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Ionova Technologies says ZIP-Cap ultracapacitors can offer 5x increase in energy density and 25x reduction in build cost (updated with graphic)

ITI_ZIP_CapVsEDLC03152013
Sketch describing the ZIP-Cap architecture and how it differs from that of the EDLC. Source: Ionova. Click to enlarge.

Ionova Technologies, Inc. reports that its zinc-ion-based ZIP-Cap asymmetric ultracapacitor is expected to provide a 25-fold reduction in build cost and a 5-fold increase in energy density (up to 35Wh/L) without the ultra-pure materials or expensive “dry-room” facilities that are necessary to build today’s ultracapacitors.

Asymmetric ultracapacitors achieve greater energy density versus today’s Electric Double Layer Capacitors (EDLCs) by combining one activated carbon EDLC ion-adsorption electrode with one ion-insertion (battery-like) electrode. ZIP-Cap is based on Ionova’s metal/ion pseudo-capacitor (MIP-Cap) architecture and 3-D Nanofilm technology developed under research programs with the US Department of Energy, NASA and the Naval Research Lab.

Asymmetric ultracapacitors based on non-aqueous electrolytes provide improvements in energy density but they typically do so at the expense of power density while providing no improvement in cost, safety or in environmental impact.

Alternatively, aqueous (water-based) asymmetric ultracapacitors can provide improvements not only in cost, safety and in some cases, environmental impact, but can also provide greater energy and power densities than the non-aqueous approach.

Under a FY 2010 Phase II Small Business Technology Transfer (STTR) from the DOE, Ionova partnered with Dr. Jim P. Zheng of Florida State University to further develop an asymmetric ultracapacitor with water-based electrolytes based on a 3-dimensional nanofilm oxide cathode (3DN) (investigated during a preceding Phase I program) that would preserve the cycle life and temperature performance of an EDLC while providing the following characteristics at the multi-cell module level:

Ionova Phase II STTR project objectives
  3DN USABC target Improvement
Energy density (Wh/L) 20 3.75 >500%
Specific energy (Wh/kg) 10 3 >300%
Power density (W/L) 2500 812 >300%
Specific power (W/kg) 1500 650 ~250%
Selling price ($/Wh) 2.2-3.5 2.17 10x better than EDLC

During the course of work on the DOE-funded program, Ionova found a problem with the double-layer charge storage mechanism in the activated carbon anode that resulted in capacitance fade over cycling, said Fraser Seymour, Ionova founder and CEO.

They found that ionic hydrogen is evolved on the surface of the AC throughout the interior of the macro-scale electrode and nanoscale AC particle interior which, when the electrode potential is increased during cell discharge, is oxidized which causes a “pseudo-capacitive” effect, Seymour said. While this does increase capacitance, it demands the anode be brought back to open circuit potential of the carbon (0 volts for the cell) or charge accumulates, causing capacitance fade over cycling.

This can be a big problem for users of an ultracapacitor since DC-DC converters necessary to most ultracap applications require cell voltage be maintained above 1/2 full cell voltage. While emerging new converters permit deeper discharge, this is actually a problem with commercial EDLCs as well so systems designers should look carefully at the testing protocols used by ultracapacitor manufacturers if they expect the advertised cycle life.

—Fraser Seymour

As a result, Ionova investigated some new anode materials, but ultimately decided to pursue the metal/ion pseudo-capacitor architecture (MIP-Cap).

The MIP-Cap can use any cathode material including our 3-D Nanofilm, other functionalized nanocarbons we have developed, or other materials altogether like carbon nanotubes, graphene etc. The novelty of the MIP-Cap is in pairing capacitive behavior with the an M/M+ anode; there is no physical anode per se. Rather, the anode is ionic species as part of a multifunctional electrolyte. Upon charge, these ions are reduced to metal on the anode current collector, and dissolved back into the electrolyte upon oxidation during discharge. Massive electrochemical capacity results.

While the MIP-Cap architecture is independent of chemistry, we have chosen the aqueous zinc chemistry to form the ZIP-Cap. By doing so, we enable ultracapacitors with up to 35Wh/L (5x EDLC) and 25x lower build cost vs. EDLCs—addressing the two most prominent ultracapacitor weaknesses. And this chemistry and architecture allow low-cost, ultra large scale manufacturing facilities used for electrolytic capacitors as well as lead/acid and alkaline batteries to be leveraged.

—Fraser Seymour

ZIP-Cap has demonstrated 50,000 charge cycles with a coulombic efficiency above 98% and without degradation of capacitance or resistance. In some configurations, ZIP-Cap could offer a power density of up to 5 kW/kg, Seymour said. ZIP-Cap is expected to provide 1 million charge cycles and withstand temperatures to –50 °C. Ionova is actively pursuing opportunities for the ZIP-Cap and present at the upcoming National Innovation Summit in May.

Seymour said that Ionova sees the ZIP-Cap as enabling to traction uses in 12V start-stop hybrid (in versions above 35Wh/L) and high-power 400V HEV applications, in power distribution for automotive, aerospace and computing applications, and in a number of roles in renewable/grid applications.

Resources

Comments

mahonj

@Ep, you don't need that much energy capacity - you only have to get it to 60mph (or 30 in town)
Thus your energy requirements drop to 160 Wh for motorway use and 40 Wh for city use (I used a 1.5 ton car).

With those requirements, you need much less to still make a big difference, and hence the price will be much less of a problem.

If this is real, this will make a big difference - you could use a 1-2 kwH lead acid battery and one of those to make a hybrid, else, leave out the battery and you still have a very fine mild hybrid.

@Dollared, this stuff is very new, so breakthroughs are possible.

Treehugger

if the reduction in cost is as they claim, the prospective of application is huge for regenerative braking, on HEV

Engineer-Poet

The other copy of this article, which had the first 2 comments to be posted (including one from me), has disappeared.

You don't need the energy storage but you do need the power-handling capacity; the 1.5 kW/kg is the salient factor.  75 kW will brake a 2000 kg car from 100 kph at less than 5 kph/sec (twice as fast at 50 kph).  This limits the amount of energy that can be captured unless braking is planned well ahead, which lots of drivers can't or won't do.

Darius

That tremendous achievement. Special interest for city public transport with fast charging during stops (1 min). This kind of enviroment requires long cycling liftime therefore conventional batteries are too costly.

Dave R

Even NiMH batteries are doing 50+ Wh/kg and 1350 W/kg, how is this super-cap better? Cycle life perhaps?

A123 batteries can do upwards of 5000 W/kg and well over 160 Wh/kg.

Must be missing something here...

Engineer-Poet

Yes, cycle life.  1 million cycles beats batteries hands-down, and cost per kWh handled is the major figure of merit for hybrid apps.

V2

A correction - A123 is LiFePO4 which is 110 Wh/kg at the cell level, at low discharge rates and 100% DOD, NOT "well over 160 Wh/kg" under any conditions.

Also, "high-power" Li-ion batteries can reach ultracap-level power density (kW's/kg) but ONLY for discharge. Charge is a very different story, you need to be careful with battery performance specs. From a power standpoint, the key advantage of ucaps is their CHARGE power and efficiency.

From a systems developer standpoint, assuming the charge/discharge power requirements are met, the key economics metric is cost per energy stored-cycle (not cost/farad of merely cost/energy). At the cell level, LiFePO4 is $.25. EDLCs are $.067 and the zinc system is more like $.0025.

kelly

If this article is true (which of us has the ZIP-Cap ultracapacitor), then something with the energy density of lead-acid, 1/3 the weight, ~near instant recharge, and <= cost could make a huge difference.

DaveD

Another slight correction: A123 produces a special version of their cells which are used by 5 different Formula 1 teams for their KERS systems.

They have disclosed that these are incredibly high power (over 20kW/kg), but they have been hiding the energy density. I'm assuming they're below the usual 110-120Wh/kg that LiFeP04 usually gets.

There is usually a trade off of power vs energy and I'm sure the same is true for those batteries.

Anthony F

This could replace a Prius hybrid battery with very similar characteristics, except for cost (likely cheaper) and the immense cycle life (but I'm not sure cycle life is a problem now on HEVs).

If they can manage to increase the power capacity (W/kg and W/l), that would be key to broad HEV applications. Energy density with HEVs and high depth of discharge from ultracaps isn't an issue, its about capturing as much power as possible, and then providing that back. I'd guess a Prius-sized battery with this tech is 40kW power output, and you'd probably want 50kW for city and highway usage, so a 25% improvement on this tech in the power area. Otherwise, it has enough energy for HEV applications.

Dollared

Help me. 500% improvement in energy density and 96% improvement in cost? Aren't we over in the "converts tap water to gasoline" territory?

DavidJ

For li-ion cost/energy is key for BEV but cost/power for HEV. Capacitors, these included, are best suited for HEV due to energy limitations. What's surprising is that capacitors are normally limited by cost/energy for HEV (?) but these are limited by cost/power.

Current HEV systems don't have 100% charge acceptance for regenerative braking so no need to when using these capacitors. Maybe 75kW would capture most of the energy most of the time for most of the drivers, and that is enough.

HarveyD

These ultra caps seem to have about the same energy density as leading Lead-Acid batteries but would last much longer, specially in Stop-Start vehicles?

Ideal to recover more braking energy for HEVs, PHEVs and BEVs and specially for racing e-cars, city e-buses, city e-cabs, garbage e-trucks etc.

Could also be a good companion for current EV batteries.

Engineer-Poet
Help me. 500% improvement in energy density and 96% improvement in cost? Aren't we over in the "converts tap water to gasoline" territory?
If only!  The improvement is over previous ultra-capacitors, not batteries.
Brotherkenny4

Typically high purity materials are necessary to prevent internal loss of charge due to shuttle species provided by the impurity. Here they mention the lack of need for highly pure materials, however, I don't see how they avoid the leakage current from impurities? Sure, cost and low energy density are two issues. What about others? Looks great if true though.

HealthyBreeze

These types of releases would be sooooo much more reassuring if they included the phrase, "...and we will be demonstrating this new technology at a public event to be held next week at..."

That said, this sounds like a step forward to micro and minihybrids for all energy storage, and as the front end of a hybrid batacitor for Prius and Plug-In systems.

HarveyD

It could work well with an aluminum-Air battery as a long range extender?

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