September 2006 Archives

A widening global recall of laptop computer batteries made by Sony Corp. have raised lots of questions about an energy source many computer users take for granted. The Wall Street Journal Online asked Donald Sadoway, a professor of materials chemistry at Massachusetts Institute of Technology, to explain how lithium-ion batteries work and why they sometimes explode in flames?

The Wall Street Journal Online: To start off, what is a lithium-ion battery, and how does it work?

Donald Sadoway: The lithium-ion battery is a rechargeable battery, that is to say you can put energy into it repeatedly and draw energy out of it repeatedly. It stores an electric charge. It consists, as all batteries do, of two electrode elements separated by a solution of ions.

Readers are probably familiar with the lead-acid battery that's under the hood of the car. As the name implies, it's got a lead plate that acts as an anode. It's got sulfuric acid as the electrolyte, which is the liquid ionic solution. And then the other electrode, which isn't in the name, is lead dioxide.

Now a lithium-ion battery is, to mimic that, instead of metallic lithium, you use a carbon host in which lithium resides. The electrolyte, instead of being an acid or an alkaline solution, [is an] organic liquid. The cathode is, as also in the case of the lead-acid battery, a metal oxide, [but] in this case it's a mixed oxide of lithium and cobalt.

Lithium wants to move from a high concentration to a low concentration, so when you try to draw current out of a battery, what's happening internally is that the lithium is leaving the carbon host in the anode. It gives up an electron, which then goes into your device, whether it's your cellphone or your laptop. The lithium ion, which is left behind when the lithium loses an electron, jumps into the electrolyte and starts swimming toward the cathode. At the cathode, lithium jumps into the cobalt oxide, where it starts to accumulate until the voltage gets low enough that we decide to call it quits and ask for a recharge.

In a recharge, you force current into the battery, and in doing so, you in essence pump lithium from the cobalt oxide across the electrolyte and re-insert it back into the carbon on the anode.

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Second Life Designers Make Real Money Creating Clothes for Simulation Game's Players

In the real world, fashionistas are recovering from the spring collections in New York and London and gearing up for shows in Milan and Paris.

But in the fast-growing virtual world of Second Life, many players are too enmeshed in the game's online fashion community to dissect what Vera Wang or Baby Phat sent down the catwalk in New York. Some players are buying up high fashion for their online graphic incarnations, known as avatars. Others, armed with Adobe Photoshop instead of a needle and thread, are creating their own clothing lines, pitching their designs to style editors, selling their creations, and -- in some cases -- even earning a living.

Second Life is a simulated world with more than 700,000 "residents," or players, who sometimes refer to their offline existence as their "first life." As in earlier computer simulation games like the Sims series, the point isn't to fulfill a quest, and there are no dragons or wizards to slay. Instead, San Francisco-based Linden Lab, the company behind Second Life, has provided a platform for players -- median age 32 and 57% male, with 40% living outside the U.S. -- to do whatever they want, whether it is building a business, tending bar or launching a space shuttle. Residents chat, shop, build homes, travel and hold down jobs, and they are encouraged to create items in Second Life that they can sell to others or use themselves.

When players buy items or services, real money is involved. That's because Second Life's in-game currency, Linden dollars, is based on real U.S. money ($1 U.S. buys about 280 Linden dollars). It's possible for users to play Second Life free of charge, but closely held Linden takes a cut of many in-world transactions (such as uploading a design to the game), and it charges players for "premium" accounts, which offer more flexibility in owning land and displaying merchandise.

Many virtual items are bought and sold in Second Life, but clothing has emerged as one of the hottest categories. Real clothing makers, including American Apparel Inc. and Adidas, sell items in Second Life that mimic apparel they sell in the real world. Thus, players can dress their avatars in some of the same clothes they wear themselves.

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A look at some clothing designed by Second Life players.

(Also appeared in the Northwest Florida Daily News and Pittsburgh Post-Gazette)