NurdRage - 2011-01-14
In this video we show how to make a Zinc Air Battery. First you'll need to make a solution of 50g of sodium hydroxide in 150mL of water. Stir it until it completely dissolves. Be careful as it will heat up a lot. Set it aside to cool. Now get a zinc sheet (we cut one out of a carbon zinc battery in a previous video: http://www.youtube.com/watch?v=knc1lSupAwQ) and attach a wire to it and attach another wire to some steel wool. We then wrap the steel wool with a paper towel to serve as a separator. The zinc is then wrapped around the paper towel/steel wool and the whole assembly is placed into a container. The steel wool has to be exposed to air to allow the oxygen to get in. The electrolyte of sodium hydroxide is added and the battery is ready.
In the previous video the biggest holdup was the aluminum oxide/insoluble hydroxide. If you get the NaOH sufficiently dilute it might dissolve the oxide of aluminum without attacking water too much, if you can create high enough overpotential, such as with acetylenic additives that hog gassing sites, similar to what's used in acid pickling rust remover additives for HCl, that removes rust from nail without generating hydrogen. Also mercury is a great way to break the oxide layer, but again, that starts auto gassing too, plus it's expensive and toxic, but gallium might be better than mercury. If there were a polar aprotic solvent that dissolved aluminum salts like it dissolves lithium salts in li-ion batteries, perhaps the aluminum could be dipped into that, and separated with a membrane that allows transfer of aluminum ions, but not water. I don't think such membranes exist, as the +3 charge and oxygen bond stregths are too much, but there are such things for sodium, beta-alumina is recently patented. In the Castner-Kellner cell the sodium-mercury amalgam has high enough overpotential for hydrogen generation, that sodium comes out on electrolysis instead of hydrogen, but magnesium does not work because the magnesium-mercury amalgam does not bind as strongly as the sodium-mercury one. I don't know about aluminum. Part of the problem of trying to get high hydrogen gassing overpotential out of aluminum-mercury or aluminum-gallium is that most commercial aluminum is alloyed with some copper, and magnesium, and the copper sets up a local battery, and the magnesium is really reactive with water. Things might be different with absolutely pure aluminum. Also, in the past even zinc based batteries used to contain mercury, for similar reasons.
Hi, I realy like your video. Can you please help me with few related questions? Is there a process to separate and recycle the products Na2Zn(OH)4 and 2OH? Would it be possible to use different electrolite to have overal reaction 2Zn + O2 → 2ZnO? Will the following reaction Zn + 2 H2O + 2 NaOH → Na2Zn(OH)4 + H2 occuring as well? Thank you, Jarda
Thank you. You make me want to strive more in Chemistry.
Did the steel wool form bubbles while the battery was in use? I'm curious how fast the oxide forms on the steel wool because it seems like this cell would start producing hydrogen on the cathode if the air isn't able to keep up with oxidizing the iron.
you helped me through sophomore chemistry :) my teacher loved your videos
I think all your videos are very educational and very well made
i dont know much about science and i have no intentions of learning about what you do but i find watching your video clips to be very amazing and very good to watch.just wish i was still in school to try it all haha keep up the good work NurdRage
Great Video, thank You! .68A short circuit current is quite impressive!
Are we to expect more air batteries? They seem rather interesting :)
@NurdRage Yep, and it's cheap. Rotometals is one source. I just picked up a sheet there which I'll use to fabricate a gravity cell. I'm exploring the possibility of using gravity cells in a practical application. Now that I've seen this demo, I'll definitely make a Zn-Air battery too! And it may even prove more suitable for my application. Thanks, NR!
This is very interesting... Question: what would happen if you galvanized a magnet? Would that increse its magnetic pull or would you have your very own battery?
@TheGreatIvan There is quite a lot that would work off of this. What you may not know is the voltage from this battery is roughly what you would get from one solar cell. You can either use electronics (search SMPS or switched cap boost) to boost the voltage (and there are plenty of ICs that are more efficient than those options), or you can just make several in series to boost the voltage. That kind of current would easily run most electronics for some time, or a LED flashlight. Thx Nurdrage!
Superb demonstration (as is usual)
;-)
@98JMA Firstly, thanks for the really quick response . . . .I love your work and your videos!! Secondly, I believe you misspoke . . . isn't the anode the positive electrode and the cathode the negative?? Anyway, what I meant is can you use a metal that does not react with NaOH to produce the metal complexes as the NEGATIVE electrode in place of Al or Zn?? Thanks:)
I'm told zinc is also available at home improvement centers. Used along roof peaks to inhibit the growth of moss. I'll be looking into that this spring as I need it desperately.
The one we made didn't output any voltage. There were bubbles coming from the clip used to attach to zinc that was submerged in sodium hydroxide. The zinc was also producing some minor bubbles. Any idea as to why?
Sounds like the reaction it was having wasn't what you wanted and instead of producing a current it was producing a gas... much like the tinfoil battery he was showing... I believe the zinc had a bunch of impurities or was corroded/deteriorated.. hope you didn't inhale!
@EMDSD40LocoDash2 I might add, the huge surface area of the steel wool is probably much more than adequate for the task. To deliver more current, I suspect more zinc (or a form with with greater surface area) and/or a freer flow of oxygen would be the best approach.
Thank you for sharing your video. I noticed something needs to be cleared out that it seems there is a lots of confusion around. Cathode is negative electrode while cations are positive ions that migrate to cathode or negative electrode and vise versa for Anode.
How much power is available from a cell like this? It would have been educational to show a few of these wired in series to a light bulb or motor. - Why steel wool? Would sheet metal work?
Thank you for your sharing useful technical knowledge. Is it rechargeable?
have you tried using activated carbon instead of steel wool as the cathode? activated carbon has a much larger surface area than steel wool for air to contact.
Could you use copper wool instead of steel?
Love these types of videos.
I don't know much about the difference between voltage and wattage. About what voltage would this be in comparison to a regular AA battery?
brilliant as always!
Thanks!! Yours are the best videos on Youtube.
That's some pretty good current there compared to the last one! :O
@3981784 the cathode receives electrons from the external circuit. it's easy to mix things up when you're looking at them from different points of view (e.g. physics vs chemistry).
Your videos make me want to pursue a career in chemistry.
Wrote a report on Metal Air batteries for my 3rd year project, last year. They have so much potential, its really to bad that more companies aren't focusing on them for things like electric cars.
How long does the charge hold for?
What about covering a saltwater magnesium air battery? What would be a way for it to be cheap, and prevent hydrogen production, making it an effective fuel cell?
Could you put a bunch in parallel to make higher current?
Is it rechargeable?
@98JMA Look at the reactivity series. Just below zinc is chromium. That would probably work (at a guess), but it's far far more expensive than zinc. Next down is iron, which is already in use as the catalyst/anode. I don't see how the cell could work with the same metal as both anode and cathode. All the ions would have the same charge. Zinc is simply ideal. It's highly reactive, low cost, utterly practical.
How long do these typically last?
sweet vids keep up the good work!
would potassium hydroxide work as the electrolyte instead and if so would it make a difference to the current?
What are you using to stir the mixture? Where can I get one?
I Used filterpaper rather than the paper towel to make the reaction i got around 1.24-1.25 volts which was vey stable for atleast 3 hours. then i diluted the concentration of NaOH to 300ml and then the emf shot up to 1.35 volts. Thanks for the experiment Dr.N Butyl Lithium
very good video, which battery would you buy for a car conversion project?
nice work!
how does the electrolyte affects the cell?
@ArtistBlade1972 Don't know of a spec, but see section 4.2.6. As you would expect, the output just goes though the resistor divider, so startup voltage shouldn't be affected by output. I could see it changing the time for startup, but not much. Anyway, the point is that its cheap and easy to turn low voltage things like this into good sources of power.
Great to that sort of thing thank you for posting keep up the great work take care stay safe : )
@EMDSD40LocoDash2 adding more of the metals would tend to increase amperage, but not voltage, so long as the components were acting as a single cell.
@JohnKapsis1985 The zinc is probably the limiting factor since there is plenty of air. As you pull electrons out, the metal will dissolve into the sodium hydroxide (per the formula he showed on the video). Pull out too many electrons, metal is gone - it will probably lose the alligator clip connection (due to metal weakening) long before it all dissolves. Still, if you don't pull much current, it should last a long time. Look up the relationship between coulombs, moles of electrons, and amps
Is it temperature sensitive???
Since this video mentions the reaction. I have never quite gotten a clear answer on the reaction equation between the aluminum and the NaOH.
sick! . can you make a lithium one? or will that be to hard?
zbret - 2011-01-14
I'd love to see you make a fuel cell. I think that would be cool. Even more interesting if you could do it with alcohol or other non-hydrogen gas method. I've seen these discussed but I'm really curious what you could come up with using home chemistry.