Al-air battery - car race challenge 

Lol Didn't you guys made fusion reactor in your time

Working on it.... but science takes time

yeah, it seems that there is no significant effect whether use zinc coated iron or nickel-iron alloy current collectors

oh, it was just school inventory

activated carbon from water filter. But carbon needs a solid contact with current collector. So a cloth could work only if pressure is applied with vices at the same time.

Hi, heating not needed, it only speeds up hardeing of the glue.

This Al-air battery method is newer and has better performance, the electrode needs heavy pressure, you may use any basic or neutral electrolyte, which has high ionic cinductuvity

Thank you for the reply. When applying epoxy glue, do I need to smear the glue into the pores of mesh or just slightly smear on the surface of mesh?

It gets inside of holes anyway. Uniform layer, as little glue as possible

It is basically 10% NaOH solution. In different brandnames, this cheap toilet clogging removal liquid should be available in any country.

Supercap has 2 carbon electrodes and closed vessel. Al-air battery has Al electrode and carbon electrode, which is in contact with oxygen

How long will this battery last?Or is it rechargable

it lasts 1h - 1day. Only mechanically rechargeable - cathodes are reuseable.

Hi, heating can be omitted if you have enough time to wait until the glue completely hardens. But pressing is important to get good electrical contact between carbon and current collector.

Fine carbon powder does not work with epoxy technology, it needs a different binder (PTFE etc) and some conductive addition (carbon nanotubes, carbon black etc)

it might do something but probably not as good as with glue and press. Similar cathodes as in the video and more professional ones can be obtained through superaccu.com

sure

will it work not having a tissue membrane? the electrolyte will serve as a medium for the magnesium alloy plate and air cathode.

mermeh tissue works fine

Depending on purity of Al, it works from 1h to several days. It must be connected to load all time, otherwise Al will dissolve uselessly

I'll tell you how he did it...nickel mesh. I am going to commercialize batteries open source using this and make it big! Thanks!

The EUSO race competition video is here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-QzRAKzsPkAk.html

The winner of the car race is Bulgaria A team 4.31 sec 2. Rumenia A team 5.01 sec 3. Sweden B team 5.03 sec 4. Germany A team 5.15 sec

cool did you check each car battery's amps and volts after the race?

+NatureHacker We did. The winner had 2.71 A and others had a bit lower, about 2.3 to 1.5 A a few minutes after their second race. One battery had 4 A, but the team got 5 sec penalty as it was a replacement cell.

Yep, this problem exists, there are two solutions: 1) after adding electrolyte, use the battery with maximum power until depletion of aluminum. When high current is flowing through, aluminum corrosion is much smaller at the same time 2) use pure aluminum - but it is expensive What power did you get

As soon as it was built we got a few amps (I don't remember how high exactly but it might have been as much as 4 amps at its peak), but that number dropped off very rapidly as the aluminum degraded. We also didn't have adequate pressure between the different layers of the cell which no doubt led to poorer contact. We used a CD case for the build, and while our carbon electrode was not as nice as the one in the video, it wasn't terrible either. (I'm in the same group as Philip Whong for reference) What source of pure aluminum can you recommend we use?

It all sounds real. Better purity Al can be obtained from electrical wires, 99.99% Al foil from sigma-aldrich is just ridiculously expensive

4A is the best result among other experimenters/commenters. How did you made carbon electrodes exactly: what glue, carbon particle size, electrode thickness and size, hydraulic press?

We used a fencing grid for the frame of the electrode, and to make the gaps smaller we pulled apart steel wool and tried to weave it into the gaps. Standard 2 part epoxy was used for the glue, and we had difficulty spreading it, so the outer 1 - 2 cm has very little carbon on it. The activated carbon was briefly ground in a mortar and pestle (when we ground it into a powder for our first try it didn't work too well). We still have to work on a clamping solution, but what we used was just some acrylic on either side with a bunch of C clamps to apply pressure. The overall electrode size was about 12x12cm, and the 4 amps was only achieved briefly when we pressed hard upon the CD case. As we only need less than a quarter amp for our purpose, and aesthetics are a large part of the competition, we will likely not delve more into working on getting more current. Instead we are more likely to experiment with different setups, such as trying something like making a round carbon electrode and wrapping aluminum wire around it. At the same time we are also working with zinc air batteries so that we can compare their pros and cons as we delve into the idiosyncrasies further. We will probably need at least 3 cells wired up in series to get the voltage we need, and the main part of our competition is consistency, so most of work will be in getting a consistent output voltage for as long a period of time as possible.

Good and large surface area cathode is the key

@@chemicum Thank you and do you think I should reduce the space between the electrodes ? I suppose, the less will be space between the anode and the cathode, the less will be the resistance of the battery. Or maybe it's not really important. What do you think ?

quentin tiefaine practically there is some gas evolution and some space is needed so that gas can go away

Al it is I think, others have lower power and in organic electrolytes (Li, Na) power is much lower

Thank you.

Not bad ideas, we have tested some already. Copper tends to corrode too easily - cannot be used repeatedly like stainless steel. The idea to use more aluminum - we have tried with rough surface (by making many holes to a few sheets of kitchen foil pressed together. And it heated too much, so that all electrolyte evaporated.

Oops I meant copper mesh electroplated with nickel, not zinc.

the best mesh to use would be copper plated with nickel then plated with chromium. You probably could then plate that with molybdenum then after that tungsten, but I'm not sure if anything past chromium works.

fyi refractory metals are the most resistant to alkaline corrosion. Noble metals are actually worse in alkaline than refractory metals. Tantalum is the number 1 best corrosion resistant element.

+NatureHacker tantalum is corrosion proof indeed, but it is expensive and it is coated with a dielectric layer. It is used in dielectric capacitors.

Graham Grecian should have twice energy density - at least fully developed batteries

true, it is a problem and there are methods being developed to work around this

@@chemicum yeah i hope they can solve that problem... :)

1.5 V micro motor quite powerful.

chemicum what about the current? Because i used a 1.5V motor with all the same exact materials and methods of making the battery but the motor won’t work because not enough current is produced😢

test first with multimeter, how many amps do you get?

I think it is possible, maybe I am working on it right now. The Al-air is only mechanically rechargeable - add new aluminum, carbon cathodes are reusable.

interestingm thanks. It's sad that they don't teach you that stuff in school (like with this as experiment), because I de-selected Chemistry in school because it was boring, if we learend stuff like that it would be interesting.... BTW do you know CodysLab?

Subbed to your chanel. What happens when you try to recharge them?

+Emiliano Viana electrolysis, production of hydrogen and oxygen. Actually, on a second thought nothing happens if aluminum is completely consumed - it cannot electrolyze with one electrode left only

+chemicum unfortunately it is not possible to plate the aluminium onto a base metal electrode during recharging because Al3+ doesn't want to come out of solution when there's already H+ in the water

It functions but not perfect. However, high temperature activation improves some carbon fiber fabric electrodes

@@chemicum I see. I guess I'd experiment anyway. Thanks!

+Abu Simbel At home - not jet. But these have been prepared for a military application and at least one company develops these for a civil use.

Mujal on väga erinevad sellelaadsed tooted, et me ei leidnud sellist rahvusvahelist kaubamärki ja jäigi kodune siil.

It is 1.65 V per single cell at the beginning, but it falls to 1 V quickly.

Frenchie tested, it does not work. Such small homemade carbon is almost isolator. It must be professionally made, but this needs laboratory tools

That is a battery

Santhosh Sandy not sure, important is high surface area and good electronic conductivity

But u said that fine activated carbon won't work on epoxy technology

Bro again on big doubt if I have to run 4 w/d 12 v dc motor of max 300 ma and 1.5 kg torque and 300 rpm, how many batteries I have to prepare

I meant carbon dust and epoxy won't work, carbon particles must be 1-3 mm large.

Wht abt that 12 v dc motor

it is ~0.5 mm

Aluminum can be only replaced mechanically, but if Zn is used, electrical recharging is possible

indeed epoxy is dielectric, therefore good contact is needed between conductive carbon particles

Jatin Goyal it is not. Glue attaches carbon to current collector

That means we can use any type of epoxy glue to bind carbon to current collector. I am quite confused how the charge collected in carbon pores will be transferred to current collector, if the epoxy is not electrically conductive

Jatin Goyal any glue. Imagine tiny droplets connecting carbon grains to current collector. Carbon must touch current collector - that is why high pressure. Glue only makes sure it stays there.

what if the epoxy (binder ) used is electrically conductive ?

Jatin Goyal that would make supercap better

Depends on quality if aluminum and cathode. From 10 minutes to full day.

slow-curing epoxy preferred. It glues carbon onto current collectors and so there is good electrical contact with carbon and metal

but glue was electrical isolator ?

glue is isolator, but only small amount of glue is used. Under pressure, is good contact between carbon and metal - glue just fixes this so that pressure can be removed

The other methods are not homemade stuff and hydroxide is better for Al-air compared to acid

Higher voltage can be achieved by series connection of single cells. Single cells must be in separate chambers.

+chemicum ok prof,

Check multimeter settings. If it is lighting LEDs, it should give at least tens of mA

@@chemicum thanks for the response. Yes sir, after a lot of tries.... It is giving 80mA. But how to increase it to 2.5A sir? Any ideas?

Yeah, it needs some experience. 80mA is good for the first time

to get 2,5A you need a lot of surface. impossible to get from that small piece. it was 2,5 V cause double cathode in serie with anode. so 1,25v x2

Doug Halpern up to a few Ampers (decreasing in time) and up to one hour.

recharge mechanically by replacing Al. Porous carbon is better than graphite. mAh and other data we will give soon in a paper

Activated carbon is there to provide Oxygen for cell reaction so graphite might not be a good idea.

Yeah, it is rather a fuel cell in this respect. Formed aluminum oxide is electrolysed back to metal aluminum outside in a cryolite bath.

some other glues also work

But does the glue have to be conductive?

Mon Dude not definitely

@@chemicum ok thanks i will probly make a battery today

Ok, now the electrodes are available at www.superaccu.com

+chemicum weird I only see 3 videos

try refreshing the page.

+chemicum got it! Btw are these capacitors recheargable? I saw another video that said they might be used only once

Al-air battery is only mechanically rechargeable - consumed Al can be replaced and cathodes can be used repeatedly after washing and drying. The Tic-Tac supercapacitor is electrically rechargeable - but energy density is much smaller and making a full cell takes more time.

sure about 300 A? :)

Reusing carbon electrodes: wash with water, let stand in pure water for few hours then take out and let dry overnight.

More than 300 mamps

But I can't run dc motors I dnt know y

Test your dc motor separately, what is the lowest voltage it starts running and how much milliampers does it take when stalled. Let me know

The cathode preparation is usually most difficult

@@chemicum And are you sure tissue paper serves the purpose of polymer separator? Instead of powdered activated carbon, I used graphene. What is your opinion about that?

Rivin Sainudeen tissue paper works. What kind of graphene ... RGO?

@@chemicum Yes, fine RGO powder And one more thing, pressure wasn't simultaneously applied whilst heating the cathode. (I couldn't find a metal plate thick enough for the job)

And Dr, do we need to stick to Ni Mesh? The mesh just need be non reactive with Al right?

bhagath s discribe your electrolyte, carbon electrode

I tried several combinations...Like NaOH/NaCl mix and KOH/KCl mix with different concentrations...In all the cases same problem...low current but very high voltage more than what we need..

bhagath s carbon electrode?

chemicum activated carbon powder on a mesh

Usually the weakest point is carbon electrode - whether it has bad contact (high pressure needed during glueing for good electrical contact) or bad carbon (only special activated carbon works, usual charcoal has too low conductivity. And this gluing method only works for 1mm or larger carbon particles.

Aluminum can be replaced only mechanically, carbon electrode is reuseable

Then it is not rechargeable

Is there any type of aluminum secondary air battery ??

GuardedDig2 not ready yet

chemicum ah thanks can’t wait to see it :)

mechanically - replace new Al. (The used Al2O3 can be electrolyzed back to metallic aluminum in a high temperature cryolite cell)

No, it does not work, it has low conductivity. It can be used after activating at 900 oCأفكار بسيطة No

thankyou bro

أفكار بسيطة graphite work better, yet it has a bur low surface area

+NatureHacker One cell in the race got 4 A and it was measured after the race.

That is insane. How long do the batteries last?

can you give me your email? I would like to buy one electrode from you for testing, the website given in the video doesn't work.

+NatureHacker wait a week, we are counting points this night.

Just smaller holes are better and take iron or stainless steel mesh

thanks a lot!

maybe, what is the resistance, measured like in the video

There was no short circuit. I tried using just G-clamps to get enough pressure on the Cathode with wood blocks, but I don't think it was enough. I've got some finer grains of carbon, steel plates and a hydraulic press now so hopefully my next test will go better. Resistance through the carbon to the electrode mesh should be fairly minimal? What kind of resistance do you get?

see also my supercapacitor video - resistance was measured there directly at electrodes. Finer carbon powder does not work well with this technology, it needs a binder like PTFE. Carbon must be special activated carbon - barbecue coal won't work without high temp activation

So current does actually flow through the carbon producing only a few ohms of resistance. I followed the coffee grinder and sieveing process from the supercapacitor video, but followed the mesh, and pressing parts of this video. Got 2 hrs till it's ready so I'll let you know how the resistance is. My first couple had mega ohm resistance and greater so hopefully these will do better lol.

yup, megaohms does not work, it must be a few ohms across the electrode, or at least less than kOhm.

the heating and pot is just needed to cure the glue faster. Alternatively, it can be just left curing overnight at room temperature.

you think you are alone ?

look closer at the multimeter, and you see it set to Ampere, not Voltage.

Santhosh Sandy a few cells in series or a step-up voltage converter

A few means how much approximately

What voltage arduino needs?

Around 5v :)

4-6 cells

no, but the glue dries faster when heated

@@chemicum can I use another glue like fevicol ?

shiva_giri maybe, you should test its durability in alkaline solution

@@chemicum if it is durable them can I use it ?

@@chemicum actually I am building a car for my college event

everyone would like to hear those

The homemade device here is very real and has short time power 1 W/33cm2=33 mW/cm2. In contrast, commercial SOFC gives continuously 1000 mW/cm2

@@chemicum Thank you for taking the time to answer my question, I will hopefully work on one of them in my coming masters program.