About Dr. Simmons …

Trevor Simmons just graduated with a PhD in Chemistry from Rensselaer Polytechnic Institute in Troy, NY. He defended his thesis in November and is currently looking for a post-doctoral research position.

His thesis work focused on carbon nanotubes. One of his cutting-edge projects was working on bringing "paper batteries" to fruition. Current lithium batteries are less than ideal; they're heavy, flammable, and environmentally unfriendly. Simmons' PhD advisor, Professor Pulickel Ajayan, has been working to develop a capacitor that is basically cellulose-infused carbon nanotubes grown on silicon and sandwiched between thin films of lithium and aluminum. The entire capacitor ends up being only 72 microns thick -- far lighter and smaller than conventional batteries. For more about the battery, read Paper Holds the Power, Beyond Batteries: Storing Power in a Sheet of Paper, and see below.

Another of Simmons' projects is using carbon nanotubes to make a flexible, single wall nanotube antiseptic bandage. See the abstract and diagram from a talk Simmons submitted to the Electrochemical Society's Pacific Rim Meeting on Electrochemical and Solid-State Science in Hawaii this fall.

Simmons talked about what it means to be "green" in chemistry in Cogito Snapshots: Research & the Earth this summer. See what he had to say.

His science = art too. One of his photographs of nanotube bundles won him 1st prize in the Science as Art Competition at the 2008 MRS International Materials Research Conference in Chongqing, China.

Carbon Lightning: Single wall carbon nanotube bundles can be seen aligning across a crack in a polymer-surfactant matrix. Photo courtesy of the Materials Research Society.

More about paper batteries....

Below is a diagram showing traditional versus paper batteries from Nanomaterials: Paper powers battery breakthrough, a Nature Nanotechnology news article about an important 2007 paper by Professor Ajayan (who recently moved from RPI to Rice University).

Legend: a, A conventional lithium-ion battery contains a graphite anode (grey hexagons), a lithium cathode (lithium cobalt oxide in this case; brown circles), and a liquid electrolyte containing lithium ions (green) in a fibre separator (orange). The removal of lithium ions by the simultaneous oxidation of cobalt in the cathode and insertion of lithium ions into the graphite anode charges the battery. Electricity is produced when ions move in the opposite direction and the cobalt is reduced.
b, A lithium-ion battery made from nanocomposite paper is more compact and weighs less than a conventional lithium-ion battery. The paper, which is made by infiltrating cellulose into carbon nanotubes grown on a silicon substrate, is impregnated with the electrolyte, thus combining the cathode (the nanotubes) and the separator (the cellulose) in a single unit. Depositing a thin film of lithium on one side of the paper and adding aluminum current collectors completes the battery configuration. Electricity is produced when lithium is oxidized to form lithium ions, which are inserted into the nanotube cathode. Charging occurs when the ions move in the opposite direction and are deposited as lithium metal. (Reprinted by permission from Macmillan Publishers Ltd: Nature Nanotechnology (2:598-9), copyright 2007.)

Forum Intro: Hi everyone! Amy here, Cogito chem beat writer. I met Trevor this spring at the American Chemical Society meeting in New Orleans. He impressed me with his clear yet deep explanation of his project, and with his consideration of green-ness in his research, and so I invited him to come to Cogito for a special event. The reason I was sitting at his particular talk, though, was because just a week or two before the meeting, Willow had started a thread about paper batteries after seeing news coverage of a cool paper from his lab. So I made sure to put Trevor's talk on my don't-miss list, and now here he is to talk about his research not just on paper batteries but nano bandages too.

Find out more about Trevor here on his Cogito interview page, and in his Cogito Snapshots: Research the Earth article. Briefly, he just finished his PhD in Chemistry at Rensselaer Polytechnic Institute in NY, and is looking for either an academic postdoc research position or a research job with a small start-up company.
Welcome to the forums Trevor!

Dr. Trevor Simmons: Hey everyone. I just wanted to pass through and say hello, and let you know I am waiting to hear from you guys about your questions. I am working in my lab now, trying to get some papers published and finish some experiments related to my PhD work. Feel free to ask me anything you want to know, from how my projects work, to what it is like to have my job, I will answer all of you personally. Peace.

.:: Q & A with Dr. Trevor Simmons ::.

What exactly are nanotubes?

Carbon nanotubes are basically cylinders of graphite, which is the black part of a pencil. Graphite is made of many layers of pure carbon and the carbon atoms are bonded together in sheets. These sheets have a hexagonal pattern which looks like a honeycomb in a bee's nest. The sheets of carbon are the same thing that make carbon nanotubes: the only difference is that the nanotubes have these sheets rolled into tubes. These structures have amazing properties: they are stronger than steel, very flexible, and cannot be easily broken down or burned, and they are also electrically conductive. These properties make them great choices for high strength applications like airplanes and the space shuttle, where we need lightweight and very strong materials. Many electronic devices like cellphones, mp3 players, and laptops, all require very small and lightweight electronics, and carbon nanotubes are being used experimentally to improve those technologies. Carbon nanotubes are one of my biggest interests, and they have too many properties and uses to all be listed here, but I suggest you read more about them and other nano-structures such as nanoparticles, they are really amazing

What's the advantage of paper batteries?

The power levels of the paper batteries and supercapacitors are similar to those which are commercially available. so we are able to reach similar values to other technologies, but with advantages like greater flexibility and being lightweight. Our paper battery design is more environmentally friendly, and the process we use is likely to both save money and reduce the environmental impacts of our work at the same time, which is very important to me. Thanks for the post, and look to the reply below to learn more about the nano-bandages.

What are the advantages of nanobandages compared to normal bandages?

What makes the nano-bandages superior to normal bandages? Normal bandages have fibers about 1,000 time larger than nano-bandage fibers, which means that the surface of a normal bandage is much rougher than the surface of a nano-bandage. When your skin is healing a wound, you want it to be very smooth so that there will not be a big scar, and the nano-bandage is superior for this. Also, the electrical conductivity of the carbon nanotubes allows the nano-bandage to stimulate nerve cells and muscles to reconnect faster and this means people with bad burns can regain feeling and use of their muscles after their wound heals. Finally, our nano-bandage has a germ-killing antiseptic attached to the surface, and normal bandages need to have antiseptic applied to them, which is inefficient and less effective.

I hope the paper I have written on these nano-bandages will be published soon so that I can keep this project going. I think these bandages can really help people who need it the most.

What did you study while pursuing your undergraduate degree?

I have studied chemistry since high school, but I always have loved science. I tried physics for a while in high school, with a focus on theoretical physics and astrophysics (stars and galaxies). But when I got to college I realized that my math skills were not good enough for a career in physics, and so I tried my hand at chemistry. I found that my mind worked better with chemical formulas: I see things as pictures more than numbers. I learned that even if you cannot do one thing well (which in my case was math) there can be many other ways to find success.

I am interested in how you chose this topic for your research. Did the paper battery and nano bandage idea suddenly come to you one day? Or was it that you started out with a basic idea, researched, and expanded upon it? Or was it a slow process of the knowledge you had, the courses you were taking, the people around you that the idea came up? What major(s) or prior experience really helped shape your career?

The ideas for my research come from a variety of different sources. The idea of the paper batteries and supercapacitors was based on ideas and work started by other researchers in my group. When those researchers left the group to work for companies or become professors, the project was handed to me. I have been able to improve the designs and direct the project in new areas. So this project has evolved and now when I leave the group to find a new position someone else will be given the chance to direct this process of invention and innovation.

I also come up with ideas just by thinking them up. For instance, one day I was looking up some details on a polymer called polyvinylpyrrolidone, or PVP for short. This is a polymer I have used a lot for making inks of carbon nanotubes, and I was showing an undergraduate who works with me some of the properties of this polymer. We were looking at a Wikipedia article and saw that PVP can form a complex with iodine. I immediately thought that this could be useful to us. After about ten minutes of brainstorming with Daniel Hashim my undergraduate research partner, we had decided to try to make an antiseptic bandage with this polymer-iodine complex and carbon nanotubes. There was no guarentee of sucess when we set out to make this material, but we were lucky and had a good result. Researchers cannot just try every idea they have, but if there is some scientific evidence to support the idea, and the researchers are motivated to try it idea, it can be tested in some preliminary experiments. In this way researchers can test the idea in a small set of experiments, then in some larger experiments, and then finally do a full study and publish the work.

Some of the best ideas come to people in a flash, a quick idea over breakfast, driving to work, or walking in the park, while other ideas come after years of hard work in the lab. Some people especially like to create exciting new ideas while others prefer to improve existing ideas, and good scientists should try to do both.

I find your career very interesting, and it might even be something I would pursue in college. I am a HS freshman and I can't wait until I can take AP Chem next year! I also love electronics. How exactly do paper batteries store electrical potential? Are electrolytes needed? I am guessing the paper is carbon since that is your topic of study? I would think that the capacitors would be very similar to current ones based on my knowledge of them. Do paper batteries have a potential for more power at a lower weight packed into, for instance, a laptop battery?

How exactly the paper batteries store electrical potential is a good, very interesting question. It is is a little complicated, but you can understand. Use your imaginations or take a look at my animated slide show below. The paper battery is made of several layers. On the top layer is a material called lithium cobalt oxide. This material is made of sheets of cobalt oxide, with lithium atoms in between these sheets. The middle layer is made of cellulose, or paper, soaked in electrolyte (electrolyte is basically like salt water). The bottom layer is made of carbon nanotubes, which are VERY small carbon fibers. The battery needs to be charged by plugging it into a voltage just like your cellphone, mp3 player, or laptop batteries. This voltage causes the lithium to come out from the sheets of cobalt oxide, travel through the cellulose and electrolyte layer, and arrive at the carbon nanotube layer, where the lithium atoms sit on the carbon nanotubes. When this charging is complete, the battery is ready to power an electrical device. This electrical potential comes from the lithium atoms crossing back across the cellulose and electrolyte layer, and back in between the sheets of cobalt oxide, and this action provides an electrical voltage to the device you are powering. You can see this in action here

Click through slowly using the arrows to see the animation.
To see it full-screen, click on the button with four arrows pointing out on the bottom right of the player.
Can't see it? Try here.

The paper we use is made of pure cellulose, which is the natural polymer that is found in wood and other plant materials. Normal paper that you use in school is made from small fibers of cellulose along with bleaching compounds and binders (glue), but the "paper" we use is not fibrous, it is a smooth sheet of pure cellulose, with small pores that allow the for the lithium to move from one side of the battery to the other.

What, exactly, is a supercapacitator, and how does it work?

What are supercapacitors? That is a good question, and is at the foundation for this 'paper battery' project. To understand what a supercapacitor is, it is important to first understand what a capacitor is. Capacitors are electronic devices which store electrical charge. These devices are somewhat similar to batteries in that they store electrical charge for later use, but unlike batteries, they cannot create their own charge, and they typically have a small charge that is quickly released. One common use for capacitors is in a camera flash, which demands a quick release of charge, which could not be supplied by a battery.

The simplest type of capacitor is a parallel plate capacitor, which is simply two metal plates that are either separated by air, or by a non-conductive material such as glass. Positive charge is held on one plate and negative charge is held on the other. The equation which governs this type of capacitor is basically written as C = e A / d , where C is capacitance, A is the area of one of the metal plates, d is the distance between the two plates, and e is the dielectric constant, a value related to how good the material between the plates insulates electrical charge. The important thing to take from this equation is that to have very high capacitance, you ideally need a very large area plate, a very good insulating material between these plates, and for the distance between them to be very small.

This is why supercapacitors were designed, to maximize the capacitance values of traditional parallel plate capacitors. Supercapacitors are capacitors with very high capacitance per weight, and in this way you can get a lot from very little, and this is why we call them 'super'. This is accomplished by a variety of methods, but all of these methods rely on the same basic idea. The normal flat plate is replaced with a very high surface area material such as activated carbon, and in our design, this is replaced by the even higher surface area material, carbon nanotubes. Another feature which improves the capacitance values of our device is that the charge is not just held between the two plates (two layers of carbon nanotubes), but also in the electric double layer. This can be best understood from watching the slideshow animation posted just above this. What happens is that there are electrolytic ions, which are charged molecules in the liquid state, that respond to the charging of the carbon nanotubes by creating electric double layers around the nanotubes. If the carbon nanotube is charged negatively, then all the positive ions nearby will be attracted to the surface of the charged carbon nanotube. The same will happen on the other side, where the negative ions will be attracted to the positively charged carbon nanotubes. Cellulose has a reasonably good value for insulating electrical charge, but this is less important in the current design, which does not require a very strong insulator since it relies on electrical double layers.

I hope this explanation will give you a basic understanding of capacitors, but to fully understand them, you will need to learn about electronics in greater detail, and I encourage you all to look into this if it interests you. I have been formally trained as a chemist, and many of my classes and research have required a basic or intermediate knowledge of electronics. It seems that with the increasing presence of electronics in all areas of technology and science, a basic understanding of these concepts will certainly serve you well.

Could those paper batteries replace all the other batteries we use today?

These paper batteries and supercapacitors DO have the potential to replace existing technologies, but not all applications are suited to our devices. The best places for these devices is where flexibility, lightweight design, and a wide temperature range are useful.

How possible do you think it is for these paper batteries to go into more widespread use? Secondly, are there any further inventions, discoveries, or developments that you think can stem from the development of these paper batteries?

I think there is a good probability that this battery and capacitor technology will go into commercial applications. It is currently being developed by a start-up company called PaperBatteryCompany, and they are in a good position to bring this idea to market, and the results can be great. I think that all researchers should think positive, and try to envision the practical application of the technology, and then try to make that happen. The business side of science is much different than the research side, but both rely on each other and the most successful technologies have come into widespread use from a good combination of these two sides. Thanks for the question, and keep your eyes open for paper batteries and supercapacitors, they may show up sooner than you think!

Now for a hypothetical question: If MASSIVE amounts of nanotubes were made, could they be constructed into a frame that is strong enough yet light enough to construct the space elevator? (By the way, my goal in life is to build the space elevator)

The Space Elevator - This is a fantastic idea but it is far from becoming reality. It is the idea of making a cable which can drag loads into space, attached to a counter-weight orbiting earth like a satellite. The problem is that the cable needs to be strong enough not to break, but also light enough not to fall back to earth under its own weight. It reminds me of Jack and the Giant Beanstalk, with a vine that goes into the clouds.If this idea is ever realized, there is no doubt that carbon nanotubes are the best material, they are extremely light and very strong and flexible. I think this idea will require significant advances in carbon nanotube production, and this will take a while, but it may come true one day and save us from wasting so much rocket fuel. Many carbon nanotube and nanotechnology research projects are funded by NASA, and nanotechnology and space exploration will be together for a long time to come.

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