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Researchers Develop Nanocomposite Paper Energy Storage Devices That Can Function as Batteries or Supercapacitors
14 August 2007
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| A sample of the new nanocomposite paper developed by researchers at RPI. Credit: Rensselaer/Victor Pushparaj |
Researchers at Rensselaer Polytechnic Institute (RPI) have developed a new nanocomposite paper energy storage technology which integrates the three basic components of an electrochemical storage device—electrode, separator and electrolyte—into single contiguous nanocomposite units that can serve as building blocks for a variety of thin, mechanically flexible energy storage devices.
These units can build various flexible battery, supercapacitor, hybrid, and dual-storage battery-in-supercapacitor devices. The nanoengineered battery is lightweight, ultra-thin and completely flexible, and can function in temperatures up to 300 degrees Fahrenheit and down to 100 below zero.
Details of the project are outlined in the paper “Flexible Energy Storage Devices Based on Nanocomposite Paper” to be published in the 21 August issue of the Proceedings of the National Academy of Sciences.
To build the devices, the researchers combined two essential materials—cellulose and carbon nanotubes (CNTs)—that fit the characteristics of spacer and electrode and provide inherent flexibility as well as porosity to the system.
More than 90% of the device is made up of cellulose. Rensselaer researchers infused this paper with aligned carbon nanotubes, which give the device its black color. The nanotubes act as electrodes and allow the storage devices to conduct electricity. The device, engineered to function as both a lithium-ion battery and a supercapacitor, can provide the long, steady power output comparable to a conventional battery, as well as a supercapacitor’s quick burst of high energy.
Two different fabrications of the device as a supercapacitor, one with an aqueous, the other with a non-aqueous electrolyte, yielded calculated specific capacitances of 36F/g and 22 F/g, respectively, with operating voltages of about 0.9 V and about 2.3V respectively.
A power density of 1.5 kW·kg-1 (energy density, ~ 13 Wh/kg) is obtained at room temperature for the nanocomposite (RTIL) [non-aqueous] supercapacitor, which are within reported ranges (0.01–10 kW·kg-1) of commercial supercapacitors and comparable to flexible devices reported.
Fabricated as a lithium-ion battery, the device used a of RTIL (room temperature ionic liquid)-free nanocomposite as cathode and a thin evaporated Li-metal layer as anode, with Al foil on both sides as current collectors. Aqueous LiPF6 in ethylene carbonate and dimethyl carbonate (1:1 vol/vol) is used as the electrolyte.
The charge-discharge cycles of the battery were measured between 3.6 and 0.1 V, at a constant current of 10 mA/g. A large irreversible-capacity (~430 mAh/g) is observed during the first charge-discharge cycle, and further charge–discharge cycles resulted in a reversible capacity of 110 mAh/g.
In recent years, supercapacitors coupled with batteries have been considered as promising hybrid devices to combine the best features of a battery and a supercapacitor. We show that our battery and supercapacitor devices could be integrated in parallel to build hybrids, as reported for conventional hybrids.
...In addition to this traditional hybrid, the nanocomposite units also allow for building new kinds of merged hybrid devices with three terminals... which would act as both battery and supercapacitor (a dual-storage device).
The device can be rolled, twisted, folded, or cut into any number of shapes with no loss of mechanical integrity or efficiency. The paper batteries can also be stacked, like a ream of printer paper, to boost the total power output.
The creation of this unique nanocomposite paper drew from a diverse pool of disciplines, requiring expertise in materials science, energy storage, and chemistry. Along with Linhardt, authors of the paper include Pulickel M. Ajayan, professor of materials science and engineering, and Omkaram Nalamasu, professor of chemistry with a joint appointment in materials science and engineering. Senior research specialist Victor Pushparaj, along with postdoctoral research associates Shaijumon M. Manikoth, Ashavani Kumar, and Saravanababu Murugesan, were co-authors and lead researchers of the project. Other co-authors include research associate Lijie Ci and Rensselaer Nanotechnology Center Laboratory Manager Robert Vajtai.
The team of researchers has already filed a patent protecting the invention. They are now working on ways to boost the efficiency of the batteries and supercapacitors, and investigating different manufacturing techniques.
The paper energy storage device project was supported by the New York State Office of Science, Technology, and Academic Research (NYSTAR), as well as the National Science Foundation (NSF) through the Nanoscale Science and Engineering Center at Rensselaer.
Resources:
Victor L. Pushparaj, Shaijumon M. Manikoth, Ashavani Kumar, Saravanababu Murugesan, Lijie Ci, Robert Vajtai, Robert J. Linhardt, Omkaram Nalamasu, and Pulickel M. Ajayan; “Flexible energy storage devices based on nanocomposite paper”; PNAS 21 August 2007 Vol. 104 No. 34 13574–13577 www.pnas.org.cgi.doi.10.1073.pnas.0706508104
August 14, 2007 in Batteries | Permalink | Comments (23) | TrackBack (0)
Comments
Posted by: Rafael Seidl | August 14, 2007 at 05:06 PM
If this can be developed into a viable energy storage technology, it could change the way all kinds of energy storage is designed. I wonder if you could put thin film solar on sheets of this nano-composite paper.
Posted by: Culpitius | August 14, 2007 at 06:43 PM
It would be cool if the body of cars were made of a tough composit material that also included multiple layers of this new material. It would be great if there were enough layers of this stuff to completly eliminate batteries all together.
The battery could be built right into the body of the car.
Posted by: Patrick | August 14, 2007 at 07:20 PM
Electric origami. Neato.
Posted by: Lou Grinzo | August 14, 2007 at 08:08 PM
I hoping for a BEV that goes 70 mph with a range of 300 miles on a 10 minute charge from a roadside charging station. Of course the charging station would have a rest room and fast food and all motels would have overnight charging service. This dream would easily obsolete almost all ICE powered cars.
Posted by: Lad | August 14, 2007 at 10:25 PM
The use of carbon nanotubes reminds me of the MIT ultracap. The trick now is to create the nanotubes at a reasonable price.
Posted by: HenryP | August 14, 2007 at 10:54 PM
Wait a minute--lithium batteries of 110 Ah/kg @3.6V, or about 400 Wh/kg? That's squarely in the too-good-to-be-true category. That must mean without electrode interconnects, case, or protection devices. And it doesn't square with the statement that over 90% of the device is made of cellulose.
Another thing that doesn't make a lot of sense is why are they using carbon nanotubules, ultra-expensive for the foreseeable future, and not mentioning simpler alternatives like graphite fiber fabric or some metal-plated mat? It's just a conductive substrate.
Posted by: P Schager | August 15, 2007 at 03:10 AM
P Schager, that's what I was thinking. Promising start though?
Posted by: clett | August 15, 2007 at 03:21 AM
Somebody check my calculations but these appear too heavy for PHEV applications. The smallest battery envisioned is 20 kwh that would weigh 20,000/13 kgs or a ton and a half.
It also seems slightly weird all the GCC articles about GMO organisms eating cellulose to have a storage device (not liquid fuel) made from the same material.
Posted by: Aussie | August 15, 2007 at 03:27 AM
Aussie:
You're looking at the supercapacitor version/part of it. This is a pair of devices or a hybrid device, with both a supercap and a battery in one. I quickly overlooked the supercap, because that has only about 3% of the storage, by the numbers given. The reason you even want to bother with it is presumably higher efficiency and longer life on typical regenerative braking.
For recovery of acceleration energy, I get for a one-tonne vehicle decelerating from 30 m/s (freeway speed) about 125 Wh, so 10 kg of these supercaps (bat-acitors?) would cover that. For a modest PHEV, such as a 20-mile AER Prius (200 Wh/mi), you would need a battery of ... 4 kWh/400Wh/kg = ... ta da! 10 kg. If the batteries work as advertised, it's overkill.
Of course they haven't promised us anything yet on battery cost, life, power density or energy efficiency. The supercap would be very underpowered at 15 kW; you'd have to at least triple your supercap size over that issue. That they position the supercap as being a burst power unit for the battery is not promising for the battery's power density. Also, I think both devices will be flammable.
Still it's good to see people working on battery chemistries that have no major (elemental) resource issues. I do think batteries of 400 Wh/kg will come out within a few years, in an case; there are several promising candidates.
Posted by: P Schager | August 15, 2007 at 04:37 AM
Yup, SION and Polyplus have both been working on 600 Wh/kg lithium-sulphur cells. Safety and cycle life are the current hurdles there - perhaps some phoshpate / nanotech alterations could overcome these? Doubtless patents remain an issue to implementing the combination.
Electrovaya have a 210 Wh/kg lithium-ion just out, seems to be the best for energy density right now (equivalent to 1 mile range per kg battery).
Posted by: clett | August 15, 2007 at 04:53 AM
Back to reality....... Altairnano nanosafe rules,right here, right now.
Evcheck.
Posted by: Altarian1 | August 15, 2007 at 05:49 AM
Great! All it needs now is a tiny little paper BEV to go with it. :)
Posted by: jack | August 15, 2007 at 07:15 AM
Seems to me that this would be really easy to short, and really easy to combust. particulalry as it bends and folds.
how much would the safety equipmrnt weigh to protect each sheet. probably alot.
Posted by: | August 15, 2007 at 07:52 AM
A few more approaches to a better battery pack for PHEVs and BEVs are welcomed. May the best ones win.
Meanwhile, the lithium iron phosphate combination seems to fullfil most requiremens, at least until a better solution is found.
Posted by: | August 15, 2007 at 08:30 AM
The low end of their numbers (.10 V) yields 40 Wh/kg - meaning a 10 kWh battery weighs in at 250kg? Sounds promising though the flammability may be an issue if the cellulose cannot be treated. The home insulation industry treats cellulose with borate to render it non-flammable. If these treatments do not upset the E/cap hybrid chemistry - that problem could be solved. However,
More interesting is the idea that energy storage made from wood is possible. Cellulose already stores solar energy efficiently - so it makes curious sense that it could be made to store electrical energy as well.
With a PV substrate matrix and strengtheners this would make a nice solar sail for lightweight electrical storage on sailboats.
Posted by: gr | August 15, 2007 at 10:27 AM
Suuure it does.
Altair picked the most expensive way to make a lithium-based battery.
$75,000 for a 35 kWh Nanosafe battery pack?
Tesla's approach is 53 kWh at about 1/3 the price.
I don't think it will end up in many production vehicles.
>Altairnano nanosafe rules,right here, right now.
Posted by: Bill | August 15, 2007 at 01:13 PM
I admit this is really cool and could have major impications as others have suggested if CNT can be made cheaper than the are now (although they are getting really cheap to make) But I wonder about the previosu research about SWCNT and their affinity to persist in water environments. As we all know if paper manufacturers get into the business of creating this product (and we all know they will since they are constantly looking at new ways to use cellulose and biomass since the forest product lobby is very strong), the volume of wastewater effluent that could contain SWCNT may be significant. Just something to think about, monitor and plan for in the future.
Posted by: griff | August 15, 2007 at 02:06 PM
"Altair picked the most expensive way to make a lithium-based battery."
The raw materials of the Altair chemistry are cheaper than existing cobalt-oxide based lithium-ion materials (as used in the Tesla etc). All they need is mass production to bring the costs lower.
Posted by: clett | August 16, 2007 at 02:18 AM
Sion's current LiS testing on UAV is half way there...
"The base cells in the battery packs used in this flight had a specific energy of 350 Wh/Kg. This is 50% greater than the best available lithium ion batteries."
Story under latest headlines....
http://www.sionpower.com/index.html
Posted by: Michael | August 17, 2007 at 07:13 PM
please sir i want to seek some more information about its compostion and its working its implementation so please let me know this...
its a fantastic invention but litium-ion based material is not cheap so mass production of it may be expensive.
Posted by: Arnia Arena | February 21, 2008 at 12:01 PM
Respected sir
I am in need of informatimn about the supercapacitor's principle and it's functioning.
How polymer as electrode material for the energy storage device's? and breif explaination about what happends when the process of charging and discharging?
Posted by: RICHARD PRABHU | July 22, 2008 at 07:41 AM
hello sir
i am interested in knowing more about this topic.so please inform me as soon as possible
Posted by: pooja | September 01, 2008 at 09:20 AM
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Interesting from an academic point of view, in that it demonstrates that batteries, electric double layer capacitors and their hybrid form, the pseudo-capacitor, differ primarily in the electrolytes used.
In practical terms, this innovation is relevant only if them material is sufficiently safe and cheap to manufacture. For automotive applications, it also has to simultanously meet stringent demands for high specific capacity, high specific power and longevity. It's possible to build battery-supercap combos with off-the-shelf components today, but they result is bulky and expensive.