Components, Contaminants

By John G. Spooner  |  Posted 2006-08-24 Print this article Print

The committee will eye the battery cell designs as well as the purity of materials manufacturers use in internal cell components such as separators, electrolyte formulations, coating mechanisms used on cathode and anodes. It will also address ways of measuring contaminants inside the cells and those contaminants effects on cells as their dimensions change, he said.
Contaminants introduced into the Sony-manufactured battery cells were the root cause of the recalls by both Dell and Apple, Sony has confirmed.
Lithium-ion cells might look like a supermarket can of soup or New England-style brown bread on the outside. But inside they look sort of like a jelly roll. Two strips of coated metal foil are separated by an insulating layer and wound up in a coil. The coil is placed in a metal can, filled with an electrolyte solution, and sealed. "Cells can potentially fail if they get very hot due to external heating or excessive current flow, if they are overcharged, or if a short-circuit occurs between layers of the coil. "This last problem was what led to the recall: metal particles, contamination from the manufacturing process, are in very rare cases causing a short-circuit in the cell that leads to a fire," Forrest Norrod, Dells vice president of engineering, wrote in an Aug. 22 posting in Dells Direct2Dell blog. For Dell, "The root cause of the recent incidents was a metal particle of just the right—or maybe wrong—size in the wrong part of the cell," Norrod wrote in the post. "In rare cases, the contamination can cause a short-circuit which creates a lot of heat and breaks down cell materials, which in turn releases more heat and oxygen. You then have combustible materials in the cell plus oxygen and heat—all the ingredients needed for a fire. The whole process occurs quickly, and once it starts, the battery pack safeguards cant stop it. The key to safety is to have a clean manufacturing process and a cell design that prevents particles from getting into the critical area." Thus the committee will also focus on testing, including taking a look at ways to discover such events by accelerating or exacerbating problems, in an effort to learn more about prevention, Grosso said. But the committee, whose members also include Cisco, Lucent, IBM and Motorola, wasnt always as intently focused on batteries. Its first standard, the April 2006 IPC 9591, governs fans used in electronics equipment. When looking ahead at a meeting in February 2006, the 2-year-old committee—its part of the IPC, an industry body founded in 1957 that bills itself as connecting different electronics industries through manufacturing standards—targeted power conversion or power supplies, components design, and also batteries are areas it could address. "We had batteries third on the list," Grosso said. "We said, Batteries are important. Lets get them on the list. But we didnt put together another team" to address them, he said. "I think we all knew that there was an opportunity in batteries. But it just didnt raise the level of concern that it should of. Two months ago… I put out a call to our steering team partners and said, Look, weve got to accelerate this…when can we put our meeting together?" Given that he works in Dells procurement operation—Grosso oversees Dells purchasing of a wide range of components, including processors and chip sets—a separate operation from the PC makers Mobility Products Group, the executive said he was unaware of any plans for a recall of Dell battery packs. Next Page: Shifting focus.

John G. Spooner John G. Spooner, a senior writer for eWeek, chronicles the PC industry, in addition to covering semiconductors and, on occasion, automotive technology. Prior to joining eWeek in 2005, Mr. Spooner spent more than four years as a staff writer for CNET, where he covered computer hardware. He has also worked as a staff writer for ZDNET News.

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