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SEPTEMBER 11, 2006
The Truth About Fiery Laptops Lithium ion batteries are potential incendiaries, but they're all we've got
The lithium ion batteries that came into widespread use in the late 1990s enabled a revolution in portable electronics by allowing a lot of power to be packed into a very small space. But if you overcharge them, or there is an electrical fault such as a short circuit, they can generate an unfortunate combination of oxygen, fuel, and heat inside the cells -- in other words, an explosive fire waiting to happen. Lithium ion batteries and their cousins, the lithium polymer batteries used mainly in phones and other handhelds, rely on protective electronics to prevent chemical mayhem. Of the millions of batteries Sony (SNE ) made for Dell and Apple, these circuits appear to have failed in several dozen, sparking fires that can be contained but not extinguished until the oxygen and fuel are spent. Physical damage to the battery can cause the same results. Laptops are far more prone to catch fire than other products because their batteries are much larger and operate in a much hotter environment, heat being an important contributing factor. DESPITE THE INHERENT RISKS, lithium ion batteries aren't going away any time soon because there are no good alternatives. But the dangers are having consequences, beyond the financial damage to the companies involved in the recalls. One is that we have hit the wall in increasing the efficiency of batteries -- at least as measured in watts per kilogram or watts per liter -- because without some major chemical breakthrough, higher power densities would cause unacceptable hazards. Making batteries larger is also not an option. The International Air Transport Assn. will not allow batteries containing more than 8 grams of lithium aboard passenger aircraft. The largest laptop batteries used today have hit that limit. An Austin (Tex.) company called Valence Technology (VLNC ) does make a lithium battery with different chemistry that is safer because its reactions don't produce fire-sustaining oxygen. The downside is that these batteries provide less power for a given size and weight. They are being used as battery backups for cell towers and could well appear in the next generation of hybrid cars, which are currently powered by safe but less efficient nickel metal hydride batteries. With no breakthroughs in battery technology on the horizon, researchers at companies such as Toshiba (TOSBF ) and Matsushita (MC ) are pursuing methanol fuel cells as an alternative. But so far, nobody has been able to develop cells that can meet the power needs of laptops, fit in the space now occupied by a battery, and be cheap enough to be competitive. Even if such cells existed, we would need a distribution system to make cartridges of the liquid fuel available everywhere. And while the International Civil Aviation Organization has approved their use aboard commercial aircraft, the methanol cartridges are unlikely to pass muster with the U.S. Transportation Security Administration. So we are stuck with lithium ion batteries for the foreseeable future, but there are a few things you can do to make them safer. One is to treat the batteries gently and protect them from overheating. Fires are much more likely while the battery is charging. If you run a laptop on in-seat power on an airplane or train, do everyone a favor and remove the battery during your journey. Fires have been rare enough that batteries, other than the defective ones being recalled, do not pose an unreasonable risk. But they are dangerous enough that the industry should step up its efforts to find a safer alternative. For past columns and online-only reviews, go to Technology & You at businessweek.com/go/techmaven/  By Stephen H. Wildstrom
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