Will a Firefly Spark a Battery Revolution?
By Bill Moore
One of the basic components of many lithium ion batteries is cobalt and its price, driven largely by insatiable Chinese demand for steel, has risen from $40,000 a ton to $60,000/ton over the last year.
The same market pressures apply to nickel, the essential ingredient in nickel metal hydride batteries (NiMH) used in today's hybrids. Here the price has risen from $10,000 to $14,000/ton in the last twelve months. Even the price of lead -- the core material in every starter battery in the world -- has doubled from $500 to $1000 a ton.
And as demand for these materials increases with the production of even more hybrid-electric vehicles, the price is likely to go even higher.
But what if someone developed a battery whose primary core material is derived from coal at just $40 a ton? Even better yet, it performed as well as either NiMH or Lithium Ion at one-tenth the cost of either and at one third the weight of lead-acid?
Think you might have a winner?
Firefly Energy, a recent spin-off of Caterpillar Corporation in Peoria, Illinois, believes it does and they are racing as fast as they can to bring it to market.
What the company has is a lead-acid battery that has had seventy percent of the lead taken out, replaced by a foam matrix developed from coal and originally intended for use as a "next generation" automotive radiator core.
After discovering a sample on a fellow engineer's shelf, a Caterpillar employee named Kurt Kelley thought it might offer a way to burst the performance barrier of dependable but heavy, cheap but environmentally-costly lead acid batteries. It now appears he was right, though it will take 24-30 months to verify it in the real world.
"What we've done", Mil Ovan, the co-founder and senior vice president of Firefly Energy explained, "is replaced the corrosive, heavy, lead metal grid found in your typical lead-acid battery and replaced it with a composite that doesn't corrode and presents a much higher surface area for (lead-acid) chemistry to generate and store energy".
He elaborated, along with battery consultant Michael Kepros, that a conventional lead battery consists of upwards of 150 lead grids (see below), half of them tied to the positive post and half to the negative post. Sulfuric acid is the medium (electrolyte) that facilitates electron exchange.
What Firefly has done is utilize a combination of a special corrosion-resistant coating developed by Kelley, who is now the company's Chief Scientist, and the coal-derived foam, substituting the new composite for the heavy lead grid and connecting straps. The potential surface area for ion exchange increases dramatically from what was essentially a two dimensional structure to a three dimensional one, with unexpected benefits.
According to Ovan, most conventional lead-acid batteries fail when corrosion builds up on the grid plates. "Those lead grids involuntarily participate in that chemistry, which causes them to corrode and therefore fail".
Michael Kepros estimated that conventional grids can be a thin as 0.0004 of an inch thick to 0.25 inches in a heavy forklift-type battery. Gradually, as corrosion sets in, less and less of the battery's active elements are available and the battery will no longer hold a charge.
[Editor's comment: For those interested in a more technical explanation of the battery's chemistry, listen to the MP3 version of the interview].
Kepros estimated that compared to a conventional lead-grid battery where as little as 5-to-50 percent of the active elements will be available, the Firefly battery has demonstrated up to 80 percent availability.
"By having this more uniform structure, when you discharge the battery, the ability of electrons to get to all the active sites is dramatically increased, and instead of getting up to five to fifty percent of the material being utilized, you're more in the regions of sixty, seventy, eighty percent or possibly higher… It moves the active material or the use of the chemistry from typically thirty or so percent to numbers that can be well over fifty, which means for the same size battery, you are talking about a significant improvement in both volumetric and gravimetric performance".
Reminding both Ovan and Kepros of the old saw about "liars, damned liars and battery salesmen", I asked them to explain assertions on their web site that their technology will offer performance comparable to more advanced chemistries, but without the cost.
Ovan pointed out the cost trends for cobalt, nickel and lead, on the materials side. On the question of performance, he explained that basic lead-acid chemistry has always had -- theoretically -- very high energy and power densities, which could never be fully exploited due to the limitations of current battery design.
"Our point is that if you look at the claims made from a single cell standpoint for lithium -- those single cell performances can be very high -- what happens though is you have to put a lot of controls on it to throttle its performance when you put it into a multi-cell application because with those technologies you worry about such issues as thermal runaway. Those kinds of requirements with lithium ion really move and shift your performance in terms of specific energy and specific power back down and to the left.
"So our point is that when you talk about an application now, instead of a single cell performance, we start to arrive in that same, similar sweet spot as where nickel metal hydride would fall and where lithium ion falls in terms of a multi-cell application. We do so with a far better cost structure, number one. And number two, the ability for our technology to operate in broader temperature extremes is much better than is the case with lithium ion and nickel metal hydride".
One claim that lead acid can't make is that it's environmentally benign. Lead is a toxic element that can have serious health consequences. Largely because of this, the industry has proactively engaged in battery reclamation/recycling efforts; and Ovan expects the Firefly battery to be handled similarly. He pointed out that the battery has 70% less lead in it and that when it is time to reclaim it, the foam core material -- remember it's based on coal -- will help the recovery process because it can be burned, reducing the amount of energy it will take to smelt out the lead.
Kepros also estimates that there is currently enough lead in circulation in existing batteries that if other manufacturers shifted to Firefly's technology, three times the number of batteries could be built just from reclaimed lead alone.
From a consumer's perspective, Firefly's battery could either have three to four times the power for the same weight and size as a conventional lead-acid battery, or could have the same power at one-third the weight or one-third the size.
But conventional starter batteries is not where Firefly plans to compete.
"We look for applications where there's a high pain point," Ovan stated. By that he means uses where current lead-acid batteries are too heavy and too short-lived -- such as in hybrid-electric vehicles -- or where advanced chemistries like lithium and nickel are simply too expensive.
A good example is outdoor lawn care equipment like electric mowers, both the push type and riding type; and it turns out that Firefly's first customer and development partner is Electrolux, which owns 40 percent of the power lawn care equipment marketplace, manufacturing everything from Weed Eaters to Poulan chain saws.
According to Ovan, after searching the world over for an affordable, low cost battery solution that offered realistic power and runtime for portable and wheeled applications, they turned to Firefly Energy.
[An announcement on how Electrolux plans to use the battery and in what type of application is expected shortly].
Beyond Electrolux, Firefly is bullish on its chances in the hybrid-electric vehicle market, where its battery could not only bring down costs, but even make affordable plug-in hybrids feasible -- and both Greg Hanssen and Felix Kramer are eager to get their hands on some ASAP.
On the question of cycle life -- which is NiMH's strong suit -- Ovan said he wants to shot for something comparable for his battery. He thinks this is feasible since the battery isn't experiencing the corrosion associated with conventional lead-acid batteries, but he also acknowledges that it will take months of testing to confirm this.
Another factor affecting all batteries is ambient temperature. Above and below optimum temperature ranges, even the most advanced consumer chemistries are affected. In lead's case, to compensate for degradation at temperatures below freezing, the power of the battery has to be doubled or tripled. For every 15 degrees above 70 degrees F, the life of the battery is cut in half, Ovan explained, due to the onset of corrosion.
Firefly's higher energy density means you don't have to oversize the battery for cold temperatures and since there is no lead grid to corrode, it is less susceptible to high temperatures, as well.
"We're seeing already from our tests that we do have a broader temperature range than those other two chemistry types (lithium and nickel)", he said.
The company is planning to set up pilot manufacturing facilities in Peoria, Illinois, their headquarters and is currently considering their options for full-scale manufacturing with "interested third-parties".