Homemade Lead carbon electrode (primary/rechargeable battery)

[derwood]

 I started experimenting with lead as a binder for carbon about a week ago. The electrode is a 2.5 in. diameter disk of lead binded granulated ac. The ac is exposed on one side. After several tests that were disappointing I later found that the electrolyte made all of the difference. Salt water started out good but quickly clouded up with zinc oxide and other oxides of anode material. KOH was very poor also. I then tried a mixture of alum and water. The results show promise. Using a zinc plated 2in. washer, the voltage was .7 volts and a short circuit test (sc test) starts out at 300 ma and after one hour it still was producing 65 ma. It can be charged to a standing voltage of 1.5 volts and sc test starts at 750 ma, drops to 500 quickly but begins to stabilize at 350 and drops much slower. after several charge 5 min. / discharge 2 min. cycles it improves. the electrolyte stays clear and clean. For some reason the oxide stays attached to the anode and there is no oxide settlement in the bottom. I think the charging pushes the fine oxide particles back out of the cathode and the battery is fresh again. I then tried solid Magnesium and the results were very good. the voltage is 2.2 volts and the amperage slowly climbs up to 500 ma and holds steady for a bit and drops very slowly. After 25min. sc test it still was producing 350 ma and holding, voltage was at 1.2 volts. This cell recharges very well back to its original voltage of 2.2 volts. Electrolyte stays clean and clear. The Magnesium seems to corrode very slowy, unlike in salt water. I do not know the whole chemical process behind this but I think the electrode could be greatly improved and the electrolyte could be improved also. Lead free solder will work also but the lead had higher voltage and amperage. the electrode contains about one tbl. spoon of ac and is very easy to make.