New Battery Technologies

I suppose they will be awfully expensive for a while.

We complain incessantly, but nothing much seems to change: Gadget batteries are fundamentally no better than they were five years ago, with the possible exception that they don't tend to explode quite as often as they used to.Finally, providence is in our grasp. Now, several companies are looking to push forward with new battery tech that uses fundamentally different chemistry from its forebears.
For starters, there's the Swiss outfit ReVolt, which is adapting zinc-air batteries -- commonly used in button-style hearing aid batteries today -- for use with larger devices like cell phones and, down the line, electric vehicles.
Zinc-air hasn't been useful in gadget situations because it is only minimally rechargeable. ReVolt reconfigures the battery's electrode design to eliminate the problems that traditionally cause it to degrade and become unable to accept a charge after it's been depleted. The full details can be found in this story, but the bottom line is that the redesigned zinc-air cell can be recharged up to 10,000 times. Since zinc-air batteries have three times the energy density of a lithium-ion cell, that could mean an instant tripling of your cell phone's battery life span if ReVolt's plans eventually pan out.
Another battery technology is in the works by a company called Fluidic Energy, which is pioneering a new battery tech called Metal-Air Ionic Liquid (MAIL) batteries. MAIL is a liquid salt-based technology that would allow for batteries that are, in theory, much denser than zinc-air cells. MAIL cells could offer up to 11 times the energy density of a lithium cell.
MAIL lets battery makers use very dense metals in the battery design, so more energy can be packed into the same amount of valume. Based on this story's analysis, a typical laptop battery could pack over 500Whr of juice into the same space as an old 95Whr battery. Electric vehicles are a specific focus for MAIL -- but there's no timeline for when it might reach the market.
Both battery technologies (especially zinc-air cells) also have another killer feature: They're very stable and should be less prone to short circuits and explosions.

More new battery technologies promise outstanding advances : Christopher Null : Yahoo! Tech