Sciencemadness Discussion Board

The Robert Murray-Smith Battery

aga - 21-11-2016 at 14:01

Bob does a whole load of videos documenting a battery design using graphene-type material on utooob, such as this one :
https://www.youtube.com/watch?v=ggLFG_dRDoc&t=8s

Not found out how to view his videos in sequence, nor how to even find the first in that sequence.

Somehow i feel that the toasted bread experiments done by violet sin et al are kind of in a place to replicate Bob's experiments.

Call it Lizard Alien tech if you will.

It still looks like a very promising avenue worthy of research.

Going from Toasted Bread to Battery ?

That would be amazing.

Morgan - 21-11-2016 at 15:20

Another battery referenced from the Robert Murray-Smith video comment section.
https://news.vanderbilt.edu/2016/11/02/making-high-performan...

From the Vanderbilt article comment section
"Don't know why my last post was removed by vanderbilt, but lets suppose
it was accidential. The supplement with all the practical details is
available for free from:"
http://pubs.acs.org/doi/suppl/10.1021/acsenergylett.6b00295/...

[Edited on 21-11-2016 by Morgan]

RMS EESD Work Outline

Geekineer - 7-12-2016 at 15:58

Hello - been following RMS for a while - thought I'd post a rough outline here and with some of this forums collaboration / agreement send it to Rob for posting on his sight if he pleases.....intent is to try and organize his work so that others spend less time coming up to speed and together can better understand and experiment on our own in this 'fun' space.

1. Initial EESD work based on a symmetric super cap made from Aluminum foil or grafoil current collectors, coated with electrode materials either Activated Carbon ink, AC, or graphene oxide ink. Rob's simple inks consist of a carrier like water if PVA is the binder or Acetone if ABS is the binder. Current collectors are dipped or sprayed with electrode material. These form a sandwich with separator material in the middle 'soaked' with electrolyte. Electrolytes are water based (1.2V charge limits) or other (ionic liquid?) typically in the 2.5 to 2.7V charge range. Typical of his original separator materials were paper based. Others such as polypropylene (from lead acid battery salvage) or his proprietary recipe for a cast and calendared poly???
2. Original demo cells were as much as 4F with the AC electrodes, 1cm>2.
3. Next came larger versions with preproduction of a major modification where the electrode material was printed not on the current conductors but onto one or both sides of a paper separator. Stated that separator was 'soaked' with electrolyte via porosity of electrode ink. Nice video of about 600 sheets of printer paper EESD powering an electric scooter. I believe these were Graphene ink coated. Electrolyte ?? but 2.5V/cell.
4. There then there were a few videos on other materials to make graphene besides graphite - like hemp. Not sure where that fits in with the latest EESD work.
5. Rob is now showing a new EESD he calls a 'battery' that eliminates the grafoil current collectors - mixes up a magic electrode that is highly conductive so it becomes its own current collector - printed ? onto substrate ? - that is highly flexible and strong. Rob showed a 'plan' to make rolls of same fit into form factor of Type27 battery case. For this battery I think he still has a water based neutral (NaCl?) electrolyte. Not sure if there are more or less power from a double layer cap or some Faraday type reaction.
6. Note how things have progressed back and forth relative to the electrodes- carbon material bonded to current collectors, carbon material bonded to separator, and now a unitized current collector/electrode material. Great work.
edit here:
7. Please add something here on how his reference to a type B or type C design match up to any of the above - must have misted that in the vids somewhere.

aga - 8-12-2016 at 01:00

Hi Geekineer, and thanks for that list which puts RMS's battery videos into some kind of order.

Hopefully soon there will be a simple-to-follow write-up, as/when time allows.

That will enable anyone to replicate RMS's experiments.

aga - 8-12-2016 at 14:59

OK. Re-watched three RMS videos relating to his battery/capacitor series and made some notes.

The idea is to put his videos into some kind of write-up so anyone can actually have a go at making batteries/super-capacitors according to some starting recipe/documented and tested procedure.

The notes posted below are simply what i wrote down while watching each video.

If you wish to assist by watching a video in that series and noting down anything, then posting those notes, please do.

--------------------------------------------------------------

How To Make A SuperCapacitor - Step By Step

Published on 18 Feb 2016

https://www.youtube.com/watch?v=1Ce2au3PWnI

3 parts. One a graphene super-capacitor, the other an activated carbon super-capacitor.

Coconut fibre said to be good for activated carbon.

Activated carbon generally used due to huge surface area.

Separators tried : bog roll, kitchen towel, paper, others.

Electrolytes: sodium sulphate, phosphoric acid, sulphuric acid,
lithium hydroxide, potassium hydroxide, sodium hydroxide, sodium chloride, others.

Build scene :

3 jars:-
One with graphene oxide. (? says a video exists)
One has activated carbon, ground, acetone carrier.
Graphoil/Graphoyl ?

Dip-coat X in the AC. Allow to dry.
(MnO2 possible for other side)

Scrapes off some graphene oxide from X.

Small slice of X, kitchen towel, some sodium sulphate, small slice of the AC material.

Charge at 1.2V, 1 min

Outputs 45mA briefly.

Cell area is 1cm<sup>2</sup>

AC version measures 0.144 Farad

Graphene version measures 3.95 Farad

--------------------------------------------------------------

Graphene - A Simple Method For Mass Production

Published on 23 Jul 2016

https://www.youtube.com/watch?v=gcwCGRXVHzQ

PSU
0.5M sodium sulphate
Electrodes : SS, Graphite
SS -ve
Graphite +ve
2v for 2 mins
then increase to 10v. Can see graphene peeling off, and gas formation.

Graphene 'worms' come off the anode. Leave for 30-60 mins

"Intercolating the suphate, then exploding it" is said (?)

Filter then wash the graphene nanoplatelets (not done in video)

Zap in ultrasound cleaner for 1hr-1hr 30 mins.

This Breaks the nanoplatelets into 80% 1 to 3 layer graphene flakes.

Result is a beaker of black graphene mush.

This process is considered 'gentle' resulting in a solution of relatively large graphene flakes.

--------------------------------------------------------------

Structured Carbon Battery - An Update

Published on 18 Nov 2016

https://www.youtube.com/watch?v=ggLFG_dRDoc

Button cells.

Previously used current-collector -> active material -> separator -> active material -> current collector.

Decided to change the binder system, which is poly vinyl acrylate or or poly vinyl alcohol (based on wood glue).

In LiPO batts they use a 70/30 mix of carboxymethyl cellulose / styrene butadene rubber.

CMS = wallpaper paste).
SBR = concrete additive.

"After we 'calend' it (@5:44) we got a tough material" ?

Now using active material, separator, active material, no current collectors, but he says there is one on the top ?

--------------------------------------------------------------

[Edited on 9-12-2016 by aga]

Aztral - 8-12-2016 at 22:29

Weeee!

This is my second post here...and you can thank (or curse) RMS.
Since I found his videos I've been going like a madman...now with a garage full of chems, and reading papers on DES everyday! I have pretty much all the chems/equip now to at least get started on his supercapacitors and hopefully around the 1st of the year I can get started and make some vids myself. Then go into making DES!

Anyway...so you've found the newset making Graphene video via electrochem (Tour) method.

The making GO video is here
https://www.youtube.com/watch?v=c17ePPuEaAk
Then you disperse the GO in distilled water using a sonicator.
(Or you can find GO solutions on ebay to get started as I did)

The Activated carbon active material "paint" is (I am pretty sure), just powdered AC (got mine at Walmart in the pet section), 3% (by weight) of Polyvinylpyrrolidone (again..ebay is mah friend). You'll find that info in the 1700F cap video https://www.youtube.com/watch?v=iD2rVGjG2HQ&list=PLbQqm4...

Oh he also mentioned Celgard separators which I decided to get. Since I'm more interested in playing with different electrolyte/active materials just using a consistent separator eliminates one variable.

Two other good RMS videos are
Making High Performance Supercapacitor Materials - 1 & 2.
https://www.youtube.com/watch?v=GSDSUFvLOEo
https://www.youtube.com/watch?v=ftAPXujssr8

His newer videos seem to be on a "Hemp" battery which (if I'm not mistaken) he has rebranded as "Structured Carbon" :P
I dont think there is an explicate video where he makes the Hemp carbon, but he did make a vid or two on hydrothermal carbonization. That plus a little Google shows that the cool kids are carbonizing hemp "bast," which allegedly has greater surface area/m^2 than graphene!

I've got a huge spreadsheet of video links, research paper links, chem suppliers,etc. related to Supercaps, Deep Eutectic Solvents, graphene quantum dots, making/doping graphene....






[Edited on 9-12-2016 by Aztral]

aga - 9-12-2016 at 01:27

Thanks Aztral !

RMS has so many videos (250+) that it is hard to sift through them for the relevant info without being led off on other interesting avenues.

Your spreadsheet sounds very useful.

Have you constructed a battery/supercap yet ?

Aztral - 10-12-2016 at 08:05

Hi aga.

I haven't built a supercapacitor or battery yet.
Been "preparing" to get started though.
I have all the supplies to build multiple versions, and beyond, and I "almost" have little workspace cleaned out in my garage.

Around the first of the year I'll start-out trying to replicate the RMS supercaps - and share some videos. :)

I DID try a quick test of coating glass with GO, but instead of using a "laser" (like UCLA did) or xenon flash I used a 250W infrared heat lamp! I didn't think it produced a conductive sheet until I noticed my multimeter max ohms is around 2Mohms. But then I setup a setup a simple circuit which ran current over the glass and lit a light :)

And..yes...the RMS videos are great!
I've been reading on various things for years, but have never taken action until watching RMS. Dye Sensitized Solar Cells caught my interest, but I didn't do squat. I've also had a desire to play with fuel cells/water splitting but again...nada. But (if nothing else) the RMS videos have really put a" fire under my rear" and have me taking action :)


aga - 10-12-2016 at 08:21

For me it's the Carbon angle that caught my attention/imagination.

With any joy i'll get time tomorrow to do his sugar & Zn(NO3)2 route to a good activated carbon, which i can then test alongside some commercial AC.

If that works out OK, onwards to a supercap with all haste !

... besides making 100ml benzene for Congo Red thing, rubbing bits of metal with sandpaper ... etc - basically all the Other stuff on my list.

Aztral - 10-12-2016 at 08:34

Yay!

There are definitely some good vids by RMS and others on making various "nanoparticles"

And OH I forgot to mention that there are actually TWO search bars on youtube...one to search all youtube, but if if you click on RMSs "videos" (not "playlists") you can search through ALL his videos. I find this very useful to find other "related" video by RMS

(I mention this only in the off-chance you're a youtube newbie like me.)

Geekineer - 10-12-2016 at 08:43

Maybe the spreadsheet is the best way to keep track of videos, recipes, suppliers etc.

I've made several caps - all simple formulas.
Best so far is 2" aluminum foil duct tape, with sprinkled activated carbon after coffee grinding and using what passes through 80 mesh screen. 3M NaCl solution soaked into regular copy paper for membrane/electrolyte. 10cm sq. ran phone vibrator motor for 3 minutes after charge to 1.2V.

Next step is working on an activated carbon ink, with a binder of either an ABS (LEGO chips) or PLA (3D printer filament) dissolved in Acetone. Binder to AC ratio of 1/20 (5%) by weight.

I tried for a membrane salvaged from Lithium 18650 cells (Robs idea) It worked OK but need better data to say better / worse than soaked copy paper.

I'm investigating the several options to build a cheap 2 wire potentiostat (google Ardustat) to be able to make better A, B, C, choices of components.

aga - 10-12-2016 at 08:45

Been watching stuff on utoob for years, but certainly did not know about that feature, so i guess i'm not a Qualified utoober !

Thanks for the info.

Right now i cannot watch any more of his videos or i'll get side-tracked again and end up in front of the laptop all day instead of actually Doing things.

aga - 10-12-2016 at 08:50

Quote: Originally posted by Geekineer  
I've made several caps - all simple formulas.
Best so far is 2" aluminum foil duct tape, with sprinkled activated carbon

Excellent !

Photos ! Photos !

How long was the charge time ?

I will certainly characterise the batteries made (IF i manage to make one work) so the charge/discharge voltage, current, time all need measuring to get relevant data.

Naturally material composition/area/volume/weight will also be important.

Temperature too i guess.

Aztral - 10-12-2016 at 09:15

GJ Geekineer!

Yes..I find the spreadsheet useful.
I also keep track of free science docs of interest, but sometimes even just an abstract provides enough info too. Worthy pdfs get downloaded.

aga - 10-12-2016 at 09:20

Quote: Originally posted by Aztral  
Yes..I find the spreadsheet useful.

We're trying to Hint that we want you to share the spreadsheet by uploading it here ;)

Aztral - 10-12-2016 at 09:49

Here's what I have on strictly supercaps.

I also posted what I have on deep eutectic solvents here http://www.sciencemadness.org/talk/viewthread.php?tid=62263#...
(*All files were save as tabbed delimited)

Includes little "thought bubbles" that may only make sense to me :)

Also in the near term, please take anything I post with a grain of salt - in solution of course ;) Although I was physics major, I got offered a really good software dev job 3rd year and left UCLA before I finished chemistry. I am still catching-up on even basic chemistry and may not know completely what I'm talking about - lol.


Code:
1700F Supercapacitor https://www.youtube.com/watch?v=iD2rVGjG2HQ&list=PLbQqm4rNo625Etz4INo2wP2X4sxgwDyNN&index=32 3-Apr-15 1cm^2 = 2.3 Farads printer's paper (aluminized polypropalene) aluminum ~100micrometer coating "0.08g, 4microns thick" etch aluminum copper sulfate/sodium cloride 50/50 in 1liter water graphene paint (Not GO) Polyvinylpyrrolidone 3% by weight of graphene PVA 10% by weight of graphene polypropalene separator (previous vids on making) used salt water in vid..but could be an ionic fluid (deep eutectic solvent) "A World First - A 10 kiloFarad Capacitor (10,000 F)" https://www.youtube.com/watch?v=9hLeydni7Ks&index=33&list=PLbQqm4rNo625Etz4INo2wP2X4sxgwDyNN&spfreload=1 electrolyte Acetonitrile-amonium salt 2.2V + alum electrodes commercial paper separator "sealed in latex dip-coated, because this electrolyte will eat through anything" conductive ink #1 https://www.youtube.com/watch?v=WR7SHPGGQ34#t=138.254467 100g of gum arabic 500mL of water 300g of flake graphite powder Homemade conductive inks https://www.youtube.com/watch?v=mOr3ZdyqgCk ceramic paint for induction heating waterproof binder sodium silcate Making High Performance Supercapacitor Materials - 1 https://www.youtube.com/watch?v=GSDSUFvLOEo Making High Performance Supercapacitor Materials - 2 https://www.youtube.com/watch?v=ftAPXujssr8 GO on graphfoil flame reduced - best method 8-Mar-16 coat grafoil with GO 1cm^2=1.5 farads flame reduce Eric Goeken https://www.youtube.com/watch?v=uujf5tpkm8M thought on making hydrogen - separate electrodes with Kiln paper! RMS on Deep Eutectic solvents https://www.youtube.com/watch?v=EDoCDM5vuwY deep eutectic (red rake) https://www.youtube.com/watch?v=nVHEYQCcuMI Home Made Ionic Liquids (Robert Murray-Smith) https://www.youtube.com/watch?v=vF0T8EaEE50&index=24&list=PLbQqm4rNo625Etz4INo2wP2X4sxgwDyNN Gel Electrolyte For Supercapacitors 2 (good for G & MnO2) asym https://www.youtube.com/watch?v=aWDol9CTjpQ&t=8s making PV Alcohol for solid separator https://www.youtube.com/watch?v=Ogpeaklho_M how to build a supercapacitor step by step https://www.youtube.com/watch?v=1Ce2au3PWnI Super Cap A activated carbon (fish tank carbon) activated carbon 3000m^2 per g grafoil current collector (dip coated) acetone Polyvinylpyrrolidone 3% by weight of carbon Super Cap B GO graphene 2630m^2 per g grafoil current collector (heat reduce GO ~50C) water hemp super capacitor http://newatlas.com/hemp-high-performance-supercapacitor/33435/ hemp buy http://www.hemptraders.com/product-p/f-l2.htm 100ml hydrothermic reactor http://www.ebay.com/itm/100-mL-Teflon-Lined-Hydrothermal-Synthesis-Autoclave-Acid-Digestion-Reactor-/371497847881?hash=item567eff4c49:g:Ru8AAOSwL7VWl1xs Aluminum should have acid electrolyte sodium sulfate Nickle could stand alkaline electrolyte separator company https://www.celgard.com/battery-innovation laser inscribe graphene https://www.youtube.com/watch?v=M0-0fbpARQg used the Kapton method Graphitic Carbon Nitride https://www.youtube.com/watch?v=Jj-nuTSjCBc&t=525s use as a hydrogen evolution catalyst? large scale graphene oxide production https://www.youtube.com/watch?v=w0jo9OmD84U Making a PVA Separator (MFCTechnology) https://www.youtube.com/watch?v=JFrEq3dMAfQ 8% PVAlc solution http://pubs.acs.org/doi/abs/10.1021/am302301t https://en.wikipedia.org/wiki/Tetramethylammonium_chloride adds porousity http://inhabitat.com/rice-universitys-carbon-nanotube-paint-turns-any-surface-into-a-solar-battery/


I have other tabs in my spreadsheet on chem suppliers, making graphene oxide, DES, etc. - lemme know :)

aga - 10-12-2016 at 09:59

Cool !

Many thanks Aztral.

Aztral - 10-12-2016 at 10:15

Here's some info on making graphene oxide too.
Hemp hydro-thermally carbonized may have greater surface area, but may still be of interest to supercap builders...
Code:
Tour Method graphene oxide https://www.youtube.com/watch?v=c17ePPuEaAk 3g graphite EXPLODES ABOVE 55C !! 18g Potassium Permanganate PP is an oxidizing agent mix powders 360ml Sulfuric acid 96-98% 40ml phosphoric acid 75% mix acids SLOWLY STIR/ADD ACIDS HEATER STIRRER AT 50C for 12hrs let sit to room temperature pour over 400ml deionized water ice "400ml deionized water frozen,chunks" add 3ml 35% hydrogen peroxide (or 9ml 12% hydrogen peroxide ) Cleaning let mixture settle pour through 45micron filter GO pours through refilter thru polyester fiber "wash with water, 30% hydrocloric acid, ethanol" result from3g graphite = 5.6g GO Improved Faster Method for Making Graphene Oxide https://www.youtube.com/watch?v=aQcMYTiUPqA r-Go from GO in DES @100C http://pubs.rsc.org/en/content/articlelanding/2013/ra/c3ra41485j#!divAbstract making high quality graphene http://m.phys.org/news/2016-09-microwaves-high-quality-graphene.html fixing defective graphene http://m.phys.org/news/2016-08-route-scalable-production-highly-crystalline.html http://www.nature.com/articles/srep28936

aga - 10-12-2016 at 12:29

Reading your notes is a bit like reading some of mine !

The research references you're posting are Exactly what i hoped this thread would be about.

With any joy, we can come up with a 'distilled' version soon so people can follow a simple, proven recipe to get started with these materials.

What's the Target ? a GigaFarad capacitor made from toenails ? ;)

Aztral - 11-12-2016 at 10:05

Lol.

So https://www.youtube.com/watch?v=iD2rVGjG2HQ&list=PLbQqm4...
is a pretty good blueprint for making a supercapacitor with 3x the capacitance of commercially available supercaps (as RMS said).
That's a 0.08g, 1cm^2, 2.3F supercapacitor. To the best of my knowledge this the highest rated supercapacitor made by RMS in his videos (in terms of F/cm^2).

In that video he made a graphene paint (not GO, not AC).
He shows how to make graphene here
https://www.youtube.com/watch?v=gcwCGRXVHzQ&t=38s

As it happens, my sodium sulfate order came in yesterday and I couldn't contain my inner-nerd so I headed out to the garage and made graphene (as per the video above) :o

Next I'll mix-up graphene paint with acetone and 3% by weight PVP binder.

Really, the only slightly difficult part of this whole process is right there - making the graphene paint. After that you choose the electrolyte you want to use, which will dictate the current collector material. In the RMS video he just used salt water and aluminum. RMS also used polypropylene separator. I found some 25micron commercial Celgard on ebay, so I'll roll with that.

That's about as "distilled" of a version as they come :)

Going forward, I've been extremely interested in deep eutectic solvents as supercap/battery electrolytes. For supercaps, the capacitance goes up as the square of the voltage. Aqueous electrolytes break-down at 1.2V, and even nasty acetenitrile breaks down @2.2V. I heard reference of some DES having potential windows around 6V. That's 5 times the potential window, or 25 times the capacitance of an equally prepared, aqueous solution supercap! (Assuming of course the DES was suitable as this kind of electrolyte).

Although I do have ChCl on hand, Ialso have ZnCl ordered so I wait for that to come in before I play with DES as electrolyte. And then of course Dot 3 brake fluid, antifreeze and glycerin are the easy store purchases I've already made. These may not be the absolute best (other HBDs might be better...I'm still reading) for our purpose, but they're a start :)



[Edited on 11-12-2016 by Aztral]

aga - 11-12-2016 at 11:20

Today i did lots of things while waiting for a batch of zinc nitrate to finish reacting.

Turns out that what i thought was pure zinc powder is pure crap, so started again with a freshly-cast bar of zinc instead.

First base (for me) is some home-made AC to test against the commercial stuff, hopefully coming out with an I.N. of > 500. (this will also serve as a verification of what RMS is saying)

When that is done, empirically test it in a cell and see what we get, hopefully setting some kind of benchmark for future materials.

I love love to shove random things into pots, boil/zap/pulverise them and then go 'woohoo!' but experience tells me that way rapidly leads to disappointment.

My gut feeling is that this tech is worth exploring properly.

WGTR - 11-12-2016 at 13:27

I'm typing on a tiny smartphone, so please bear with me. The electrochemical window of a solvent or electrolyte depends also on the electrode materials. An ionic liquid with an EC window of 6V on platinum or glassy carbon electrodes will normally only work to 2.5-3.5V on graphene electrodes made from flake graphite precursor. The edges of the flakes are electro chemically more active than the basal plane, so it's possible that a flat, non-porous sheet of graphene would work at these high voltages, but then such an electrode would be useless in a capacitor.

This also means that acqueous cells do not really work over about 0.6V, unless asymmetrically-sized electrodes are used. The anode gets oxidized over this potential (on the flake edges). This oxidation is partly reversible, and this can give the appearance that the cell capacitance is gradually increasing. This is a faradaic effect, much like what happens in a battery. If allowed to charge continually over about 0.6V, however, the anode pores gradually clog with functional groups, and cell capacity drops.

Leakage current and short life at usable operating voltages are the bane of graphene supercapacitors. All of this information can be found in the literature, if one reads in between the lines. In most cases, however, the journal articles are written to generate more research dollars, so in many cases such candidness isn't forthcoming. After a while one develops a critical eye, and can immediately spot "weasel words", omissions, intellectual sloppiness, and other annoying things that pop out in graphene research.

I've built an aqueous cell that works up to about 0.6-0.65V. The leakage current at that voltage was good enough that its self discharge time constant was over a month (Measured). With ionic liquids I found that leakage currents became a significant problem over about 2.5-3V, even with very dry electrolytes under a vacuum. In other words, the operating voltages aren't any better than Maxwell supercaps, which have excellent cycle life and low leakage current.

aga - 11-12-2016 at 14:33

All material published so far should be regarded as 'weasel words'.

Empirical testing and experimentation will provide hard data to be analysed.

Personally i have the idea that the capacitor/battery chemistries can be somehow mixed or drastically altered to be Something Else.

It's just Electrons after all ...

No idea yet. Time will tell.

[Edited on 11-12-2016 by aga]

RMS latest video

Geekineer - 11-12-2016 at 15:36

In Robs latest vid - about 2 weeks ago - he seems to abandon his graphene ink on grafoil electrodes, or ink on both sides of copy paper membrane (used in his 600sheet bat/cap for the electric moped). He's now happy with a magic mix that forms both the current collector and electrode - looks like some form of conductive poly???. About 1.5" wide strips will sandwich a poly? membrane and maybe (rolled?) and inserted into the Type 27 repurposed battery case as a demo?

PS - forgive my ignorance but in this forum how do I reply to a specific message vs. just replying to the newest post?

Also I'm not getting any email notifications if messages are replied ?????


Morgan - 11-12-2016 at 15:42

Quote: Originally posted by aga  
All material published so far should be reagarded as 'weasel words'.

Empirical testing and experimentation will provide hard data to be analysed.

Personally i have the idea that the capacitor/battery chemistries can be somehow mixed or drastically altered to be Something Else.

It's just Electrons after all ...

No idea yet. Time will tell.


I recall reading this comment on the Towards a 1 MegaFarad video.


WGTR1 year ago
That's an interesting project, Robert. Might I suggest hooking the cell up to a stable voltage for 72 hours, and then measuring the charging current? Bonus points if the following test measures self-discharge, with voltage charted against # of days. Those are pretty easy tests to do. Only connect the meter when actively measuring voltage, to avoid having the voltmeter continually load the cell.

The leakage current test is a good measure of cell quality. Ideally the current should be zero, but impurities in the electrodes and electrolyte, choice of collector material, and ohmic paths through the separator will cause it to be greater than this.

The self discharge test is probably the most important one, if the supercapacitor as an energy storage device is considered. For example, even if a cell has an energy density rivaling Li-ion chemistry, it won't be useful if it self-discharges in 15 minutes. Also, the shape of the discharge curve indicates if there are faradaic reactions occurring, if there is moisture contamination, etc.

Cell lifetime is related closely to the previous test results. A cell with high leakage current will usually have a short lifetime at rated voltage. There are other tests that measure quality, but I think the first two are the most important and practical for a home hobbyist. For reference, my own aqueous cells lose half their stored energy after about 3 weeks. The self-discharge time constant is > 2 months. The ionic liquid-based ones currently self-discharge more quickly. Those lose half their energy after 5-7 days. By contrast, cells from the "Big Boys" like Maxwell may lose only 10% of their voltage after a month.

Finally, as you've already mentioned earlier, I'd suggest measuring capacitance by calculating the voltage drop vs. time with a fixed load. The load should be > 10x the leakage current, small enough that internal resistance is insignificant, and small enough that the discharge takes place over 10-60 seconds (to improve measurement accuracy).

Standard capacitance meters are useless for measuring EDLCs, as measured EDLC capacitance depends on test frequency (a graphene electrode is similar to a transmission line of sorts, with distributed resistance and capacitance).

Hopefully some of this information will be useful to some people. I think if testing methods are standardized a bit more in the hobbyist world, it may be easier to compare the results different people are getting.
https://www.youtube.com/watch?v=MfEroyS6Ix0


WGTR - 11-12-2016 at 18:56

Quote: Originally posted by Morgan  


I recall reading this comment on the Towards a 1 MegaFarad video.


WGTR1 year ago

Weird. I wonder who THAT guy is?

Morgan - 11-12-2016 at 19:16

Quote: Originally posted by WGTR  
Quote: Originally posted by Morgan  


I recall reading this comment on the Towards a 1 MegaFarad video.


WGTR1 year ago

Weird. I wonder who THAT guy is?


Well it's going to be hard to beat the "big boys".

WGTR - 12-12-2016 at 16:03

I've watched a lot of Robert's videos in the past, although I haven't seen his recent ones. I borrowed a clever idea from him once to use a galvanized pipe as a hydrothermal reactor. That worked out pretty well. He is quite clever and insightful.

I'm not sure where his business ventures have turned up, but at the time I last checked, I would've considered any of my money invested to be a personal gift, not something with a chance of positive return. The reason for this is that commercializing good supercapacitors takes both a large team and deep pockets. Maxwell Technologies (I use them as a convenient example because I use their products, there are other good manufacturers), spent about $25 million last year in R&D. They already have good products, they're just trying to maintain their market share. The piles of money it takes to survive in that cut-throat market are mind-boggling.

There are small companies that have tried to come out with revolutionary energy storage devices. EESTOR and the Zap & Go Charger come to mind. EESTOR is just, I don't know...there was a theoretical assumption made from the outset that turned out to be wrong, that made their entire product idea impossible. They are still trying to milk it for everything they can, years later. Zap & Go, at least, has offered to refund their original backers' money. This was an Indigogo campaign that offered the promise of a cell-phone charger with integrated graphene supercapacitor storage, that was much smaller than anything else on the market. The tipoff was that they claimed to operate directly at 6-7V, enabling very high density storage, whereas their competitors where still stuck at 3V. Right away, I knew they were trying to use these high voltage ionic liquids. There's published literature that shows why this wouldn't work in that application. When a project has a small team working on it, however, it's likely that crucial mistakes and oversights like these can be made.

Anyway, it's a lot of fun to build these devices, and a great learning experience. Just don't expect to get rich off of it, and don't get taken to the cleaners by someone else. I spent a lot of time researching it myself, with the eye towards possible commercialization, but we never came up with anything competitive. The whole process was a lot of fun, however.

I can offer some hopefully useful advice on how to make certain parts of the cell. The big one is to not allow aqueous electrolytes to make contact with metal collectors, unless that metal is platinum or something. Aluminum and copper will corrode eventually. Aluminum collectors can be used in some non-aqueous cells, provided that the electrolyte is compatible with it. One way that I got around this problem in aqueous cells, is to coat the copper collectors with conductive wax.

A combination of nano-graphite and flake graphite was mixed into microcrystalline wax, and this was applied to the collectors, trimmed and shaved, etc., to give a flat surface. Both graphite and wax are hydrophobic, and resist aqueous electrolytes (phosphoric acic/PVA, etc.) pretty well, protecting the metal collector. The bulk conductivity of the conductive wax is low compared to copper, so this wax is shaved as thin as practical without causing cracks or porosity. This composite metal/wax collector is a good starting point towards building aqueous cells that have low leakage current and good lifespan. The one that I built this way, several years ago, still works fine.


Geekineer - 14-12-2016 at 06:08

Hi WGTR
In RMS lastest vid he shows a cell concept without separate current collector - but part of a "very conductive" electrode material.
Any thoughts on its make up - graphene plus poly???
Dennis

Morgan - 14-12-2016 at 06:45

I remember this tidbit about ruthenium oxide being used and wondered if it was that great or not, all things considered.

"Ruthenium oxide has great capacity to store charge when used in aqueous solutions.[11] Average capacities of ruthenium(IV) oxide have reached 650 F/g when in H2SO4 solution and annealed at temperatures lower than 200 °C.[12] In attempts to optimise its capacitive properties, prior work has looked at the hydration of ruthenium oxide, its crystallinity and particle size."
https://en.wikipedia.org/wiki/Ruthenium(IV)_oxide


http://www.nature.com/articles/srep04452/figures/1
Hydrous Ruthenium Oxide Nanoparticles Anchored to Graphene and Carbon Nanotube Hybrid Foam for Supercapacitors
http://www.nature.com/articles/srep04452


aga - 14-12-2016 at 09:36

Thanks WGTR !

It certainly looks like fascinating stuff.

Currently i'm stuck trying to get Zn(NO3)2 to crystallise so it can be used to follow RMS's activated carbon route.

(chances are that he found many routes to things elsewhere, just that i first saw them in one of his videos with no mention of the original reference, hence attributing it to him.)

WGTR - 14-12-2016 at 11:40

Quote: Originally posted by Geekineer  
Hi WGTR
In RMS lastest vid he shows a cell concept without separate current collector - but part of a "very conductive" electrode material.
Any thoughts on its make up - graphene plus poly???
Dennis


Please link to the video and let me know what part of it to watch.

Quote: Originally posted by Morgan  
I remember this tidbit about ruthenium oxide being used and wondered if it was that great or not, all things considered.

"Ruthenium oxide has great capacity to store charge when used in aqueous solutions.[11] Average capacities of ruthenium(IV) oxide have reached 650 F/g when in H2SO4 solution and annealed at temperatures lower than 200 °C.[12] In attempts to optimise its capacitive properties, prior work has looked at the hydration of ruthenium oxide, its crystallinity and particle size."
https://en.wikipedia.org/wiki/Ruthenium(IV)_oxide


http://www.nature.com/articles/srep04452/figures/1
Hydrous Ruthenium Oxide Nanoparticles Anchored to Graphene and Carbon Nanotube Hybrid Foam for Supercapacitors
http://www.nature.com/articles/srep04452



A true electric double layer capacitor (EDLC), which a supercapacitor is, doesn't allow charges to cross the Helmholtz double layer. The electrodes don't get reduced or oxidized, like they do in a battery. A true supercapacitor can have a cycle life in the millions, whereas a battery starts losing its capacity after a few hundred or thousand cycles.

In cells that use ruthenium oxide, or other compounds that rely on redox reactions to deliver high energy storage capacity, look at the results of the cycle tests to see where the cell's cycle life is trending. This is an important metric, especially since ruthenium oxide isn't cheap.

Since a supercapacitor is essentially two capacitors in series (one for each electrode), the capacitance is half what it could be with one electrode only. The idea is to make one electrode the "battery", and the other electrode the "capacitor". This way you have a capacitor with better energy storage (or a battery with better power density, depending on how you look at it). On the flip side of this, it's also like having a battery with lower energy density, combined with a capacitor with poor cycle life.

Personally, I think it's better to keep a battery and a capacitor as physically separate devices, and let them each do what they do best (high energy density for the battery, high cycle life for the capacitor). The exception to this would be if the cycle life was approaching 100,000 or more.

Quote: Originally posted by aga  
Thanks WGTR !

It certainly looks like fascinating stuff.

Currently i'm stuck trying to get Zn(NO3)2 to crystallise so it can be used to follow RMS's activated carbon route.

(chances are that he found many routes to things elsewhere, just that i first saw them in one of his videos with no mention of the original reference, hence attributing it to him.)


As the ruthenium goes, so goes the zinc!

Anyway, there is some special terminology in the world of supercapacitor journal articles. Whenever the word "specific" is used in a measurement (i.e., volumetric specific capacitance), this measurement refers to one electrode only, and only to the active material (unless otherwise said). In other words, the gravimetric specific capacitance of a particular electrode may be 250F/g, but this is for only one electrode, and doesn't include the collector material, packaging, or the electrolyte. Because there are two electrodes in series, this capacitance figure is divided by half when both electrodes are considered. Since the weight doubles with the addition of the second electrode, this figure is halved yet again. In other words, the gravimetric capacitance of the assembled cell is always less than one fourth of the gravimetric specific capacitance figure.

[Edited on 12-14-2016 by WGTR]

aga - 14-12-2016 at 12:24

Personally i'm starting out thinking about Electrons, how to store them and rapidly pumping them out of a 'device'.

Battery/Capacitor technology is awesome, yet it all started with some metal and an acid, and has folowed a Route from there.

I really do think it *might* be worth taking a look back at where it started.

Perhaps there are Other possibilites, perhaps not.

Geekineer - 15-12-2016 at 08:51

WGTR - the vid I referred to is titled "Structured Carbon Battery" see segment 1.5 minutes to 3.5 minutes where RMS introduces this latest flexible creation.

That said the vid from yesterday on his new strategy is back to flat, thick, 'paste' coated plates. 10 X 15 cm, my guess, looks like 15 mm thick, and quoted as equivalent to 40Ah 12V Pb acid battery.

He said he abandoned 'printed' battery due to issues with reliable means to attached and maintain tabs etc.




Tum tee tum tum ...

aga - 15-12-2016 at 12:18

Zn(NO3)2 is proving very hard to get as actual crystals.

Boiling down the ZnO + HNO3 reaction liquid goes OK, then the temperature rises to 120 C, and it is stated to decompose at 125 C, so still wondering what to do to get crystals.

In the meantime, may as well 'have a go' at these battery/capacitor thingies.

3 bits of paper, 2 bits of aluminium kitchen foil and some 'sous-vide' plastic, plus some materials to try out.

Materials messed with :-

succinimide + potato starch
isocyanuric acid
PVAc glue
glycerol
activated charcoal/PVAc glue/NaCl

packs.JPG - 82kB

Some material is plastered onto a bit of photocopy paper.
The tinfoil is cut to be a kind of L shape and slapped on top.
Another bit of paper is put on top of that just to stop whatever material being all gunky to mess with.
Whole thing flipped over, repeat.

Finished thing stuffed into some plastic, then 'vacuumed' and heat sealed in a cheap sous-vide machine (€34 from Lidl, the vac is pitiful).

Give it a second of charge from 2x clapped out AA batteries.

charge.JPG - 55kB

Here's Glycerol as the electrolyte/dielectric after about 50 seconds.

hold.JPG - 57kB

:)

Characterising them will need a dedicated machine, so got to build one of those now.

Apparently you need to know the load resistance and the time it takes to get to discharge to the 'tau' point which is 36.8% of the original charge voltage.

This Fluke 15B says it has > 10M Ohm imput impedance (not resistance i know) so have to work with that, which incidentally makes these cells' capacitance utter pants !

Looking into this kind of thing opens door after door of new things you have to do !

No wonder RMS smiles, laughs and jokes a lot.

It is Excellent fun.

[Edited on 15-12-2016 by aga]

WGTR - 15-12-2016 at 14:14

Quote: Originally posted by Geekineer  
Hi WGTR
In RMS lastest vid he shows a cell concept without separate current collector - but part of a "very conductive" electrode material.
Any thoughts on its make up - graphene plus poly???
Dennis


He mentions CMC (carboxymethyl cellulose) and SBR (styrene-butadiene rubber) as binders, and mentions "calendering" the assembled electrode. This means high temperature and pressure, and is a standard process for assembly.

There is research into self-assembled and supported electrodes, but the most common method is to mix the active electrode material (graphene, activated carbon, etc.) in a solvent (DMF, NMP, etc.), with a conductive additive (carbon black, i.e.) and a binder (PTFE, etc.), dry, and then hot press to bond the electrode components together. The pressure and heat is necessary to activate the binder and form the electrode structure. It sounds like this is what Robert is doing.

Two references, but there are many others:

http://www.electrochemsci.org/papers/vol11/111008270.pdf

Attachment: Effect of binder_supercaps_Q-Abbas et al, 2014.pdf (585kB)
This file has been downloaded 408 times

RMS Vid on Battery Strategy Dec 14, 2016

Geekineer - 15-12-2016 at 14:16

Note - there is typically as much info if you read all (hundreds) of comments on the videos as opposed to just watching the vid.
-----------------------------------------------------------------------
From the last group of videos and this one on strategy I think I'll try to summarize Robs technology and plans.

1. Commercialize a battery in a Type 27 form factor - having at least 40Ahr at 12V. Targeting Q2 2017.

2. Aqueous electrolyte (he mentioned salt water)

3. Electrode and current collector is one component with a carbon base - likely made from hydrothermal carbonization of hemp fibers. Binder used turns it into a strong flexible component, made up of a 70/30 mix by weight of CMC (cold mix wall paper paste from cellulose) and SBR (latex rubber used in concrete mixes.) Binder to carbon again in the 5 to 10% range.?

4. The relatively low resistivity, 7 times 10 to the minus seven ohms / sq. meters allows for a common current collector/electrode and interconnecting tab. Unlike the thin layers of electrode that earlier were printed from graphene ink, these are (my guess) about a mm thick paste that is spread or cast the rolled into plates.

5. No mention of membrane - is there on - he did refer to one comment/question and said its paper but not sure if that is the latest or from earlier work.

Questions still out there - is the cell symmetric - if its truly a battery that maybe not - what is the other half??

As part of Robs strategy - brilliant if it can be a reality- is to quickly follow this 350mahr / gram battery with ones at 700, 1400, 4000, and 8000. This keeps ahead of those that steal ideas without any litigation costs.....

aga - 15-12-2016 at 14:52

Nice one WGTR.

Good analysis and references

Probably because you've done some of of this stuff ?

If so, did you get anywhere, and by what route(s) ?

Geekineer - 16-12-2016 at 06:18

WGTR
From your last post, I'm trying to understand the carbon black component.

There is research into self-assembled and supported electrodes, but the most common method is to mix the active electrode material (graphene, activated carbon, etc.) in a solvent (DMF, NMP, etc.), with a conductive additive (carbon black, i.e.) and a binder (PTFE, etc.), dry, and then hot press to bond the electrode components together. The pressure and heat is necessary to activate the binder and form the electrode structure. It sounds like this is what Robert is doing.
---------------------------------------------------------------------------------------------------------------------------
Carbon Black - I think added to aid in electrode conductivity due to its thickness (Robs 1mm)
If you add too much - its a short circuit - if you add too little it won't help with ion migration through
the thick electrode (as opposed to a micro thin ink electrode).
Do I have this right? Any experience with how much is 'just right'.

aga - 16-12-2016 at 13:48

Built an arduino based charger/discharger/measuring thing to get some data on these cells.

It's not an accurate instrument by a long shot, but good enough for comparative testing.

Basically it charges the cell for 'CHARGE_SECS' (see attached sketch), measures the voltage, then calculates the 1 tau point of 36.8%, then lets the cell discharge until that point.

It chucks out the readings via the usb-serial interface which can be easily copy/pasted into excel for graphing.

This version uses an LCD shield just cos i have one, and requires a few additional components : 1k resistor, 1M resistor, 1N4148 diode, 2n3904 (or any NPN transistor) and a 5V relay. An external battery does the charging as the voltage can be measured and relied on to be what it says with no ripple.

schematic.bmp - 11kB

The 1M resistor goes across the cell under test.
Here's the arduino sketch. You need to rename it battery.ino to get it to work.

Attachment: battery.txt (4kB)
This file has been downloaded 595 times

The best so far was just PVA glue smeared on some paper.

rig.JPG - 62kB

According to the readings/calculations it is a pitiful 1.1 uF capacitor !

PVA2.png - 16kB

Not bad for a start i reckon.

On a brighter note, made some Zn(NO3)2 yesterday.

As woelen foretold, it did not crystallise and went directly from a liquid mass to a solid. Quite heavy too.

It should work fine for the Activated Carbon that is coming up next.

Conc Nitric would probably work the same.

We'll see, as i got a procedure to test the results.

Morgan - 16-12-2016 at 19:36

That was interesting about the Teflon binder in those two articles WGTR. I was going to ask if they ever used Teflon in the electric double-layer capacitors when you posted those references -"Therefore, PTFE is the best suitable binder for supercapacitors and the optimal content is 10 wt% to achieve the best electrochemical performances."
http://www.electrochemsci.org/papers/vol11/111008270.pdf

Teflon is nice because it doesn't hold moisture and it's such a good dielectric or insulator. As an aside, it was impressive how well this 1/8 inch thick PTFE sheet contributed when charging up objects like this grapefruit arcing over to ground. It seems to build up trapped charges in itself like those acrylic lichtenberg figures. But I guess high voltage is the last thing supercapacitors have to worry about.
https://www.youtube.com/watch?v=P-NbshIOJmc

Tidbits
https://www.tecategroup.com/ultracapacitors-supercapacitors/...

aga - 17-12-2016 at 02:12

Testing some normal capacitors with the arduino rig <i>without</i> the fluke meter attached came out at about +/- 1% of what the meter's capacitance function showed, and what is printed on the cap.

Turns out that the meter introduces some significant load on the cell under test, throwing off the readings quite a lot.

The PVA-only cell averages 9.2 uF, not 1.1uF !

Oddly, it measures higher if the cell is shorted out prior to testing.

Definitely some chemistry going on in there as it self-recharges :-
sec volt
000 0.00
030 0.10
070 0.12
104 0.13

Edit:

Updated arduino sketch that does not need an LCD shield.

Attachment: Battery.txt (4kB)
This file has been downloaded 560 times

Kick off the measurement by sending 1 to 9 (= charge time in seconds) via the serial console.

It outputs the readings in a comma-separated format, easy to graph in excel, with the tau point plotted as well.

PVA3.png - 18kB

By using a 1 meg resistor, the seconds to the tau point = capacitance in microfarads.

[Edited on 17-12-2016 by aga]

WGTR - 17-12-2016 at 07:42

Good job, guys. Typing on my phone again, which means that I may be missing some context. Aga, your Arduino setup looks good, except that it might be loading your cell. Did you measure the cell performance without the 1M load, just to see how the discharge curve differs? Also, 2.5V is far too high for an aqueous cell. You're performing electrolysis at that potential, which is causing the cell to self discharge when the power is removed. Shoot for about 0.6V.

Ten seconds isn't enough time to charge the cell. There's not only electronic conductivity in the electrode structure itself, but also ionic conductivity, as the ions try to migrate through the porous electrode structure. Some of those areas may not be very accessible, and it will take time for charging. For your purposes, perhaps charge it for an hour at first, and then measure the self discharge voltage drop to see how fast it drops. If it's more than a few seconds, then disconnect the Arduino, etc., between measurements, that way it doesn't contribute negatively to the results.

I also apologize; I'm probably explaining things in too complicated of a way, when what you're trying to do is just build something that works. When I get back to a normal computer, I'll look this thread over again.

I did build a device of about 0.1F (100,000uF) using a PVA/H3PO4 electrolyte. The active material was thin, and about the diameter of a small button. The collectors were coated in conductive wax, as I mentioned earlier. The outer edge of the cell is sealed with epoxy to protect it from oxygen. The separator is Celgard. The cell is a couple of years old. I have it charging at 0.65V in the lab. I'll check it when I go into town some time this weekend.

Also, it's normal for cell voltage to recover like that after a discharge, because of the various distributed impedances throughout the electrode.

[Edited on 12-17-2016 by WGTR]

aga - 17-12-2016 at 09:09

The Fluke meter definitely loaded the cell.
The arduino far less, as the comparative capacitance tests showed.

These were all capacitors rather than batteries.

I just finished a battery cell and a 'joule thief' to play with.

Point taken regarding the 0.6 V - the battery cell bubbles at 2.7V, which is probably not good when it's sealed in a plastic bag !

Is 'PVA' poly vinyl acetate or poly vinyl alcohol ?

WGTR - 17-12-2016 at 11:00

Quote: Originally posted by aga  

These were all capacitors rather than batteries.

Is 'PVA' poly vinyl acetate or poly vinyl alcohol ?


It's possible to have a battery of capacitors! Ha ha! (...just to be annoying)

The PVA here refers to polyvinyl alcohol. I bought a pound of it on eBay some time back.

Also, here is a good source for battery research materials (ultra-high purity):

http://www.mtixtl.com/li-ionbatterybinders.aspx

It's easy to spend a lot of money at this place, but it's possible to source a lot of the more common materials elsewhere. This place does provide pretty much one-stop shopping, though.



[Edited on 12-17-2016 by WGTR]

aga - 17-12-2016 at 12:01

Quote: Originally posted by WGTR  
The PVA here refers to polyvinyl alcohol.

Great. Thanks for clearing that up.

Quote: Originally posted by WGTR  
It's easy to spend a lot of money at this place

The Spirit is to Make/Do stuff rather than just buy things.

Well, it is for me at least, as i like Making/Doing stuff, hopefully understanding Why at some point ...

Unlikely i'll ever make a device more efficient than any of the five manufactured 2200mAh 40 C Li-Ion cells that seem to have accreted around one of these (remaining) quadcopters.

Buying things can easily get out of hand, and very little is learnt in the process :o

Aztral - 18-12-2016 at 20:31

RMS also mentions Polyvinylpyrrolidone as active material binder (3% by weight), mixed up with acetone to form a "paint." That's what I did this weekend (aside from continuing to clear a working space in my garage).

I ground-up some activated carbon, ran through a mesh, added PVP and acetone. Then I painted this onto Ni current collectors. (I'll also try graphene instead of AC at later point).

I also mixed up my first deep eutectic solvent 1:2 ZnCl and Dot 3 brake fluid :o

Separator was just 25micron Celgard.

I charged at ~2V for just a few secs really. Volts dropped rapidly to 0.7V then continued dropping...but not fast.

My apologies for lack of rigor or more detail, but this was my first attempt. Just playin' at this point. Everything was very far from "perfect," but I'd say it's an OK start.:P

Going forward I have lots of ZnCl. Considering starting to play with -amides as HBD.

[Edited on 19-12-2016 by Aztral]

PS..OH...this was pretty tiny supercap. 3-4 cm^2

[Edited on 19-12-2016 by Aztral]

aga - 19-12-2016 at 00:51

Hey ! Any start is a good one !

It'd be nice to see what your Ni current collectors look like with the 'paint' applied.

[Edited on 19-12-2016 by aga]

Aztral - 19-12-2016 at 21:49

supercap_1.jpg - 73kB

One current collector has the CelGard on it.
The DES is on the left, the AC/PVP/Acetone paint is on the right.

As you can see very far from perfektion :P

Prolly away from playin' with this stuff for a couple weeks.
When I get back to it will work on making these puppies consistently.
I also should build a few "standard" supercaps with salt water, acids and KOH just for reference. I'll keep using the paint I made because it's easy, but I also have some graphene (80% 1-3 layers) that I can mix up too.

I've got a bunch of ChCl and ZnCl, and lots of generic store bought chems like Glycerine, Dot3, Radiator fluid to play with.

Looking for amides that may be suitable for supercap/battery electrolytes if anyone has any suggestions :)

Baseline Cell

Geekineer - 30-12-2016 at 04:38

Here is the 'recipe' and test results for my base line cell.

1. Size: two discs 1.5" diameter covered with aluminum duct tape form the current carriers. Discs were 3D printed.
2. Electrodes formed from paste - 4g AC ground and through 80 mesh sieve, 4ml H20, .3ml PVA glue, .1ml PEG.
3. Spread paste onto Al tape discs. - maybe .5 mm thick.
4. Add NaCl soaked blue shop towel piece for separator.
5. Compress with spring clamp. Wipe off excess paste that extrudes out.
6. Charge to 1.0V, discharge to .5 V.

After several charge discharge cycles and rewetting of separator:
Powered small DC motor for 3min. 18 sec. or discharged into 120 ohm resistor 19 min. 20 sec. Motor draws 78 ma at 1V, 43 ma at .6V.

Next steps?
Try sugar foam instead of AC. Try new electrolytes and higher charge voltage i.e. KOH, NaOH , try adding 20% carbon black to paste and mabe thicker electrodes ??????

All comments welcome.
Dennis

aga - 30-12-2016 at 05:39

Quote: Originally posted by Geekineer  

6. Charge to 1.0V, discharge to .5 V.

After several charge discharge cycles and rewetting of separator:
Powered small DC motor for 3min. 18 sec. or discharged into 120 ohm resistor 19 min. 20 sec.

Wow ! Sounds like an awesome success !

If it was charged to 1v and discharged to 0.5v, the resistor/time calculation says it's > 9 Farads (if it were a capacitor) !

Should be discharged to about 0.37V for the tau thing.

What's PEG ? Poly Ethylene Glycol ?

Was the AC standard OTC stuff ?

Next step would be for someone to replicate and verify your process, then it truly would be a Baseline that everyone could easily get to.

aga - 31-12-2016 at 10:25

IT WORKS !

Maybe we need to call this the Geekineer Baseline EESD !

Today the recipe above was followed as closely as possible.
Measuring 0.3ml of PVA glue is pretty much impossible by volume (weight would be better). No PEG was available, so some car screenwash was added (it says -5 C n the bottle so there's some kind of antifreeze in it).

ac.JPG - 76kB

Two pieces of 1mm Al plate were cut to size/shape, some paste smeared on, then squashed/scraped with another piece of Al to get the layer as thin as possible.

A piece of paper from my notebook was put on top, wetted with a few drops of saturated NaCl solution, then the other Al plate put on top of that. The whole thing held together with clothes pegs.

cell.JPG - 59kB

The excess paper separator was left on so that more NaCl electrolyte could be added easily.

A few manual cycles of 30 secs charge, then discharge to tau took absolutely ages, so i altered the arduino program to make it automatically run the charge/discharge cycle and just print the result each time.

Attachment: Battery_Characteriser.ino (6kB)
This file has been downloaded 540 times

Been running for almost 2 hours to complete just 6 measurements !

testing.JPG - 82kB

The graph shows the Farads (yes, Farad measurement) of the cell on the Y axis versus the 30-second charge-then-discharge cycle number on the X axis.

You read it right : 6 Farads so far, and climbing with each cycle.

The active area is approx 13.5cm<sup>2</sup>

FvCycle30sec2.gif - 8kB

Enormous thanks to Geekineer for the recipe !

His/Her recipe is <i>definitely</i> the Baseline from which to get started. It works.

[Edited on 31-12-2016 by aga]

aga - 31-12-2016 at 15:40

Over 30 charge/discharge cycles the graph looks like this :-

FvCycle30sec3.gif - 6kB

More electrolyte and an extra clothes peg added at cycle #13 (the bit where it dips a lot).

aga - 1-1-2017 at 00:50

144 charge/discharge cycles.

Max: 11.2 Farad
Average : 3 Farad

FvCycle30sec4.gif - 8kB

Seems to be 'losing' electrolyte.

Might be the water evaporating, but where is the Salt going ?

Aztral - 5-1-2017 at 22:06

Excellent job guys!

Although, I'm just regurgitating what I've read...Lithium Sulfate aqueous electrolyte can be bumped-up to 1.9V.

I have some and will take a shot.
Planning more of a head-to-head supercapacitor comparison between rGO, AC, and graphene "paint" with Li2So4, NaCL and a deep eutectic solvent.
That gives me 9 supercaps to make :o

froot - 6-1-2017 at 02:57

Aga thanks for posting.

Could it be that your cell is losing capacity due to degradation of the aluminium current collectors?

In that article it states: For aluminum, pitting corrosion is most commonly produced by halide ions, of which chloride (Cl -) is the most frequently encountered in service.

Speculative equation: 2 Al + 6 H2O --NaCl--> 2 Al(OH)3 (s) + 3 H2 (g)

If this is what's happening then there's partly where your water's going.

Maybe stainless steel plates worth a try?




aga - 6-1-2017 at 05:06

Yes, pretty sure the Al plates are corroding.

An earlier try with Al foil saw them dissolved almost completely.

froot - 18-1-2017 at 09:52

Interesting article on aqueous supercapacitor electrolytes.

http://jes.ecsdl.org/content/162/5/A5140.full.pdf+html

anilmaddala - 9-2-2017 at 10:21

I was looking at onw of the latest RMS videos, any idea what RMS is holding at https://youtu.be/lCtP85gN8So?t=1m26s the felxible electrode sheet? any previous video where he shows how its made?

[Edited on 9-2-2017 by anilmaddala]

opcan - 12-3-2017 at 10:39

Hi,
I am also into RMS videos. Has anybody seen his latest one on the bipolar plate batteries ? I am wondering how are they made. The material + electrolyte. Stainless steel, graphite foil with active material, separator, and the second collector could be Pb? I thought of Al as well. Any idea ?
Thanks
O.

Pseudocapacitance only?

CharlesWood - 15-4-2017 at 01:27

I've watched quite a few of the RMS videos and I'm not sure I've seen any of the rechargeable battery ones that actually used normal chemical reactions - as used in say NiCad or NiFe cells.

I think that all his batteries are of the same basic design of a sponge structure - usually carbon based - that adsorbs ions rather than chemically reacting them, and so holds charge by a process of pseudocapacitance.

Is this observation correct? Or are there other types of rechargeable batteries in his collection?

[Edited on 15-4-2017 by CharlesWood]