Capacitor Specs

Finished Capacitor

Finished Capacitor hold 4.58V

Highest Voltage Run: 11.8V

Discharge Time from 11.8V to 0V: 4 hours 22 minutes

Capacitance of 1 of 4 piece of circuit capacitor (singular) : 42 μF

Capacitance of whole circuit capacitor (wired in series): 11 μF

Surface Area of Graphene: 32 sq inches

Surface Area of Graphene under PVA solution: 24 sq inches

Volume: 32 sq inches x 0.000984251969 inches (25 micrometers) = 0.0354 cubic inches

Weight of Graphene: 1 gram

Weight of PVA Solution: 6 grams

Weight of plexi-glass: 320 grams

 

 

Final Capacitor

So I have now all the components to build a capacitor. For display and presentation purposes I will be using a 10″x8″ piece of plexi-glass with the graphene, PVA, and copper tape electrodes on it held down by kaptom tape. The design will be able to let everyone see the pieces of a capacitor and how electricity is transferred through it.

Below is the piece of plexi-glass that is divided up by the kaptom tape. The kaptom tape divides the glass into 4 sections that are all 1.25 inches wide and 10 inches long. The piece of green paper is representing a template that was used to size and cut the graphene pieces that are below also on the plexi-glass.

IMG_6381

 

Now the other 4 pieces of graphene will be placed onto the glass and secured by a .75 inch wide piece of kaptom tape so that the extruding end will have a .25 inch lead for the copper tape and the other 3 inches of graphene will be covered with the solution. The same process is to be repeated on both sides.

IMG_6389

In this picture the 3 inches of each piece of graphene is clearly covered with the solution as well as the ends are covered with the kaptom tape. The kaptom tape is acting as a buffer to contain the PVA solution.

After the solution was in place. I let the capacitor fully dry overnight. Below are pictures of the capacitor after the PVA solution dried clear.

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I wanted to test to see if the capacitor worked. So I charged it with a 9V battery and put a multimeter on it to check voltage. Below is a photo of the capacitor with a starting voltage of 4.58 volts.

IMG_6398

 

Now that I have a function capacitor that will not dry out or crystalize, I can begin testing my capacitor for voltage, capacitance, and compare it to batteries.

PVA Gel Electrolyte

Two days ago I finally created a working Poly Vinyl Acetate solution using the original elmers glue the phosphoric acid and a little bit of water. I started out by measuring 8mL of the phosphoric acid. Show Below:

IMG_6376 IMG_6375

Then I mixed the phosphoric acid with cold tap water. The mixture was 80% phosphoric acid and 20% water. Afterward I weighed out 4 grams of the glue on a scale. Show below:

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Once I had measured out the glue, I added 1.5mL of the phosphoric solution to the glue and stirred it. After about 5 minutes of mixing the glue and acid solution began to fully mix. The PVA solution is show below:

IMG_6377

Now that I have this solution I can begin to use it for the final capacitor design.

Break Post Catch Up

So I made this list prior to break to do some work during the break.

Test Different Electrolytes (PVA vs Potassium Chloride Solution) (semi-complete)

Start on Slides for PowerPoint(Write about normal capacitors and graphene)(Started)

 Calculate batteries VS capacitors(Slides started but calculations still Incomplete)

Capacitance, Voltage, Charge, Size, Volume

 Develop and Build PVA capacitor(started)

Over break I attempted to build a PVA capacitor but It would not take a charge. I believe this to be because the solution I was using wasn’t dense enough and had no water added as well as it was PVA as in poly vinyl acetate not poly vinyl alcohol. I will make a PV alcohol solution today to use as the electrolyte. But I think I will be prepared for approval next week with a working reusable capacitor. I will post videos and pictures from break later.

Solid Polymer Electrolyte

I am going to test using a capacitor with a solid polymer electrolyte instead of the potassium chloride solution as an electrolyte because the capacitor will not have a liquid component. This will make it easier to work with and will hopefully allow the capacitor to be used multiple times instead of just discharged and charged a few times now before the potassium chloride becomes crystalized and ruins the contacts between the graphene and copper tape. Also the potassium chloride when high voltage over 3.5V is run through it, a chlorine gas is let off and that should not happen. A video of this reaction is below:

 

 

12-8-14 Update

Last Friday I ordered some conductive graphene sheets found here:

https://graphene-supermarket.com/Conductive-Graphene-Sheets.html

These sheets are almost exactly what I have obtained after burning graphene oxide with the light scribe drive. These sheets are being purchased in the essence of time to do testing with different sizes of capacitors because the burning of one singular disk takes about 2-3 days. I will be testing different sizes of graphene against each other for energy density, power storage, and capacitance. As well as against batteries and similar sized capacitors to determine if they are better cost wise, efficiency wise, and power wise. I am hoping to be able to create a few parallel plate capacitors using aluminum or copper to test the graphene capacitors against. I will be working with rectangular cut outs of the graphene sheets although I’m hoping to figure out a way to create a cut out circuit pattern to use as well to see if they are more or less efficient by way of greater or lesser surface area.

Finally a breakthrough!! Dec 2-4 2014

So I have successfully created a graphene capacitor using pieces of graphene burned using the light scribe drive. Not the original pattern that I had hoped to use with the circuit board patterns but a capacitor nonetheless. I decided to use the half disk of full burned graphene I had to build some capacitors while I was waiting for the circuit patterns to finish burning. So yesterday morning I started with a glass microscope slide and two pieces of graphene to create a parallel plate capacitor and to use the glass as the dielectric and seal the whole capacitor with kaptom tape. The diagram would look something like this:

2000px-Parallel_plate_capacitor.svg

Parallel Plate Capacitor Diagram

I finished making this first test capacitor on glass and it looked like this:

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Graphene-Glass-Graphene Parallel Plate Capacitor

So naturally I was excited to test it out after all this waiting I finally had something that looked somewhat complete although it was not the original idea. I hooked it up to a 9V battery and let it charge for about 5 seconds, after that I put a multimeter on it to check voltages, and it only read .26V! It barely held a 1/4 volt! I was at first really confused. So I did a little reading up on a website about graphene and super capacitors, the same website I ordered my graphene solution from and read some very interesting information.

http://www.graphenea.com/pages/graphene-supercapacitors#.VIBWQ0tGk1c

“A conventional capacitor is made up of two layers of conductive materials (eventually becoming positively and negatively charged) separated by an insulator. What dictates the amount of charge a capacitor can hold is the surface area of the conductors, the distance between the two conductors and also the dielectric constant of the insulator. Super capacitors are slightly different in the fact that they do not contain a solid insulator.

Instead the two conductive plates in a cell are coated with a porous material, most commonly activated carbon, and the cells are immersed in an electrolyte solution. The porous material ideally will have an extremely high surface area (1 gram of activated carbon can have an estimated surface area equal to that of a tennis court), and because the capacitance of a supercapacitor is dictated by the distance between the two layers and the surface area of the porous material, very high levels of charge can be achieved.

While super capacitors are able to store much more energy than standard capacitors, they are limited in their ability to withstand high voltage. Electrolytic capacitors are able to run at hundreds of volts, but super capacitors are generally limited to around 5 volts. However, it is possible to engineer a chain of super capacitors to run at high voltages as long as the series is properly designed and controlled. “

I knew I had to use the potassium chloride solution in the capacitor and thought it a bit weird I wasn’t using it in the capacitor I built. Well thats because you have to use a gel or liquid electrolyte in a graphene capacitor to fill the voids in the graphene and thats what makes the capacitor work, its like having millions of tiny capacitors on one tiny sheet of single layered graphene all working together to produce the larger capacitor. Its no wonder my first build didn’t work and only could hold a voltage of .26 volts and had a capacitance of 25 pico-farads (pF) which is almost nothing.

I then tried a capacitor build on the table using a model diagram from a youtube video found at : https://www.youtube.com/watch?v=K7E5NSFJIYU that I watched in which a capacitor was build with a piece of buffed graphene on glass with a paper towel soaked in salt water and aluminum foil as a electrode. Is it crude and poorly put together, probably. But it does work. My capacitor was slightly different in that I used copper tape as my electrode and Potassium Chloride solution as my electrolyte instead of salt water. My capacitor looked like this :

IMG_6076

Graphene with copper tapped electrodes and Potassium Chloride soaked paper towel.

This capacitor was able to charge up to 1.1V and hold a charge of over 1V for about one minute before it dropped off to .7V for another two minutes and then held a charge of .45V for another three before it dwindled out. Also this capacitor had a average capacitance of about 25-26 nano-farads(nF). When compared to the first capacitor on glass without the electrolyte solution this capacitor had an average capacitance 1000x higher than the parallel plates glass capacitor. Oh, just another thing a scale below shows capacitance values.

Capacitance Scale

1 Farad is the same as
1 000 000 micro Farads is the same as
1 000 000 000 nano Farads
1 000 000 000 000 pico Farads

So now having at least a somewhat working capacitor I decided I would try it out sealed on a piece of glass with a small piece of denser soaked paper and two copper electrodes on a piece of graphene on a microscope slide sealed with kaptom tape. My capacitor looked like this:

Graphene on glass with two copper(tape) electrodes and a piece of paper soaked in potassium chloride.

Graphene Capacitor on glass with two copper(tape) electrodes with a potassium chloride soaked paper electrolyte.

Excited to test this capacitor out I charged it up with the 9V and put a multimeter on it and it read 1.7V!! It quickly dropped to 1.5V then 1.4V where it hovered for two to three minutes before dropping to a 1V for another three minutes and finally down to .5 for over twenty minutes! Also this capacitor had a high capacitance over just over 73nF almost triple the previous capacitor that was just on the table. Below is a picture of the capacitor connected to a capacitance meter with a meter output of 73.1nF.

IMG_1291

Capacitance Meter with a reading of 73.1nF

I also checked the capacitor for any discrepancies with the potassium chloride electrolyte, kaptom tape, or copper tape just to make sure no voltage was being stored in them or giving me an incorrect capacitance reading. I did this by just using a glass slide with a soaked potassium chloride paper square and two copper electrodes sealed with kaptom tape. Below is a picture:

IMG_6078

Soaked Electrolyte paper with copper electrodes-sealed with kaptom tape on a glass slide.

The capacitance meter barely read .02 pF and when charged with a 9V and measured with the multimeter it only read a charge of .18V for less than thirty seconds before it dissipated. This meant that my readings were close to accurate and that the energy was actually before stored in the graphene!

I finally had a working capacitor!! Not the original circuit pattern that I had hoped for but still working and designed well enough to show someone what a graphene capacitor is, I am hoping to try and get a interdigitated circuit pattern capacitor built this week as well, but my my next thought was how could I get this capacitor to show it had power storage and demonstrate it to someone. So we have these little LEDs in the Innovation-Lab that needs about 3Volts to power up. I built two more capacitors exactly like the last. All had a capacitance between 68nF-73nF and could hold about 1.4V-1.7V. Then I looked up series and parallel wiring diagrams to make sure I knew what I was doing when wiring them together. Below are three diagrams that illustrate the difference with visuals and equations:

fig4

capacitors-in-parallelph207-6-eqn06

 

Basically what these diagrams illustrate is that when capacitors are wired in parallel voltage acceptance does not increase as in (V1=V2=Voltage) but capacitance increases as in (C1+C2=Capacitance), and vice versa for series wiring meaning that voltage acceptance increases(V1+V2=Voltage) but capacitance is lowered as in (1/C1+1/C2=Capacitance).

So obviously I needed to increase the voltage to achieve the needed minimum of 3V so series wiring was the way to go. My series looked like this :

IMG_6077

Three Capacitors wired in series.

The capacitance was low but the voltage after the initial charge was about 3.4V and of which this capacitors wired series held for over three minutes. Enough to run a small LED, I think so!!  Below is a picture of three capacitors wired in series connected to a small board with a LED in it:

IMG_1293

Three Capacitors wired in series powering an LED.

The LED stayed powered up for about two minutes before the voltage dropped below 2.9V which was not enough to power the LED. But I was able to power it up for some time! This is a breakthrough for me because I actually now have something that works! The next step that I will be taking will be to increase the surface area of the capacitors by building new capacitors which will increase capacitance as well as voltage, these new capacitors will have larger pieces of graphene than the previous as soon as I have another full disk burned. I also want to look into getting LEDs that have a lower voltage input so I can power them off of one or maybe two capacitors. Also I will be trying to build a capacitor with the interdigitated circuit patterns that will hopefully be finished burning today! But for now I am excited with what I have accomplished the past three days!

 

Catch Up Post 11-26-14

My last post was about receiving a new light scribe drive. Since then a lot has happened..

So yes the new drive arrived. Good news is that the drive burns disks faster and more usable than the prior drive. Below is a disk burned 3 times and it is all almost fully burned.

IMG_5996

Graphene Disk 3x burned

So this seemed to be great, but unfortunately the drive wouldn’t refocus when I put a disk in it to burn again meaning when I tried to burn circuit patterns,  the patterns would burn slightly off center and not in the same place over and over again, which messed up the disk and rendered it useless. I don’t know what is causing this and I am trying to address it currently. But although I couldn’t get a circuit pattern to burn, I thought I would go ahead and cut out a piece of the above disk and try and build a capacitor with the graphene I had.

IMG_6013

Cut graphene disk

I cut out the graphene from the disk and made sure the two pieces were of equal size. After I placed both the pieces of graphene that were still on the PET substrate on a piece of kaptom tape I then placed 5 droplets of the potassium chloride solution on the two pieces of graphene. Then I took copper tape to use as the two electrodes that I taped to each piece of graphene. Afterword I sealed the potassium chloride solution with another piece of kaptom tape. part of the process is photographed below.

 

IMG_6011

Finishing Building the First Capacitor

Afterword I tried to get a reading using both a capacitance meter and charging up the capacitor and reading it with a multimeter.

IMG_6012

1st Finished Capacitor

The capacitance meter had a lot of fluctuations in its reading which when I checked online was not suppose to be the case when obtaining an accurate measurement of capacitance.

Although I was able to charge the capacitor to a voltage of .6 volts using a 9 volt battery I couldn’t use this low voltage to, for instance power ,an LED because it was so low. The capacitor did however hold a measurable charge over .2 volts for about 6 minutes. When back at school on Monday I will make another capacitor this time using bigger pieces of the graphene as well as not letting the copper electrodes touch the kaptom tape as that could be a possible reason for the fluctuations in the capacitance meters reading.

Update 11-17-14

I received a new light scribe drive today and connected it. I am going to try and burn some graphene later this afternoon. Hopefully this drive works better than the slimmer drive I have been using. I hope to have a complete disk burned and set to be built into a capacitor by the end of this week.

Set back 11-7-14

Last time I posted I said I was going to try burning a circuit pattern into the graphene disk about 10 times. After 10 trials the disk is still not complete. This is a major setback because I really need to have a grapheme circuit pattern to build the capacitor. I have emailed the professor and grad students at UCLA to see if they experienced similar issues. I am also going to look into other methods to convert the Graphite Oxide into Graphene. On the bright side the little bit of graphene that was converted on the disk burns I tested. It had resistance which means that it is conductive. As soon as I I enough graphene burned I can build the capacitor. I am hoping to be able to still use the light scribe drive method. Possibly a new drive that is a little bit taller and bigger in volume- like the ones used in the youtube videos may be helpful, or trying to convert granite oxide to graphene by lasering with an infrared beam on a CNC machine, or by the xenon flash method may be more useful. I am researching these methods today, as well as hope to hear back from the students at UCLA this afternoon. Below is the double layered graphene solution 10mL water 10mL graphene solution, which was burned 8-10 times over the past 2 days.

IMG_5802

Double Layer 10mL H20/ 10mL Graphene Solution 8-10 burns

 

Currently I am burning the graphene disk with a thinner coating only 5mL graphene solution and 15mL water with almost the exact same results after 7 burns. I will post a picture of that disk this afternoon. So that leads me to believe that it is the drive laser or model drive we are using. The results we have are not anywhere near anyone else’s by 10 burns so somewhere I have this formula wrong. I will have this taken care of by monday, so I can continue on with my project.

11-4-14

After trying to scribe the single layered graphene thinned disk a few times, the disk was barley showing any signs of the circuit pattern. I emailed the team at UCLA and asked if they had experienced the same problems. They responded by saying that you have to scribe the disk 5-10 times with the same pattern to really get a defined pattern scribed on the disk. I am currently scribing the double layered disk 10 times while I am waiting for the new single layered disks to dry. I am hoping that by scribing on the single layered disks 10 times I will be able to use the circuit patterns for the capacitor. It will probably take me today and tomorrow to scribe a disk 10 times because it is a 25 minute process each time you scribe. I will upload pictures of the burned disks later this afternoon or tomorrow.

Thinning the Graphene (New Disks)

Yesterday to combat the not burning issue, I decided to thin the graphene out. To do this I decided to start with a scale factor of 1/2. I mixed 10mL of Graphene Solution with 10mL of water and stirred it for a good 5 minutes until both were mixed. Then I set the graphene on two new PET plastic sheets to dry over night.

10mL Graphene Solution being Mixed with 10mL of Water

10mL Graphene Solution being Mixed with 10mL of Water

Two new 1/2 graphene 1/2 H2O solution on PET paper

Two new disks with  1/2 graphene 1/2 H2O solution on PET paper set to dry overnight

Failed Again- Burn with Better Line Weight and Program

Yesterday after increasing the line weight of the two interdigitated circuit patterns and trying to burn the graphene disk on the Acoustica windows program(the program that burnt the first light scribe disk so well), it didn’t work. This only leaves two things that can be our problem. The laser isn’t strong enough, in which case I will need another light scribe drive or the graphene is too dense for the laser. I am going to try and combat the second factor by setting new graphene disks and trying to burn with a less dense layer of graphene.

The disk below shows that you can barely see the pattern.

1st Graphene Set Disk

1st Graphene Set Disk

Illustrator Interdigitated Patterns

I will be testing two different patterns that I made using illustrator. Here are pictures of the two patters that I will burn into the graphene this afternoon. Both of these patterns are using a thicker line weight than the previous failed burn yesterday. I will be testing which pattern the 32 line or the 16 line will be the better of the two circuit patterns to use for my capacitor.

32 Line Interdigitated Pattern

32 Line Interdigitated Pattern

16 Line Interdigitated Pattern

16 Line Interdigitated Pattern

1st Graphene Disk Failed 10-29-14

Yesterday I tried to burn the graphene in the light scribe drive for the first time. It did not work. This in my opinion could be due to four factors.  Three of which I can control the fourth I cannot.  The four factors in my opinion are:

1. The line weight or density of the actual interdigitated design.

2. The quality of the picture being exported from adobe illustrator to the burning program.

3. The density of our actual graphene solution

4. The laser inside the drive not being powerful enough to burn the graphene.

To try and change the controllable factors I am going to recreated the interdigitated patterns directly within the burning application so that the quality of the pattern is a lot higher resolution than before. I will also increase the line weight of the pattern to hopefully insure a better burn. I am going to start there and try to burn the graphene disk I currently have. If that does not work I will cut the graphene solution with water before I set new disks and then try with all three methods to burn a usable pattern. If all of these methods fail I will need to further diagnose the problem and possible obtain a better light scribe drive with a better laser.

 

Setting the 1st Graphene Disk

Last friday I started to set the first graphene disk to dry. This means that I used a dropper to extract the graphene oxide from the bottle and place it on the PET substrate that was previously glued to the graphene disk. I let it dry over the weekend and will hopefully be burning my first graphene disk this afternoon. Here are a couple pictures from the process last friday. The overall process was very slow and it was hard to keep the graphene oxide from dripping off the disk, so I used napkins to catch any run off.

IMG_5705 IMG_5706 IMG_5708 IMG_5709 IMG_5710 2

Making KCI Solution

Yesterday I made the potassium chloride(KCI) solution that I will be using for the electrolyte in the capacitor. I made a 5 mol solution of KCI in 250ml of tap water. First I used a scale to measure out 93 grams of KCI. Show below:

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Then I measured out 250ml of tap water. Show below:IMG_5703

Then I poured the KCI into the tap water and set it on hot plate to heat the water to let the KCI dissolve better. I then mixed the solution for about 12-13 minutes until the solution was completely dissolved. Show below:

IMG_5704

I now have my electrolyte for my capacitor.

Practice Lightscribe Disk Burns

I used the acoustica label making software to create a very basic interdigitated pattern that I scribed on the disk. Here are a few pictures of the process. I am hoping to do a little more research on tuesday and wednesday next week about the surface area between the two electrodes and how that affects capacitance and electrical storage before I burn the interdigitated patterns on the graphene later next week.

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