Friday, March 01, 2013

Breakthroughs Made in Flexible Battery Design

We all know how technology is constantly evolving and engineers/technicians are always looking to re-invent things - anything to make it more efficient, faster, smaller, easier to operate, etc. The latest redesign researchers from Northwestern University and the University of Illinois are working on is the battery. The breakthrough is that they are trying to find ways of making the battery more flexible - that's right, literally flexible in that you may soon be able to bend and flex batteries instead of them being rigid. These advances are going to be mainly geared toward the medical field, at least for now.

Of course, there are some difficulties with this due to the electrical circuits and replacing traditional materials like silicon wafers with more elastic materials. This is something that is currently being worked on by developers in Massachusetts, Cambridge-based MC10.

The other issue has been powering and charging these new flexible batteries. While traditional batteries must be charged via a wire/cable, researchers are looking into ways to make that flexible as well - but more in the sense of flexible capabilities, possibly doing away with the wire altogether. "Batteries are particularly challenging because, unlike electronics, it's difficult to scale down their dimensions without significantly reducing performance,"says John Rogers, a researcher at the University of Illinois at Urbana-Champaign. So, keeping these wires could certainly cause limitations for this new technology.

One way Rogers and his colleague at Northwestern, Yonggang Huang, have tried to get around this limitation is through the development of a new kind of lithium battery. One that has all the components  woven into a sort of mesh that holds together an array of wavy wires. The mesh is then bunched together in a larger wavy formation. With this type on configuration, not only are the wires connecting all the battery components together, but they are also providing the battery a great degree of flexibility. When the battery is stretched, the larger wave formation of the wires will straighten, followed by the internal wave pattern of the individual wires if the tension continues. "We call this ordered unraveling," Huang explains. "And this is how we can produce a battery that stretches up to 300 percent of its original size."

The pair refer to this as a 'space filling technique', since the battery does not place components on a stretchable substrate, but instead packs in an flexible material as a key component of the battery. Because the design can include an inductive coil, these types of batteries can be recharged wirelessly - providing endless possibilities for medical applications.

The engineering research is being published in the journal Nature Communications, but Rogers and Huang have already demonstrated how flexible this type of battery can be by using it to light up an LED while simultaneously folding and stretching it well beyond its normal shape.