iPad: Pushing the Limits of Materials
In addition to the famed design sense and technological know-how that make the iPad possible, Apple also must call in some key material innovations to fit all that fun into such a small package.
In this week's issue of C&EN, I talk to the companies that make materials for today's hot mobile devices and their sleek touch screens. Like Corning's Gorilla Glass. And I show how surface chemistry's contributions to making better consumer goods is spreading to other categories including sneakers, make-up, house paint, and new LED light bulbs.
The new iPad, with its 4G internet speeds and energy hogging retina display, is also pushing the limits on battery materials. It is a bit thicker and heavier than the first version, mainly due to needing a larger battery. In a guest post on a Forbes Tech blog aimed at executives, Noam Kedem, VP of marketing for Leyden Energy, says that the new iPad's need for more power also makes it run hotter, and also is the reason it takes longer to recharge the battery. Heat, and irreversible chemical changes over a battery's lifespan, are major materials problems for lithium ion batteries, he writes.
Leyden Energy is a Calif.-based firm has developed a new electrolyte chemistry for batteries that the company claims will help to fix the heat/degradation process. Almost all consumer rechargeable li-ion batteries use LiPF6 as their electrolyte; Leyden is working with a chemistry based on lithium imide. According to the firm, lithium imide makes batteries much less temperature sensitive.
I hope that Apple's engineers have seen this week's lead news story by my colleague Mitch Jacoby on research that tantalizingly suggests new chemistry for "low-cost batteries with greater capacity and longevity than today’s commercial Li-ion batteries." In this case, it is not the electrolyte but rather the anode that has been improved. In research published in the ACS Journal NanoLetters, Pacific Northwest National Laboratory scientists were able to make anodes of silicon-carbon nanocomposite. Li-ion battery anodes are normally made of carbon.
Past efforts to make silicon anodes ran into problems; during charging, they swell to three times their size. In addition to making a more stable version, the PNNL folks found the resulting battery "exhibited a charge capacity more than five times as great as that of conventional carbon anodes." Wooo! That's a lot more YouTube on the ol' iPad. The story comes complete with descriptive photos and a video of the anode undergoing the charging process.
[3/27/2012 - updated to reflect that Leyden "has developed" and add corrected "imide"]