Toyota is set to launch its first lithium ion battery-powered hybrids in 2009, but it is already undergoing R&D for the next generation of batteries in search for battery technology with capabilities beyond what lithium ion battery technology can offer.
One of the technologies being researched are metal-air batteries. Typical metals used in metal-air batteries include zinc or aluminium, with zinc being the most popular one by far, a popular choice to power hearing aids.
Metal-air batteries have often been compared to fuel cells in terms of operation. The anode is pure metal, and the cathode is a supply of air, which is pretty much considered inexhaustible. Water is used as a catalyst. There are also lithium air batteries and carbon air batteries being researched.
Please refer to the links below for more information on metal-air batteries.