Graduate Student Profile: Ayan Ghosh
The Flexible Future of Batteries

• Hometown: Hyderabad, India
• B.S.: Chemical Engineering, N.I.T. Trichy (National Institute of Technology), India
• Advisor: Professor Peter Kofinas (Fischell Department of Bioengineering)
• Year Started Program: Fall 2004

Have you ever had a battery burst or leak, ruining an electronic device? If ChBE graduate student Ayan Ghosh's research is successful, not only will that kind of damage be a thing of the past, but it could also pave the way for new kinds of batteries that could radically change the size, shape, and weight of all kinds of battery-powered devices.

Typical batteries contain an anode (the negative portion) and a cathode (the positive portion). These are separated by an electrolyte, an ionically-conductive medium—often a liquid or gel— used to move ions and carry the current inside of the battery. The highly reactive nature of the electrolyte requires it to be sealed in a bulky casing to guard it from exposure to air and moisture.

Ghosh, who works at the Functional Macromolecular Laboratory with advisor Professor Peter Kofinas (Fischell Department of Bioengineering), is focusing on replacing the more dangerous liquid and gel electrolytes we use in lithium batteries today with a solid, flexible polymer membrane. The polymer, he says, is safer for consumers and the environment. When it is compromised by air or moisture, it doesn't generate corrosive byproducts or explode—it simply crumbles. Since only a layer of lamination is needed to seal out moisture and air, it makes it possible to design light, flexible, thin film rechargeable batteries.

Ghosh's polymer films are only a fraction of a millimeter thick, but, he says, with techniques that are widely used in industry it is possible to make them even thinner. Unlike liquids or gels, the polymers can be assembled into batteries at the sub-micron scale, using manufacturing techniques similar to those used to create computer chips. These new batteries could be used in sensors and other devices that are light enough to be dispersed through the air or safe enough to be implanted in the body.

Batteries have been a roadblock for scientists in the development of miniaturized technology. An example Ghosh likes to cite is the wireless endoscope, a medical device containing a tiny light and camera used for diagnostic purposes inside our bodies. "A significant portion of the volume and weight of that endoscope is the battery," he says. But batteries that use a polymer like his could be the breakthrough everyone is hoping for. "Suddenly your device is no longer constrained by the size and shape of your battery," he explains. "Instead we can make a film or a flexible substrate that could be both the battery and the base for the electronic circuits. The device coating itself could be the power source!"

Ayan Ghosh working with the glove box.

The potential is amazing, but so are the challenges. Creating batteries out of material that cannot be exposed to air or moisture is one of them. Ghosh must work with a glove box filled with argon gas. Materials are put into an airlock, rigorously vacuumed for prolonged periods, and then moved into the argon-filled main chamber. "The setup needs to be regularly maintained," he says. "I cast all of my films and prepare my test cells inside it. The samples are sealed, so that when I take them out there's no chance of oxygen or moisture permeating through. If I don't prepare my sample properly, it's going to go bad."

More crucial, and at the center of Ghosh's research, is engineering the polymer to be an effective enough conductor for batteries to be able power our devices. A polymer by nature is an insulator. Designing one to behave like a conductor has been the major hurdle this area of energy research has faced for 30 years. After an extensive review of prior research, Ghosh decided to design a new electrolyte by using block copolymers: two polymers, covalently linked, selected to enhance the characteristics that improve conductivity while suppressing those that don't.

Ghosh's work has gotten him noticed: In 2006, he and Professor Kofinas were featured in the energy-themed issue of the Clark School's E@M magazine, and in 2007 he was awarded the Harry K. Wells Endowed Fellowship, which supports graduate students working on energy engineering and alternative energy sources.

While the work is progressing, it will be some time before we'll see the batteries he envisions in stores. Ghosh's research on polymer electrolytes is only one part of the development process—other researchers are working on the design and construction of other battery components . When the new batteries do appear, he predicts, they will initially be very expensive, and will likely be used for medical and military applications before coming down in price and reaching consumers.

The road to and through graduate school has been one of exploration for Ghosh, in which he's tried to survey the many research and career options a degree in chemical engineering has to offer. "My [undergraduate] research [at IISc Bangalore, India] was with bacteria and bioremediation," he explains. " But the professors' message was, 'With research getting extremely interdisciplinary, don't constrain yourself to one field right now. '"

He recommends that students considering a graduate degree in ChBE keep an open mind about their path and take the time to gage their level of commitment. "It is very, very important that you pick something which has your absolute fascination, because you need that to drive you forward, no matter where the results go. It's not always going to be in your favor."

Ghosh likes the Clark School's graduate program in ChBE for its flexible environment in which new students can explore their options. Like many people he wasn't completely sure about what he wanted to focus his research and career on before coming here. "One thing about this department that I really can't emphasize enough," he tells us, "is that you get this amazing amount of freedom in your first semester that makes a big difference. You go around and meet the faculty, find out what projects they have, talk with the people in their labs, and see what kind of work environment they have."

Ghosh cites his advisor and lab group as the best things about his graduate experience so far. "I think I've been extremely lucky to have an excellent advisor and an excellent group. It was definitely not what I had expected. I thought it would be a very serious environment, just work-work-work. But we're very good friends. We know when to work hard and when to play hard."

When he needs to take time out, the location of the College Park campus gives him a variety of social opportunities in Maryland, Virginia, and Washington, D.C. One good way to get to know the area, he says, is to become involved with ChEBES, the Chemical Engineering and Bioengineering Society for graduate students, which hosts several expeditions, such as canoeing and skiing, throughout the school year. It is also an excellent way to interact with other students going through their various stages of graduate life.

After completing his doctorate, Ghosh would like to put his knowledge to use in the industry, working for a company focusing on energy research and innovation. "I want to see how I can apply my research and make it more commercially viable," he says. "In the end, I want to see a product I can reach the masses with."