Firefly carbon foal electrode vs. lead acid battery plates

Firefly Promises

Co-founder Mil Ovan talks to EV World about progress at the carbon-graphite foam lead electrode developer.

By Bill Moore

The last major innovation in the century-old lead-acid battery was thirty years ago when maintenance-free batteries that didn't require periodic watering were introduced. That's the view of Firefly Energy co-founder Mil Ovan, when talking about his company's breakthrough carbon-graphite foam, lead-impregnated battery electrodes.

Since talking with Ovan some 18-months ago (See Firefly Energy Update), the company has raised some US$11 million in a series B financing round and another US$6 million in debt financing, which will allow the Peoria, Illinois spin-off for Caterpillar to "expand the company and build the engineering team."

He pointed out during our 35-minute telephone discussion, that Firefly's science promises to unlock more of the energy potential of a well-known, but easily degradable battery chemistry. The benefit is not only the reduction in size and weight visible in the above photo but just as importantly, it also improves the durability of the battery while shortening the recharge time.

We encourage you to listen to the entire interview by using one of the two MP3 players above or by downloading the 8.4MB file to your computer for transfer and playback on your favorite MP3 device.

We should also note that among the photos that Firefly's public relations firm sent us to help illustrate the story was one taken in Iraq of a military storage depot where thousands of dead lead batteries sit cooking in the sun on wooden pallets. Both heat and cold severely harm conventional lead starter batteries as the photo illustrates.

IN BRIEF: Synopsis of Interview

  • Ovan clarified that Firefly's business model is to manufacture the lead-impregnated carbon-graphite foam electrodes which it will then supply to larger battery manufacturers who will, in turn, assemble the finished batteries for Firefly to market. The obvious advantage here is keeping a tight reign on its intellectual property which includes secrets on how it introduces the lead into the highly porous foam and how those foam electrodes conduct electrons. It already has penned agreements with two major battery manufacturers and the nation's largest lawn care equipment maker. He noted that manufacturers like the low cost of lead-acid by hate its "weight and poor cycle-life. Lithium ion offers a different set of challenges for manufactures because while its lower weight and higher-energy density is exceptional, so are its costs per watt. Firefly finds itself favorably positioned in the middle of this volatile situation. The manufactured batteries using Firefly components will then be branded and sold by Firefly under its own name.
  • To verify and demonstrate the durability of its expanded foam electrodes, Firefly sent early prototype batteries over to its parent, Caterpillar who has equipment for shaking components to simulate off-road, earth-moving environments designed to induce failures. The machine shakes batteries at 5 Gs, usually for 100 hours. Not only did the Firefly battery go several hundred hours beyond that, but the company asked Caterpillar engineers to shake it at 9 Gs, which they did for another 900 hours with no apparent ill effect.
  • When car makers experimented with lead-acid batteries in their early prototype hybrids they discovered that because of the thousands of discharge/recharge micro-cycles, the lead lattices were corroding with sulfate build-up, shortening the life of the battery. In contrast, Ovan contends, the Firefly's unique foam electrodes, which have vastly more surface area than conventional lattices, simply weren't affected during the partial state of discharge cycle. As a result, he predicts that someday both original and replacement packs in today's hybrids will be based on Firefly batteries rather than expensive nickel-based batteries.
  • While lithium ion battery chemistries offer high energy densities it comes with substantial costs, including battery management hardware and other thermal management equipment that isn't necessary in a lead-based battery, Ovan argues. The carbon foam also has superior heat dissipation characteristics. In a UPS application where lead batteries are discharged over a 5-minute period to protect, for example computer or telecomm systems, the number and volume of Firefly batteries would be half that of conventional lead-acid batteries. In a military battery, like those below, where Firefly has been asked to stuff as much power as possible inside the standardize case, the battery will still weigh 15% less.
  • In part because of the war in Iraq and growing world demand, lead is becoming increasingly expensive, trading recently for $4,000 a ton compared to the $500 a ton when Firefly was formed in 2003. Similarly, nickel was $7000 a ton and has been as high as $45,000 a ton, while the cobalt used in many lithium chemistry cells has climbed from $14,000 up to $75,000 a ton . This growing scarcity is in the company's favor because their mission is the "get the lead out" by replacing as much of it as possible with relatively abundant and affordable graphite. By contrast, the carbon foam used in Firefly batteries can be derived from coal, synthetic pitch or petroleum. Ultimately, Firefly is looking to remove up to 70% of the lead metal out of its batteries.
  • Firefly has a US$5 million contract to develop prototype vehicular batteries for the military (see photo below). In about a year, the first commercial batteries will be in a Group 31 truck battery to power the Class 8 driver's "hotel load" of air conditioning, sleeper berth lights and accessories while parked to rest at a truck stop. Unlike normal lead batteries that begin to be damaged when discharged below 80% SOC, Firefly has demonstrated that it can completely discharge and then recharge back up to 100% 'time-after-time." Tests against a good Japanese battery have shown the Firefly chemistry has up to seven times the cycle life.
  • Ovan thinks that someday carmakers will opt to offer Firefly batteries in their hybrids perhaps in addition to more advanced chemistries. He doesn't see the market coalescing around just one type of motor or battery just as there are different gasoline and diesel engines offered today. Firefly's technology will be viewed, he believes, as a far more pragmatic and cost-effective solution for a variety of hybrids from micro to plug-in.
  • Noting that a flooded, lead-acid battery would cost somewhere around US$50/kWh, while a VRLA (valve-regulated lead-acid) like that being used in the BMW 100 Series micro-hybrids will come in around US$150/kWh, Firefly is aiming to have their batteries priced in the US$250-300/kWh range in volume production.
  • Using FreedomCAR's battery specification, Firefly has tested its batteries over "hundred and fifty thousand micro-cycles" before they had to take the experiment apart and use their test equipment for "paying customers", which strongly indicates to Ovan that it will be a good substitute for NiMH in many automotive applications.
  • To the question of recycling the battery, Ovan listed several key factors that favor their battery over other chemistries including the fact that less lead is used, which means less has to be recycled. It also turns out that carbon is used in the smelting process to raise the temperature of the furnace, which means that less energy has to be used to recycle Firefly batteries than other lead batteries.
  • Every 15 degrees Fahrenheit rise in temperature above 70 F doubles the corrosion rate of conventional lead batteries, hence the graveyard of military vehicle batteries in Iraq where daytime temperatures in August approach 130 F (54.4 C). On the cold-side, where a normal Pb battery will have only about 20% of its capacity available at -20 F, a Firefly will have 60%. This should translate into much better range during cold months in an electric car application.
  • Beyond its current 3D Microcell negative electrodes made of carbon foam, Ovan explained that as part of the US$5 million military contract, they are developing a 3D2 system that also replaces the positive electrode with carbon foam, which make the battery even smaller and lighter.
  • Finally, Firefly won the 2007 R&D 100 Award for its innovative carbon-graphite foam battery technology. This places it in the same historic category as the Polaroid camera, the flash cube, the Nicoderm patch and high definition television, all of which have been recipients of this same award.

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    Times Article Viewed: 13111
    Published: 03-Aug-2007


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