Tuesday, July 29, 2008

Reader Mihkel on EEStor Purity Announcement

Here's another interesting technical dissection of from todays blog comments...this time from Mihkel.  Again, I just want to pull out some of these technical comments and separate them from the discussion of zenn stock, etc.  My hope is other technical folks will add to the commentary and even, hopefully, add a little relief in terms of providing some plain english verbiage that average joes like me can follow. 

Mihkel said...

Word wraps removed (sorry for 2x post).

While considering solid state electrical energy storage device's (capacitor's) ability to store energy, maximal upper bound for volumetric energy density (energy per unit of volume) can be obtained knowing only operating device's dielectric's permittivity and (operating) electrical field strength. If we allow dielectric's material density (mass per unit of volume) to be known, we have one more energy storage characteristic: gravimetric energy density (energy per unit of volume).

So, formulae for both type of characteristics are:
volumetric: Uv = ε*E^2/2,
gravimetric: Ug = Uv/ρ = (ε*E^2/2)/ρ,
U - Energy density,
ε - actual permittivity of substance,,
E - Electric field,
ρ - material density.

ε and E can be calculated: E based on article and ε based on information known before. ρ can be obtained by encyclopedia lookup and making some assumptions. ε = εr*ε0 where εr (or k) is relative (to free space) permittivity of dielectric and ε0 permittivity of free space or the electric constant. Then take the voltage and divide it by the distance it was applied over (over dielectric's thickness) and you get E (E = U/l).

Now we can get computable formulae for a given dielectric considering source data available to us:
volumetric: Uv = εr*ε0*(U/l)^2/2,
gravimetric: Ug = Uv/ρ = (εr*ε0*(U/l)^2/2)/ρ.

I must emphasise we are considering only maximal bounds based on given numbers (not it's production feasibility) about dielectric. To ceramic capacitors, this bound depends only on dielectric's characteristics.

Let's get now source data. U = 350 V and l = 1 µm we take from the article. εr = ~18k has been stated before. For barium titanate, ρ = 6.02 g/cm^3 can be taken from Wikipedia, but we make a wild assumption here, that the actual material has the same density as barium titanate. ε0 can taken from any table of physical constants (ε0 = ~8.85 * 10^(-12) F/m).

Filling formulae with data and letting google's compute engine step into play, we have:
volumetric: Uv = ~2700 Wh/l
gravimetric: Ug = ~450 Wh/kg
Uv – http://www.google.com/search?hl=en&rlz=1G1GGLQ_ENXX252&q=18000*8.85*10^-12F%2Fm*(350V%2Fmicrometer)^2%2F2+to+Wh%2Fl&btnG=Search
Ug – http://www.google.com/search?hl=en&rlz=1G1GGLQ_ENXX252&q=(18000*8.85*10^-12F%2Fm*(350V%2Fmicrometer)^2%2F2)%2F(6.02g%2Fcm^3)+to+Wh%2Fkg&btnG=Search )

To put these numbers into perspective, consider enerergy density of current production lithium-ion energy storage: Uv = 270 Wh/l and Ug = 160 Wh/kg.

The key point to make such numbers available is EEStor's proprietary technology achieving dielectric material with outstanding properties, namely: Electrical field E = 350 V/µm (at production level) while maintaining permittivity εr (or k) = ~18k. At field 350 V/µm, one has to watch for two types of breakdowns: electrical and permittivity. 1st one occurs if dielectric (insulator) becomes conductor due to field's strength, 2nd one is the natural property (until EEStor proves wrong?) of high-k (high relative permittivity) dielectrics to loose their permittivity in high field strengths (orders of magnitude below 350 V/µm). I suspect the 1.1 kV/µm stated in the article is the lower one of the two.

This remains the point over which scientific community remains sceptical. EEStor seems to have resolved this problem some time ago and seems to deal with production issues.

To get some clue how these hypothetical maximum bounds relate to real world, one has to take into account that ceramic capacitors need also conductive plates sandwiched between dielectric layers. This makes Uv and Ug smaller, because you have to take plate material into account, which does not store energy. There are also packaging and structural materials, electronics, etc... They also use fields 350 V/µm instead of 1.1 kV/µm (as stated in the article) because of manufacturing process' mistakes and impurities in some points of dielectric material, which brings the electric field value for the two (possible) breakdowns down.

Imagine, if you can enhance the manufacturing process and rise operating electric field from 350 V/µm to somewhere higher? You get a nice boost in energy density, as it is quadratically (as seen from the formulae) proportional to electric field.

Reader Zawy on EEStor Purity Announcement

If you read this blog, it doesnt take long to realize that many of the comments are more interesting than the original posting.   I'd like to start  highlighting some of these interesting comments by pulling them out into their own separate posting to allow some focused discussion around the concepts involved.   Regarding today's EEStor PR, reader ZAWY had the below comments.  

Blogger zawy said...

They have revealed a few tasty tidbits.

1) pure aluminum oxide (AlO3) coating of the pure 1 micron powdered composition-modified barium titanate (CMBT) allow "the **potential** to reach its target working voltage. " The 2 "sentences after that indicate that purity is needed for resistance to breakdown (catastrophic leakage).

2) the AlO3 coating and the closely-sized 1 micron CMBT "assists" in "meeting the energy storage stabilization over the temperature range"

3) the plastic PET matrix is key to physically turning the particles in a strong electric field to get the best polarization. Polarizing BT in a strong electric field while the material is still hot during manufacturing is standard practice, much the same way magnets are created by using a magnetic field while the metal is very hot. "Polarization along with other proprietary processing steps provides the **potential** of a polarization saturation voltage required by EEStor." The plastic matrix is unique and this may be the explanation I have been looking for. I believe i had guessed here before that better polarization was the reason for the PET.

to better explain polarization: the CMBT crystals work best when oriented in a certain way. That orientation is forced up the crystal by a very strong electric field as the last stage in manufacturing. However, it's not completely effective when the crystal are "bumping" against each other. This causes some "domains" (localized volumes) of the BT to be better oriented than others. However, using the plastic PET keeps the particles seperate so that they can achieve perfect polarization if the plastic is melted during the manufacturing polarization, with each 1 micron particle having a homogeneous single domain. The plastic also allows the domains to expand/contract more during use which allows more energy to be stored so that energy saturation is not reached. Being perfectly aligned also helps for greater expansion/contraction.

The press release states very clearly that either they DO NOT have any prototypes ... or ... DO NOT KNOW if they can achieve production of a high energy capacitor described in the patents by their use of the word "potential" in the following sentence:

"Polarization along with other proprietary processing steps provides the potential of a polarization saturation voltage required by EEStor."

"polarization saturation voltage required" means "energy storage" (high permittivity saturation) as the crystal is polarized during use and not to be confused with the polarization step during manufacturing which is the meaning of "polarization" in the first part of the sentence.

1,100 V/micron applies only to the AlO3 and not to the BT which is 350 V/micron. And "breakdown voltage" does not mean energy storage or maintaining high permittivity.

Zenn Motors on EEStor Announcement

I spoke to Ian Clifford this afternoon. At the time, he had not read the EEStor announcement but said ZENN was working on their own release regarding the announcement which may be out later this evening. As long as he's not swamped dealing with the battle with Ontario, we'll speak again tommorrow. The battle is also covered here and here. What would you like me to ask him? Don't go crazy...it'll be a brief phone call, I'm sure.

More info on the EEStor press release today

About 2 weeks ago, Edward Golla from Texas Research International, acting on his own behalf and not that of TRI entered the EEStor facilities to perform some analysis related to chemical analysis, an engagement that would take no more than half a day. First, his task was not to run any tests himself but rather validate two main things: 1) that EEStor possessed the equipment necessary to perform the tests whose results are touted in the recent announcement and 2) that persons who work for EEStor are competent in their use. According to Golla, that equipment is made by Perkin Elmer and is known as an Inductively Coupled Argon Plasma (ICAP) spectrometer. The model in use was an Optima 2100. After verifying that EEStor had the equipment necessary to make the purity measurements of the materials in use, Golla interviewed the chemist in charge of operating the equipment and found him (at the time I spoke to him, Golla did not have the gentleman's name in front of him) to be competent and able to operate the equipment.
Golla wanted to make it clear that he has a chemistry background and not an electrical energy background of the type required to evaluate EEStor's capability claims...but, he was aware of concepts like break down voltage, etc from his former days operating radio equipment. He is as in the dark as everyone about whether or not EEStor can deliver on it's ultimate claims to"have the capability to compete against all existing battery and capacitor technologies." (EEStor Press release). He was not provided with a tour of the facility and instead worked in a lab with the chemist personnel. For some background, Golla went on to explain that in scenarios such as these where companies like EEStor are purchasing bulk chemicals, they need a way to test for impurities. So, his certification was related to testing chemicals for impurities prior to and after an EEStor process. Thus, in the course of his work, Golla followed the chemist to the location of the ICAP, verfied that things were clean and orderly and then proceeded to interview the chemist and validated that he knew what he was talking about....none of which revolved around knowledge of capacitors but rather only chemical analysis.
Note: it does appear to be the first time that EEStor has solicited "requests for more information" by emailing them at info@EESTOR.US.

EEStor Announces Certification of Additional Key Production Milestones and Enhancement of Chemical Purity

Wouldn't you know the one day I'm on the road, I miss an EEStor announcement. Thanks to those who emailed me at eestorblog@gmail.com with links to the story:

Here is the press release.

Another link to the story.

Here's the link to the PRNewswire release.

Here is a related and humorous Treehugger Article

Tyler Hamilton's take

Also, many people are trying to figure out what the significance of this press release is for interested parties. Among the other signficances discovered in this press release, let's not forget that it did already cause a moderate earthquake in Los Angeles, home to all those future electric vehicles.