Oscillating electric field drastically reduces battery recharge time

Wait, there's more!

(PhysOrg.com)

-- Part of the headache of having to constantly recharge batteries is not just how often they need to be charged, but also the time it takes to charge them. In a new study, researchers have proposed a charging method that could greatly reduce the charging time of lithium-ion batteries, which are used in everything from electronic devices to electric vehicles. The new method uses an additional oscillating electric field (besides the charging field) that should be capable of charging a lithium-ion battery in a fraction of the time compared with traditional methods.

Researchers Ibrahim Abou Hamad from Mississippi State University and coauthors have developed the new charging method thanks to revolutionary developments in molecular dynamics simulations. In their study, the researchers simulated the lithium-ion battery-charging process by simulating the intercalation (i.e. “insertion”) of lithium ions into the battery’s graphite anode. Although intercalation is just one part of the charging process (along with diffusion), it dominates the charging time.

In the charging process, lithium ions first diffuse within the battery’s electrolyte until they reach the graphite anode. At this interface, ions must overcome an energy barrier in order to be intercalated into the anode.

In their simulations, Hamad and his team found that an additional oscillating electric field can lower this energy barrier, enabling lithium ions to intercalate more quickly into the anode. The oscillating field also increases the diffusion rate, which helps further reduce the overall charging time, albeit to a lesser extent.

Specifically, when the scientists applied an oscillating square-wave field with a frequency of 25 GHz and an amplitude of 5 kCal/mol to the graphite sheets in the anode, the lithium ions intercalated into the graphite sheets within an average time of about 50 nanoseconds. By changing the amplitude of the oscillating wave, the researchers found that they could further improve charging time by lowering the energy barrier and speeding up intercalation. Their simulations showed that the dependence of the intercalation time on the amplitude is exponential, meaning that a small increase in amplitude leads to a large increase the intercalation speed, which offers the potential for very fast charging times.

In the future, the researchers plan to further investigate the new method, including analyzing how changing the frequency of the oscillating field effects the charging time. They noted that the new method might provide an increase in battery power densities, as well.

More information: Ibrahim Abou Hamad, M. A. Novotny, D. Wipf, and P. A. Rikvold. “A new battery-charging method suggested by molecular dynamics simulations.” Available at arxiv.org. Doi: 10.1039/b920970k.

Thermopower Waves in Carbon Nanotubes Create Electricity

Thermopower waves? New ways to produce electricity? Why are my "bogus" alarms going off?
First "sferics” and now this. I've never seen such a bizarre group of articles at one time in Physorg...

Physorg.com:

MIT researchers discover new way of producing electricity

March 7, 2010 by David Chandler

Enlarge

A carbon nanotube (shown in illustration) can produce a very rapid wave of power when it is coated by a layer of fuel and ignited, so that heat travels along the tube. Graphic: Christine Daniloff

(PhysOrg.com) -- A team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.

The phenomenon, described as thermopower waves, “opens up a new area of energy research, which is rare,” says Michael Strano, MIT’s Charles and Hilda Roddey Associate Professor of Chemical Engineering, who was the senior author of a paper describing the new findings that appeared in Nature Materials on March 7. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.

Like a collection of flotsam propelled along the surface by waves traveling across the ocean, it turns out that a thermal wave — a moving pulse of heat — traveling along a microscopic wire can drive electrons along, creating an electrical current.

The key ingredient in the recipe is carbon nanotubes — submicroscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms. These tubes, just a few billionths of a meter (nanometers) in diameter, are part of a family of novel carbon molecules, including buckyballs and graphene sheets, that have been the subject of intensive worldwide research over the last two decades.

A previously unknown phenomenon

In the new experiments, each of these electrically and thermally conductive nanotubes was coated with a layer of a reactive fuel that can produce heat by decomposing. This fuel was then ignited at one end of the nanotube using either a laser beam or a high-voltage spark, and the result was a fast-moving thermal wave traveling along the length of the carbon nanotube like a flame speeding along the length of a lit fuse. Heat from the fuel goes into the nanotube, where it travels thousands of times faster than in the fuel itself. As the heat feeds back to the fuel coating, a thermal wave is created that is guided along the nanotube. With a temperature of 3,000 Kelvin, this ring of heat speeds along the tube 10,000 times faster than the normal spread of this chemical reaction. The heating produced by that combustion, it turns out, also pushes electrons along the tube, creating a substantial electrical current.

Combustion waves — like this pulse of heat hurtling along a wire — “have been studied mathematically for more than 100 years,” Strano says, but he was the first to predict that such waves could be guided by a nanotube or nanowire and that this wave of heat could push an electrical current along that wire.

In the group’s initial experiments, Strano says, when they wired up the carbon nanotubes with their fuel coating in order to study the reaction, “lo and behold, we were really surprised by the size of the resulting voltage peak” that propagated along the wire.

After further development, the system now puts out energy, in proportion to its weight, about 100 times greater than an equivalent weight of lithium-ion battery.

The amount of power released, he says, is much greater than that predicted by thermoelectric calculations. While many semiconductor materials can produce an electric potential when heated, through something called the Seebeck effect, that effect is very weak in carbon. “There’s something else happening here,” he says. “We call it electron entrainment, since part of the current appears to scale with wave velocity.”

The thermal wave, he explains, appears to be entraining the electrical charge carriers (either electrons or electron holes) just as an ocean wave can pick up and carry a collection of debris along the surface. This important property is responsible for the high power produced by the system, Strano says.

Exploring possible applications

Because this is such a new discovery, he says, it’s hard to predict exactly what the practical applications will be. But he suggests that one possible application would be in enabling new kinds of ultra-small electronic devices — for example, devices the size of grains of rice, perhaps with sensors or treatment devices that could be injected into the body. Or it could lead to “environmental sensors that could be scattered like dust in the air,” he says.

In theory, he says, such devices could maintain their power indefinitely until used, unlike batteries whose charges leak away gradually as they sit unused. And while the individual nanowires are tiny, Strano suggests that they could be made in large arrays to supply significant amounts of power for larger devices.

The researchers also plan to pursue another aspect of their theory: that by using different kinds of reactive materials for the coating, the wave front could oscillate, thus producing an alternating current. That would open up a variety of possibilities, Strano says, because alternating current is the basis for radio waves such as cell phone transmissions, but present energy-storage systems all produce direct current. “Our theory predicted these oscillations before we began to observe them in our data,” he says.

Also, the present versions of the system have low efficiency, because a great deal of power is being given off as heat and light. The team plans to work on improving that.

1 Gigawatt Mag-Lev Windturbines from China—with a return on investment of 12 months!!??

I can't stop. Here's one more from gizmag.com:

July 31, 2007 — Sustainable generation of electric power is the key to realizing the vision of a world free from dependency on fossil fuels – the challenge is to ramp up the production of electricity to a level that can begin to approach the energy we get from burning coal and oil, without the perceived dangers of going nuclear. The combined threats of Peak Oil and global warming are spurring science into a furious new age of innovation. . . . almost daily breakthroughs in solar energy capture, battery technology and tidal energy harvesting, but the biggest contribution to green power thus far is coming from wind farming. The common windmill design used to capitalize on air currents, while centuries old, operates at around 1% efficiency in terms of the power it harvests from the wind, due to the deflective blade design and friction losses. But a new technology unveiled last year in China seeks to dramatically boost the output of wind-driven generators by using the virtually frictionless advantages of magnetically levitated turbines. Since there’s virtually no touching of moving parts, the MagLev wind turbine requires far less servicing than a traditional windmill – which dramatically lowers the operating costs to under five U.S. cents per kilowatt-hour. If projections are accurate, giant 1-gigawatt versions of these machines could have a 12-month ROI - a scenario sure to catch the eye of investors worldwide.

Magnetic levitation uses the repelling properties of magnets to lift an object off the ground. In this case, the object is a wind-harvesting fan. The benefit of having it floating in midair is that it cuts down on the friction that causes so much inefficiency in the traditional windmill-style wind energy harvester we see dotting our coastlines. Friction is also the key factor necessitating frequent maintenance of windmill turbines, adding considerably to the cost of running them.

Without rotational friction to overcome, a wind turbine generator can begin to harvest power from air speeds as low as 1.5 meters per second.

Chinese researchers unveiled a prototype MagLev wind generator device at the Wind Power Asia exhibition in June 2006. The devices were hailed as a huge breakthrough in a vast and spread-out country that has more than 70 million households with no electricity. One innovative possible use could be to harvest wind energy from passing cars on freeways to power the roadside lighting.

American company Maglev Wind Turbine Technologies believes that scale is the answer and has released plans for a massive-scale installation. Pointing out that the low power outputs of current windmill units render them cost-ineffective to install and repair, the company proposes the building of giant 1-gigawatt units, each the size of an office building.

The company proposes that a one-unit wind farm of such scale would be less than half the price of windmill generatorsof equivalent output - it would last longer, be cheaper to build and run and therefore result in higher profits. In ideal conditions such a plant could have a power output similar to a nuclear power station and a 12-month return on investment.

Finally! The Ion-Propelled, Remotely-Powered Jet Pack!

this and the following item from a site I just discovered, gizmag.com:

Simple ion-propulsion craft, such as those shown in these videos, can be easily built and are thus often a popular science fair project for students.

The PFS patent adds a few key elements to this well-established technology; most importantly a new design for the capacitative thrust plates that emit and receive the electrical charges, and a system that pre-conditions the air between and around the plates to maximize thrust. The company also plan to remove the heavy power pack from the vehicle and "broadcast" pulses of DC power to the vehicle from ground stations based on theories from Nikola Tesla, the famous inventor and physicist responsible for the AC power system in the early 20th century.

PFS claim their ion-propulsion personal flight vehicles will be safer than helicopters or rockets, with their massive moving parts and explosive gases respectively. Ion propulsion, however, carries its own set of risks - particularly an elevated risk of throat and lung cancer if an individual is to breathe in too much ionized air - although this can be mitigated through a number of techniques.

[. . .]

The Inventor PFS is a start-up by Scott Redmond, a San Francisco-based tech executive and self-described "venture solutionist." While nobody talks his abilities and achievements up quite like Redmond's own webpage ("superhero-like ability" is quite a statement!), he is unquestionably an overachiever.

His recent projects have been focused on green, sustainable and new energy, including sustainable and self-powered homes like his NowHouse demo home, various electric vehicles and hydrogen power patents. He's also been active in virtual reality and a host of other areas. Clearly a brilliant man, Redmond suffers from a strange form of dyslexia that leaves him unable to aurally process numbers, sequences, times or time spans. to overcome this obstacle he developed a visual system of mathematics he calls "organic math" which has clearly been more than sufficient for him.