Flexible batteries

One of the big reasons that mobile phones and other personal gadgetry are still simple cuboids, and not more interesting shapes, is that they need a lot of energy storage, and batteries are simple cuboids.

Yo Han Kwon and colleagues working for LG Chem in South Korea are working on something a bit moreflexible - Lithium ion batteries, like those in your phone or laptop, which look like a piece of cable.

Chemically the battery is conventional, but rather than using flat metal plates for the anode and cathode, the cathode is arranged around the outside and the anode is a hollow copper spiral coated with Niobium and Tin which runs down the middle.

The hollow spiral increases the surface area, which increases the capacity of the anode. It also makes the battery easy to fill with electrolyte, by injecting it down the middle, and makes it much more flexible.

The battery will still work when bent or even tied in a knot, and has powered LED displays and an mp3 player. They are still working on increasing the capacity which is about 100mAh per meter, but this technology could mean that you could use your headphone cable as a topup battery for your phone, make a flexible bracelet or belt which powers your devices, or even weave a battery into an item of clothing.