The slick Tesla retails for more than $100,000 partially because of the high prices of Lithium-ion batteries.

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Lithium-ion Battery Cost and Longevity

The Tesla Roadster can go the equivalent of 256 miles per gallon. Just plug it in overnight, and you can go up to 250 miles (402 kilometers) without stopping by the gas station. But there's a catch -- a 2009 model retails for more than $100,000.

Part of that hefty price is the sleek, sports car design and amenities and the power to go from zero to 60 miles per hour in under four seconds -- an acceleration that ranks among the best-performing gasoline sports cars. But that power doesn't come cheap. In fact, Li-ion batteries are around four to five times more expensive than nickel-metal-hydride­ ones [source: Popely]. Since the car-capable packs can cost between $10,000 and $15,000 each, finding a cheaper alternative will be a major hurdle for car companies that want to market them [source: Popely].

There's also an issue with the battery life. Like the AA batteries that you put into your TV remote control, Li-ion batteries eventually die. Even if you aren't using them, they'll begin to degrade as soon as they're made. You can recharge them, but only a limited amount of times. It's like trying to fill up a pitcher of water that has a tiny hole that grows bigger and bigger with each use.

We measure battery longevity in cycle lives, or the number of times that you can run it down, charge it up and use it again. With Li-ion batteries, starting from a 100 percent fully-recharged battery will give you a longer individual cycle life, but will reduce the total number of cycles you'll get from it. For that reason, the Tesla Roadster doesn't allow you to re-charge more than 95 percent of the original power or let it drain down to less than 2 percent [source: Eberhard and Straubel]. Also, the company projects the battery pack to last 100,000 miles, or five years. At that point, you would have to replace the battery.

As with the safety issue, researchers are looking for a longer-lasting Lithium alternative. And once again, nanotechnology seems to be leading the pack of potential solutions. One company, Altair Nanotechnologies announced in 2006 that it had found a new material that would far outlast Li-ion batteries and recharge faster for the same price, called lithium titanate [source: Bullis]. Canadian car company Phoenix Motorcars is using lithium titanate batteries in its line of electric cars that have a 100-plus mile range.

Toshiba has also come out with a fast-charging Li-ion battery initially for bicycles and construction vehicles that it eventually wants to test in cars [source: MSNBC]. In June 2008, Toyota also publicized plans to join forces with the company that produces its current hybrid batteries to develop Li-ion batteries by 2009 [source: Kim].

With so much energy going into Li-ion battery development, there's a strong possibility that they could be fueling our cars in the near future. For more information about tomorrow's cars and related information, visit the links on the next page.

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