Tuesday, December 8, 2009
At Stanford, nanotubes + ink + paper = instant battery
Dip an ordinary piece of paper into ink infused with carbon nanotubes and silver nanowires, and it turns into a battery or supercapacitor. Crumple the piece of paper, and it still works. Stanford researcher Yi Cui sees many uses for this new way of storing electricity.
Post doctoral students in the lab of Prof. Yi Cui, Materials Science and Engineering, light up a diode from a battery made from treated paper, similar to what you would find in a copy machine. The paper batteries are treated with a nanotube ink, baked and folded into electrical generating sources like the one wrapped in foil seen here.
BY JANELLE WEAVER
Stanford scientists are harnessing nanotechnology to quickly produce ultra-lightweight, bendable batteries and supercapacitors in the form of everyday paper.
Simply coating a sheet of paper with ink made of carbon nanotubes and silver nanowires makes a highly conductive storage device, said Yi Cui, assistant professor of materials science and engineering.
"Society really needs a low-cost, high-performance energy storage device, such as batteries and simple supercapacitors," he said.
Like batteries, capacitors hold an electric charge, but for a shorter period of time. However, capacitors can store and discharge electricity much more rapidly than a battery.
Cui's work is reported in the paper "Highly Conductive Paper for Energy Storage Devices," published online this week in the Proceedings of the National Academy of Sciences.
"These nanomaterials are special," Cui said. "They're a one-dimensional structure with very small diameters." The small diameter helps the nanomaterial ink stick strongly to the fibrous paper, making the battery and supercapacitor very durable. The paper supercapacitor may last through 40,000 charge-discharge cycles – at least an order of magnitude more than lithium batteries. The nanomaterials also make ideal conductors because they move electricity along much more efficiently than ordinary conductors, Cui said.
Bing Hu, a post-doctoral fellow, prepares a small square of ordinary paper to with an ink that will deposit nanotubes on the surface that can then be charged with energy to create a battery.
Cui had previously created nanomaterial energy storage devices using plastics. His new research shows that a paper battery is more durable because the ink adheres more strongly to paper (answering the question, "Paper or plastic?"). What's more, you can crumple or fold the paper battery, or even soak it in acidic or basic solutions, and the performance does not degrade. "We just haven't tested what happens when you burn it," he said.
The flexibility of paper allows for many clever applications. "If I want to paint my wall with a conducting energy storage device," Cui said, "I can use a brush." In his lab, he demonstrated the battery to a visitor by connecting it to an LED (light-emitting diode), which glowed brightly.
A paper supercapacitor may be especially useful for applications like electric or hybrid cars, which depend on the quick transfer of electricity. The paper supercapacitor's high surface-to-volume ratio gives it an advantage.
"This technology has potential to be commercialized within a short time," said Peidong Yang, professor of chemistry at the University of California-Berkeley. "I don't think it will be limited to just energy storage devices," he said. "This is potentially a very nice, low-cost, flexible electrode for any electrical device."
Cui predicts the biggest impact may be in large-scale storage of electricity on the distribution grid. Excess electricity generated at night, for example, could be saved for peak-use periods during the day. Wind farms and solar energy systems also may require storage.
"The most important part of this paper is how a simple thing in daily life – paper – can be used as a substrate to make functional conductive electrodes by a simple process," Yang said. "It's nanotechnology related to daily life, essentially."
Cui's research team includes postdoctoral scholars Liangbing Hu and JangWook Choi, and graduate student Yuan Yang.
Janelle Weaver is a science-writing intern at the Stanford News Service.
Sunday, December 6, 2009
Now the next step will finnaly be mounting this motor to the frame of the bike using a 8 inch diameter steel tube cut to about six or seven inches and placed right behind the seat tube.I do believe after taking the motor apart that the claims of the motor being waterproof are possible with a bit of modification and precaution in the placement of this motor on the bike. The weak points seem to be at the axle berrings and where the motor cover and the rear housing meet. I think that if the berrings on the drive shaft are kept inclosed and the rear housing/cover joining is treated to some sort of sealant this baby should be able to ride in the rain no prob. This comes as a relief to me as I really wanted to be able to have a good portion of the motor exposed not only to show off the motor but to alow the motor case to sink that heat away with air flow.
Now if I can just get my hands on a bunch of A123 cells I might actually be able to get this project rolling. But the light at the end of the tunnel is still quite a ways down cosidering I haven't even begun to think about a BMS.
Saturday, December 5, 2009
Voltage range: 36V - 100V
Peak Current: >300A
Current Limit: 5A - 120A
Regen Voltage: < style="text-decoration: underline;">Features
Fully Programmable via supplied USB cable
3 Speed control
Cycle Analyst Ready
Reverse Switch Grip
60 degree or 120 degree compatible
Genuine IRFB4110 Mosfets
Precision Calibrated 4W shunt
10AWG Teflon coated tinned copper cabling
6AWG equivalent traces
Precision 1% Reference
Cleaned and inspected
Large Heat Dissipating Case
High Pedal Lockout
90V Regen Mod
100V Power Resistor Mod
3K Base Mod
250uOhm Shunt Mod
50V / 100V Switch Mod
10AWG Wire Mod
4110 Fet Mod
Tuesday, November 24, 2009
yup, thats right, pink is back! I whiped up a hot wire knife from some copper wire lying around and some big 'ol six volt batteries I used for my tv head costume wired in series to eachother. Split it right down the middle and used some bamboo skewers to hold the pieces on there. The next step is to cover the mold in something to protect the styrofoam from being dissolved by the fiberglass resin and allow for some finish sanding. Someone recomended bondo so I will see how affordable that option is and might start working tommorow night on that.
Sunday, November 22, 2009
Those crazy kids at the EV shop not only have tons of nanophosphate cells just plain kickin it, but they have a single cell that has been doing four minute fast charges and discharges back to back for weeks now and will continue to until it has completed 1000 cycles as it is rated to. The purpouse of this is to see how the fast charge system affects cell life. Aparently the cells progress is viewable online and even will send one of the crew a text message if something goes wrong.
Dont tell anyone that I spent a good amount of time under that table cuddling with those boxes of a123 cells...kidding
...or am I?
Sunday, November 15, 2009
Friday, November 13, 2009
Thursday, November 12, 2009
Inspired by aussiejesters fiberglass battery box I decided to make a controller housing using the same technique. By the way, that guys work is crescent fresh. Take some time to check out his trike video on youtube with the same screen name.
Originally I was just shaping this piece as a mock up to use as a guide to make the housing out of wood. But I'm starting to think that wood might be too vulnerable to the elements and cause heat build ups. Not that the solid wood idea is totally out the window but the fiberglass option just keeps looking better. I'm shopping around for a large styrofoam block to shape the final piece out of at the moment.
Sunday, November 8, 2009
So if you're into volts, amps, watts and speed let's get together and see what we can come up with. The bay area is a great place to be if you're into technology so it would seem a crying shame not to take advantage of that.
Friday, November 6, 2009
so due to special request I'm attempting to take a look inside the motor today, and after fetching some snap ring pliers I've hit another stumbling block. I cant seem to get the rear housing to pop off. Currently I'm looking to the forum crew to help me out but unless yao yan at golden motors gives me some direction I might be up shit creek sans paddle.
Friday, October 23, 2009
Monday, October 19, 2009
As for the batteries, I'm thinking a123 systems has what I need but I'm going to have to learn to build my own pack. They also have developed a prismatic battery that is about a quarter inch thick by 12"X 8" with 3.3v and 20ah, but there's no way to buy them and the developers kits they sell are really expensive and they don't offer developers kits for the prismatic battery......but, I found out that their headquarters is about five miles from my apartment. So I took a little bike ride out there today to see what was up with a123. It turns out they are in the quite phaze of the ipo so they must have been pretty busy so there was no one in the office that could talk to me. I did though manage to flag down a supply guy though to talk to and though he didn't really have alot of technical knowlege he was very helpfull and said he would pass my email address to one of the engineers who has ev dreams of his own. I'm not holding my breath for the prismatics but I would do anything short of killing a man to get my hands on some...anything.
Well enough of my battery woes, I got alot of stripping down done with the frame and put that large marge wheel together and mounted it. Here's some pics
Thursday, August 27, 2009
After staying up to the wee hours of the morning with my laptop researching various motors on the internet I decided to go with this one right here. It's a 5000w brushless motor from Golden Motor Company model number HPM5000B. Apparently the company got its start in the electric wheelchair business and for the past few years has made a name for itself making ev motors, mostly of the hub variety. From what I've read people seem pretty happy with the product but all I saw for reviews were on thier hub motors. None with the power that I wanted for this project. Then I noticed this high power brushless motor on thier web site www.goldenmotor.com . It compares nicely with the mars brushless motor I was also considering and seems to be built with much higher quality. The motor weighs about 25 pounds and has an impeler fan on the opposite side and I just love the big ol heat sink going around the whole thing. I still dont know what I'm going to use for a controller, the company that makes the motor also sells controllers, though the heavy duty one they have is bulky and does not support regen braking. They have a small one they call the "magic controller" and it has a bunch of bells and whistles in addition to regen but I dont know if it can handle that much power. I'm currently looking into alltrax and kelly controllers but they are quite pricey.
So as long as we're talking about switching stuff out next up on the hit list is going to be the rear wheel setup. I first thought I was going to go with disk brakes on the front and back but being as this thing is going to be belt drive I cant put disks on the back as the axle will have to move along the horizontal drop outs to put tension on the belt. I remembered seeing scooters that had disk on the front and a drum brake on the back. I found a company, sturmey archer that makes a decent one that fits a freewheel and the local shop quoted me at $115. It only comes in 34 and 36 hole style so sigh...those pink 68 spoke rims are gonna have to go. Surly makes a 65mm wide rim I want to pair with a maxxis hookworm tire.
The forks and the front wheel are gonna have to go too as they are both uncompatable with a disk brake setup. Taking a little inspiration from old school choppers I would like to go with a double crown dual springer fork for added suspension as this is goiong to remain a hardtail. I dont know if anyone even makes such a thing as so far I've only been able to find them for motorcycles. But I'm sure something can be worked out
So after some extensive hunting on ebay I found this greenline bikes stretch beach cruiser on ebay for $200 shipping included. And let me tell you, the picture does not do it justice. It's frikin massive, it has an eight foot wheel base and 26" rims. Though I must say, I did not realize it had pink rims untill after it was allready on its way here from california and my friends have been relentless in giving me shit for it. But hey, real men wear pink. Riding this bike makes me feel like a kid again and there is a part of me that will miss pedeling this beast around so I've been riding it as much as I possibly can this summer while I still can. Thank god boston is a mostly hill-less town because I must say this thing is an absolute bitch to climb up hills with.
I'm not looking to copy that build though, I find the chain noise horrendous and I just cant hang with those heavy, short lived lead acid batteries. I know harley has been using belt drives as well as a few others and chopper builders, though some efficiency would be lost the gain from getting rid of that chain noise would make it worth it. And lets just face it, lithium phosphate batteries are just the best you can get at the consumer level and in the long run will make the initial investment well worth it. I would like to work in some regen braking and a led light setup but thats going to take a bit more technical research. So hopefully with some ingenuity and a couple lucky breaks I can make a comparable EV with not too much more money having to be spent.