehicle (EV)  with a home charge up unit that quickly charges the car in 5 minutes.   I can even see some solar cells so that you can use to generate and store your own power.  Gas stations could have charging stations like they do with the compressed air now.. or the propane tanks you can switch out for $20. (That reminds me.. I burned my eyelashes off one time trying to light my propane gas grill.. I had the lid shut and let too much gas build up in there.. when I opened the lid all I heard was one giant "POOF".. and I was patting the fire off my face. My first thought was: “Don’t’ try this at home kids.. this is a paid professional”)

Readers have left 14 comments.
 No.1  Untitled
Does anyone actually know if EEStor's product will ever come out?
It's a long time ago they announced their breakthrough (more then 1˝ years), but nothing new has come out since (tests, facts or anything factual).

It sounds, in my ears, like a bad hoax, but I whould really like their claims to be true.
Mark Urup (Unregistered) • 2007-11-24 07:00:00
 No.2  Untitled
That is the mystery question. I have read somewhere that they have had some major person pull out of the company. Not sure the name of them though. I looks like a lot of hype so far.
Guest (Unregistered) • 2007-11-26 13:48:25
 No.3  Untitled
I would be secret too if I have a product that could upset one of the largest industries in the world. They need to be careful and get everything right before stepping out.
Guest (Unregistered) • 2007-11-26 17:23:55
 No.4  Untitled
EEstor does not report either a new material, or any data that indicates the ability to store more energy than known titanate dielectrics. EEstor calculates the amount of energy they expect their capacitor to store. A fundamental oversight results in an invalid calculation that is inaccurate by more than a factor of 100! The error is uncomplicated. Simply, energy does not equal ˝ CV2 for a capacitor made from a nonlinear dielectric. For all high permittivity ceramics, the dielectric permittivity (K’) decreases markedly with increasing electric field E (dielectric saturation). Energy increases roughly linearly with voltage for these materials, as opposed to with the square of the voltage (ref 2).

Importantly, this is not a case wherein EEstor claims to have made some specific breakthrough regarding this issue. No such breakthrough is reported. There are no energy storage measurements, no permittivity versus field data, and no mention of eliminating or reducing dielectric saturation. Their patent and presentations indicate a complete lack of awareness (or lack of acknowledgment) of this issue. EEstor simply purports to make (or aspires to make) high K barium titanate based material, with a K of 18,000, and ultimately with an incredibly high breakdown strength of up to 300V/um. They then calculate the energy stored as ˝ CV2 without comment on the use of this equation.

How large of an error does this cause? Calculated energy density is ˝K’E2 when calculated total energy is ˝CV2. For K = 18,000, and a field 100 V/um, this invalid calculation gives 800 J/cc. (˝K’E2 = (0.5)(8.85×10-12 F/m)(18,000)(1×108 V/m) = 8×108 J/m3 = 800 J/cc). Eight references describing actual studies of energy storage in high permittivity ceramic dielectrics (including barium titanate and BST) are noted below. All of these studies indicate a maximum energy density ranging from about 2 to 12 J/cc, depending on the exact material and the maximum breakdown voltage (which is on the order of 100V/um in most cases). Notably, for the studies involving very high K materials, if the authors had simply calculated energy storage using ˝ CV2, as EEstor does, it would have similarly resulted in reported values on the order of 100 times greater than the actual measured values!

Hence there is no basis for concluding EEstor has made any advance in the field, and clear evidence that the sole basis for their claim of unbelievably high energy storage is the simple, invalid calculation. Their aspiration (with no reported results) to triple the breakdown field to 300 V/um in combination with the invalid calculation adds an additional factor of 9, giving an absurd 7200 J/cc (along with all of the corresponding hype and speculation about a new miracle material).
Guest (Unregistered) • 2007-12-07 21:49:04
 No.5  Untitled
Wow. Great response... how do they say what they say then? I guess they havent produced anything yet though so they can say what they want.
Gem (Unregistered) • 2007-12-07 22:00:37
 No.6  Untitled

1. (My work, unpublished), 1987 – Report to Maxwell Corporation on energy storage potential in high permittivity ceramics. Measurements were made on thin films up to 100V / um on barium titanate and PLZT based dielectrics. K varied as ~ 1/E over much of the voltage range, resulting in an approximately linear increase in energy density with field. Maximum energy storage was 4 – 8 J/cc.

2. Love, Journal of the American Ceramic Society 1990 – Also observed a linear increase in energy with voltage for several classes of high permittivity (up to 12,000) thick film ceramics (barium titanate, PLZT, PMN). Reported up to 5 J/cc at 80 V/um.

3. Triani,, (ANSTO and CSIRO – Australia, 2001 – J. Materials Science and Engineering. They reported 8 – 10 J/cc for PbSr titanate, and noted that the energy densities were similar to those of the best BaSr titanate materials for a given field, but the maximum fields of up to 100V/um (100KV/mm) were superior for the PST.

4. Kaufmann, et.,al, Penn State and Argonne, 1999. DOE Contract Report. They report sputtered BaSr titanate thin films with a K of 500 and a breakdown field of 100 V / um. K decreases to 120, and the energy storage is 11 J/cc. Also reported are data for hot pressed AFE/FE lead zirconate. These had a maximum K of 12,000, and a breakdown strength of 12 V/um, resulting in an energy storage of 3.2 J/cc.

5. Fletcher,, 1996 Journal of Applied Physics D. They report a theoretical analysis based on Devonshire theory of ferroelectrics. Optimal energy density is predicted for materials with Curie Temperatures well below the operating temperatures. Applied to BaSr titanate, the model predicts an energy density of 8 J/cc at 100 V/um. The model was verified in actual materials.

6. Randolf, et. al, (Austria, 1996) – IEEE Annual Report - Studied dielectric energy storage for powders embedded in polymer matrices. They reported using a PbTitanate-PbZnNiobate material with K = 5000, and reported energy densities of 1 – 10 J/cc.

7. Lawless, et. al., Ceramphysics Inc. 1992 report a high permittivity ceramic (K = 8000) for which a maxium energy density of 6 J/cc was observed for samples with optimum breakdown strength.

8. Freim, Nanomaterials Research Corp NASA SBIR Proposal 1998, reports reduced dielectric saturation for nanocrystalline microstructures, and states that “Commercial coarse grain dielectric based ceramic capacitors are ineffective for use in high energy storage and delivery applications since the dielectric’s permittivity decreases sharply when the applied voltage is increased.” They target 5 – 10 J/cc for the proposed new improved materials.

If you aren’t familiar with dielectric saturation, or even if you are and you don’t think back to where ˝ CV2 comes from – you miss it. And until you collect information and compare with the calculation, you have no clue it makes a factor of 100 difference in this case. People don’t even realize what EEstor is asserting. If they said, “we are going to use barium titanate based materials, which up until now how only been able to store 8 J/cc, but our barium titanate will store over 1000 J/cc – people would ask themselves how is that possible and what is the basis for that claim.

Then you would find out it’s not just a case of them not providing data or proof of their claims. They don’t even claim to have observed or measured a property indicating their barium titanate would be different. There is nothing left but the calculation. The sole origin for their high numbers is that they simply start with the K of high permittivity modified barium titanate (eg., K = 18,000 not a new achievement), and simply calculate energy = 1/2CV2. Anyone could have done that at any time for any high K material and gotten the same outrageous numbers.

So at that point, one should ask why people ge...
Guest (Unregistered) • 2007-12-07 22:29:58
 No.7  Untitled
Some clarifications on the analysis above: The point being made is that the energy density values that have been the basis for many blog and article discussions appear to be (based on the discussion in the issued EEstor patent) calculated values. Calculating based on 1/2CV2 ignores dielectric saturation, which makes a huge difference at high fields. The analysis above gives examples of measured values for various related materials, versus the values one gets based on calculations that ignore dielectric saturation.

The suggestion that ignoring dielectric saturation is the critical flaw in the whole story is not new – it has been brought up many times. The first posted comment to the Technology Review article early in the year made this exact point, and included several references:

(EEStor hype by Emosson 01/22/2007 12:50 AM.) (I keep getting a "spacing errors" message when I try to post the full comment by Emosson).

I am not happy that there seems to be a clear flaw in the story. My reason for posting is simply so that if people didn’t really appreciate what they are being told about dielectric saturation, they might see the issue more clearly, and have a chance to adapt their approach or application to a new area. It’s possible there is good work going on related to processing large format barium titanate structures – but dielectric saturation should severely limit the total energy that can be stored.
Guest (Unregistered) • 2007-12-12 08:49:39
 No.8  Untitled
Very interesting. I look into this.
RW3 (Unregistered) • 2007-12-12 10:15:35
 No.9  Untitled
I have no idea about the calculations involved.
Basic "common" sense tells me that they could not make a simple
mistake that would go undetected by peer review. At this stage of
the game, even if it went undetected, test results would have proven
it wrong by now. That does not mean that their product will work,
only time (and much work) will tell. Brian
Brian (Unregistered) • 2007-12-16 17:14:41

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