Warning: Concentrated sodium hydroxide is very corrosive, wear gloves when handling it.
Greetings fellow nerds.
In a previous video i made an aluminum-air battery. 
 It wasn't very good and produced very little current. 
In this video we're going to make a zinc-air battery.
First we make our sodium hydroxide electrolyte by getting 150 milliliters of water 
 and adding to it about 50 grams of sodium hydroxide. 
Stir the mixture until it dissolves. 
Be careful as the solution will get very hot.
When it's done, set it aside and let it cool.
While that's happening, we'll build the rest of the cell.
 I'm going to use this 200 milliliter beaker. 
For our anode, or negative electrode, we use a large sheet of zinc metal. 
We originally got this sheet out of a carbon zinc battery from a previous video.
For the cathode, or positive electrode we'll again be using steel wool. 
Now get some wires with alligator clips and attach them to the electrode materials.
Get a paper towel and wrap the steel wool,
 the idea is that we don't want it to touch the zinc metal. 
Now get the zinc metal and wrap it over the paper towel and steel wool.
Push the entire assembly into the container.
Make sure the wool on top is exposed so air can get in.
At this point this is known as a dry charged zinc-air battery. 
 It won't work until we add the electrolyte,
 but it can be stored for decades like this until you need it. 
To activate it, we just mix up and pour in the sodium hydroxide electrolyte.
And that is a zinc air battery. Let's measure its output.
Connecting it to the multimeter we see the voltage is around 0.84 volts. 
Let me measure the current. 
Whoa, it's off the scale. Let me switch the multimeter to high current mode. 
 Let's give it a few minutes to stabilize. The current is very good at 0.67-0.68 amps. 
 This is much better than the 17 milliamps of the homemade aluminum air battery of the previous video.
The reactions are similar, 
 the iron is catalyzing the reaction of oxygen and water to make hydroxide 
while the zinc metal reacts to make sodium zincate. 
What makes this battery work better is that the sodium zincate is soluble 
and doesn't block the reactions like the aluminum oxide formed in the aluminum air battery. 
That's why we can get a much higher current.
We can't use sodium hydroxide for the aluminum air battery 
because aluminum metal reacts with sodium hydroxide itself to produce hydrogen. 
This wastes power and renders the cell dangerous to use. 
 Commercial cells get around this by using better chemicals and aluminum alloys 
but that's beyond the ability of most amateur chemists. 
Anyway, thanks for watching, please subscribe like and comment.
