Wearable Tech World Feature Article
March 18, 2013

UCLA Researchers Deliver Truly Bendable Super Lightweight Batteries

Many of us are by now familiar with the idea of bendable smartphone displays. Samsung and Nokia are both on the leading edge of developing such displays, and in their own right, they are certainly at the cutting edge. One thing you always notice about them in current demonstrations, however, is that they are always tethered to a cable that delivers the actual video or image streams being displayed. That is, you never actually see those bendable displays in anything resembling an actual bendable smartphone. Why?

For one thing, bendable circuit boards and chips are not quite there yet in being able to "roll" with the display, so to speak. Another issue is the battery that powers the entire thing. Batteries - even today - need to be relatively large in order to supply enough power to drive a smartphone all day, and much of that power goes directly into lighting up the display itself. LCD, super AMOLED or OLED – it doesn't matter…displays require a lot of power. The other end of the story here is that those lithium-ion batteries don't bend; they're stiff as a board and will stay that way.

But thanks to several UCLA researchers and various advances elsewhere, the bendable battery conundrum is about to change, and it's about to change in a major way. Now, Richard Kaner, a professor of materials science and engineering at UCLA's Henry Samueli School of Engineering and Applied Science and a member of the California NanoSystems Institute (CNSI) at UCLA, along with his graduate student Maher El-Kady, have hit on a way to mass produce a true bendable and extraordinarily lightweight battery technology using a substance called graphene.

 The implications for mobile devices and wearable technology are suitably profound.

CNSI itself was established in 2000 with $100 million from the state of California and is located at UCLA and UC Santa Barbara. Its mission is to foster interdisciplinary collaborations in nanoscience and nanotechnology, to train a new generation of scientists, educators and technology leaders and to generate partnerships with industry that will take experimental results and turn them into real, practical and applied products.

Various CNSI teams are engaged ongoing in measuring, modifying and manipulating atoms and molecules, with the goal of uncovering an enhanced understanding of nanoscale phenomena and discoveries leading to applied products to be used in health, energy, the environment and information technology. Total research funding for CNSI projects has now topped over $900 million.

Graphene Micro-Supercapacitors

Before we get into the "how it's done," we need to talk a bit about the “what.” What "it" is refers to a micro-scale graphene-based supercapicitor. Capacitors of course have been around since the dawn of electrical technology - they gather and store up an electrical charge and then pass that charge on to whatever electronics require it. The graphene -based micro-capacitor is amazingly thin, bendable and able to both charge and discharge at a far more accelerated rate, ranging from 100 to 1,000 times faster than current battery technology is able to achieve.

Graphene itself is an amazing thing – a one atom thick layer of graphitic carbon. A sheet of graphene might be 120 micros tall and wide, but it's literally only one atom thick. To date, the theory and the technology to use graphene as a micro-capacitor (micro-supercapicitor is probably more accurate) have both been proven. What has been missing is a way to reliably and cost-effectively produce an actual graphene-based micro super-capacitors and batteries that can be put to real world uses.

This is exactly what Professor Kaner and El-Kady have done. It is a major and trailblazing achievement, but what's even more amazing is the technique and equipment they've uncovered to do so - it isn't expensive and the production equipment has been around for several years. There is nothing even remotely mysterious about it; in fact, many consumers know the technology quite well, and many of us even own it.

The current means for fabricating thee micro-supercapacitors relies on lithographic techniques not much different than what Intel uses inside of its multi-billion dollar chip manufacturing facilities to create its microprocessors and other chips. Such super-high cost requirements do not lend themselves to building cost-effective batteries, which in turn kills any ability to easily monetize the technology and apply it to real-world problems.

The new cost-effective fabrication methodology uncovered by Kaner and El-Kady was described by them in a study recently published in Nature Communications. What Kaner and El-Kady have unveiled is that they've created these micro-supercapacitors using nothing more than a typical consumer-grade LightScribe DVD burner. 

It is technology that allows a user to write or create images directly on a LightScribe DVD (hence "scribe") that was originally invented at Hewlett-Packard, and which in turn was included by HP on many PCs they have sold since 2011. HP itself no longer ships LightScribe drives, though Samsung and LG, among several others, still do. We ourselves own and have used a LightScribe DVD burner.

From Graphene to Bendable Real World Batteries

Using the LightScribe burner, Kaner and El-Kady have shown that they can easily produce graphene micro-supercapacitors over large areas at a tiny fraction of the cost of the lithographic processes we noted earlier. Using this technique it has been possible to produce more than 100 micro-supercapacitors on a single disc in less than 30 minutes, using inexpensive materials and devices. The image below, courtesy of UCLA, shows what is actually produced.

LightScribe discs are coated with a reactive dye that changes color on exposure to the laser light from a LightScribe burner. El-Kady's and Kaner's technique requires a layer of plastic to be glued onto the surface of a DVD and then coating the plastic with a film of graphite oxide that can then also be precisely and directly printed on. The LightScribe burner, though a consumer product, brings an enormously high level of precision to the game at an enormously inexpensive price point, and this is key to the new process.

The two were led to this technique by way of an earlier discovery, when they found out that when graphite oxide is exposed to ad absorbs laser light it is converted into graphene. Prior to the out of the box thinking in using the LightScribe burner, what was lacking following the discovery of the conversion from graphite oxide to graphene was the lack of precision necessary to create the very intricate circuit patterns that define the actual resulting graphene circuits. The LightScribe burner handles the needed precise rendering of the patterns with ease.

There is more to the technology (especially in how the circuit patterns themselves need to be designed) than we are able to cover here. Suffice it to say that another aspect of their research allowed Kaner and El-Kady to develop patterns that deliver graphene-based supercapacitors having both a greater charge capacity and rate capability than was previously possible using older techniques. Again, it is the precision of the LightScribe laser that makes it all possible.

The micro-supercapacitors deliver excellent cycling and rate stability, which is important for such as applications as biomedical implants, active RFID tags and embedded micro-sensors. These are all applications where replacement of the battery is not possible - having a higher charge and great stability is critical.

As the image above shows, the micro-supercapacitors are also quite bendable, and though this bendability will improve over time, it is already enough to begin thinking about such applications as bendable mobile device displays, e-paper applications, and of course, for wearable electronics.

The micro-supercapacitors can also be fabricated directly on chips using the same LightScribe technique. Think as well of such things as fabricating them directly onto solar cells – whether in large installations such as rooftop solar panels, or in small installations such as a solar-powered mobile device. The electrical characteristics of the micro-supercapacitors on this scale become quite substantial. In fact, they may be the near future of the electric car holy grail – super lightweight, non-lethal, chemical-based batteries that don't require much to charge them. Here's another thing to consider – ultimately, they are made out of carbon, which means they are bio-degradable!

Kaner notes that the research has reached the stage where he and El-Kady are now looking for industry partners to help move the graphene micro-supercapacitors to mass production. The sooner the better.

The full Nature Communications study is available for a nominal sum. The following video provides some very useful elaborations on what we've discussed above.

Edited by Allison Boccamazzo

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