The ability to manufacture flexible lithium-ion (Li-ion) batteries is not new, as evidenced by some of the commercial efforts over the last couple of years to bring this technology to market.
However, the quest to achieve flexibility for these Li-ion batteries has typically meant using materials that sacrifice performance to the degree that they have little hope of powering consumer gadgets, like a flexible display.
Keon Jae Lee, a professor in the Department of Materials Science and Engineering, Flexible and Nano-bio-energy Device Lab, at Korea Advanced Institute of Science and Technology (KAIST), and his colleagues have developed a new manufacturing technique that should allow for inorganic materials to be used that will produce better battery performance. (A demonstration video of the flexible Li-ion can be seen below.)
You may remember back in May that Lee developed a method for producing nanogenerators more cheaply and easily than ever before. It seems Lee has done the same with flexible Li-ion batteries.
The current research, which was published in the journal Nano Letters (“Bendable Inorganic Thin-Film Battery for Fully Flexible Electronic Systems”), demonstrated the use of high-density inorganic thin films employing a newly developed universal transfer approach. The process results in what the researchers describe as the “highest performance ever achieved for flexible LIBs [Li-ion batteries].”
The so-called “universal transfer approach” involves physical delamination of the battery’s mica substrate using sticky tapes. One of the key steps of the process comes right before the delamination when lithium cobalt oxide (LiCoO2) is exposed to high-temperature annealing to create the crystallinity of material that results in the high-performance solid-state LIB.
"We would like to emphasize that solid state thin-film battery has been developed for quite a long time and commercialized for various applications," says Lee in Nanowerk. "Our achievement is not the development of a thin-film battery but focused on the development of a flexible thin-film battery using a transfer protocol for the ultra-thin battery film itself – with less than 10µm thickness."
What is perhaps most intriguing about the manufacturing process is that it manages to create an “all-in-one” product in which both the LED display and energy source are produced all together in one flexible device.
Lee further notes in the Nanowerk article: "Our novel transfer approach can be expanded to various high-performance flexible applications, such as thin-film nanogenerators, thin-film transistors, and thermoelectric devices. As far as we know, this is the first prototype of a fully functional all-flexible electronic system.”
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.