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South Korean capacitors for next generation of hybrids/EVs

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  • RemyC
    Super Charged A tiny South Korean company is out to make capacitors powerful enough to propel the next generation of hybrid-electric cars By Glenn Zorpette
    Message 1 of 1 , Feb 13, 2005
      Super Charged

      A tiny South Korean company is out to make capacitors powerful enough to
      propel the next generation of hybrid-electric cars

      By Glenn Zorpette

      Let's say it's 2010, and you're boiling off midlife ennui or burnishing your
      golden years in time-honored fashion: by zooming around in a
      high-performance road machine. The car accelerates powerfully, and yet it
      moves quietly and nimbly, slaloming through curves like a go-cart. Best of
      all, it sips gas like a connoisseur enjoying 40-year-old Armagnac. Would you
      believe you owe these rejuvenating, guilt-free thrills to a bunch of

      Not just any capacitors, of course. To understand what's going on under the
      hood of this car, you'll need to leave behind the Lilliputian world of the
      picofarad and the microfarad and enter the realm of the kilofarad. It is a
      place where NessCap Co., in Yongin, South Korea, holds sway.

      750-8, Gomae-Ri, Kiheung-Eup, Yongin,
      Kyonggi-Do, 449-901, Republic of Korea
      Tel 82-31-289-0721~5 Fax 82-31-286-6767~8
      marketing@ nesscap.com

      NessCap is one of about 10 makers of ultracapacitors, devices that can store
      so much charge that they are beginning to blur the functional distinction
      between the capacitor and the battery. And according to some experts, nobody
      does it better than NessCap, which offers a unit rated at an impressive 5000
      farads at 2.7 volts in a package a little bigger than a half-liter soda
      bottle. NessCap's capacitors "perform as well as or better than any others
      we've ever tested, in terms of energy and power density," says Marshall
      Miller, a research engineer at the University of California at Davis, where
      he specializes in testing advanced capacitors and other devices.

      Marshall Miller
      Research Engineer, ITS-Davis
      University of California, Davis
      One Shields Avenue
      Davis, California 95616-8762
      (530) 752-8758
      mmiller@ ucdavis.edu

      Ultracapacitors made by NessCap and others are just now starting to show up
      in products ranging from toys to experimental buses, basically as
      alternatives to batteries. The worldwide market isn't large; it was just US
      $38 million in 2002, the most recent year for which figures are available,
      according to the research firm Frost & Sullivan, in San Antonio. But NessCap
      and the handful of other makers of the largest ultracapacitors all have
      their sights set on the automotive market, which could do for their business
      what the iPod did for sales of MP3 songs. Frost & Sullivan, at least, is a
      believer; the company optimistically predicts total 2007 revenues for
      ultracapacitors of $355 million.

      Frost & Sullivan
      7550 W Ih 10
      San Antonio, TX 78229
      (210) 348-1000

      Danielle White
      Corporate Communications
      North America Team Leader
      210-247-2403 Fax: 210-348-1003

      Melina Gonzalez
      Corporate Communications
      Environment, Aerospace & Defense, Transportation, and Chemicals
      210-247-2440 Fax: 210-348-1003
      melina.gonzalez@ frost.com

      Stacie Jones
      Corporate Communications
      Best Practices
      210-247-2450 Fax: 210-348-1003
      stacie.jones@ frost.com

      Asia Pacific, Australasia & China
      D. Jeremiah
      Corporate Communications
      Tel: +603 6204 5832
      djeremiah@ frost.com

      More contacts:

      On paper, anyway, the idea is not far-fetched. In comparison with batteries,
      ultracapacitors can put out much more power for a given weight, can be
      charged in seconds rather than hours, and can function at more extreme
      temperatures. They're also more efficient, and they last much longer-in
      tests at the Idaho National Engineering and Environmental Laboratory, in
      Idaho Falls, upwards of 500 000 charge-discharge cycles have been recorded.
      Automotive traction batteries, for comparison, have much shorter lifetimes,
      particularly if they are discharged deeply.

      Pondering the relative strengths of capacitors and batteries, Joel
      Schindall, associate director of the Laboratory for Electromagnetic and
      Electronic Systems at the Massachusetts Institute of Technology, in
      Cambridge, says: "In all ways other than energy density, an electric field
      is superior to chemistry for storing energy regeneratively, because it is
      completely reversible" and therefore intrinsically efficient and durable.
      Part of Schindall's research focuses on advanced materials that could be
      used as electrodes in future ultracapacitors.

      Joel Schindall
      Professor Of The Practice and LEES Associate Director
      (617) 253-3934 Office: 10-097
      joels@ mit.edu
      Double Layer Capacitors: Automotive Applications and Modeling

      Ultracapacitors are now establishing themselves in niches demanding a power
      source that can recharge quickly, be sealed into a system that has to last
      for years, or put out prodigious amounts of power in short bursts.
      Tokyo-based Ricoh Co. is using them in copier machines to store the energy
      needed to warm up the machines quickly, minimizing time spent in the
      energy-wasting standby mode. Makers of high-end car stereo amplifiers are
      using ultracapacitors to deliver the surges of power demanded by musical
      crescendos, without straining the vehicle's battery.

      Another use is in solar tiles; a new twist in landscape architecture,
      they're used to guide pedestrians at night, by storing solar-generated
      electricity during the day and using it to power a small light-emitting
      diode panel after dark [see photo, "Bright Idea"]. Sealed into a walkway,
      wall, or staircase, these clear, rugged tiles have to last for a decade or
      more, working without fail night after night, withstanding subfreezing and
      sweltering temperatures alike-criteria only ultracapacitors can fulfill.

      And then there are cars. The hybrid-electric vehicle, in its various forms,
      is poised for an increasing share of the automotive market in several parts
      of the world, including the United States. And ultracapacitors have already
      found their way into hybrids, albeit in a minor role: hardly noticed among
      the Toyota Prius's many celebrated technical breakthroughs is the fact that
      it uses ultracapacitors, from Panasonic, to power an electric-hydraulic pump
      in the mechanical braking system.

      It's just the start of what some experts say ultra-capacitors will do for
      hybrids. For example, with their lightning-fast charge and discharge
      capability, ultracapacitors could handle the power surges needed for
      accelerating, allowing engineers to use a smaller battery pack in the
      vehicle (and eventually, perhaps, no battery pack at all). Shielded from
      high-current pulses, the batteries would last longer, too.

      There are other intriguing possibilities, such as using the devices to give
      more or less ordinary cars "stop-and-go" operation, in which the gasoline
      engine is extinguished at stops and started instantly when the brake pedal
      is released. Ultracapacitors and a powerful starter motor would instantly
      jolt the engine back to life. Such vehicles would also make use of
      regenerative braking, converting into electricity the kinetic energy
      otherwise thrown off as heat in the brakes and storing that electricity in
      the ultracapacitors.

      SO WHAT WILL IT TAKE FOR ULTRACAPACITORS to find a home under the hood?
      First, they've got to be a lot cheaper. Today, at roughly $9500 per
      kilowatthour, ultracapacitors are too expensive by a factor of five, at
      least, for cost-conscious carmakers. Second, automotive engineers would like
      to see the devices store more energy (as opposed to power) per unit weight,
      which would let the devices take over more of the energy-storage burden from
      batteries in future vehicles.

      If NessCap and its competitors can achieve those goals and crack this
      market, the long-term future looks good. No one knows when, or even if, the
      fuel-cell car will become a mass-market reality-the estimates range from 10
      to 30 years. But if it does happen, it's likely that ultracapacitors will be
      a big part of the reason. Fuel cells, by themselves, deliver power too
      sluggishly to briskly accelerate a full-size car. They must be mated to a
      faster-acting energy-storage device, and for this coupling, ultracapacitors
      are superior in many respects to batteries.

      "Capacitors and fuel cells are made for each other," insists Andrew Burke, a
      specialist on ultracapacitors and a research engineer at the University of
      California, Davis. Honda, for example, used only ultracapacitors to
      supplement the fuel cell in its experimental FCX-V3 and FCX-V4 vehicles,
      several of which have been leased in California and Japan [see illustration,
      "Fueling Around"]. For these vehicles, Honda used its own ultracapacitors.

      Andrew F. Burke
      Research Engineer, ITS-Davis
      (530) 752-9812
      afburke@ ucdavis.edu

      At first glance, at least, NessCap may seem an unlikely candidate to get
      ultracapacitors into a production car. NessCap's three main
      competitors-Maxwell Technologies in San Diego; Epcos in Munich, Germany; and
      Panasonic in Osaka, Japan-all have either deep-pocketed parent companies or
      revenue from other product lines with which to support their ultracapacitor
      development. (Panasonic ultracapacitors are manufactured by Matsushita
      Electronic Components Co., in Kadoma City, Japan.)

      But what NessCap lacks in resources, it makes up in resourcefulness and
      determination. The company was founded in 2001 by Sun-wook Kim, a Korean
      entrepreneur and former research director at the Daewoo Group. Although Kim
      has a few other ventures, including a new organic-LED display factory in
      Singapore, NessCap is basically a stand-alone enterprise that will either
      succeed or fail on the strength of its ultracapacitors and on its
      executives' ingenuity in promoting them.

      Certainly, the company is efficient: all of NessCap's 65 employees work in a
      boxy, yellowish, blue-trimmed building in a gritty suburb outside the Korean
      industrial city of Suwon. It houses NessCap's factory, offices, and R&D
      laboratories and its quality-control, testing, and shipping and receiving
      departments, as well as a subsidiary consumer-electronics spinoff and a
      warehouse. And though it's a small company, NessCap makes all its own
      electrodes for its capacitors. Among the company's closest competitors, only
      Panasonic can also make that claim, says NessCap's chairman, Inho Kim (who
      is not related to Sun-wook Kim).

      This distinction is important, he says, because he expects electrode
      refinements to be the main source of future improvements in ultracapacitor
      performance-greater energy storage, for example-and decreases in cost.
      Electrode technology, Inho Kim estimates, determines "70 or 80 percent" of
      the capacitor's performance. "If you own the electrode-manufacturing
      technology, you can basically do anything," he argues.

      GOAL: Cut the cost of ultracapacitors are superior to batteries in many
      respects and will almost certainly be used increasingly in hybrid-electric
      and fuel-cell cars
      ORGANIZATION: NessCap Co.
      CENTER OF ACTIVITY: NessCap's facility in Yongin, South Korea
      BUDGET: Approximately US $2 million

      TO GET AN IDEA of where these improvements will come from, you've got to
      understand what separates an ultracapacitor from an ordinary capacitor
      (other than a whole lot of farads). First, consider the classic
      parallel-plate capacitor, a sandwich of two conductive plates separated by
      an insulator, or dialectric. When the plates are connected to the positive
      and negative terminals of a battery, opposite charges separate from each
      other and accumulate on the plates. Driven by the battery's voltage, an
      electric field permeates the dielectric. Associated with that field is a
      voltage that opposes the battery's voltage.

      The field holds the accumulated, opposing charges apart; in doing so, it
      stores energy. So, unlike a battery, which stores energy in chemical form, a
      capacitor stores energy in an electric field; there are no moving parts and
      no chemical changes of state. To use a capacitor's energy, you just let its
      accumulated charges flow through a circuit, driven by the voltage associated
      with the field.

      Capacitance is simply a measure of how much charge a capacitor can store for
      a given voltage. In mathematical terms, the capacitance equals the charge on
      the plates divided by the voltage difference between them. The charge,
      however, is proportional to the area of the plates; larger plates can hold
      more charge. And the voltage is related to the distance between the two
      plates; less separation allows more charge to accumulate for a given
      voltage. So to wring the most capacitance from a device, you want plates, or
      electrodes, that have a large area, and you want to separate those plates by
      a very small distance.

      In the early 1960s, at the once mighty research laboratories of Standard Oil
      of Ohio (Sohio), researchers discovered that two pieces of activated carbon
      immersed in a liquid electrolyte formed an amazingly good capacitor, owing
      mainly to the fact that the activated carbon's myriad microscopic nodules
      had enormous surface area. Sohio licensed the technology to NEC Corp.,
      Tokyo, in 1971, but it was Panasonic that pushed the concept hardest in the
      1980s, followed by various projects sponsored by the U.S. Department of
      Energy in the 1990s.

      Since Sohio's initial experiments 40 years ago, the basic concept has not
      changed much. Coat two metal-foil electrodes with activated carbon and put a
      paper separator between them. Immerse the whole thing in a liquid

      Attach wires from the terminals of a battery to the two metal foils, and
      electrons immediately start accumulating in the carbon coated on the foil
      attached to the battery's negative terminal [see illustration, "Pluses and
      Minuses"]. Those electrons, in turn, attract positive ions from the
      electrolyte into the pores of the carbon on that foil. In the other
      electrode, meanwhile, positive charges accumulate, attracting negative ions
      from the electrolyte into the pores of the carbon. Both kinds of ions
      migrate freely through the paper separator that prevents the electrodes from
      touching each other and conducting current.

      Notice that this so-called capacitor is actually a pair of capacitors in
      series with each other. At each electrode, there is a separation of
      charges-electrons and positive ions at the negative electrode, and positive
      charges and negative ions at the positive electrode. So at each electrode
      there are two layers of charge, which is why ultracapacitors are also known
      as electric double-layer capacitors.

      The activated carbon's huge surface area comes from the great porosity of
      its microscopic nodules. It enables the positive and the negative ions
      migrating through the electrolyte to find plenty of nooks and crannies to
      occupy as they insinuate themselves as closely as possible into the
      oppositely charged carriers inside the carbon. Basically, as an electrode
      material, the activated carbon provides exactly the characteristics you want
      for high capacitance: vast surface area and the opportunity for the
      oppositely charged carriers to get atomically close to each other.

      The surface area of the carbon varies, but 1500 square meters per gram is
      not unusual. So for typical electrodes weighing 250 grams, the total area
      would be 375 000 square meters-or roughly 50 soccer fields.

      THE TRICK, OF COURSE, is getting that carbon onto the metal foil as
      uniformly and efficiently as possible. It is the first step in NessCap's
      manufacturing process-and the first topic of discussion on a tour of the
      company's small but spotless factory. All manufacturing at NessCap goes on
      in a series of three brightly lit rooms, whose Kelly green floors are all
      marked with yellow lines to show visitors where to walk.

      In big, shiny, stainless steel mixers-think Cuisinarts on
      steroids-technicians mix several types of activated carbon with water and
      with binding agents that cause the carbon-powder particles to stick to each
      other and to the long strips of aluminum foil electrodes. The resulting
      slurry gets coated onto one side of the aluminum, dried in a kiln, and then
      coated onto the other side. After more drying, the coated strips are run
      through a hot press to increase the density of their carbon layers and give
      those layers a uniform thickness.

      In the next room, machines scratch the carbon off the aluminum precisely and
      at regular intervals to make places where electrical leads are attached.
      Then the same machine winds together two long strips of the carbon-coated
      metal-one will be the anode, the other the cathode-with a strip of paper in
      between. "No other such machine exists in the world," says Inho Kim proudly.

      In the third room, the wound electrode-separator assemblies are dried in a
      kiln and inserted in aluminum cases that are filled with electrolyte and
      welded shut. The finished capacitors are tested in a room across the hall;
      every single capacitor is tested before leaving the factory.

      Upstairs, NessCap's R&D department occupies a couple of rooms that take up
      about the same total area as a decent restaurant kitchen. As in an old-time
      apothecary, glass cabinets filled with bottles of powders and reagents line
      the walls.

      Not surprisingly, ultracapacitor researchers are mainly interested in two
      things: electrolytes and carbon. In virtually all high-performance
      ultracapacitors, the electrolyte is acetonitrile. It's great stuff, in the
      one way that really matters: it has terrifically low ionic resistance,
      roughly 15 ohm-centimeters, and that means high power density. But when
      acetonitrile burns, it can release cyanide, a fact that makes automakers
      unhappy. "Everybody's looking for a replacement for acetonitrile," says
      Burke at UC Davis. Several organic compounds, notably propylene carbonate,
      show promise, but none at the moment has ionic resistance as low as
      acetonitrile. (Honda used propylene carbonate in its own ultracapacitors, in
      the FCX fuel-cell cars.)

      Still, it is the carbon challenge that most consumes ultracapacitor
      researchers now, because it is the key to the two main goals: getting costs
      down and improving the energy (as opposed to power) density. In a typical
      ultracapacitor, the electrode materials-the carbons, essentially-account for
      more than half the cost of the device, Sun-wook Kim says.

      During a tour of the laboratory, NessCap's R&D director, Young-ho Kim,
      casually mentions that he's in the midst of running tests on no fewer than
      10 mixtures of activated carbons, looking for a combination of low cost,
      high performance, and durability that has so far eluded ultracapacitor

      It all comes down to pores, he explains, drawing little circles on a piece
      of paper. You want pores that are all about 20 to 30 angstroms in diameter.
      Pores that are smaller than that aren't big enough to allow the ions to move
      in and out freely, which hurts performance. Lots of big pores, on the other
      hand, mean that the overall surface area is less than it should be, which
      also limits performance.

      Ultracapacitor makers are working with two main types of carbon,
      phenyl-resin based and pitch based. Phenyl-resin carbons perform better and
      are the standard now. But the attraction of pitch-based carbons, which are
      derived from coke and are used in asphalt, is their low cost-about one-fifth
      to one-tenth that of phenyl-resin carbons.

      The problem, Young-ho Kim says, is that it's harder to control the pore-size
      distributions in the pitch-based carbons, so they wind up with poorer
      characteristics. Their capacitance is usually about 30 percent less than
      that of the phenyl-resin-carbon devices, he explains. That means that 30
      percent more material must be used, which, of course, detracts from the cost
      savings and makes the finished devices larger. Still, Sun-wook Kim is
      confident that work on the pitch-based carbons will be a key factor in
      reducing the overall cost per farad of the devices.

      In the next breath, though, he dismisses the conventional wisdom that the
      carbons have to get down to $10 a kilogram to make ultracapacitors
      cost-competitive, from about $100 today (for the phenyl-based carbons). He
      insists that getting costs down will depend as much on manufacturing as on
      carbon prices. He points out that NessCap is now changing its manufacturing
      process to put its largest capacitors in cylindrical rather than rectangular
      cans. The simple shape change allows the electrode assembly to be wound more
      quickly, which in turn shaves more than 20 percent off the cost of making
      the capacitors, Inho Kim estimates.

      WHILE NESSCAP AND ITS COMPETITORS FOCUS on getting the cost of the carbons
      down, a few other researchers are investigating exotic, pricey forms of
      carbon that could eliminate the one clear drawback of ultracapacitors-low
      energy density-and let them mount a serious challenge to batteries.
      Commercially available ultracapacitors generally can be counted on to store
      about 3 or 4 watthours per kilogram, Burke says. That's a far cry from the
      60 or 70 Wh/kg typical of nickel-metal hydride batteries or the 110 to 130
      Wh/kg delivered by lithium-ion batteries.

      An ultracapacitor with batterylike energy density would be almost
      irresistible to automakers, to say nothing of countless other manufacturers,
      says John M. Miller, a retired Ford Motor Co. researcher. With high enough
      energy density, ultracapacitors could reduce or even eliminate the need for
      traction batteries in a hybrid car. "It's a pivotal time for energy-storage
      systems," he concludes.

      Tantalizing claims have surfaced of exotic carbon-based technologies that
      could boost the energy density of ultracapacitors 10- or even 100-fold-well
      into the realm of advanced batteries. But so far, these claims have not held
      up to independent scrutiny, say both Burke and Marshall Miller at UC Davis.
      An independent Japanese researcher, Michio Okamura, claims to have developed
      a carbon-based electrode material that he calls nanogate, which is nonporous
      and can deliver energy densities well above 50 Wh/kg. But solid, independent
      verification of his claims is not yet available, according to Burke.

      At MIT's electromagnetic laboratory, Schindall and lab director John
      Kassakian, with Ph.D. student Riccardo Signorelli, are leading a project to
      investigate the use of carbon nano-tubes, the latest miracle material, in
      electrodes. They are creating materials in which the nanotubes grow out
      perpendicularly from a substrate, like hair on a piece of scalp. The
      nanotubes would become electrically charged, just as the activated carbon
      does, so they would attract oppositely charged ions in the electrolyte. The
      nanotubes would also be spaced so as to hold these ions, much as a sea
      anemone grips small sea creatures in its tentacles. The advantage is that
      this arrangement can in theory trap many more ions than even the pores of
      activated carbon-enough perhaps to raise the energy density of an
      ultracapacitor 100-fold, Schindall estimates.

      So far, he and Signorelli have demonstrated technology that can grow the
      right kind of nanotubes and space them appropriately. By next summer, they
      hope to grow a patch of electrode big enough to test in an electrolyte, in
      order to assess its capacitance characteristics. If it works as well as
      their studies suggest, and if it can be easily manufactured-two big ifs-the
      dream of a near-ideal energy storage device will be that much closer to
      realization. "Suddenly, electrical energy storage turns on its
      head-potentially," Schindall says.

      MEANWHILE, FOR NESSCAP and its competitors, the game is basically this: find
      enough niche markets to stay afloat until technology advances make
      ultracapacitors even more attractive and automotive markets develop. And
      NessCap isn't waiting for the niche markets to come to it. Last year, the
      company started its own consumer-electronics firm, Infinity Inc., which is
      selling everything from crank-powered radios to solar tiles, all outfitted
      with NessCap capacitors.

      NessCap is also working with several other companies on niche automotive
      applications. A well-known courier company, for example, is about to start
      using NessCap's ultracapacitors in 200 of its delivery vans. As they go
      about dropping off packages in densely populated areas, these vans must stop
      and restart their engines as many as 200 times a day. The short distances
      between stops means that the starter batteries can't recharge sufficiently
      and soon wear out. But the short distances are not a problem for
      ultracapacitors, which recharge in seconds and can easily store enough
      energy to fire up the engine. So the delivery-van system couples
      ultracapacitors for short-term energy storage with lead-acid batteries for
      longer-term storage.

      Looking beyond these niche applications, Inho Kim has high hopes for
      "micro-hybrids," which would have a 12-V battery, as in a conventional car.
      Micro-hybrids are basically a very mild form of mild hybrid, propelled
      mainly by a gasoline engine but with a beefed-up electric starter motor fed
      by a small rack of ultracapacitors. The capacitors and motor provide the
      stop-and-go operation described above; the car could also make use of
      regenerative braking.

      The guilt-free ultracapacitor-based roadster is probably more than a couple
      of years away. But a conventional car with a more reliable starter system,
      or even a micro-hybrid with an ultracapacitor boost, could be in your
      immediate future. If so, the revolution in energy storage will be well under


      Kilofarad International, a trade group formed to promote the ultracapacitor
      industry, is an affiliate of the Electronic Components, Assemblies, and
      Materials Association. Its Web site is at http://www.kilofarad.org

      Andrew Burke of the University of California, Davis, has written numerous
      technical articles on ultracapacitors. Several are available online,
      including a survey from 2000:

      Menahem Anderman, president of the consulting firm Advanced Automotive
      Batteries, plans to release a report on ultracapacitors for automotive uses
      in February. You can order the US $7200 report at
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