Warning: Potassium hydroxide is corrosive, zinc is a heavy metal, and manganese dioxide is an irritant. Wear gloves when handling them. Get a 5 mL plastic syringe . Discard the plunger and cut off the tip. Also cut the back up to the 5 mL mark. Get a 5 by 3 cm sheet of zinc metal about 0.5 mm thick. Cut into the 3 cm side a series of cuts about half a centimetre long. Roll the sheet so it fits into the syringe tube. Don’t roll it too tight so it falls out. It should be big enough that it stays in by friction. Once you have the right diameter, pull it out and bend inward the tabs we cut earlier.This should now form a zinc can. Prepare the cathode powder by mixing 8 grams of manganese dioxide and 3 grams of carbon powder. This will provide enough cathode powder to make about ten batteries. The carbon is just a conductor for the oxidant which is the manganese dioxide. The best manganese dioxide to use has the gamma type crystalline structure. The more common beta type crystalline structure will still work but will give lower current. So try and get the gamma type if you can. If you make your manganese dioxide electrochemically then it will be of the gamma form. While manganese dioxide made pyrolytically is usually of the beta form. Now get some filter paper or a coffee filter and cut a rectangle, about 5 by 10 centimetres. To that pour a five centimetre line of about one gram of the cathode powder. Also insert a 7 centimetre length of 2 mm thick pencil lead into powder. Roll that into the paper and fold over one side so it doesnt spill out. Now get the zinc can we made earlier and insert the cathode roll into it. Cut off or tear any excess paper. If there is too much cathode powder that it doesnt fit then you’ll need to pour some off. If there is too little then you’ll need to take it out and add more. Now insert the assembly pencil end first into the syringe container from earlier. Make sure the pencil lead goes through the hole in the tip. Then break off the exposed pencil lead and leave 2 mm for electrical contact. Fill the battery with electrolyte by dropping the whole thing in solution of 30 g of potassium hydroxide in 50 mL of water. Leave it for several minutes to soak in and then take it out and leave it on some tissue for another several minutes to drain out any excess. And that’s your battery.
Posted on: Sun, 21 Dec 2014 13:46:00 +0000
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