UCLA Chemistry: How to charge your phone in seconds
Dr. Maher El-Kady (Postdoctoral Researcher, Kaner Lab) presented a talk about the "Super Supercapcitor" at TEDxCairo, held earlier this year.
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The Super Supercapacitor—the battery tech that could charge your phone in seconds: Dr. Maher El-Kady at TEDxCairo 2014.
Mobile phones…Mobile phones are ubiquitous today. They have revolutionized the way we communicate with one another. Not only do we use mobile phones to call each other but they also allow us to access the internet, listen to music, watch videos, read books, download apps, play games, etc. Even if you’re driving your car somewhere and all of a sudden you realize you’re lost. What would you do? Well, you ask your phone how to get to your destination. The answer would be: “you idiot! You’ve been there before”. So, it will map out the directions and take you to the final destination safely. So, the mobile phone is our friend. But how many times has your mobile phone run out of charge and you find yourself disconnected? Probably very frequently! Now imagine if you have a phone battery that recharges in a matter of seconds (instead of hours like the traditional battery) and what if this battery can run your phone for days or even weeks? Life would be different! Our research team at UCLA has been working on these problems for the past 5 years; we designed a research project to address these questions. Of course, we had to look at the starting point. Battery experts agree that the vital part of the battery that defines all of its properties is the material that makes the battery electrodes. It was clear to us that we needed a new material if we wanted to solve the current battery issues. Since our research lab at UCLA has over 30 years of experience in materials research, it didn’t take too long to select this material from a whole lot of alternatives—graphene. Graphene is marvelous, it’s the material of superlatives, the material many scientists believe could transform our world. It possesses many interesting properties due to its unique chemical structure. I put together this model to help you understand the structure of graphene (model in my hand). Graphene is a form of carbon where the white balls represent carbon atoms and the blue sticks are the bonds connecting them. The carbon atoms are arranged in a hexagonal pattern and connected via a very strong chemical bond, making it the strongest material ever known. Interestingly, graphene conducts electricity at room temperature better than anything known. What’s even more interesting is that graphene is only one-atom thick, this makes graphene the thinnest material ever made. It takes about 3 million sheets of graphene stacked on top of each other to make a film the thickness of a regular print paper. That’s why graphene has an extremely large surface area. Actually, I’ve brought some graphene along from UCLA (sample in my hand). This sample looks small to you but its surface area is large enough to cover an entire football field like Cairo Football Stadium which we are all familiar with. These interesting properties make graphene an excellent battery material. Unlike today’s batteries which store charge in the interior of the electrode material, graphene stores charge on the surface and that’s why it has very fast charging time. And because it has extremely large surface area, graphene can store a huge amount of charge comparable to batteries while at the same time can be recharged very quickly. So, our goal was to make graphene batteries or what we called later “the super supercapacitor”. The question is how? It turns out that you make graphene every day since you started learning how to write. Pencil lead is made of graphite that exists in nature in large quantities. Graphite is made up of millions of layers of graphene. These layers are held together only weakly – which is why they slide off each other when a pencil is moved across the page upon writing. Taking advantage of this interesting property, researchers isolated graphene for the first time in 2004 using a regular roll of sticky tape. They used the tape to pull stacked layers of graphite apart until there was only one layer remaining. However, the graphene made using this process is not enough to make a supercapacitor run. We set out to find a better method for making graphene. We used a chemical approach, rather than a mechanical approach, for the exfoliation of graphite. By treating graphite with simple chemical compounds, oxygen atoms get inserted between graphene sheets and blow them off into individual layers of graphite oxide, which forms a brown solution as shown in the picture on the left. We used a consumer grade LigthScribe DVD burner to turn graphite oxide coated onto a DVD disc into graphene. The disc was coated with graphite oxide dispersion and allowed to dry in air. This was followed by the laser irradiation of the disc inside the DVD burner where graphite oxide absorbs the laser light and blows off oxygen as carbon dioxide, leaving behind a large film of graphene. So, it’s a process for making graphene that you can even do at home. A supercapacitor is produced by sandwiching a drop of electrolyte between two pieces of this laser-made graphene—that simple. After charging this supercapacitor for a few seconds, we were able to run an LED for an hour or more. Our measurements show that this graphene supercapacitor stores as much energy as a lead acid battery, yet it can be charged in seconds. Our data suggest that this supercapacitor could revolutionize the mobile phone industry. So, our discovery is about quick charging batteries, is that it? No, not just that. So, what else? When you buy a new laptop computer the battery is powerful enough to run your computer for maybe 10 hours. Two years later the battery can only run your computer for one or two hours because of battery degradation. That’s why you need to replace your battery every two years or even buy a new computer. We can solve this problem with graphene supercapacitors too. We found out that graphene supercapacitors are stable enough to be used for over 10 years even when used many, many times a day. This means that you may never need to replace your laptop battery again. What other applications do we expect for graphene supercapacitors? Electric vehicles (EVs) are receiving more and more interest nowadays. They are pure electric cars that run entirely on batteries with no gas engines. When the battery dies you pull into an electrical charging station, instead of a gas station, and charge up your car. However, the long charging time of traditional batteries is the bottle neck for EVs. But imagine if you could pull into a charging station and within minutes or less you will be ready to go. This is going to be a game changer for EVs! Graphene supercapacitors could also have a major impact on renewable energy sources. For example, you might be interested in installing solar panels on your roof to power your house. This is an interesting idea but keep in mind that this works perfectly during the day time but what would you do after the sun goes down? Well, you can use graphene supercapacitors to store energy during the day time and then use that energy to power your house at night. The same applies to wind energy since the wind does not blow all the time. Graphene supercapacitors are also promising for patients who need a pacemaker to regulate the beating of their heart. Pacemakers run on batteries that often fail every 5-7 years, the patient then needs to do an operation to replace the pacemaker, which is painful. But imagine if the pacemaker used graphene supercapacitors instead; the patient would have a lifelong pacemaker and if the graphene supercapacitor is combined with a nanogenerator (something that is a very hot research topic today), it would be even more reliable. We are also working closely with researchers from NASA-Kennedy Space Center to develop graphene supercapacitors to be used in space missions. Apple is interested in our technology too. In fact they wanted to buy the technology from UCLA but UCLA had to turn them down because there is a law that prevents the school from selling the technology rather than licensing it. I believe that our research efforts should strive for solving real world problems. I chose to work on energy because of the ever increasing energy needs of our planet. Consider this, when scientists identified the top 10 problems of humanity for the next 50 years they found out that energy comes out on the top of the list. I recommend that you guys work on something that has a direct impact on people’s lives if you want them to appreciate what you’re doing. Now let me tell you a little bit about the early versions of mobile phones and how it has changed. The picture on the left shows the first mobile phone ever. It was huge in size and needed two people to carry. The battery itself was the size of a starter battery we use in our cars nowadays which is gigantic for a mobile phone. This was 90 years ago, but now we have the iPhone with all the possibilities that you are all familiar with. So what’s the future phone going to look like? It might be smaller, better functioning, stretchable, transparent, thin and flexible. It’s possible that you will be able to wrap it around your wrist like a wrist watch. It could be even self-cleaning, a property that can be controlled by tailoring the surface of the material. It’s also possible that the next generation mobile phone will work with touchable holograms rather than the touch screens we all have nowadays. What I wanted to say is that there are a lot of possibilities! However, in order to get to this level of technology we need to continue to miniaturize the different electronic components. While there has been a lot of success with the miniaturization of transistors, one component has always lagged behind in this trend and that’s the capacitors. If you take a look at the board of any electronic device, you will find bulky capacitors like the one I am holding—often cylindrical in shape with two terminals. Using graphene, we developed a capacitor that stores about 10 times the amount of charge this regular capacitor can hold and in a much smaller volume. Here is –in my hand– the graphene capacitor we developed at UCLA, it’s the black dot in this small box. I realize that you can’t see it but to help you realize how small they are, let me give you an analogy. A human hair is about 50 to 100 microns in thickness but our graphene capacitors are only 10 microns thick. Thus, I think it is fair to say that graphene would allow us to make future electronics smaller and at the same time more powerful! So, what’s the take home message? Graphene was first isolated 10 years ago by Kostya Novoselov whom I met twice in the last year. Kostya and his advisor received the Nobel Prize for the discovery of graphene in 2010. I was also lucky enough to meet about 30 other Nobel laureates during my research career. Whenever I approached a Nobel Laureate I always wondered…what makes them different? What’s the secret behind their success? I found out they are normal people like you and me but they challenge beliefs that everyone else takes for granted and that’s how big discoveries are made. Take graphene as an example, we knew about the existence of graphene but some theoretical studies led scientists to have a dogmatic idea that graphene is unstable and could never exist. But no one gave it a try to test whether this was true until Kostya and his team tried it and received the Nobel Prize in physics in 2010 for their discovery. I believe that you and I have met similar situations. For example, how many times you had a revolutionary idea that could change your life and then find out that most of your colleagues do not believe it is possible. However, if you believe in your idea and before that believe in yourself, you can be successful. You can transform the world as we know it today! Thank you!