Firefly Energy Eyeing the Hybrid Market; Lead-Acid Foam Batteries for Mild-Hybrid Applications Heading to DOE for Testing and Validation
12 January 2008
|Firefly Energy’s 3D2 2V cell compared to conventional lead-acid 2V cell. Click to enlarge.|
On Friday, Peoria, Illinois-based Firefly Energy presented US Senator Dick Durbin (D-IL) with a mock up of an HEV cell (based on its first-generation 3D technology) for a mild-hybrid application, similar to what the company will begin to ship to the Department of Energy (DOE) this quarter for validation and testing. Senator Durbin had earlier announced that $3.2 million in federal funds had been budgeted for Firefly, building on approximately $4 million in previous military funding. (Earlier post.)
Buoyed by that funding from the Department of Defense (DOD) '06, '07 and '08 budgets, Firefly Energy has been developing future generations of its carbon graphite foam lead-acid battery technology (earlier post) with an eye to eventually targeting the hybrid electric and plug-in hybrid electric markets.
The hybrid market is quite promising in the long term but currently fairly small and fragmented (as compared to existing lead-acid battery markets). Our strategy on this market has been to get the technology noticed and validated, keeping a small footprint of awareness in that market, until such time we’re financially and technologically capable of addressing it full force.—Ed Williams, Firefly Energy CEO
The DOD funding is to support applications of several generations of Firefly technology to military battery requirements. Currently, that work includes both the first generation 3D technology and the second-generation 3D2 technology, according to Williams.
The 3D technology enables traditional lead-acid chemistry to function at levels closer to NiMH and Li-ion in terms of cycle and calendar life, including a weight/volume reduction of 20-40%—depending upon the application—compared to a traditional lead-acid battery. The 3D technology also eliminates the sulfation problem.
The 3D2 technology offers performance improvements over the original 3D, and will be the likely foundation for hybrid applications due to the performance and weight characteristics. While the 3D batteries still rely on a conventional positive plate, the 3D2 batteries use the porous foam material for both the negative and positive plates, replacing up to 70% of the lead utilized in traditional lead-acid batteries (or, another 30-40% weight reduction over the 3D batteries).
The 3D2 batteries deliver a jump in power, energy, and cycle life beyond the 3D product, and approximates the performance of lithium and nickel metal hydride batteries without the higher cost and/or potential safety issues.
The 3D batteries are easily delivering 38 Wh/kg, according to Williams, and the 3D2 cells deliver an even better gravimetric performance.
Foams used in the positive plate are affected to varying degrees when exposed to extreme overcharge conditions, according to Firefly. Electrochemical testing by Firefly has found that foams of certain graphite grades react differently in the upper potential ranges commonly experienced during recharge of the positive plate. Firefly says that it is actively refining and stabilizing foam chemistry as well as increasing the robustness of the foams used in positive plates through manipulation of both foam chemistry and processing, as well as methods of plate preparation.
In October 2007, Firefly Energy announced it was expanding into the trucking market with the commencement of a BCI Group 31 battery development program. (Earlier post.)
Firefly technical white paper
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