A progression toward hybrid and electric cars seems like a natural step in the evolution of automobile technology. Analysts aren't predicting a drop in oil and gasoline prices anytime soon, effectively shifting car manufacturers into high gear to find the next best way to power vehicles. If the recent concept cars revealed by major automakers are accurate predictors, Lithium-ion batteries (Li-ion) may be that magic bullet.
Take, for instance, the Chevrolet Volt. This is General Motors' plug-in hybrid concept car designed to run for 40-mile (64.3-kilometer) stretches entirely off of Li-ion batteries. After that, a small gas engine will take over for another 600 miles (965 kilometers). That means many people could complete their daily commute without burning a drop of gas. In addition, the company plans to start cranking them out en masse by 2010.
And Chevrolet isn't alone in the Li-ion trend. Jeep, Cadillac, Dodge, Land Rover, Chrysler and Saturn all previewed 2008 concept cars that feature Li-ion battery packs for greener driving [source: Mahoney].
Why this fawning over Li-ion batteries in the first place? The Toyota Prius and two new hybrids the company unveiled in June 2008 use a nickel-metal-hydride battery. According to the most recent EPA standards, the Prius gets a combined 46 miles per gallon -- not to mention that it has sold like hotcakes. [source: fueleconomy.gov].
But in energy terms, Li-ion batteries simply pack a more powerful punch. Li-ion batteries store more energy in smaller spaces than the more traditional lead-acid and nickel-metal-hydride ones. Lithium has the most energy density and electrochemical potential of all metals, which is what gives it that stamina [source: Buchmann]. The nickel-metal-hydride batteries in hybrids on the road are also heavy, limiting their potential, whereas Li-ion batteries can amp the speed without weighing the car down. Because of this property, you can find smaller versions of them in many consumer electronics products, such as laptops, cell phones and iPods.
But there are a few bumps in the road for Li-ion batteries to become tomorrow's gasoline, namely safety, costs and longevity. We'll check out the safety issues on the next page.
Lithium-ion Battery Safety Concerns
Remember when laptops were bursting into flame in 2006? It was the lithium-ion battery.
Random explosions from overheating weren't a widespread problem, but nevertheless, lithium-ion battery manufacturer Sony, which came out with the first commercialized Li-ion battery in 1991, had to recall more than 6 million computers because of it [source: Lamb].
In the couple of years since then, the Li-ion battery hasn't completely recovered its reputation for safety. Now you can see why putting it inside of a car makes some people a little antsy.
Why is there a chance for explosion? Li-ion batteries work by separating its positive and negative sides by a thin layer, called an electrolyte. The electrolyte is perforated to allow the lithium ions to pass through from one side of the chamber to the other, thus generating a current. Tiny bits of metal that result from the manufacturing process can potentially get stuck in those perforations, preventing the ions from freely flowing. Pressure and heat can then build up, causing an explosion. Also, allowing the ions to move too quickly can lead to overheating as well.
So how does the all-electric Tesla Roadster manage to pack 6,831 Li-ion batteries under its hood without risking a major blow-up? The Tesla's energy storage system that propels the car is equipped with a cooling system, which ensures the batteries don't overheat. It also regulates the speed of the flow of ions to keep them from re-charging or draining too quickly.
Since car companies and scientists realize the broad potential of Li-ion batteries, they have poured time and money into finding ways to reduce any safety hazards. For instance, nanotechnology, the study of atoms and nanostructures, may be able to prevent those dangerous explosions. New nanomaterials, such as nanophosphate, aren't prone to shorting out like graphite, the traditional Li-ion electrolyte [source: Peter].
And speaking of time and money, before Li-ion batteries make their grand entrance into the consumer automotive world, they need to be cheaper and longer-lasting. Learn why and how on the next page.
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.
More Great Links
- Buchmann, Isidor. "Is lithium-ion the ideal battery?" Battery University. Updated November 2006. (June 26, 2008)
- Bullis, Kevin. "The Lithium-Ion Car." Technology Review. MIT. March 24, 2006. (June 26, 2008) http://www.technologyreview.com/Biztech/16624/page1/
- Cotta, Rick. "Hybrid Batteries: None the Worse for Wear?" Consumer Guide Auto. (July 1, 2008) https://consumerguideauto.howstuffworks.com/hybrid-batteries-none-the-worse-for-wear-cga.htm
- Eberhard, Martin and Straubel, JB. "A Bit About Batteries." Tesla Motors. Nov. 30. 2006. (June 26, 2008) http://www.teslamotors.com/blog2/?p=39
- Hall, Kevin G. "High Oil Prices Fuel Development of New Hybrid Batteries." McClatchy Newspapers. June 8, 2008. (June 26, 2008) http://www.mcclatchydc.com/226/story/39869.html
- Kim, Chang-Ran. "Toyota to start lithium-ion battery output in 2009." June 11, 2008. (June 26, 2008) http://www.boston.com/news/world/asia/articles/2008/ 06/11/toyota_to_start_lithium_ion_battery_output_in_2009/
- Lamb, Gregory M. "Search for a Better Battery Keeps Going and Going." Christian Science Monitor. Sept. 18, 2006. (June 26, 2008) http://www.csmonitor.com/2006/0918/p13s01-stct.html
- LaReau, Jamie. "GM's Lutz talks lithium ion batteries, cars and Toyota." Automotive News. Nov. 19, 2007.
- Mahoney, Patrick G. "Concept cars of a different color…Green." Machine Design. April 10, 2008. (June 26, 2008)
- MSNBC Staff. "Breakthrough battery for electric cars?" MSNBC. Dec. 13, 2007. (June 26, 2008) http://www.msnbc.msn.com/id/22240865/
- Peter, Tom A. "Battery Tech Starts Catching up to High Tech." Christian Science Monitor. March 15, 2007. (June 26, 2008) http://www.csmonitor.com/2007/0315/p14s01-stct.html
- Popely, Rick. "Battery-powered car race is on: Despite current cost and safety concerns, automakers see plug-ins and hybrids as remedy to future $5-a-gallon gasoline." McClatchy -- Tribune Business News. June 18, 2008. (June 26, 2008) http://www.chicagotribune.com/business/chi-wed-car-batteries_06-17jun18,0,4936123.story