Self-Powered Flexible Electronics

Touch-screen computing is all the rage, appearing in countless smart phones, laptops, and tablet computers.

On a bender: This machine is testing the electrical properties of a graphene sheet. Korean researchers have incorporated these stretchy electrodes with thin-film nano-generators to make an energy-harvesting screen. Credit: Advanced Materials

Now researchers at Samsung and Sungkyunkwan University in Korea have come up with a way to capture power when a touch screen flexes under a user's touch. The researchers have integrated flexible, transparent electrodes with an energy-scavenging material to make a film that could provide supplementary power for portable electronics. The film can be printed over large areas using roll-to-roll processes, but are at least five years from the market.

The screens take advantage of the piezoelectric effect--the tendency of some materials to generate an electrical potential when they're mechanically stressed. Materials scientists are developing devices that use nanoscale piezoelectronics to scavenge mechanical energy, such as the vibrations caused by footsteps. But the field is young, and some major challenges remain. The power output of a single piezoelectric nanowire is quite small (around a picowatt), so harvesting significant power requires integrating many wires into a large array; materials scientists are still experimenting with how to engineer these screens to make larger devices.

Samsung's experimental device sandwiches piezoelectric nanorods between highly conductive graphene electrodes on top of flexible plastic sheets. The group's aim is to replace the rigid and power-consuming electrodes and sensors used on the front of today's touch-screen displays with a flexible touch-sensor system that powers itself. Ultimately, this setup might generate enough power to help run the display and other parts of the device functions. Rolling up such a screen, for instance, could help recharge its batteries.

"The flexibility and rollability of the nano-generators gives us unique application areas such as wireless power sources for future foldable, stretchable, and wearable electronics systems," says Sang-Woo Kim, professor of materials science and engineering at Sungkyunkwan University. Kim led the research with Jae-Young Choi, a researcher at Samsung Advanced Institute of Technology.

The same group previously put nano-generators on indium tin oxide electrodes. This transparent, conductive material is used to make the electrodes on today's displays, but it is inflexible.

To make the new nano-generators, the researchers start by growing graphene--a single-atom-thick carbon material that's highly conductive, transparent, and stretchy--on top of a silicon substrate, using chemical vapor deposition. Next, through an etching process developed by the group last year, the graphene is released from the silicon; and the graphene is removed by rolling a sheet of plastic over the surface. The graphene-plastic substrate is then submerged in a chemical bath containing a zinc reactant and heated, causing a dense lawn of zinc-oxide nanorods to grow on its surface. Finally, the device is topped off with another sheet of graphene on plastic.

In a paper published this month in the journal Advanced Materials, the Samsung researchers describe several small prototype devices made this way. Pressing the screen induces a local change in electrical potential across the nanowires that can be used to sense the location of, for example, a finger, as in a conventional touch screen. The material can generate about 20 nanowatts per square centimeter. Kim says the group has subsequently made more powerful devices about 200 centimeters squared. These produce about a microwatt per square centimeter. Kim says this is enough for a self-powered touch sensor and "indicates we can realize self-powered flexible portable devices without any help of additional power sources such as batteries in the near future."

Solar Cost ­Cutter

A highly reflective thin film made of microlayers of silver and copper, protected by a polymer and backed with adhesive, could cut the cost of solar thermal power plants by hundreds of millions of dollars. In most such plants, glass mirrors concentrate heat from the sun to create steam that spins conventional turbines. The thin film--which replaces those mirrors--reflects more light, increasing power output.

Courtesy of 3M

New Life for Old Tires The process involves freezing old rubber and shattering it into small particles--resulting in new, low-cost materials.

Of the nearly 300 million tires discarded in the United States each year, more than half end up either as landfill or are burned for fuel in cement kilns and in other industries.

Lehigh Technologies of Tucker, GA, has developed a process for rejuvenating discarded rubber that could open up new recycling opportunities. If the company's technology catches on, it could carve out a billion-dollar market for high-performance recycled rubber.

Used rubber is hard to recycle because it is vulcanized--hardened and rendered chemically inert--by the addition of sulfur and other compounds to the material's long molecular chains. Small chunks of used tires can be partially melted and used as filler in asphalt, but devulcanizing rubber involves expensive chemical and thermal processes.

Lehigh Technologies instead shatters rubber into a fine powder using a process that involves freezing old rubber and smashing it to pieces. This starts with tires that have been torn into half-inch chunks using conventional shredding equipment. Lehigh mixes these rubber pieces with liquid nitrogen, cryogenically cooling the rubber to -100°C. The rubber is then fed into a high speed "turbomill" that shatters it into particles no more than 180 microns in size.

Creating such fine powder transforms the rubber from a highly inert filler material to one that can bond with other materials. "We deliver a huge increase in surface area relative to size, and that allows for a much more intimate mixing with other materials," says Lehigh Technologies CEO Alan Barton.

In 2006, Lehigh Technologies opened its first commercial facility, which has a capacity to produce 100 million pounds of rubber powder and to process four million tires per year. Sales of the company's products increased by 40 percent last year, but the facility is still operating at less than half capacity. Barton says that his firm has sold recycled rubber to a number of leading tire manufacturers. He estimates that 30 million tires now on the road in the United States are made in part with his company's recycled rubber, although only about 3 to 7 percent of all the rubber in these tires is their recycled material.

This is largely because Lehigh's rubber is still technically vulcanized. Carbon atoms in the rubber are still bound to sulfur atoms, and these bonds prevent them from forming covalent bonds with surrounding materials.

The company recently opened an in-house research center that is looking to change the chemical properties of powders it produces, to make their surfaces more reactive. The company has also developed ways to make recycled rubber bind to surrounding materials via noncovalent, intermolecular bonds.

Nearly a third of Lehigh's annual output also goes to specialty applications, from paints and coatings to injection mold plastics. Lehigh's PolyDyne and MicroDyne powders can be used to replace as much as 40 percent of the polymers that normally go into plastic.

PolyDyne, the larger and less expensive of Lehigh's two rubber powders, sells for just under 50 cents a pound; finer grained MicroDyne requires colder temperatures and higher milling speeds, making it significantly more expensive. PolyDyne is half the cost of nonrecycled synthetic rubber, a third of the price of natural rubber, and nearly half the cost of polypropylene, a polymer commonly used in plastic moldings.

This is an area that Lehigh's investors are particularly interested in.

"Pick whatever plastic product you want to make and it will have specific technical performance requirements," says Ben Kortlang a partner at venture capitol firm Kleiner Perkins Caufield & Byers, which recently invested in Lehigh Technologies. "Using a blend of PolyDyne and traditional materials, there will typically be a cost savings and, in many cases, a performance improvement. And many of these markets could be very, very large."

Big Energy Storage in Thin Films New ultracapacitor material could be fabricated directly on chips and solar cells.

Energy storage devices called ultracapacitors can be recharged many more times than batteries, but the total amount of energy they can store is limited. This means that the devices are useful for providing intense bursts of power to supplement batteries but less so for applications that require steady power over a long period, such as running a laptop or an engine.

Micro ultracapacitor: This thin-film carbon ultracapacitor electrode, shown in a microscope image, is about 50 micrometers on each side. The zigzagging, porous regions are the active part of the device. Credit: Min Heon

Now researchers at Drexel University in Philadelphia have demonstrated that it's possible to use techniques borrowed from the chip-making industry to make thin-film carbon ultracapacitors that store three times as much energy by volume as conventional ultracapacitor materials. While that is not as much as batteries, the thin-film ultracapacitors could operate without ever being replaced.

These charge-storage films could be fabricated directly onto RFID chips and the chips used in digital watches, where they would take up less space than a conventional battery. They could also be fabricated on the backside of solar cells in both portable devices and rooftop installations, to store power generated during the day for use after sundown. The materials have been licensed by Pennsylvania startup Y-Carbon.

An ultracapacitor is "an electrical energy source that has virtually unlimited lifetime," says Yury Gogotsi, professor of materials science and engineering at Drexel University in Philadelphia, who led the development of the thin-film ultracapacitors. "It will live longer than any electronic device and never needs to be replaced." While batteries store and release energy in the form of chemical reactions, which cause them to degrade over time, ultracapacitors work by transferring surface charges. This means they can charge and discharge rapidly, and because the electrode materials aren't involved in any chemical reactions, they can be cycled hundreds of thousands of times. Researchers have begun developing thin-film ultracapacitor materials but have had difficulty getting high enough total energy storage using practical fabrication methods, says Gogotsi.

Gogotsi's group uses a high-vacuum method called chemical vapor deposition to create thin films of metal carbides such as titanium carbide on the surface of a silicon wafer. The films are then chlorinated to remove the titanium, leaving behind a porous film of carbon. In each place where a titanium atom was, a small pore is left behind. "The film is like a molecular sponge, where the size of each pore is equal to the size of a single ion," says Gogotsi. This matching means that when used as the charge-storage material in an ultracapacitor, the carbon films can accumulate a large amount of total surface charge. The Drexel researchers complete the device by adding metal electrodes to either surface to carry current into and out of the device and adding a liquid electrolyte to carry the charges. They found that the performance of the device is best when the carbon material is about 50 micrometers thick, about the same as the width of a human hair.

The Drexel researchers first developed this ultracapacitor material a few years ago; today in the journal Science they report the first demonstration of thin films made from it. Conventional ultracapacitors are made from powdered activated carbon. These powders can't be used to make large, thin films because they won't stick to the surface. Other groups have developed printable thin-film ultracapacitors based on carbon nanotubes; Gogotsi says his devices can store more charge.

Gogotsi says there is, in theory, no limit to the size of the films that could be made using these methods, which are used by the solar industry and display industries to make panels as large as nine square meters. Because the carbon films are thin and can be made at temperatures as low as 200 ºC, it might be possible to integrate them with flexible electronics.

Wind Turbines Shed Their Gears

Wind turbine manufacturers are turning away from the industry-standard gearboxes and generators in a bid to boost the reliability and reduce the cost of wind power.

Power ring: This three-megawatt wind turbine uses permanent magnets and a design that makes it significantly lighter than a conventional geared turbine. Credit: Siemens

Siemens has begun selling a three-megawatt turbine using a so-called direct-drive system that replaces the conventional high-speed generator with a low-speed generator that eliminates the need for a gearbox. And last month, General Electric announced an investment of 340 million euros in manufacturing facilities to build its own four-megawatt direct-drive turbines for offshore wind farms.

Most observers say the industry's shift to direct-drive is a response to highly publicized gearbox failures. But Henrik Stiesdal, chief technology officer of Siemens's wind power unit, says that gearbox problems are overblown. He says Siemens is adopting direct-drive as a means of generating more energy at lower cost. "Turbines can be made more competitive through direct-drive," says Stiesdal.

Siemens's plans hinge on a new design that reduces the weight of the system's generator. In conventional wind turbines, the gearbox increases the speed of the wind-driven rotor several hundred fold, which radically reduces the size of the generator required. Direct-drive generators operate at the same speed as the turbine's blades and must therefore be much bigger--over four meters in diameter for Siemens's three-megawatt turbine. Yet Siemens claims that the turbine's entire nacelle weighs just 73 metric tons--12 tons less than that on its less powerful, gear-driven 2.3-megawatt turbines.

Much of the weight reduction comes from the use of permanent magnets in the generators' rotor--a trick that GE is also using. Conventional turbine generators use electromagnets--copper coils fed with electricity from the generator itself. Henk Polinder, an expert in permanent-magnet generators at Holland's Delft University of Technology, says that a 15-millimeter-thick segment of permanent magnets can generate the same magnetic field as a 10- to 15-centimeter section of copper coils.

Stiesdal says Siemens reduced weight further by inverting its generator's design. Rather than a steel rotor covered with permanent magnets spinning inside a stationary doughnut-shaped stator (the design GE is using in its four-megawatt direct-drive turbine) Siemens's rotor is a steel cylinder with permanent magnets on the inside, and this rotor spins around a column-like stator.

A Caltech group has created materials that could improve the efficiency of solar cells.

In an advance that could lead to solar cells that more fully utilize sunlight, researchers at Caltech have designed materials that can bend visible light at unusual but precise angles, no matter its polarization. The scientists hope the materials are a step toward perfectly transparent solar-cell coatings that would direct all the sun's rays into the active area to improve solar power output.

Solar material: Caltech researcher Stanley Burgos uses a focused ion beam microscope to examine a new metamaterial. The material’s microscopic structure, visible on the computer screen, can be tuned to interact with light in unusual ways. Credit: Stanley Burgos

Many groups are working on novel antireflective solar cell coatings in the hopes of getting more light into solar cells. The Caltech group, which includes Harry Atwater, professor of applied physics and materials science, and researcher Stanley Burgos, is addressing the problem by precisely tailoring the structure of materials at the nano and micro scales, creating "metamaterials" that exhibit optical properties that are not found in naturally occurring materials. In the most recent work, Atwater and his coworkers demonstrated a material that precisely controls the path of visible light regardless of the polarization of the light--a first for metamaterials.

The Caltech metamaterial is a metal film several hundred nanometers thick. The films are patterned with circular cavities, each of which surrounds a wirelike column made of the same material. The space between the wire and the cavity wall is filled with a second metal. Depending on the dimensions of the patterns, the material bends, or refracts, light of different colors to a different degree. Atwater says the goal of his project is to make films with a refractive index exactly equal to that of air. Such a material would not bend light at all but would transmit it perfectly, with no reflection. When light moves from one medium to another, it scatters--this is why a straw in a glass of water appears to be broken. There's a mismatch between the refractive index of water and air. A solar cell coated with a material whose refractive index is identical to that of air would reflect no light at all.

The films that Atwater's group is making are metallic conductors, and could also serve as the top electrode on a solar cell. Atwater says that while some metamaterial designs have been complex to make and involve multilayered structures, these single-layer films can be made using lithography and etching techniques commonplace in the chip-making industry.

The ability of the material to work with both polarizations of light is exciting, says Nicholas Fang, professor of materials science and engineering at the University of Illinois at Urbana-Champaign. But, he says, one of the major remaining challenges in engineering metamaterials is loss. As these metal structures interact with light, they lose energy to heat. This heat loss is so great in Atwater's current materials that just 40 percent of incident light passes through them.

For solar applications, Atwater says his goal is a metamaterial film that passes 90 percent of the light. To that end, his group and others in the field are developing ways to amplify light as it passes through metamaterials. Optical amplifiers are used in lasers and in telecommunications; incorporating them with thin films like Atwater's will enable metamaterials to find their way into practical applications in devices like solar cells.

Salt and Paper Battery May One Day Replace Lithium Batteries

A new thin-film battery has electrodes made of polymer-coated paper and an electrolyte made of salt-soaked paper. A laboratory prototype shows the cell pressed between glass slides and packaged At Uppsala University in Sweden, researchers have developed a flexiblebattery made of two inexpensive materials: cellulose and salt.

The cellulose is derived from a polluting algae found in seas and lakes. The algae's walls contain cellulose that has a different nanostructure, which gives it 100 times the surface area.

The battery is made by coating the paper, made from this cellulose, with a conducting polymer and inserting a salt-solution-soaked filter paper between the paper electrodes.

Chlorine ions travel from the batteries positive terminal to the negative terminal while current is produced in the external circuit by the flow of electrons.

The battery can be recharged in tens of seconds because the ions flow through the thin electrode quickly. In comparison to a lithium battery that would take 20 minutes to recharge.

The salt and paper battery is still in the early stages of development as compared to other thin-film technologies. For a battery to be cost effective you need to able to obtain the material at relatively low cost and have a good manufacture process in place.

The battery could be produced commercially in about three years and made available to distributors. link..

$21 Billion Orbiting Solar Array will Beam Electricity to Earth

Artist conception of the SSPS (Space solar power system). Image credit: USEFThe project, to be undertaken by a research group from 16 companies including Mitsubishi Heavy Industries Ltd, aims to spend the next four years developing the technology needed to beam the electricity produced to earth. They expect that as fossil fuels run out, an orbiting solar power plant in space may be needed to provide a significant source of electricity in the future, according to the Kensuke Kanekiyo, from the Japanese Government's Institute of Energy Economics.

The planned solar station will produce 1 Gigawatt of electricity from its four km² (approximately 2.5 square miles) array of solar panels, which is enough to power just under 300,000 Tokyo homes, at present usage levels. Since the array will be in orbit some 36,000 km (22,500 miles) above the earth's surface, it will be unaffected by weather conditions and will be able to generate power constantly.

The U.S. agency NASA has been investigating the possibilities of a space-based solar system for several decades and has spent around $80 million on the research. They and other government agencies estimate the cost of electricity supplied from an orbiting solar array could be around $1 billion per megawatt, which is too expensive to be commercially viable.The Japanese realize the cost of building the solar station in orbit would be prohibitive at the moment, and the array could not be commercially viable at today's prices. The Japanese consortium therefore has to find ways of drastically reducing the costs. With the launch of a single rocket costing around 10 billion yen, the cost of the space solar station could be as high as two trillion yen, according to Koji Umehara, the Director of the Japanese Space Development and Utilization ministry, making the electricity supplied exorbitantly expensive.

The first step in bringing the plans to fruition will be the launch in around 2015 of a satellite fitted with solar panels that will beam electricity to earth.

JAXA, the Japan Aerospace Exploration Agency plans to have the orbiting space solar system operational some time in the 2030s. link..

Germany paves way to offshore wind farms

The German government on Wednesday agreed a plan to set aside special zones off its northern coast for a host of wind farms that could provide energy for more than eight million homes. link..

Toyota to Deliver Plug-In Hybrids

The new Prius is designed so that its battery pack can be swapped out for a plug-in lithium-ion battery.Today at the North American International Automotive Show, in Detroit, Toyota announced that later this year, it will release a version of the Prius hybrid car whose battery can be recharged from an ordinary power outlet. By moving up the delivery data of the plug-in vehicle--originally scheduled for 2010--Toyota has slipped ahead of GM, whose Chevy Voltplug-in is promised for late 2010.

Plug-ready Prius: Toyota will roll out 500 plug-in hybrid cars later this year by adding lithium-ion batteries to the 2010-model Prius unveiled yesterday at the Detroit auto show. Toyota is a full year ahead of GM’s schedule for the Chevy Volt plug-in but behind China’s BYD, which launched its F3DM plug-in sedan in China last month. Credit: Toyota Motor

Toyota's fidelity to hybrid technology marks a sharp contrast with rivals such as Renault and Mitsubishi, which are planning to leapfrog the hybrid in favor of fully battery-powered electric vehicles (EVs). At the auto show, several U.S. automakers appear to be leaning in the same direction, with Ford Motor, in particular, vowing to release an EV commercial van next year and an EV commuter car in 2011.

Even Toyota is hedging its bets, presenting a battery-powered EV based on its four-seat iQ and promising to begin selling a similar EV commuter car in the United States by 2012. But Toyota explicitly ruled out abandoning hybrid technology anytime soon, issuing a definitive statement on the eve of the Detroit show calling hybrids its "long-term core powertrain technology."

The 2010 Prius available to consumers will still come equipped with a nickel-metal-hydride (NiMH) battery pack and no plug, but Toyota says that it is "plug-in ready"--designed and engineered to accept a lighter and more energy-dense lithium-ion battery pack that can be charged from the grid. Toyota will also produce 500 lithium-powered plug-in Priuses for its commercial and government leasing customers starting later this year. Toyota-Panasonic joint venture Panasonic EV Energy will supply the lithium batteries.

The fact that the plug-in battery pack can be swapped in for an ordinary hybrid battery suggests that it will be relatively small, and that the plug-in Priuses will have a smaller electric-only range than the Volt and the Chinese-built BYD F3DM. The plug-in vehicles that Toyota has been testing in Japan, France, California, and the United Kingdom are Priuses equipped with a second NiMH battery pack that gives them less than 10 miles of electric-only range. link..

A Gas-Sipping Van

A spinoff from the Rocky Mountain Institute has developed a 100-miles-per-gallon plug-in hybrid.Last week, Bright Automotive, a startup based in Anderson, IN, unveiled a plug-in hybrid utility van designed to travel 50 miles on half a gallon of gasoline. The company plans to start producing the Idea vehicle in large volume by the end of 2012, and it hopes to sell 50,000 a year starting in 2013.

Bright Idea: A plug-in hybrid from Bright Automotive called the Idea. Credit: Bright Automotive

At a time when dozens of automakers are developing new hybrids and electric vehicles, Bright is notable because of its history. Its CEO, John Waters, designed the battery pack for the EV-1, GM's first electric vehicle, and the company is a spinoff from the Rocky Mountain Institute, a highly regarded nonprofit based in Boulder, CO. The institute is famous for proposing in the mid-1990s to radically change the design of cars to make them more efficient. The Idea is the partial realization of its Hypercar concept, a hybrid vehicle that would use as little as one-fifth the amount of fuel that today's vehicles use. It does so by combining a hybrid of gas and electric propulsion (and eventually fuel cells instead of the gas engine) with lightweight composite materials, an aerodynamic design, and more efficient electronic accessories. The Rocky Mountain Institute had started another company to develop the Hypercar, but that vehicle never made it into production.

Bright thinks that its new business model, which involves selling vehicles to commercial and government fleets rather than to the public, could help make things different this time. Fleet customers look at the total cost of ownership, Waters says, not just the up-front cost, which is higher for plug-in hybrids, since they incorporated both a gas engine and an electric motor and also require a costly battery pack. He says that over the life of the vehicle, fuel savings will make up for the higher initial cost. Several potential customers have already signed letters of intent to purchase the vehicle once it's in mass production, says Lyle Shuey, Bright's vice president of marketing and sales. The van was designed in cooperation with a number of potential customers, including Duke Energy--an investor in Bright--and Cox Communications. link..

IBM Invests in Battery Research

IBM Research is beginning an ambitious project that it hopes will lead to the commercialization of batteries that store 10 times as much energy as today's within the next five years. The company will partner with U.S. national labs to develop a promising but controversial technology that uses energy-dense but highly flammable lithium metal to react with oxygen in the air. The payoff, says the company, will be a lightweight, powerful, and rechargeable battery for the electrical grid and the electrification of transportation.

Waterproof power: This protective casing envelops a functioning lithium-metal battery electrode, excluding water but letting lithium ions pass. It’s part of a prototype battery made by PolyPlus Battery of Berkeley, CA. Credit: PolyPlus

Lithium metal-air batteries can store a tremendous amount of energy--in theory, more than 5,000 watt-hours per kilogram. That's more than ten-times as much as today's high-performance lithium-ion batteries, and more than another class of energy-storage devices: fuel cells. Instead of containing a second reactant inside the cell, these batteries react with oxygen in the air that's pulled in as needed, making them lightweight and compact.

IBM is pursuing the risky technology instead of lithium-ion batteries because it has the potential to reach high enough energy densities to change the transportation system, says Chandrasekhar Narayan, manager of science and technology at IBM's Almaden Research Center, in San Jose, CA. "With all foreseeable developments, lithium-ion batteries are only going to get about two times better than they are today," he says. "To really make an impact on transportation and on the grid, you need higher energy density than that." One of the project's goals, says Narayan, is a lightweight 500-mile battery for a family car. The Chevy Volt can go 40 miles before using the gas tank, andTesla Motors' Model S line can travel up to 300 miles without a recharge.

One of the main challenges in making lithium metal-air batteries is that "air isn't just oxygen," says Jeff Dahn, a professor of materials science at Dalhousie University, in Nova Scotia. Where there's air there's moisture, and "humidity is the death of lithium," says Dahn. When lithium metal meets water, an explosive reaction ensues. These batteries will require protective membranes that exclude water but let in oxygen, and are stable over time. link...

A Better Battery for Laptops

Boston-Power says that it's poised to enter the market for portable power, with a notebook battery the company claims is safer, lasts longer, and can be charged faster. The Westborough, MA, startup recently announced that it is more than tripling production of its high-performance battery, called the Sonata, after receiving $45 million in a third round of venture financing. The move puts the company in a position to mass-produce and commercialize its next-generation lithium-ion battery within months.

Staying power: These battery cells are capable of recharging up to 80 percent of their capacity in 30 minutes, and they retain 80 percent of their strength after three years. The image on bottom shows a side-by-side comparison of the heat given off by two batteries generating the same level of energy: on the left is a battery from a current market leader, and on the right, Boston-Power’s Sonata battery. The green colors represent cooler temperatures. High temperatures can lead to explosive battery malfunction. (The brightly colored section outlined in black represents the batteries. The remaining area shows heat emitted by the laptop.) Credit: Boston-Power

"In partnership with GP Batteries, one of Asia's largest battery manufacturers, we now have our second factory up and running in the greater China region," says Christina Lampe-Onnerud, the company's founder and CEO. In 2002, Technology Review named Lampe-Onnerud one of its top innovators under the age of 35 for her efforts to develop better-performing lithium-ion batteries with less volatile substances. Based on that research, she founded Boston-Power in 2005. Now, after raising $68 million in total, she says that her company will be able to manufacture a million battery cells per month by the end of 2008.

Oak Investment Partners, based in Westport, CT, provided this latest infusion of capital, building upon earlier investments by Venrock Associates, Granite Global Ventures, and Gabriel Venture Partners.

Although the Sonata will not offer greater energy capacity per use--with a four-hour run time, its performance will be average for the market--the company hopes that the battery's three-year life span, innovative safeguards, and ability to recharge quickly will help it gain a foothold in the battery market. As opposed to existing notebook batteries, which can take an hour to recharge to 80 percent capacity, the Sonata can reach that same level in just 30 minutes, according to Boston-Power. And whereas current batteries degrade very quickly, permanently losing up to 50 percent of their capacity within months, the Sonata retains up to 80 percent of its capacity over three years. In fact, since the typical laptop battery tends to degrade very rapidly, the Sonata will have a greater per-use capacity in the long run. link...

John McCain, Battery Booster

The senator's proposed $300 million prize for an electric-car battery prompts excitement, skepticism.Earlier this week, Senator John McCain, the presumptive Republican presidential nominee, proposed a $300 million federally funded prize to spur the development of a vastly improved battery for electric cars and plug-in hybrids. While McCain offered few specifics, industry experts say that in targeting battery costs, he has identified a major obstacle to reducing fuel consumption in cars.

Credit: Technology Review

"Current vehicle-battery developers all recognize that reducing battery cost is instrumental in the adoption of hybrid-electric and plug-in hybrid vehicles" that recharge from the power grid, says Yet-Ming Chiang, founder of A123 Systems, a Watertown, MA, company that develops advanced lithium-ion batteries and is working with several carmakers on plug-in hybrids. "Offering this prize is a great way to focus attention on the problem and get the dialogue going on how we will solve it. I would love to compete for this prize, and the wheels are turning in my mind."

McCain said that new batteries should "leapfrog" the size, capacity, and power of commercially available models, and at 30 percent of current costs. But since plug-in hybrids are not on the market yet, there is no clear basis for estimating a cost savings. "It's hard to measure without a benchmark," says Gerbrand Ceder, a professor of materials science and engineering at MIT. Ceder calls the McCain statement a "political stunt" and says that the money would be better invested in R&D than in an after-the-fact prize. The McCain campaign did not return a phone call seeking more specifics.

Ceder estimates that it will cost around $5,000 to manufacture a plug-in-hybrid battery that holds 10 kilowatt-hours of electricity. But 10 kilowatt-hours doesn't get you very far; the Volt, a plug-in hybrid being developed by Chevrolet, lists an electric-drive range of 40 miles on a battery that holds 16 kilowatt-hours of electricity. Cutting battery costs by 70 percent--while further boosting capacity and range in a battery of manageable size--"will require a serious amount of innovation, new materials, and new manufacturing procedures," Ceder says. link..

A Blended Battery Pack for Cars

Combining different battery technologies could improve vehicle performance and reduce costs.The race is on to find the ideal battery chemistry for plug-in hybrids and all-electric vehicles, but a startup in Indiana believes that a combination of different storage technologies might be the best way to improve vehicle performance and reduce cost. The company's technology allows vehicles to run on a combination of fuel cells, ultracapacitors, and old-fashioned lead-acid batteries.

Smart switch: Indy Power Systems has developed the Multi-Flex Energy Management System, a laptop-size power converter. The system allows makers of plug-in electric vehicles to use a combination of power sources--including lead-acid and lithium-ion batteries and ultracapacitors--and optimizes the blend to increase battery life, improve performance, and reduce cost. Credit: Steve Tolen

Noblesville-based Indy Power Systems has developed an energy management system for vehicles that can quickly switch between two or more energy sources, even when their voltages are different. "It's basically a switch that directs energy in any amount and any direction," says Steve Tolen, chief executive officer and founder of Indy Power, which operates out of Purdue Research Park. "The hardware handles the switching, and the software handles the timing and amounts."

Tolen says that the power electronics package--called the Multi-Flex Energy Management System--is only slightly larger than a laptop computer. He describes it as a custom, software-controlled, DC-to-DC converter that's bidirectional and variable.

"Imagine adding hot and cold water to a tub. We can add a variable amount of hot and a variable amount of cold in different volumes to match the outflow of the drain, which can also be variable," Tolen explains. "In other words, the motor can ask for different amounts of current, and we can provide that, and in different ratios from the two (or more) power sources, regardless of the voltage of the power sources."

link..

Waterproof Lithium-Air Batteries

A company based in Berkeley, CA, is developing lightweight, high-energy batteries that can use the surrounding air as a cathode. PolyPlus is partnering with a manufacturing firm to develop single-use lithium metal-air batteries for the government, and it expects these batteries to be on the market within a few years. The company also has rechargeable lithium metal-air batteries in the early stages of development that could eventually power electric vehicles that can go for longer in between charges.

Water power: A prototype battery made by PolyPlus uses lithium metal as the anode and salt water as the cathode to power an LED. As the battery discharges, lithium ions diffuse into the water, but the device doesn’t harm the surrounding clown fish. Credit: PolyPlus

Interest in lithium metal-air batteries has been growing in recent years, along with the demand for lighter power sources for devices ranging from plug-in hybrid vehicles to laptops. In lithium-ion batteries, the electrodes are made of materials such as graphite, while in a lithium-metal battery, the anode is made up entirely of lithium metal, and the surrounding air can act as the cathode.

Lithium-metal batteries approach the energy density of fuel cells without the plumbing needed for these devices; in theory, the maximum energy density is more than 5,000 watt-hours per kilogram, or more than 10 times that of today's lithium-ion batteries. Lithium metal-air batteries are also very lightweight because it's not necessary to carry a second reactant. Lithium metal is "the holy-grail battery material," says Steven Visco, chief technical officer and founder of PolyPlus.

IBM recently announced that it would develop lithium metal-air batteries for the energy grid and for transportation. "Lithium ion is the gold standard, but what can beat it is lithium metal," says Paul Beach, president of battery manufacturer Quallion of Sylmar, CA.

Using lithium metal as a battery electrode, however, has proved problematic, mainly because the material reacts rapidly and violently with water. "People have thought about lithium-air batteries for decades, but there's always water in the air," says Visco. Exposure to even traces of water rapidly degrades the material link..