It looks like Re Volt has cracked the nut of how to effectively reduce the zinc oxide (recharge) back to zinc within a contained battery and they claim they can do this many times over. Viola you have a less expensive lightweight powerful rechargeable battery. This is truly big news if indeed Re Volt has cracked this nut and solved this trying problem other have struggled with for quite some time.
This zinc to air talk had me thinking about the possibilities of an aluminum air battery. When aluminum oxidizes it too yields an electric current. School kids can perform a science experiment with a small piece of aluminum foil and create an aluminum air battery. The problem with aluminum is that once the surface of the aluminum has oxidized with the thinnest of layers of aluminum oxide, the oxide forms a passivation layer that prevents further oxidation. This is great for aircraft, windows, RVs etc. that are made from aluminum as they do not rust. It is terrible for a battery though as the moment the oxidation reactions atop the battery stops yielding any current. A single aluminum soda can contains about 200 watt hours of possible oxidation energy. By comparison one needs a lithium battery that has a mass of 2 kilograms to yield the same quantity of energy. If once could safely convert the used soda can into aluminum powder it would then be possible to have a longer lasting battery as the surface are of the aluminum is increased many fold and the oxide passivation would be less immediate. Unfortunately aluminum powder is highly explosive and if it catches alight the more water you pour on it the more it burns. Please recycle your aluminum soda cans as we do save as much as 3 hours of electricity to power your television if a single aluminum can is recycled rather than thrown into a landfill.
I will be watching Re Volt with great interest to get developing information on whether they have really cracked this nut or are they simply another company like many other that have short circuited when air was allowed to pass over their zinc and simply became a money sink. In case you have not seen the youtube video of the German Coast Guard guy who mixed up sinking with thinking here is a link to that video. http://www.youtube.com/watch?v=6zkZ3f8DnKs I pray the Norwegian words for zinc and sink are not too close.