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Graphene Enables Next Generation of Mobile Rechargers
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Graphene Enables Next Generation of Mobile Rechargers


An Interview with Stephen Voller, Founder and CEO of Zap&Go


A creative approach to exploiting graphene’s properties in supercapacitors could change the way we charge our mobile devices



In this edition of the Graphene Council Newsletter, and in previous editions, we have covered the large amount of research that has gone into applying graphene to supercapacitors. 


The hope in all this research has been that graphene with its large surface area would increase the storage capacity of supercapacitors to the point where they could compete in that regard with lithium-ion (Li-ion) batteries. As we report in this latest edition, and all previous coverage of graphene in supercapacitors, the storage capacity has been improving slightly, but still falls pretty short of the Li-ion batteries.


However, a few things have become clear about graphene in supercapacitors. Graphene’s extraordinary conductivity makes it uniquely capable of being used in high-frequency applications, such as high-frequency filtering. 


High-frequency (120 hertz) filtering means converting alternating current (AC) “wall power” to direct current (DC). Once you make this conversion, you can adapt the frequency to whatever is necessary to any application. The conversion process involves diode rectification, followed by removal of voltage fluctuations and then followed by filtering with a capacitor.


What this would allow someone to do is run modern portable electronic equipment, such as laptop computers or other portable devices. Supercapacitors currently on the market cannot do this so they can’t be used in AC and high frequency circuits because their time constant is not suitable.


This is a critical need in supercapacitors and is thought to be the place where graphene could offer a solution.


Also, graphene as an electrode material for supercapacitors can take on very different structures and geometries from typical activated carbon. This means very small or slim supercapacitors can be produced with graphene that cannot be made with activated carbon. 


One company in the UK, called Zap&Go, has come up with a creative spin on graphene’s unique properties in superconductors to create a fast recharger for portable devices. 


While there are other lithium-based rechargers on the market, they take a long time to get charged and then take even more time to charge your mobile device. The Zap&Go supercapacitor charges up quickly and delivers that charge to your mobile device in a few minutes.


We interviewed Founder & CEO, Stephen Voller, about this imaginative approach to exploiting graphene’s strengths in supercapacitor applications. 


Q. Could you describe the product that Zap&Go is developing?


Stephen—The ZAP&GO charger is the first graphene-based supercapacitor charger for smart phones and tablets.


Q. How is the technology related to graphene?


Stephen—Supercapacitors charge quickly. By using the high surface area and high conductivity of graphene the ZAP&GO takes in enough energy to fully recharge a smart phone in a few minutes.


Your phone uses lithium batteries that recharge slowly. If lithium batteries are charged too quickly or overcharged they can catch fire or even explode. The standard USB charge adapters and cables provide a low-rate of charge to protect the phones from being overcharged. The bigger the phone or tablet, generally the bigger the internal battery. So the iPhone 6 takes longer to recharge than the iPhone 5 for example.


Q. Why did you look at graphene-based supercapacitors as the basis for this quick charging solution? What are the benefits of using graphene in this solution rather than activated carbon on the electrodes?


Stephen—Supercapacitors are like a battery capacitor hybrid. Lithium batteries are used inside phones, tablets and laptops because they discharge slowly, giving you many hours of usage, but they have to be charged slowly. If you are familiar with electronics you may be familiar with capacitors that charge very quickly but also discharge quickly. So, if you had a mobile phone using a conventional capacitor it would charge up in seconds, but would only give you a few minutes of talk-time. Supercapacitors are the best of both worlds, they charge quickly like a capacitor, but retain their charge so they provide the talk-time of a battery. 


Existing supercapacitors are made from double wound aluminum foils, and a supercapacitor sufficient to fully recharge a typical Apple iPhone battery would require it being the size of a soda can and weigh about 0.5kg or one pound (1lb). This is too bulky and heavy to package into a phone charger. We are replacing the aluminum with a new advanced carbon material called graphene. Graphene is orders of magnitude more conductive than aluminum and so the foils inside the supercapacitors can be made far thinner and lighter. This means that our new graphene supercapacitors are now small, light and low-cost enough to be made into a competitively priced phone charger.


Q. Where are you currently in the developmental process, i.e. prototype, initial production run, securing funding for scaling up production, etc.?


Stephen—We are now taking pre-orders for the chargers, and expect to be in production by the end of 2015.


Q: What do you believe is the potential market for this technology?


Stephen--Anyone who has travelled extensively on business knows that a smart phone is an essential connection to the wider world. But whenever you travel you see fellow travelers clustered around charging points at airports, train stations and conference venues – in fact, wherever people can attempt to charge their mobile devices. This is because lithium batteries need to be charged slowly. Now new security controls mean you must be able to power-on your device if you want to carry it in hand luggage. Existing charger products are also lithium battery based so also charge slowly. By contrast ZAP&GO is supercapacitor based and charges fast.


People evolve their own personal strategies to keep their mobile device charged but this is often stressful and time consuming. It also means carrying a whole bunch of cables, plugs and general clutter. It can take between 2 and 4 hours to recharge a regular smart phone.


ZAP&GO was founded in 2013 with the aim to build a whole new type of charger specifi­cally for the traveler. The ZAP&GO charger is designed to charge any type of mobile device from a phone to a tablet that has a standard 5v USB (Universal Serial Bus) port. This includes Android, iOS and Windows devices and all of the major manufacturers including Apple, Amazon, HP, HTC, LG, Microsoft, Nokia, Samsung, Sony, etc.


Could the technology you are developing for Zap&Go potentially have other applications?


Stephen—We are also currently developing a charger for cordless power tools that will charge in minutes. We are also interested in cordless cleaners. In time we hope to develop rapid charge solutions for wind turbines and electric vehicles.


What has been the most difficult hurdle to overcome in developing your product, i.e. technological issues or sourcing funding?


Stephen—We have raised our Seed round of funding and are planning an A round later this year. Our biggest challenge currently is focus, because there are so many markets where our technology could apply.