By on March 3, 2011

What was the problem of EVs again? It’s the battery. Too expensive. Empty too fast. Also known as price and range.

Japan’s Sumitomo Electric thinks they have a solution, in the true sense of the word. Their molten salt battery is said to cost about 10 percent of the price of lithium ion batteries. It also holds twice the charge. That according to The Nikkei [sub] .

  • Molten salt technology has been around for decades, but existing molten-salt batteries need to be kept at a temperature higher than 300 C. Sumitomo Electric and researchers at Kyoto University developed a sodium material that melts at 57 C.
  • The new battery has roughly double the energy density of a typical lithium ion battery. That would give a car twice the range as when powered by a lithium ion battery of the same size.
  • Molten-salt batteries have high heat and impact resistance and are less prone to go up in flames than lithium ion batteries.
  • Sodium is much cheaper than lithium. It is in abundant supply. The new battery is expected to be priced at about 20,000 yen ($ 243) per kilowatt-hour — about 10 percent of Made in Japan li-ion batteries and a fifth of Chinese batteries.

An where’s the catch, you ask? There is a little problem: The new battery must be kept at 80 centigrade (176 F) to output power. In a car, most of the energy would be used to heat the battery. Until that problem is solved, Sumitomo Electric wants to use the battery in controlled environments; such as homes and electric buses. Sorry!

Sumitomo Electric wants the hot battery ready for sale in 2015.

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26 Comments on “Hot New Battery: Twice The Charge At One Tenth Of The Money...”

  • avatar

    80 C is not all that hot, probably easier to run in a hybrid settings, where engine heat will supply that.

    • 0 avatar

      I had the same thought.  The only problem I see with that approach is that you have the opposite of what you want:  car uses ICE for short trips but switches to mixed-mode *AFTER* the first 5 miles of driving.  Also, the larger you make the battery (for longer around-town electric only use) the longer it takes to warm the battery with the ICE.
      To me, though, what is most encouraging here is that when scientists and engineers put enough time and effort into improving batteries, there is plenty of forward progress made.
      Maybe these batteries can be combined with improved insulation so that batteries, once warmed, will stay warm for 24 hours.  Do EPA tests require that the vehicle be “completely cold” before starting the city cycle or just that the car sit for a certain number of hours?

    • 0 avatar

      You nailed it – another heater loop – and it thriftly uses waste heat. I like BEVs as a technically sweet solution, but have never understood the level of fascination – the new, new thing, I guess. To me, the big difference between hybrids and BEVs is the length of the transmission line between the genset and the battery. Well, the power co’s gensets are a leetle larger, and the power generation more efficient. But somewhere you have a burner/prime mover and mostly it eats carbon-based fuel. Unless you are French.

    • 0 avatar
      SVX pearlie

      Agreed. Great for stop/start and similar city applications where there’s a ton of waste heat available to keep the battery warm.

  • avatar
    Dr. Kenneth Noisewater

    Keep the battery in an insulated ‘thermos’ enclosure with coolant tubes running thru it, and have that coolant regulated to the correct temp via gas motor or electric heating (that could be running while the car is plugged in)..

  • avatar

    if they got the melting temp for the sodium down this much, maybe they can get a bit further. this does sound encouraging.

  • avatar

    In an accident, this battery would spray/leak hot salt? That’s a problem (though probably not insurmountable).
    That being said, this looks like a possible way to take advantage of “demand-based pricing” for electricity at home – charge the battery at night, when the $/KW-h is low, and use the battery during the day.
    Looking forward to more information….

    • 0 avatar

      At double the charge density, for 50KW-hr, you might get to 125kg battery weight (based on specs from an older Li ion battery case I had handy.) 180 million joules of energy vs 130 million for a gallon of gas (often discounted by the efficiency of the ICE – IIRC, 1 gal = 28KW-hr). In an accident I guess you wouldn’t discount either. If you can contain 20 gallons of gas energy, you probably can contain 50 KW-hr of electric energy plus the thermal energy in a battery.

  • avatar

    No kidding- a thermos is the obvious solution.  It’ll also provide some crash-safety.  A heater will keep the battery up to temp when it’s plugged in, and the thermos will mean this heater won’t draw much power.

    Alternatively, it might be a good idea for electric cars to have a gas-fired heater for quick warm-ups, and possibly even to heat the cabin. This would probably be necessary regardless for emergency use. You can’t be left stranded just because your car has been sitting outside for a couple weeks.

    In a hybrid setup, I could see a small turbine being used as a range extender/heater.

  • avatar

    This is great news! Global warming needs to move quicker so we can start using this thing!

  • avatar

    Actually I remember reading about a Volkswagon/Saab’heat battery’ heat storage (to eliminate cold starts) system that actually used a salt compound almost 20 years back. Here’s a couple of links:


    • 0 avatar

      I remember reading as a boy about thermal energy storage system using Glauber’s salt for solar energy storage in Popular Science/Mechanics…interesting that there is nothing new under the sun…

  • avatar

    The article is nonsense as it sets up a phony comparison.
    $250/KWh is NOT 1/10 to 1/5 the price of Lithium batteries.
    About $500/KWh is typical these days. Tesla is delivering under $500/KWh.

  • avatar

    Okay, I need a chemistry lesson here.  If the Na material melts at 57 C, what happens if there is a failure of some sort, the battery cools below that, and the material solidifies?  What happens to all of the energy that it was previously storing?

  • avatar

    If these are similar to the sodium-sulfur batteries that Ford and BMW were experimenting with in the 1980s (and before), then they must be heated constantly, not just when they’re in use.  In those old batteries, letting the electrolyte freeze permanently damaged the battery.

    • 0 avatar

      That Ford battery, which was found to be not practical for automotive use, is alive and well as money saver (NYC Transit Authority for compressing natural gas with electricity charged during off-peak hours, for example) and peak shaver/buffer for the grid throughout the world. It is now called NAS battery and manufactured by an NGK (of sparkplugs) affiliate.  If the low-temperature Sumitomo battery is realized, it can also be used as a money/environment saver (off-peak charge, peak time discharge) and as a buffer for rooftop solar panels and natural gas fuel cell for ordinary households.

  • avatar

    Oh, well, that’s easy; just put an RTG into every car to keep the battery hot.
    (note: this is not a serious suggestion.)

  • avatar

    They could use a dewar or thermos type setup with a solar powered heating element. Minimal heat transfer and a green energy source to keep it warmed up.  Perhaps a second 12V battery connected to the ICE could trickle power overnight when it’s cloudy.

  • avatar

    This technology was already used in the Th!nk car (a former Ford subsidiary in Norway)

  • avatar

    A margarita on wheels — I love it!

  • avatar

    Why not have something like the engine warmer on diesels.  You plug it when when the car isn’t running to keep the temperature up.  Considering all the heat generated by the electric motor and various parts of the car there should be enough heat to keep the battery going while you are driving but it would take good design to make good use of that heat.  Either way this is an interesting development.  I think I would rather have to deal with molten salt than flaming lithium during a crash.

  • avatar

    This seems a better solution for a residence that uses solar or wind energy, in order to store and use energy overnight.

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