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JM Energy Introduces Lithium-ion Capacitor

The energy and power densities of the Lithium Ion Capacitor compared to other storage technologies. Click to enlarge.

JM Energy, originally a 50-50 joint venture between MIPOX and JSR Corporation formed in August 2007 (now 100% owned by JSR Corporation), has developed a new lithium-ion capacitor (LIC) that combines the electrode coating technique of MIPOX’s ultra-fine coating technology and new material technologies of JSR Corporation. The new LIC offers about four times the energy density of a conventional electric double-layer capacitor (EDLC) and has a voltage of 3.8V, compared to the 2.5V of a conventional EDLC.

For automotive and transportation, JM Energy is targeting LIC usage in regenerative breaking as well as start/stop applications, among others.

The electrochemical difference between EDLC and Lithium Ion Capacitors. Click to enlarge.

The lithium-ion capacitor achieves its 4x increase in energy density by using a lithium-ion pre-doping technique to increase the capacity and lower the potential of the anode. JM Energy says safety testing shows that runaway heat reactions do not occur in the LIC because the electrode and electrolyte do not react significantly.

Capacitors are characterized by very long cycle life, high power density and instantaneous charge and discharge, but with low energy densities. The JM Energy LICs—the company is introducing two series initially based on capacitance (1100F and 2200F)—improves the energy density, offering volumetric density of 21-25 Wh/L, and  gravimetric density of 12-14 Wh/kg.

The LICs feature a self-discharge of less than 5% after 3 months, and less than a 10% drop in capacity after 100,000 cycles.

Basic properties of JM Energy LIC. Click to enlarge.

JM Energy has begun LIC production at a pilot plant (10,000 cells per year) and is building a full-scale production facility scheduled for completion in October 2008.

A number of automakers and suppliers are investigating the potential of lithium-ion capacitors, notably Fuji Heavy for its Subaru vehicles. (Earlier post.)


  • Shibuya Hideki, Hato Yukinori, Hatozaki Osamu, Ando Nobuo, Kojima Kenji, Tasaki Shink’ichi, Miyagawa Risa (2006) Lithium Ion Capacitor Pre-doping and High Performance. Subaru Technical Review, No. 33, pages 80-87



.... less than a 90% drop in capacity after 100,000 cycles.

Should be less than 10% drop, I think.

A123 and other lithium batteries have much higher power desnity than the chart indicates.

No mention of cost. Maxwell at $10/Wh headed toward $5 is still a little too expensive for mainstream hybrids. If JM can beat Maxwell on cost they might have a shot. Even if not they'll probably find a home in Formula 1 race cars and other niches.


re: 10%, right, thanks! Mike


Wow! This alone could be the best BEV option, if only the 3rd box can be checked!

[x] "self-discharge of less than 5% after 3 months" is as good as any rechargable battery!

[x] In pilot production!

[ ] competitive cost?


I'm thinking this is not so hot.

Energy density lowish, cost high, power density comparable to the better Li-ion compositions.

Nice try, but I'll put it on the back burner for now.



The target for this product is not BEVs but instead mild hybrids. A .5kw/hr pack for mild regen and start/stop functionality would save an enormous amount of fuel if used across the entire vehicle fleet.

John Taylor

This is an ideal battery for a pure hybrid.
It is not so useful for a plug in hybrid.
There is no place for it in a Battery Electric Vehicle, unless it is coupled with batteries that cannot easily recharge to recover breaking power.

In short, it was the battery needed for the past 5 years, not the one needed for the future, the next 5 years.


It's basically a more compact ultracap (price is unknown).
Probably the most suitable use in cars would be as coupled with existing Lead Acid batteries for Stop-Start systems (that can also handle regen braking).

Even if in the near future some ultracaps with comparable energy density (and price) with batteries become available, it may be better to use batts coupled with ultracaps, than ultracaps alone. Batteries usually provide far more stable voltage, and it simplifies control electronics.


You would use this like you'd use any other supercapacitors: To provide and absorb bursty power that the battery couldn't handle.

BEV, HEV, PHEV, this would still be a small part of the overall electrical system, not replace the whole thing.


Oops, this seems remarkably close to what EESTOR are attempting (the barium titanate is only half the story). Could there be intellectual property disputes?

Reality Czech

It is doubtful that a Li-ion technology could infringe BaTiO2 patents.

Healthy Breeze

If you did a 0.5Kwh mild hybrid with this, that would still be ~52Kg of supercap for a few seconds of impulse power (may 1-2 miles). Dunno if that makes mild-hybrids attractive or not. You're adding the weight and cost of the electronics, the super cap, and the electric motors to make city driving more like highway driving in a heavier good can that really be?

Jim AZ

Caps could work very well in a hybrid.
The extra cap power and regenerative braking efficiency could be used to downsize the battery pack and replace low reliability batteries with high reliability caps.
Since LIC has 4 times the energy and twice the power of conventional caps; fewer caps are needed, space and weight are saved too.
The caps can be recharged and dischared faster than batteries; using caps for power reduces heat stress on the batteries and increases their life.
AFS Trinity's hybrid drive train is available now and it uses caps and batteries.
Caps for power and batteries for energy.
I think you'll see more of this combination in the future.


I think what this battery does is reduce the size of the battery pack of a conventional hybrid to drastically reduce the "dead weight" of the battery pack. This would be perfect for Honda's new hybrid-drivetrain family car that they plan to officially unveil in January 2009.

Henry Gibson

LOOK super ultra capacitors at 10% of the energy density of LiIons. If you have spent the money for an electric motor and electronic drive you are wasting your time and money if you do not put the Smallest ZEBRA battery along side the CAPS. Remember hills take more than a few seconds to climb and Plug-in-Hybrids can charge with cheap electricity. EFFPOWER is prototyping Lead-Acid bipolar hybrid batteries that have more five times more energy per pound and a lot of power. FireFly technology added to EFFPOWER's will improve even this and give longer life. Eventually Atraverda might get its lead bipolar units working as well. ..HG..



According to your post the energy density of the mentioned Lead-Acid batteries would be about 60-70% of lower capacity LiIons (ie 50-70 kWh/kg).
What about their cycle life and costs per kWh ?
LiIons usually have enough power density for car applications, so they don't need ultracaps.
If Lead-Acid ones need ultracaps, it increases costs and requires extra room.

To me Zebra batteries seem suitable only for vehicles that are driven all day, like some delivery vans, as operating temp of ~300 oC must be maintained.


This lithium capacitor looks more like a lithium battery/ double layer capacitor hybrid. There are plenty of these being patented for all types of battery chemistry at the moment, including lead acid versions.
It seems to have a minimum operating voltage which capacitors do not have but batteries do, especially litium based batteries.
Comparing the lithium "capacitor" 3.8 volts to 2.2 volts against a capacitor of the same capacitance 2.7 volts to 1 volt there is indeed more energy stored in the lithium" capacitors" than a standard carbon EDLC but only 52% more and not 5 times more as is indicated in the Ragone plot.

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