Graphene supercapacitor production using scotch tape

[ecgoeken]

I have had a question on my mind for a while now. Would it be possible to make a graphene supercapacitor using the scotch tape method for making graphene? Except unroll the entire roll of tape and cover it in graphite and then press it against another entire roll of scotch tape, peel off and repeat a few times with other rolls of scotch tape. Add a dielectric between two of your rolls of scotch tape graphene and roll the assembly up for a crude DIY graphene supercapacitor.

 

[PhysTech]

No, the scotch tape technique is only used for research. This technique is extremely painful and has a terrible yield. Not to mention that the graphene flake sizes you would get would not be longer then a couple of tens of microns. When the properties of graphene were reported for the first time in 2004 by Geim and Novoselov, the scotch tape technique was the only one available. Since then an enormous list of alternative techniques of producing graphene have been developed. Current state-of-the-art techniques of producing graphene would probably not be useful in fabricating the type of capacitor you are proposing. It would be an extremely difficult engineering problem. I admit, however, that I am not familiar with ALL efforts on producing graphene. If you are interested you can take a look at this recent review article on graphene production techniques:

http://onlinelibrary.wiley.com/doi/10.1002/adma.201202321/full

Maybe you will notice something I missed. But my intuition says that what you're proposing is still a couple of years away.

 

[ecgoeken]

Yeah, I was afraid of that. I was hoping that the accumulation of many small flecks of graphene would have similar attributes to one monolithic layer of graphene. What about using the lightscribe method of producing graphene. The guy from UCLA has made the a small graphene capacitor using this method and has reported very high energy densities. Do you think this is scale-able? I wonder if you could make a "battery" by stacking several layers of graphene supercapacitors together? Or even modifying the lightscribe machine to laser scribe a ribbon of graphite oxide similar to the way old dot matrix printers worked. Then you could roll that ribbon together with another ribbon and some electrolyte to create a usable graphene super capacitor. Here is a link to a video of UCLA's work using this method:

 

[PhysTech]

This lightscribe method appears to be one of the large-area graphene production methods. Although, in the video he does not explain how he made the super capacitor. To me it seems like he simply cut out a rectangular section of graphene from the disc and made a capacitor (without any kind of rolling). According to what you were suggesting, with the unrolling of an entire scotch tape, you would need a continuous graphene sheet which is a couple of meters long (i.e. length of a typical scotch tape). With this lightscribe method you could probably get graphene lengths of the order of the diameter of the disc (4.75") if you just cut straight. If you cut in spirals you could probably get more. But that is also very delicate work. You know what would seem like a good idea: growing a couple of meters long graphene on an equal sized boron nitride layer stack and then roll up this entire composite sheet. I don't know how many layers of boron nitride you would need in the stack. I would need to look that up. Anyways, whatever number that prevents any kind of tunneling or drag effects between consecutive graphene layers.

On a related note (but nothing to do with super capacitors) there are efforts being made to use graphene lithium-ion batteries. The current state-of-the-art lithium-ion batteries use a graphitic anode. In 2007, this guy at Stanford Yi Cui proposed this so-called silicon nanowire battery which can improve the anode capacity without any instabilities such as swelling and cracking (which one would encounter in bulk silicon). This is one of the main reasons why graphite was chosen over silicon for the anodic material even though silicon has a higher storage capacity. This is an effort which is one step further:

http://onlinelibrary.wiley.com/doi/10.1002/aenm.201100426/abstract

where they use a silicon-graphene composite a structure to increase the anode capacity.