MIT Technology Review

Wednesday, January 16, 2013

Flexible Smartphone Batteries

A discovery from a Korean research team gets us closer.

The road to a bendable smartphone has proved, perhaps fittingly, long and winding. Most efforts so far have focused on making flexible displays (see “Towards Flexible Mobile Screens”), with interesting advances from the likes of Samsung. But even if you succeeded in making the screen of a smartphone flexible, you’d still have to tackle the phone’s innards, too, if you ultimately want to be able to roll up the thing like a sheet of paper. To tackle that problem, you’re going to need to have a flexible battery.

Some new research from a team of Korean researchers points to just that: a flexible battery. Their Advanced Materials paper has a cumbersome title: “Imprintable, Bendable, and Shape-Conformable Polymer Electrolytes for Versatile-Shaped Lithium-Ion Batteries.” But the world it points to is just the opposite of cumbersome: lithe, convenient, and ultraportable (see “Are Bendable Smart Phones the Future?”).

Traditional batteries use liquefied electrolytes in square cases, explains Korea’s JoongAng Daily. There’s a dual downside to these liquefied electrolytes; first, those hard casings prevent that quested-after flexibility, and second, there’s a risk of explosion, should heat melt the film that separates electrolytes.

You’d think that fluid electrolytes would have an advantage in the flexibility department. But in fact the trick is to make polymer electrolytes that are “fluid-like”–with both the flexibility of a fluid and the stability of a solid–which is just what the team has done. “Because the new battery uses flexible but solid materials, and not liquids, it can be expected to show a much higher level of stability than conventional rechargeable batteries,” explained one Korean official in the country’s Ministry of Education, Science and Technology.

There are further benefits of this “fluid-like” material. Manufacturing could be faster, since it’s apparently as simple as “spreading jam on bread” to apply these electrolytes to electrodes. Furthermore, the electrolytes are said to be “imprintable,” meaning “they can have various patterns printed on them, helping chemical reactions that raise the output of the batteries,” per JoongAng Daily.

I’m not going to lie: bendable batteries are exciting, but only because they enable the full capabilities of a bendable phone to begin with–and specifically the promise of the bendable screen. At CES last week, Samsung showed off a few prototypes that used flexible screen technology, and they look amazing. Check out around the 44:00 mark in the video below to see a flexible OLED from Samsung (brand name: Youm). With a bendable display, for instance, you can even have a screen wrap around the side of a device–displaying important messages along the side of a smartphone instead of its face (that neat trick is around the 45:00 mark).

Finally, according to Samsung, flexible displays can also apparently get you the phone number of a sexy person at your neighborhood café (that lesson comes around the 47:00 mark). Early adopters get all the perks.