Finding some carbon graphite electrodes is usually a pretty easy thing to do. You first need to buy or find some zinc carbon batteries. Ypi need to make sure they are zinc carbon and not alkaline or rechargeable types such as Nickel Metal Hydride (NiMh) or Lithium Ion (LiIon or LiPo).
I also recommend wearing gloves, because the process is dirty. I begin by taking the packaging apart and looking for a way to disassemble the batteries.
The cylinder batteries have an outer steel wrapper that can easily be twisted apart at the seam using a pair of pliers.
With the wrapper taken off, I removed both end caps and the plastic protection sheet. Then, using the same pliers I gently take out the carbon graphite electrode by twisting and pulling. I wipe it down with a paper towel. I repeat the process for the second battery
For the 4.5 Volt square battery, I first remove the top cover revealing 3 identical smaller cylinder cells. I follow the same principle as for the larger batteries. The graphite electrodes in these batteries is much smaller but still useful.
With the electrodes removed, I proceed to dump out the manganese oxide from within the batteries. This step is not necessary, but if you want some manganese oxide for other projects, this is a good source. However, please note that this manganese oxide will also contain a lot of carbon powder, usually graphite. If you want zinc metal, you can keep the bodies of the batteries
I then cleaned the electrodes and tested the conductivity and resistance. The electrodes also contain a wax layer on the surface. I remove it by three methods, the first of which is to run current through the electrode. This will of course melt the wax and create some wax smoke
The second method I used was to burn the wax off using a torch. The third removal method I tried was acetone. This was not very effective
You now have graphite electrodes, some manganese oxide and some zinc metal from the battery cans.