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Sumitomo considering marketing new lower-temperature molten-salt electrolyte battery to automakers for EVs and hybrids

Construction of the molten-salt electrolyte battery. Source: Sumitomo. Click to enlarge.

Sumitomo Electric Industries Ltd. is considering targeting its lower-temperature molten-salt electrolyte battery, being developed in partnership with Kyoto University (earlier post), to makers of electric and hybrid passenger cars, according to Bloomberg.

Sumitomo had earlier said that it intended to commercialize the battery around 2015 for commercial-vehicle fleet operators and stationary applications, and was targeting revenue of more than ¥1 trillion (US$13 billion) from it.

Being non-volatile and non-flammable, and with high ion concentrations, molten salt makes an excellent battery electrolyte and can offer high energy and power densities; Sumitomo earlier reported that it has achieved energy densities as high as 290 Wh/L with the new battery. A drawback to the general class of molten salt batteries (e.g., the ZEBRA battery, or GE’s Durathon sodium-metal halide batteries, earlier post) has been the need for high operating temperatures to keep the salt molten.

In a joint project with Kyoto University, Sumitomo developed a molten salt with a melting point as low as 57 °C. Using this salt, it developed the new molten-salt electrolyte battery.

Since it comprises only nonflammable materials, the new battery will not ignite on contact with air from outside, nor is there thermal runaway from overcharging or temperature rises in the battery. For this reason, Sumitomo says, there is no need for waste-heat storage or fire- and explosion-proof equipment, so the batteries can be packed close together.

The company earlier reported that based on its trial calculations, assuming equal capacity, the new battery had half the volume of lithium-ion batteries and one quarter that of sodium-sulfur batteries, enabling miniaturization.

Sumitomo is continuing work on the battery to find molten salt that can be used at still lower temperatures.




could be a breakthrough, maintening the temperature of the cell at 57C might not always be easy but possible


"The company earlier reported that based on its trial calculations, assuming equal capacity, the new battery had half the volume of lithium-ion batteries and one quarter that of sodium-sulfur batteries, enabling miniaturization.

Sumitomo is continuing work on the battery to find molten salt that can be used at still lower temperatures." sounds encouraging.


This sounds VERY encouraging. I'm still waiting to see figures for power density and specific energy (Wh/kg) as they only talk about energy density which is technically Wh/l.

It always worries me when a battery maker throws out a couple of good numbers and then mumbles something un-intelligible about the other specs. Usually means they have some problems to overcome in those areas and they don't want to talk about them.

It would still be great to have a battery "half the size of a lithium battery" but will it weigh as much as a city bus and take a battery as large as a city bus to give you 100kW of power???

I hate to be cynical but I want this to be great so bad that I'd rather know any bad news now rather than get my hopes up and be disappointed later.

Molten salt batteries are usually good for cycle life but terrible for power density. Of course, the power density can be solved with a 10 kg of A123 batteries or supercaps to bolster the power and use the molten salt batteries as the main "energy store". :-)


Yes, I'd like to hear more information about this. They might as well include all the parameters.


Hot water is normally stored around 60 degrees C so you could have a pretty useful combined system of hot water and battery storage, an ideal mix for using solar thermal and PV.


Better batteries, of all kinds, ARE coming.

Advances on many fronts - many synergistic.

Nick Lyons

Looks really promising. The source article (annual report) says they are looking at stationary applications as well as trucks and buses. These might be a great application for off-grid solar storage.


Excellent. With a small trickle charge the battery pack could be kept at temp - except for long periods of no use. Henry G has long touted the ZEBRA, but the tests of those showed them hard to keep at temp (200C) and very heavy.

This new salt sounds like it could solve both issues with ZEBRAs...


The major difference seems to be lower (+58 C) operation temp instead of (+250 C). Another advantage would be much lower cost, claimed to be 1/10 of Lithium batteries.

The claimed volumetric energy density of 290 Wh/L is within the normal range of 170 to 345 Wh/L for that type of unit. The gravimetric energy density, at the cell level could be around 170 Wh/Kg and about 115 Wh/Kg at the battery level.

Specific power is normally rather low at 250 W/Kg.

Combined with super-caps it could work for 30+ years (in heavy vehicles where the extra weight is not so important??)


So much potential, so few products.


energy density is not too important for stationary applications.


Excellent battery.
From now until 2015, the year of the sale of this battery there will be other technologies to compete, as Lithium or metal-air, anodes to Graphene etc., new super capacitors, better hydrogen's storage system, and others tecnologies we cannot imagine now.
The road is still long. Hurry up and check it out!


joe...well said. The world will be flooded with many new and/or improved battery-super.cap-FC technologies by the end of the current or next decade. Energy storage and production technologies could take giant steps in the next 20 years. The movement has started and it will not stop.

This would be fantastic for grid storage applications. There has been a lot of talk the last few weeks about how wind will be cheaper than coal and natural gas in the next few years, and solar will be cheaper before 2020. But how to we make those sources useful? Using these batteries to level out the power generation would help make this better.

Plus grid storage doesn't worry about higher temperatures, density or weight issues. If it takes a bus-sized device to deliver 100kW, as long as it can store enough power for 5 hours, it'll be fine.


Good point siromega. Frankly, the strong suit for a battery like this would be grid storage. At that price point, it would be a dream come true for load balancing for solar and wind.

Stan Peterson

The best use for such batteries is probably to allow Full Hybridization of diesel-electric locomotives. The diesel engine can be downsized, and emission controls added, while the batteries and the electric generator driven by the Diesel combine to produce sufficient torque for handling grades.

Volume and weight are not a true considerations in such appplications. Long life and high energy from the batteries are.

Locomotives are capital equipment with long projected life-spans. Selling new locomotives that are somewhat more fuel efficient than the older ones, is a tough sell as the gains are not that dramatic.

But fuel economy gains, and cleaner locomotives as amandated by law and only now becoing in force for Tier IV emission levels, and downsized diesel engines producing greater fuel economy, may just be sufficient to attract the purchase by the RailRoads.

There is no doubt that the next target to attack for toxic emissions, are the largely un-regulated toxic emitting locomotives.

Some Railroads were objecting to going to Tier IV as retrofitting emission equipment on older locomotives to meet Tier II levels is feasible but not so feasible for tougher Tier IV levels.

On a different subject. As for using batteries for buffering the output of Wind and Solar, y'all are dreaming. The buffered output is simply way too large for any reasonably sized battery pack.


"As for using batteries for buffering the output of Wind and Solar, y'all are dreaming."

Stan, thank you for sharing your *OPINION*

Of course, there are others who actually do this today that might disagree with you.

"The basic concept has been proven. Since 2003, the world’s largest battery backup has been storing energy for an entire city: Fairbanks, Alaska. Isolated as it is, and not part of any regional electricity grid, the metropolitan area of about 100,000 residents needs an electricity backstop more than most:"

And those are old cheapo lead acid batteries. Something like these molten salt batteries with low cost, high specific energy and long cycle life would make things like this even more realistic.


Or the salt-manganese battery.

Bob Wallace

During the first phase of large scale battery grid storage batteries need to compete in price only against natural gas "peaker" plants. Those turbines which spend much of their time parked and are then spun up as demand requires.

The price of electricity from peaker plants can be quite high. Utility scale batteries are probably already cost competitive.

Then add in the extreme rapid response time of batteries as opposed to the 10-15 minute 'off to full-speed' response time of gas peakers and batteries bring another level of value to the grid.

Bannor Haruchai

Instead of this being ready "any day now" - yes, 2015 is just 2 months away - we're more likely to have flying cars & fusion reactors before this is ready.

Here's an excerpt from the link above:
" Hagiwara envisions such technology being used for emergency power supplies, saying it could end up in cellphone base stations in three to five years, household stationary batteries in five to 10 years and batteries for electric vehicles in a decade."

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