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Bendable battery and LED make up the first functional all-flexible electronic system



August 10, 2012 – Comments (0)

Lots of potential applications for this! Check out the pictures in the link, very cool.


Bendable battery and LED make up the first functional all-flexible electronic system
August 10, 2012 by Lisa Zyga

( -- By connecting a new flexible, thin-film Li-ion battery to a flexible organic LED, a team of researchers from South Korea has demonstrated the first fully functional all-flexible electronic system. In other words, they have shown the total integration of a flexible display and battery on a single plastic substrate without the help of bulk electronics. The achievement relies on a new fabrication method that enables flexible batteries to work with a variety of electrode materials, overcoming previous electrode limitations.

The researchers, from the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon, South Korea, have published their study on the new bendable Li-ion battery in a recent issue of Nano Letters.

Although several other flexible Li-ion batteries have been developed already, none has achieved a sufficient performance in operation stability to be applied to commercial products, such as rollable displays and other flexible consumer electronics. The reason is that the electrodes for these batteries can only be made of a few materials due to fabrication difficulties, and these materials don’t have very good performance. As coauthor Keon Jae Lee of KAIST explains, one type of ideal cathode material would be a lithium transition metal oxide, although this is one of the materials that currently cannot be incorporated into bendable Li-ion batteries.

“Lithium transition metal oxides used as a cathode electrode have to be treated at high temperature (e.g., about 700 °C for lithium cobalt oxide) for the crystallinity,” Lee told “However, it is not possible to thermo-treat the active material on flexible substrates like polymer materials.”

Bendable battery and LED make up the first functional all-flexible electronic system The bendable Li-ion battery in the bent position turning on a blue LED. Image credit: Koo, et al. ©2012 American Chemical Society To overcome this limitation, the researchers developed a fabrication technique that allows them to thermo-treat the electrode material, enabling the use of almost any material as an electrode. This technique, called the universal transfer method, involves originally depositing the battery materials onto a brittle mica substrate, similar to that used in standard non-flexible battery fabrication. Then, using sticky tape, the researchers peeled the mica substrate away, layer by layer. After about 10 minutes of peeling, the researchers could remove the entire mica substrate without damaging the thin-film battery.
Next, the flexible battery is transferred onto a flexible polymer sheet and capped with another flexible polymer sheet. The result is a flexible Li-ion battery that can be made with almost any electrode material. Here, the researchers used lithium cobalt oxide as the cathode material, which is currently the most widely used cathode in non-flexible Li-ion batteries due to its high performance. For the anode, they used traditional lithium.

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