HOT ITEMS: Cases of overheating, even fire, have recently been reported for popular personal electronics that harbor lithium ion batteries.
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Bigger does not always mean better in the world of electronics—unless, of course, we're talking about the width of a flat-screen plasma TV. The latest generation of the iPod shuffle, for example, is just a fraction of the size of the original 2004 iPod mini, yet holds just as many songs. Part of this reduction in size and increase in power for personal electronics is due to improvements in the way that batteries—specifically those that rely on lithium ions—hold and release energy.

But are there drawbacks to this kind of technological miniaturization? Recent reports that some models of the most popular MP3 player can literally burst into flames may suggest so.

An investigative reporter from KIRO-TV in Seattle recently got hold of 800 pages of documents from the U.S. Consumer Product Safety Commission (CPSC), which included descriptions of "15 burn and fire-related incidences blamed by iPod owners on their iPods," according to KIRO. There were cases of damaged homes, an injured child, even an iPod catching fire on a 2,000-passenger cruise ship. Fortunately, none of the reports noted any serious injuries.

Flaming iPods have also lit headlines overseas. The Local (which covers Swedish news in English) reported last month that a car fire was allegedly started by an iPod Nano. The heat-damaged music player was recovered, in this incident, from the front seat of the parked Saab, the newspaper noted. The very next day Apple recalled all first-generation iPod Nanos in South Korea, according to The Korea Herald, which also noted iPod Nano batteries overheating or exploding.

Overheating is not limited to iPods. Laptop computers and cell phones have had their share of problems: Sony recalled more than 400,000 Vaio laptops last September for this reason, and potential iPhone recalls in response to overheating have also been circulating in the past few months.

So, how concerned should consumers be? What can be done to mitigate risks—or are these incidents simply too rare to worry about? And given the possible fire hazard from small lithium ion batteries, should we reconsider using large, heavy-duty versions of them in upcoming fleets of electric cars?

We recently sought answers from Zonghai Chen, an electrochemical engineer at the Argonne National Laboratory in Illinois.

[An edited transcript of the interview follows.]


Why has the lithium ion become the battery of choice for personal electronics?
The lithium ion battery is currently the dominant power source for most consumer electronics due to its high energy density. In other words, in order to store the same amount of energy for electronics, the lithium ion battery is the smallest and lightest compared to other battery types.

And it's getting even more compact. The design of modern electronics has sought more energy while leaving the room for the battery unchanged, or even smaller. In order to meet this demand, battery manufacturers have had to design the battery to load materials in the same size cell. Currently, the same size lithium ion cell stores almost triple the power of its original design.