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Japanese start-up seeks to commercialize dual-carbon battery technology; anion intercalation

14 May 2014

Capacity vs. cycle number. Source: Power Japan Plus. Click to enlarge.

Start-up Power Japan Plus announced plans to commercialize a dual-carbon battery technology, which it calls the Ryden dual carbon battery. Power Japan Plus says that its battery currently offers energy density comparable to a lithium-ion battery, but with a much more rapid rate of charge and the ability for full discharge over a much longer functional lifetime with improved safety and cradle-to-cradle sustainability.

Dual-carbon (also called dual-graphite) batteries were first introduced by McCullough and his colleagues at Dow Chemical in a 1989 patent, and were subsequently studied by Carlin et al. (1994) and Seel and Dahn (2000), along with many others. The basic concept of the cell is that lithium ions from the electrolyte are inserted/deposited into/on the anode (negative electrode), while the corresponding electrolyte anions are intercalated into the cathode (positive electrode). Both electrodes are carbon (e.g., graphite). During discharge, both anions and lithium ions are released back into the electrolyte. As Rothermel et al. noted in their 2013 review of challenges and opportunities for the technology, the electrolyte in such a system thus not only acts as charge carrier, but also as the active material.

Cartoon of charge and discharge in the dual carbon battery. Source: Power Japan Plus. Click to enlarge.

The Power Japan Plus cell is based on the work of Professor Tatsumi Ishihara at Kyushu University in Japan; Power Japan Plus will continue developing the dual carbon battery technology in partnership with Prof. Ishihara and the university. In a 2013 patent filing on the technology, Ishihara and his colleagues explain the charge and discharge reactions thusly, using a LiPF6 salt (as did Seel and Dahn):

Positive electrode: PF6 + nC ⇄ Cn(PF6)+e

Negative electrode: Li+ + nC+e ⇄ LiCn

→ charging reaction; ← discharge reaction

Discharged capacity is determined by the anion storage capacity of the positive electrode; the amount of possible anion release of the positive electrode; the cation storage capacity of the negative electrode; the amount of possible cation release of the negative electrode; and the amount of anions and cations in the non-aqueous electrolyte.

US Army researchers develop their own dual-graphite battery
In a recent paper in the RSC journal Energy & Environmental Science, a team from the US Army Research Laboratory reported a reversible dual-graphite intercalation chemistry with simultaneous accommodation of Li+ and PF6 in graphitic structures using a high voltage electrolyte based on a fluorinated solvent and additive, which is capable of supporting the chemistry at 5.2 V with high efficiency.
This all-graphite battery promises an energy storage device of low cost, high safety and high environmental friendliness that are critical for large scale energy harvesting/storage needs, that team concluded.

To improve the discharged capacity in the dual carbon cell, it is necessary to increase not only the positive-electrode active material and the negative-electrode active material but also the amount of the non-aqueous electrolyte including a lithium salt. Because the ion concentration of the electrolyte changes during cycling, there must be enough electrolyte salt in the cell to guarantee conductivity, and there must be enough solvent to enable the salt to be disolved at any state of charge or discharge.

In their patent filing, Ishihara and colleagues note that in such a dual carbon cell, precipitation and dissolution of a lithium salt as a supporting salt may take place at any location in the cell where a non-aqueous electrolyte exists. However, precipitation of a large amount of the supporting salt on electrode surfaces causes a problem of decreased power density of the cell because the supporting salt in a solid state is an insulator.

Prof. Ishihara and his team claim, among other things, that they have devised a way to prevent the supporting salt from precipitating on an electrode surface, along with improved high discharged capacity and improved gravimetric energy density.

Power Japan Plus says that its battery charges 20 times faster than lithium ion batteries; is rated for more than 3,000 cycles; and can slot directly into existing manufacturing processes, requiring no change to existing manufacturing lines.

The ability to charge the battery so rapidly could, the company proposes, enable longer-range electric vehicles, as regenerative breaking will be more efficient. Because the dual carbon battery can be 100% discharged, it can further extend the length of each usable charge cycle, the company also suggests.

Power Japan Plus will begin benchmark production of 18650 Ryden cells later this year at the company’s production facility in Okinawa, Japan. This facility will allow the company to meet demand for specialty energy storage markets such as medical devices and satellites. For larger demand industries, such as electric vehicles, Power Japan Plus says it will operate under a licensing business model, providing technology and expertise to existing battery manufacturers to produce the Ryden battery.


  • Jeffrey A. Read, Arthur V. Cresce, Matthew H. Ervin and Kang Xua (2014) “Dual-graphite chemistry enabled by a high voltage electrolyte” Energy Environ. Sci. 7, 617-620 doi: 10.1039/C3EE43333A

  • Onagi et al. (2013) US patent application 20130288113: Non-aqueous electrolyte storage element

  • S. Rothermel, G. Schmuelling, O. Fromm, P. Meister, H.-W. Meyer, T. Placke, M. Winter (2013) “Challenges and opportunities of dual-graphite cells based on ionic liquid electrolytes,” ECS 224, #891

  • Tatsumi Ishihara, Yuji Yokoyama, Futoshi Kozono, Hidemi Hayashi (2011) “Intercalation of PF6- anion into graphitic carbon with nano pore for dual carbon cell with high capacity,” Journal of Power Sources, Volume 196, Issue 16, Pages 6956-6959

  • Tatsumi Ishihara, Yuji Yokoyama, and Shintaro Ida (2010) “Intercalation of PF6- anion into Graphitic Carbon with Nano Pore for Dual Carbon Cell with High Capacity,” IMLB 15 #224

  • J. A. Seel and J. R. Dahn (2000) “Electrochemical Intercalation of  PF 6 into Graphite” J. Electrochem. Soc. vol. 147, issue 3, 892-898 doi: 10.1149/1.1393288

  • Carlin, R. T.; Delong, H. C.; Fuller, J.; Trulove, P. C. (1994), “Dual Intercalating Molten Electrolyte Batteries” Journal of the Electrochemical Society141, (7), L73-L76 doi: 10.1149/1.2055041

  • McCullough, F. P.; Levine, A.; Snelgrove, R. V., U.S. Pat. 4,830,938 1989

May 14, 2014 in Batteries | Permalink | Comments (13) | TrackBack (0)


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Holy. Guacamole.

Is anyone going to the EDTA conference in Indy next week? I cannot attend. Pjp will be presenting there and if anyone can share their technical impressions we would surely all be very grateful. TIA

I hate it when statements like "20 times faster" are made without stating faster than what.

Suppose this means charging rates go from 1C to 20C.  A 4 kWh battery could be charged at 80 kW, which makes for good regnerative braking in a HEV.  The capability for repeated deep discharges would allow even a small battery to be used as a PHEV battery, with limited but significant all-electric driving range.

Anything that replaces petroleum with electricity is good at this point.

Yes, a lower cost, quicker charge/discharge, wider charge/discharge cycles battery would be a possistive asset for existing HEVs.

This battery, when coupled with a very light weight small (660 cc) ICE genset could potentially make price competitive PHEVs to replace most current small and mid-size ICEVs and reduce fuel consumption by up to 80%.

If this is low cost it has great potential for home storage of solar panels. The real killer for domestic storage systems is cycle lifetime at low cost. If this costs $250/KWHr it will be a game changer for home Solar PV. I currently pay 25 cents per KWHr when buying from a grid. Exporting to the grid nets me 8 cents/KWHr. Having 2.5K$, 10 KWHr of storage would make a huge difference to the current economics of solar PV. Of course the next step will be for utilities to change much higher connection fees. This is already happening in Australia.

BTW this would have a huge market in laptops and power tools where rapid recharge and long cycle life are important features.

If this isn't just vapor, it's a game changer, especially if the voltage increase per cell is an honest 4 volts. That changes even a starter battery to three cells instead of four.

I have a garden tractor I converted to an electric mule...runs on 48 volts of Pb, that would be a reduction of four cells.

So far the company is light on specifics, we'll see.


Your best bet for a PV storage system is a liquid electrolyte that can be stored in mass quantities for days or even months at a time. This would shrink the relative cost of the charger-generator system to the whole.

That was the idea of a vanadium bromide proposal in New Zealand for wind power. Whatever happened to that? We are told since the electrolyte is redox, neither it nor the electrodes can actually be contaminated in the same manner that say lead can be rendered inoperable eventually by sulfuric acid.

My guess is that this battery has the LiPF6 in a thin gel. Which is OK since fluoride is abundant from aluminum smelting and the whole electrocell would resemble Polaroid film. And graphite (or graphene here, really) is getting cheaper.'s the catch? If it runs at 5.2V and 100mAh/g then we're talking about something probably over 400Wh/kg even at the pack level. And over 3,000 cycles? With deep discharge? And carbon so it's not poison?

Uhhhh, what's the catch? Price? Either there's a catch or these guys are going to be worth a LOT of money.

There are no real specifications just vague superlatives from an unknown company without any track-record or reputation to guard. As a good rule of thumb treat all such announcements as hoaxes. This is another JSTORE. Just forget it.

looking at 1rst graph Coulombic eff. ~93% and this one if I interpret it right shows it even worse


"which is capable of supporting the chemistry at 5.2 V with high efficiency."

That is the capability of the electrolyte, not the operating voltage of the battery.

@SJC....good point.

Yeah, Henrik is probably right. Sounds too good to be true. Another eestor most likely. :-(

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