Introduction: Make a Graphene Supercapacitor
This Instructable (loosely) follows the method of graphene production described by C&EN, who cite a paper published by Parvez, Wu, et. al. In the paper (Exfoliation of Graphite into Graphene in Aqueous Solutions of Inorganic Salts), it is explained that putting a graphite electrode and a platinum electrode into a solution of inorganic salts (ammonium sulfate works best, they say) with a 10V supply (graphite = anode, platinum = cathode) causes the graphite to be torn apart by electrochemical activity to become graphene! Graphene has attracted much hype and study recently. One of its near-term applications may be in high density supercapacitors.
Attachments
Step 1: Making the Graphene
To make the experiment conditions described in the paper, pure platinum was required for electrode material. Unfortunately, all I had on hand was 90%/10% Pt/Ir wire, a deplorable situation no doubt shared by many in the audience. (Those who do not have either on hand may try gold, or carbon, but I have not tested these.) Also, instead of graphite sheet of some sort that was used by the referenced experimenters, we used a piece of graphite mold blank. This choice is probably why our experiment time was around 19 hours but the published one was 3-5 minutes. Surface area to volume ratios...
To make graphene, you need:
10-15V supply, a car battery would work
0.1 molarity solution (NH3)S04, in water, and awareness of how to calculate molarity (ammonium sulfate weighs 132.14 g/mol)
graphite, we used a piece of a mold blank (it may be possible to use carbon fiber but I haven't tried)
Pt electrode or platinized electrode or possibly many of the noble metals (we used 90%/10% Pt/Ir wire)
See attached lab notes for a detailed description of the exfoliation procedure as completed by me.
Step 2: Making a Capacitor
To make a capacitor for testing, I used two carbon rods extracted from "heavy-duty" (leclanche, carbon-zinc) cells as electrodes, and poured settled graphene mixed with paper pulp around each. Paper separators were glued in with hot-melt adhesive to enable compartmentalization of the graphene (it can't touch). Then, imprecisely mixed sodium chloride contaminated with iodine was poured into each compartment (and stirred with the graphene). This structure can be tested for capacitor action.
Step 3: Test the Capacitor
I found mine wouldn't light an LED. However, when tested with a millivoltmeter after being charged to 2.2V, it did have a capacitor-ey type of curve, though it doesn't seem to be good for storing more than 0.7V without really high self-discharge. A table of values for the capacitor's voltage vs. time with just a 10MOhm meter in parallel with it is included in the lab note transcript.
-V
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38 Comments
6 years ago
nice stuff! Look forward to using this design!
6 years ago
You got graphite there, not graphene. Graphene floats. Check youtube Robert Murray-Smith's channel.
Your issue is too high voltage. You need to first saturate the piece with low voltage, then run it at around 10V. Higher voltage will cause more activity at the platinum electrode, and basicly you are spending the electricity on making gasses (likely hydrogen + oxygen).
Had the same issue. It's kinda hard to hit just right.
7 years ago
sir i want to do my M.Tech dissertation on this topic
is this possible for dissertation work
7 years ago
. . . . . . or you could try firing your laser at a piece of kapton?
https://www.youtube.com/watch?v=NqIa5j0Oo9E
See what Rice has done . . .
8 years ago
I remember reading a dryly humorous magazine article somewhere that described researchers making graphene with exactly a brand-new kitchen blender, just to see if it was possible. Their results said it would work, but would require cleaning before making margaritas in again+. It made sense as the punchline to the article and I still get a chuckle from it. I wish I remembered what magazine, but it was years ago.
9 years ago on Introduction
Nice project, but what is now the capacity of the capacitor?
Reply 9 years ago on Introduction
So low that I couldn't get it to light an LED. Very high self-discharge above 0.7V. Proof of concept only with this method, unfortunately. The graphene needs to be processed differently, I think, to be a more usable capacitor electrode material. I remember reading somewhere that graphene powder could be compressed and sintered...
Reply 8 years ago
https://youtu.be/gTt_YBzJ_Dk
8 years ago on Introduction
require items and avail list plese
9 years ago on Introduction
Quite interesting!
Graphene has been made by pulling sticky cellophane tape off a graphite block. Could this give a nice insulator/conductive/insulator/conductive surface if cut and stacked for a capacitor? Or is attaching electrodes too difficult with clear tape as a base?
Reply 9 years ago on Introduction
I've never tried to attach electrodes to such a structure -- try and let us know!
Reply 8 years ago
Hey how or where can I buy ammonium sulfate?
Reply 8 years ago on Introduction
Google it. Or visit a local hardware and garden center. But you can get better results from an online search.
Reply 9 years ago on Introduction
They (electrodes) may need to be electroplated onto the graphene to get a grip.
9 years ago on Introduction
Nice work! Hope you will keep us updated on your progress. Oh, I like your lab notes too: "insect shows no sign of life, even after drying." ROFL.
9 years ago on Introduction
what is the capacity of it sir? can we calculate?
Reply 9 years ago on Introduction
Probably not too well, since we don't know the equivalent parallel resistance, unfortunately.
9 years ago on Step 3
hola. mucho muy interesante. Gracias por dejar verlo
Reply 9 years ago on Introduction
De nada
9 years ago on Introduction
As a possibly cheaper approach, you might try producing your defect-free few-layer graphene by shear exfoliation in liquids (AKA throw the graphite in a blender.)