Disclosure | Energy Storage Feeds

What We Have Learned – The Topic.

This discussion is a continuation of the blog post of the same name. When I posted the first post on that thread I honestly believed that all the members of the forum (who have technical back grounds) understood and accepted the “brick model”. When I found that was not true I attempted to explain the model more clearly. I am afraid that I failed in that, but one thing led to another and I have kept on posting. Essentially I am reviewing points that were raised on the old site and which I think are pertinent to “How the EESU Works”. Just a few more posts and I will be done.

The usual rules apply: Please keep replies short, to the point and polite. ee-tom is banned.

I had started to review the possible polarisation mechanisms (for the EESU) so I am going to repost the two posts concerning that, then I will continue.

Regards,

Peter

Views: 11012

Reply to This

Replies to This Discussion

Why the EESU Will Not Work:

In order to understand this you must first understand how the EESU is supposed to work. One theory is that the EESU is a capacitor with a high k dielectric which has been improved by an optimum doping regime. Let us look at that possibility.

1 The EESU is a High K Capacitor.

In this case the polarisation mechanism is orientation polarisation. The ferroelectric nature of CMBT enables orientation polarisation, the alumina shell is ignored (or it is assumed that it too is doped to have a high k). The Voltage Coefficient of Capacitance (VCC) depends on the orientation phenomena and is predictable. The reported variation of capacitance in the patent does not behave in this manner. Therefore the measurements are faked.

It is however worse than this, because the maximum polarisation possible for orientation polarisation is limited to the intrinsic polarisation of the unit cell – about .26 C/m^2; far less than the required 60 C/m^2. To any rational person it is inconceivable that doping could give the required improvement.

Clearly, as the EESU is a high k capacitor it cannot work as reported.

Regards,

Peter

PS: Dick Weir has announced that Eestor operates the dielectric “deep in the paraelectric phase”. Orientation polarisation is not enabled (poling would disable it anyhow).

Why the EESU Will Not Work (part 2):

If not orientation polarisation; then what?

To be useful the polarisation must be induced. Polarisation is simply due to the relative movement of charges in the direction of the field. The possibilities are:

1 Orientation (of domains, say) – This is “out”.

2 Ionic

3 Electronic or atomic

4 Space Charge. There are various manifestations of this, most are actually harmful (reduce breakdown (trapped charge), result from leakage currents, etc)

Let us look at ionic polarisation.

The thing is, you can buy single crystal barium titanate. You can get it cut so the orientation is in the [1,1,1] direction. You can heat it above the Curie point so it is paraelectric.

When you have done this you will have something which behaves exactly like the crystallite that Eestor are producing (or trying to produce). You can get it very pure, too. It will be uncoated so the parameters of the core material can be measured directly. You can make a graph of polarisation as a function of field and calculate the energy density.

If you were Lucas Pettey you could do an atomistic simulation of this material (not the coated particle, that is too hard) and work out all its parameters. After all he had five years to play around with this stuff, did he not?

The answer? Sorry – much less than 400 J/cc (and that is ignoring the effect of the alumina coating).

Ionic polarisation is “out” (as a mechanism that can store 10000 J/cc, anyhow).

Regards,

Peter

Why the EESU Will Not Work (part3):

Ionic Polarisation (continued).

In my previous post I said that if the alumina coating was ignored then ionic polarisation would not allow the Eestor energy density to be achieved. Of course you cannot ignore the coating. So what is the effect of this coating? There are a number of effects and straightforward analysis will reveal some of them.

The thing is; dielectrics are big business, core/shell dielectrics are big business. So analysing core/shell dielectrics is important and the cost can be justified. Most research labs will have the means to do this.

The method is to use software which solves Laplace’s equation numerically. This software has existed for many years and is readily available. I was taught to use Rayleigh’s Method; this is a relaxation method for finite difference equations. Programs for finite element analysis also exist. The only difficulty is to choose which one to use. Dr Cross will have access to such a program, so will Dr Perry. I would be surprised if the guys at Imperial College did not have such software. Certainly the guys in the laboratory at Acme Electrical Supplies Proprietary Limited do (but they are a close mouthed bunch!). I don’t think Lucas Pettey would work for a firm which did not have such software.

I have recently written such a program myself. I spent most of the time writing the output section in order to produce equipotential curves. You can see some of the results on the thread “A Line of Charge”. However the thin layer of alumina on the Eestor particle necessitates some enhancement of my program in order to give accurate results for that case. Perhaps an “adaptive multigrid” approach or maybe the use of an unstructured grid (a cloud of points).

Anyhow analysing the Eestor dielectric using such a “Continuum Analysis” program will have been done (many times, I suspect).

The results show that the “effective permittivity” of the composite dielectric is less than 500 and that the alumina breaks down at about 200 volts across the EESU (as predicted by the brick model).

So below 200 volts the EESU does not work. Above 200 volts? Well I am afraid above 200 volts you have “space charge”. Continuum mechanics cannot handle that. Well, not without producing an appropriate model for the “space charge” region anyhow. Of course everybody knows that space charge will not store energy, but I will discuss this later – it is the fourth mechanism.

Regards,

Peter

The brick layer model argument for low k is simple and not easy to circumvent. (And BTW gives similar results to the Hashin Shtrikman coated sphere model). I have seen no very good way out. However there are some straws meaning that I question its application - or rather treat it as something to continue to think about:

(1) Both (questionably) EEstor and (definitely) Chung et al claim contrary experimental evidence.

(2) The Chung dielectric (20,000 k for 500nm dia particles coated with 5nm SiO2) has 3 followup papers investigating its physical and electrical properties: it is well documented and not likley a mistake. In the latest followup paper the group address for the first time the fact that measured permittivity is much higher than would be expected from BLM. They suggest this is because the particles agglomerate and when coated therefore the coating is incomplete, with percolation through uncoated interfaces between particles. However they do not give any real evidence that this is what actually is happenning.

I should also point out that when (ages ago) challenged by me, Maglioni avoided the question by saying that IBLC effects (space charge) inside the grain led to very high k. While this is true, it does not explain how the high k could persist when the particles are coated, since IBLC inside the insulating coats is not possible. Good that their followup accepts that there is an anomaly, and proposes an explanation, even if it is not substantiated.

Best wishes, Tom

ee-tom,

You are banned from this thread. Unfortunately you cannot delete your post. In future I suggest you post on your own thread; "The Chung Anomaly". Please refrain from placing further posts on this thread.

Regards,

Peter.

Moderators,

Could one of you please transfer ee-tom's post to his own thread (and delete this post).

Regards,

Peter

Why the EESU Will Not Work (part 4):

Recap:

1 Orientation Polarisation: “out” as the Eestor energy storage mechanism.

2 Ionic Polarisation: “out” as the Eestor energy storage mechanism.

Now read on:

The next polarisation methods to consider are:

3 Electronic and Atomic:

Electronic polarisation is due to the distortion of the electron cloud caused by the applied field. Atomic polarisation is due to the movement of the nucleus of the atom due to the applied field. In both cases it is the movement of the centre of charge that is important.

The centre of charge can be located by the following calculation:

Select an arbitrary origin, let ri be the vector distance of a charge qi from this origin.

Calculate the sum:

S = Sum( ri*qi ) for all positive charges, let Q be the sum of all positive charges.

Let rp be the distance to the centre of positive charge.

rp = S/Q

Similarly for negative charges we get rn.

Now we know that rn will be moving because the electrons are zipping about (some say as far as light years, but I don’t believe that). However there are billions of atoms in even a small amount of matter so the average position will be well defined.

And of course the polarisation is equal to:

P = N*Q*(rp-rn)/vol................where N is the number of atoms in volume vol.

You can distinguish between the two types of polarisation by plotting permittivity (or better susceptibility) as a function of frequency. Atomic polarisation will “drop” out at a lower frequency because the nucleus is more massive.

Of course these measurements are easily made and the results are well known. Permittivity from these polarisation methods is generally less than 3.

Of course the number I have quoted is easily refuted. Just quote the measurement you have made and the conditions under which it is made.

However as far as I can see; these methods of polarisation are also “out” as candidates for the Eestor energy storage mechanism.

Regards,

Peter

Everyone can delete their own posts.  It was probably a change slipped in at the point where the threads became single-level, instead of having a multi-level hierarchy where deleting a post would have logically had to delete all responses to it by others in levels below it.  Of course in a single level structure that cannot happen so deletions seem to be allowed.

Regards,

Peter


PeterP said:

Why the EESU Will Not Work (part 4):

Recap:

1 Orientation Polarisation: “out” as the Eestor energy storage mechanism.

2 Ionic Polarisation: “out” as the Eestor energy storage mechanism.

The next polarisation methods to consider are:

3 Electronic and Atomic:

...

Permittivity from these polarisation methods is generally less than 3.

Of course the number I have quoted is easily refuted. Just quote the measurement you have made and the conditions under which it is made.

However as far as I can see; these methods of polarisation are also “out” as candidates for the Eestor energy storage mechanism.

Regards,

Peter

That doesn't seem to leave anything left on your list.

So what would you suggest?  Are you giving up?

Regards,

Peter

Sorry PeterP,

I did not read the "small print" in the header.  However, having contributed an entirely useful post that no-one could possibly mind, I see no point in deleting it.

It is burdensome having to check every header in detail before replying to posts on science threads. So perhaps something could be done about this. Anyway, as long as I remember which thread it is (not guaranteed if it gets long) I will not post again.

Best wishes, Tom

Technopete Wrote;

Everyone can delete their own posts.

Thanks for that. If I had inadvertently broken a rule about posting I would delete my post. I wouldn’t be pleased though!

Regards,

Peter

Technopete Wrote;

That doesn't seem to leave anything left on your list.

So what would you suggest? Are you giving up?

Space Charge Polarisation (SCP) is left. If I could prove that SCP could not store the energy, I would not regard that as giving up. It would just be a fact.

Yes, I said everybody knows that SCP cannot store energy. That is, everybody except a few people like me.  I do not “know” that. I think that if it is true, it can be proven.

I don’t think you can prove the EESU does not work, but I think you can evaluate the various ways in which SCP can manifest and maybe eliminate them.

There are a few things I want to discuss before I do discuss SCP. In the meantime you might like to consider the Maxwell-Wagner effect.

Regards,

Peter



PeterP said:

Space Charge Polarisation (SCP) is left. If I could prove that SCP could not store the energy, I would not regard that as giving up. It would just be a fact.

Yes, I said everybody knows that SCP cannot store energy. That is, everybody except a few people like me.  I do not “know” that. I think that if it is true, it can be proven.

I don’t think you can prove the EESU does not work, but I think you can evaluate the various ways in which SCP can manifest and maybe eliminate them.

There are a few things I want to discuss before I do discuss SCP. In the meantime you might like to consider the Maxwell-Wagner effect.

Oh good, you are going to get into Maxwell-Wagner, Thomas-Fermi screening lengths, band theory/band bending, quantum capacitance and density of states.  That should be interesting, particularly the quantum-mechanical aspects!!!  You should readily be able to include the All Electron Battery patent claims in your disproof too.

Regards,

Peter

Reply to Discussion

RSS

...

© 2014   Created by B.

Badges  |  Report an Issue  |  Terms of Service