The problems Dell is having stem from impurities within the anode and cathode of the battery, said Kay, who was briefed on the problems by Dell executives. Over time, those impurities, usually tiny pieces of metal, can work their way to the edge of the anode or cathode and rupture the isolator that sits between the two, he said. Once that happens, you get a short circuit and possibly a fire.
Lithium ion batteries have two to three times the energy density of nickel-cadmium and nickel-metal hydride batteries and four times the energy density of lead-acid batteries. Higher energy density translates to longer battery life. Lithium ion batteries are used in consumer electronics and notebooks, which only require a limited amount of energy. Hybrid cars and power tools, however, generally use more traditional batteries, in part because of the risk of explosion. Several companies, including Valence Technology and PowerGenix, are working on safer lithium ion batteries or batteries which rely on different chemicals.
Not only in laptop batteries, but in cell phones, lithium ion batteries can also overheat because of a short circuit. If the temperature rises slowly, the battery case may melt. If it rises rapidly, however, enough pressure may be generated to create a small explosion in a lithium ion battery. Consumers have suffered severe burns as a result of these failures. The chemical reaction that produces energy in a lithium ion battery is considered quite violent.
The analyst Sam said that the timing of this does buy dell goodwill with customer and potential customers. It's possible that other PC vendors are using the Sony batteries in their product. Dell executives said that the company was one of the first to begin using this type of battery, and that they think other problems will crop up down the road for other PC companies. But even if two companies use the same batteries, they don't necessarily design the technology that connects the battery to the notebook in the same way. For example, Lenovo's notebooks use software that's designed to shut down the battery if it notices a problem and they charge the batteries more slowly than others in the industry, a company representative said. A Dell representative was unable to comment on the specific technology it uses to enclose its batteries.