Ioxus, a young (2006) ultracapacitor spin-off from Custom Electronics, an established supplier of high-reliability capacitors to commercial and military clients since 1964, is targeting the development of higher power density, compact ultracapacitors, applied in a full range of applications spanning military, industrial and automotive needs. (Earlier post.)
Typical ultracapacitors are characterized by high power density compared to batteries (but poor energy density), as well as quick charge and discharge. Ioxus says that the power density of its 100F carbon-carbon ultracapacitor solutions is 2x over that of competitive comparable 100F cells. On the larger cells, such as the 2000F, Ioxus offers 20% more power than Ness, is at parity with Maxwell, and is higher in volumetric density, according to the company.
Ioxus expects a new set of cells, targeted for release at the end of the year with different terminations, to surpass Maxwell’s large cells in both volumetric and gravimetric power densities.
Smaller Ioxus cells offer a power density of 22-28 kW/kg, and larger cells offer densities of 12-15 kW/kg, said Chad Hall, COO of Ioxus. Energy densities for the cells are typically around 2-4 Wh/kg. Ioxus says that it is working on increasing the energy densities as well.
Ioxus makes carbon-carbon ultracapacitors—i.e., both electrodes are carbon, as opposed to the hybrid (asymmetric) ultracapacitors in which in one of the electrodes is carbon and the other electrode utilizes a different material. Energy densities of hybrid ultracapacitors can be significantly greater than that of carbon-carbon ultracapacitors, but power densities are lower.
To achieve its power densities, Ioxus says that it essentially uses multiple types of carbon to pack the material as best as possible and a variety of different types of carbon with different conductive properties. Ioxus has also optimized binders to adhere to special foils, Hall said. The packaging of the cell is also a factor, he noted. (Ioxus offers a prismatic ultracapacitor as well as cylindrical.)
Ioxus has filed 12 patents, with others under preparation.
Like its competition, Ioxus is interested in transportation applications—mass transit, hybrid-electric, train/light rail, and stop/start applications—sometimes in cooperation with a battery, depending upon the application requirements.
With its compact, high power-density cells, Ioxus is also interested in applying ultracapacitor solutions at different points of use in a vehicle—for example, replacing power steering with electric steering using ultracapacitors. Other potential applications include smart airbags, instrument clusters, multimedia/telematics, seatbelt releases, and power seats, locks and windows. Another application could provide “instant heat” to heat up the catalytic converters in vehicles.
Ioxus is also interested in working with battery companies on integrated solutions.
Two lithium-ion battery companies are working with us now. We’d like to see the ultracapacitors integrated into the battery—two separate chemistries integrated into the pack—so that the customer sees only two terminals.—Chad Hall
As Ioxus moves forward with commercialization, it will produce modules for customers as well, first standard modules and then customized modules. The company has already designed an integrated ultracapacitor module to provide regenerative power assistance in retrofitting lead-acid battery powered forklifts.
According to Hall, one materials handling equipment manufacturer is projecting a purchase of up to 250 of the 36V, 450-Farad (10kW) EDLC Energy Reservoir System, or “EERS” modules. Each ultracapacitor module incorporates sixty 1,700F cells, control electronics, safety circuitry, interconnects, and a safety enclosure to deliver a complete stand alone power assist module. The module is compact and can be installed in about an hour.
A forklift equipped with an EERS module will increase the useable time of the battery pack by 30% allowing an operator to complete a full eight hour shift on a single charge of the lead acid storage pack. The use of the module also prevents the battery from deep cycling, extending the life of the battery.
Preliminary data suggests battery life may be extended four to eight times as opposed to using the battery without the power assist module, according to Ioxus. The incorporation of the power assist module also allow the size of the battery pack to be reduced by as much as 15% if desired.
The Ioxus ultracapacitor-based EERS module is designed to have sufficient energy storage to aid the forklift when under load—more specifically the module aids the lead acid storage pack when lifting loads of 3,000 lbs. As the ultracapacitor provides the bulk of the power when the lift is raised, the life of the battery is increased.
Potential applications outside the transportation sector include power quality (e.g., utility grid stability; telecom support, factory UPS, fuel cell starting and load leveling) and renewable energy (wind mill pitch control; solar positioning; variable generation; energy dispatching; and wave energy).