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Report: Sumitomo and Kyoto University developing lower temperature molten-salt battery; about 10% the cost of Li-ion

The Nikkei reports that Sumitomo Electric Industries Ltd., in partnership with Kyoto University, has developed a lower temperature molten-salt rechargeable battery that promises to cost only about 10% as much as lithium ion batteries. Sumitomo intends to commercialize the battery around 2015 and market it as an alternative to lithium-ion batteries used in automobiles and homes, according to the report.

Molten-salt batteries use highly conductive molten salts as an electrolyte, and can offer high energy and power densities. The ZEBRA battery is an example of a molten salt battery. A drawback to the general class of molten salt batteries has been high operating temperatures.

The new battery uses sodium-containing substances melted at a high temperature. The technology has been around for decades, but existing molten-salt batteries require keeping the electrolyte in a liquid state at a temperature higher than 300 C. Sumitomo Electric worked with researchers at Kyoto University to develop a sodium material that melts at 57 C.

Having roughly double the energy density of a typical lithium ion battery, the new battery would let an electric vehicle travel twice as far as a lithium ion battery of the same size. Automakers would be able to reduce the space taken up by batteries in their EVs. Molten-salt batteries also boast high heat and impact resistance and are said to be less susceptible to igniting than lithium ion batteries.

Unlike room-temperature lithium-ion battery, the new battery must be kept at 80 °C to output power; hence, Sumitomo Electric reportedly envisions it being used in applications where it is operating continuously, such as in homes and electric buses. The company and the university have applied for patents.



"has developed a lower temperature molten-salt rechargeable battery that promises to cost only about 10% as much as lithium ion batteries."

So many promises, always years away..


Wow, this is BIG. we used to talk about NaS batteries thirty years ago, but the 300C (572F) temps were not practical. 80C is only 176F, hot to touch but won't boil water. Anyway it will be insulated.

Double the energy for 10% the cost and on the market in four years would be a game changer if it's true.

At that price, you could plug in your car to the house or the grid and charge it or get paid for the output, and not worry about the battery's lifetime.

Seems to me power companies already have large high-temp NaS batteries being installed for grid storage. This would make it a lot cheaper for them too.


I don't think this is practical for cars, let the temperature drop and your battery will takes hours to be re-heated. Asides this might found interesting applications, where like they says there is continuous use, bus, trucks etc.

Yes Kelly like you say when a company says that product is just 5 years away, don't count too much on in, it means "they have no idea if it will make it through"


If it really costs only 10% as much as Li-ion, it would be crazy not to pursue the concept. 80°C is trivial to maintain for days (vacuum-insulated panels plus air cooling) and allowing the battery to freeze (if it wouldn't be damaged) would be a great way to eliminate self-discharge over an extended idle period. Just leave the car plugged in and send it a text message a few hours before you need it (or set it on an alarm).


A high temperature battery would be a great addition to a district heating system, it could sit in the middle of a thermal store and the whole system would have a good flexibility to meet heating and electric demands which can vary in short term but are quite seasonal at a wider scale


Trickle charging could keep a well insulated battery container (s) at 80C for extended periods. However, parked outside in very cold weather, without access to a power plug, may be a challenge unless some of the battery's own energy is used to keep it warm. Alternatively, a mini very low cost gas or ethanol heater could do the job.

At 1/10 the cost and twice the energy density (if it materializes) it could store the e-energy required for practical/affordable BEVs with 60+ Kwh units and up to 500 Km range.


If this development comes to fruition it's a game changer. It's highly unlikely that the cost of Lithium Ion batteries will ever drop by an order of magnitude. All the effort being spent on Lithium Ion batteries is misplaced as far as I'm concerned.

Henry Gibson

Firstly, lead batteries and a range extender generator will work for plug in hybrid automobiles. Even Firefly has been slightly resurrected. Atraverda is reducing the lead in its new bipolar batteries to nearly the active material alone. The Sulphuric acid solution takes up most of the active volume, and glass mats take up some more.

Secondly, ZEBRA batteries are in an insulated case that keeps them very hot for days and they have been tested for at least fifteen years, and they can be cheap because the material costs are low and a mass market would reduce the manufacturing costs.

Thirdly, ZEBRA batteries are used in submarines and some versions of the TH!NK and were tested in many cars over ten years ago. They must be kept plugged in if they are not operated for several days and the consume 100 watts to keep hot. A Prius with a ZEBRA long range battery would work in normal mode until the battery was heated and activated. Fast electric heaters that use the power of the Prius generator for fast heating could be an option, but why not keep it fully charged and hot. The computer is left on most of the day with even more watts. Good thinking HarveyD.

Forty miles is adequate full electric range and range extenders or a different automobile take care of the rest. A small diesel engine VW or other can get very good efficiency.

INNAS NOAX proposes a hydraulic hybrid car with a simple low power electric hydraulic pump for full electric operation with the engine hydraulic pump ready to go in an instant.

Cerametec got a PM award for their proposed low temperature Sodium battery in 2009. ..HG..


ZEBRA batteries lose 18% of their energy in a day, not very efficient or practical. Hopefully these new lower temp units will do better.

Rob Dekker

I've been studying ZEBRA's NaNiCl molten-salt battery for a long time, and there are really only 2 downsides to that technology (when used for electric vehicles) :
- 100 W is needed to keep it at its operating temperature (some 250 C).
- Energy density is at 90 Wh/kg, which is good, but not as good as Li-ion.

Production cost of the ZEBRA was always very low (at least in high volume production), so I have to assume that these two points were the two main issues that prevented their large-scale use in EVs and PHEVs.

Seems that the Japanese now solved both problems with one design, which is very promising for future EVs and PHEVs.

I wonder if anyone has found more details on this battery. At 57 C, Sodium is solid and thus this battery would not require the ZEBRA's (beta-alumina) solid electrolyte. That means the design will be significantly different from the ZEBRA design. Also, does anyone have info on the liquid electrolyte that they used ?

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