Startup Introduces 330MPG Diesel Hybrid Design
Toyota’s Hybrid Outlook in the US for 2006

Firefly Energy Awarded Patent on New Foam Lead-Acid Technology; Targeting Hybrids and Plug-ins

100x magnification sketch of the network of foam pores. Pore size may vary by application.

Firefly Energy (earlier post) has received a US patent for a new carbon-foam lead-acid battery technology that it believes has the potential to revolutionize the existing global lead-acid battery market as well as serve applications such as hybrid electric vehicles and plug-in hybrids.

Firefly contends it can deliver lead-acid battery performance comparable to NiMH, but at about one-fifth the cost, and with greatly reduced weight compared to traditional lead-acid batteries.

As a result, the company believes it can play an important role in accelerating the adoption of hybrid and plug-in hybrid vehicles through cost reduction and availability.

The Firefly battery replaces the conventional lead plates in a lead-acid battery with a lightweight carbon or graphite foam to which the chemically active material—in the form of a paste or slurry—has been applied.

The use of the foam structure increases the interface between the electrodes and the active chemistry; the carbon material resists corrosion and sulfation build-up, reducing weight and delivering a formidable jump in specific power, energy and cycle life. The technology is not limited to use in lead-acid batteries.

Firefly is a spinoff from Caterpillar, which had assigned the problem of pursuing increased performance for lead-acid batteries used by Caterpillar’s product groups to Kurt Kelley, who is now Firefly Energy’s Chief Scientist.

Since Kurt, an accomplished material scientist, had never designed a battery before, his problem-solving approach was unconstrained by the conventional battery wisdom held by lead acid battery technologists.

—Edward Williams, CEO and Firefly Energy co-founder

Kelley came up with the idea of using a foam carbon composite to address the corrosion and sulfation issues, and to remove the bottlenecks to achieving the theoretical power of the lead-acid chemistry.

A major restriction to lead-acid battery efficiency is the lack of interface area between the active chemistry and the electrodes. Although the chemistry is theoretically capable of delivering approximately 170 Watt Hours per Kilogram (Whr/kg), lead-acid batteries only average around 30 Whr/kg.

Up to now, achieving a higher surface area within a given lead-acid battery box required the addition of more and thinner lead electrodes. However, lead electrodes corrode, so increasing surface area by putting thinner lead electrodes in the battery increases corrosion and decreases battery life.

Removing the corrosive heavy lead grids and replacing them with a graphite foam addresses both issues (increased surface area and decreased corrosion). Furthermore, the design of the Firefly battery removes one-half to two-thirds of the lead out of the battery.

Firefly Energy is now beginning to promote the use of its foam lead-acid batteries in plug-in hybrid applications. Senior Vice President Mil Ovan most recently made that pitch at the Energy Independence 2020 Summit organized by US Senator Dick Durbin (D-IL) in Chicago.



Nick Flynn

I'm a little confused here. 170 watt hours per gram is consdierably better than the best nimh and better than a lot of lithiums. So why compare with nimh?


Where did you get 170 watt hours?

John W

The article talked about 170 watt hours per Kilogram, not gram, Nick. Small and easy to make mistake, but what a difference! :)

Nick Flynn

: 0


I am wondering what this does for all-electric cars. People have said for ages that batteries were the limiting factor there - assuming that these batteries live up to their potential, what type of electric car would be possible (both speed and range)?


I was thinking of doing an EV conversion with regular lead-acid for cheapness, but if these aren't so much more expensive it would definitely be worth waiting for them.


The potential benefits of this technology are profound even if its adoption were limited to today's lead acid batteries.
1) weight saving - reduced fuel/energy consumption throughout the vehicle's life. From forktrucks to transport trucks, lead acid batteries are ubiquitous.
2) reduced demand for lead. Lead is among the "worst-of-the-worst" materials on the planet in terms of negative impact on living things. From lead mining, smelting, lead leachate from landfills, human exposure from manufacturing, handling batteries, etc. lead is bad stuff.

Question: Does this technology adversely affect the ability of lead acid batteries to be recycled?


I don't think you should wait for these, Schwa.
Everything I saw on their website says the gains are still theoretical and the technology to build them in quantity is still a dream. I'd guess they're at least several (4+ ?) years from production. High-power lithium-ion is much farther along the development cycle but is still at least a year or two away.


On the recycling, no barrier. According to Firefly the batteries can take advantage of the exisiting recycling infrastructure. Plus there is less lead to recycle...

Harvey D

If mass produced, this improved lead battery may become an economical alternative to MiMH and Litithim Ion batteries to lower the cost of Hybrids, PHEVs and EVs. Nothing wrong with competition, specially when Toyota has to curtail Prius production due to battery shortages. Could commercial production be accellerated?


Good time to buy a hybrid I believe. If the lifetime of the batts in a hybrid are between 7-10 yrs, imagine the slot-in battery solutions available then (2013-2016). These foam lead acids and even super Lithium Ion batts will have come of age in a a big way.

Rob McMillin

Dude, the hyperlink in the lead in for Firefly Energy is busted.



James May

I have a EV converted petrol car and I have just followed links here frmo Mine runs on 16 golf cart lead acid batteries and they are definitely the limiting factor when it comes to range. My batteries weigh 414 Kgs and I can't wait for these carbon-lead batteries to come out. Hope they come out in golf-cart format. What a difference it will make! James - Coventry UK


Please don't hold your breath. If you search around there's all sorts of new potential solutions to our battery problem fron the super iron battery to nickel zink to this. The problem is battery use has many many aspects that people don't often think about. Can it be produced economically? Are the metals available (in leads case yes)? Can it be mass produced? Does the price fall significantly with mass production, or are the resources exhausted? Is it safe to manufacture? Is it safe to use? How many times can it be recharged? Is it recycleable? How much of it can be recycled and can this be done economically? Is the capacity adversly effected by temperature? Can the battery offer high drain capability suitable for EV use? Does it survive shock (very important in EV use)? Does it survive shock throught its life cycle? Does DOD (depth of discharge) effect its cycle life adversly? Can it accept charge quickly? Is the chemical reaction relatively efficient? Can the battery cells be produced in large enough size to be practical for EV use? Can the battery cells be manufactured economically to be matched in capacity well? Despite energy vs. weight, how does the battery compare in energy vs. volume (also important in EV use)? Is the voltage per cell high enough to be useful? How does the battery stand up to abuse (i.e. high rate discharge, high rate chargeing, 100% discharge, over charging, very high/very low temperature, high shock) is it safe under these conditions, and how do they affect its life cycle?

I just want to pount out that battery research has been on going for more than a hundred years. More money and research doesn't always bring about solutions, and at any rate they are slow to happen. Right now current lead-acid batteries stand up to all the things previously mentioned which says alot for how long it will continue to be the most used battery in the world.

henry gibson

EFFPOWER of sweden has high power lead acid bipolar battery in prototype production. They use ceramic cell separators instead of carbon.

THERE is also a company in england that sells a conductive material called ebonex that they use in prototype bipolar batteries and other electrolysis cells. They seem to reject carbon as too suseptible to oxidation. They even consider plating their ceramic with gold or platinum. Actually gold and platinum plated thin pure lead might be the best cost wise. One could even hide a copper screen totally by the lead.

There is a consortium of companies in europe that is making an expensive effort to develop plastic bipolar lead acid batteries. They intend to use conductive polymers to separate the cells.

It must be remembered that the electrical conduction through the acid is in most cases the limiting factor in the conduction of the batteries. That is why most lead acid batteries have many plates in parallel for each cell. Lead is however a very bad conductor compared to copper. Some batteries had copper hidden in the negative lead plate. Destruction of the lead positive grid was always too rapid to hide copper in it.

In bipolar lead acid batteries the cell separator must be conductive, highly-corrosion-resistant, and liquid tight. The batteries must also have plate separators like ordinary lead acid batteries. Fine fiber glass is usually used, as in AGM, absorbed glass mat, batteries.

I built my first bipolar lead acic battery about 1966. Volta built the first bipolar battery before 1800. Polaroid put bipolar batteries in their instant film packs in the 1970's.

The fact that lead is poisonous should not prevent us from using it. Lead probably has more press agents as a poison because it has been known since before the bible was written and perhaps before anything at all was written.

Every metal in common use and most other substances are poisonous in one form or another. Iron, copper, nickel and phosphorous are needed for every second of human life, but not very large amounts of any of them will kill you. The use of lead in sanitary systems and even in water supply systems before plastic became available probably saved ten-thousand times more man hours of human lives due to death than it ever cost.

Water supply systems with lead pipes in most parts of africa and many other parts of the world would still save ten-thousand times more man-life-hours than they would cost by poisoning. Fortunately plastic is cheaper now and safer?

People use nickel-metal-hydride batteries considering them safer than nickel-cadmium batteries but without knowing what metals are in the metal hydride. Since the metals are rarer than cadmium it is likely that our bodies are not used to small quatities of them. What are the poisonous properties of the metals used in your NiMH batteries.

Statistically the best way to prolong your life is to stay away from automobiles. They have enough Iron, Copper, Nickel and lead in them to kill dozens of people. In the United States more people have been killed in car accidents than in wars. Europe has more effective wars and less effective cars. Lead is statistically insignificant compared to tobacco, legal drugs, home accidents, fires etc as to the number of years cut off human lives even after we ignore automobiles.

Actually it is a lot easier to build bipolar nickel-iron (edison) batteries than lead ones, and they could have an energy density equivalent to the NiMH batteries. Their low voltage per cell is negated by the bipolar construction, and their horrible voltage curve can be corrected with small integrated electronics.

One of the most interesting metal hydrides is Ni5La. Five parts of nickel to one part of lanthanum. At about five atmosheres of pressure, a solid cube of this metal will absorb more gaseous hydrogen than the equivalent volume of liquid hydrogen and decay into dust. The hydrogen comes out again if the pressure is reduced enough. The dust can then absorb hydrogen again. Iron pipes also decompose under high pressures of hydrogen.

The best battery available now for automobiles is the ZEBRA battery. It is in actual current production. It was developed as an alternative to the sodium-sulphur battery by BETARD UK. and uses nickel chloride instead of sulphur. It could even, and does already to a small extent use iron chloride. It is used in hybrid busses and is used in marine applications by ROLLS-ROYCE, and will be used by them for a submarine rescue vehicle. It has a very long deep cycle life and no maintenance. It now has probably twice the energy density as any lead acid battery and could in large scale production cost less for lifetime use. It has a clear disadvantage of needing to be kept hot; if instantaneous use is required after a long pause in service. But in cold climates this could mean instant heat and defrosting for the price of keeping it plugged in. It operates so hot that neither cold nor hot climates have any effect on its operation; as it is sealed in a vacuum box. Its operating temperature is far less than that of your catalytic converter.

It uses a small fraction of the nickel required for the same capacity nickel metal hydride battery. The only materials needed in large portions for its construction are steel, nickel, aluminum and salt. A total iron version could be developed for lower voltage that needed no nickel.

The present type of construction required for this battery does not give it enough peak power in small units. But in units big enough to run a car for 100km they have plenty of power. Low tech flywheels in combination would give more than adequate stop go power for small nickel cloride units in present hybrid cars.

Low tech flywheels were used in several locomotives in England during the 1930's 40's and 50's to run freight trains electrically on tracks to the coast from london that had interrupted third rail electrification. Energy could even be stored in the flywheels by slowing the trains on hills and at stops. These locomotives have been replaced by electric locomotives with auxilliary diesel generators....

man of la mancha

great post henry gibson.

i was interested in reading about the new zebra battery and wondered if it was suitable for diesel/electric submarines.

has there been any progress on the traditional lead acid submarine batteries in recent times or are things much as they were back in WW2??


Dear sirs
what admirable work!
lead acid foam battery is very beautiful. I research about foam structures for battery and make carbon foam as current collector with lead coat . result were very delightful.
thank you.


I'm getting sick to death of reading about "potenial".
Everything from thin, light, roll-to-roll, lithium to euorpositron's aluminum batteries to fireflies ??? what pie in the sky?
COME ON!!!! Lets see some F#%king RESULTS!! Lets see some product! Somebody with a pet lab project is USELESS!!!! Contrary to what most people think there are applications where weight is NOT factor, although size is. Like forklifts, tractors, construction equip, all kinds of estate/farm maintenance, use your imagination!! Problem is EVERY SINGLE idea is balanced against it's possible use in what??? - - - * * * CARS * * * - - - !!!. And for one reason or another get dropped, usually too high of a wieght to power ratio. So it's never produced. I'm thinking lack of imagination here. Or short-sightedness, or stupidity, or conspiracy, or ......some damn thing. Here is another case of the ***PERFECT*** GETTING IN THE WAY OF THE GOOD!!! Industry wants us to wait for some pie in the sky fuel cell. ( Which will not be available in my lifetime, so I don't give a shit about it.) Corporate greed along with the damn patent trolls is going to kill all inovation, and just may kill the human race. Maybe we should get them first?


andrew is obviously not current on battery technology; there are at least a dozen new variants that will move to replace lead acid in the coming decade.


Can this new batt be built to supply 370 to480 volts and how much will it weigh i have a big lead dodge trk dacota with 30 deep cycle batt wired for 380 volts that converts thru a contreller to three phase a/c and runs a three phase elec motor that powers the trk and how much re charge can the batt take from brakeing i know more than most people and i belive i have tech no one has in some areas of better econ and can prove it but who do you talk to how can i get involed and if im right whats in it for me. my # is 763-438-9111

[email protected] email me thanks

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