Batteries Oxis Energy Li-S cell.

Published on July 1st, 2015 | by Nicholas Brown


Oxis To Manufacture Li-S Batteries Achieving 400 Wh/kg

July 1st, 2015 by  

Originally published on Kompulsa.

Many years ago, I learned of a technology that could turn the energy industry upside down — the lithium-sulfur battery. It could achieve a gravimetric energy density of 400 Wh/kg. The majority of electric vehicle batteries are well under 200 Wh/kg. This means that lithium-sulfur battery technology could at least double EV range without adding a single pound of weight, and quadruple most of them. Imagine a Tesla Model S that could travel up to 800 miles per charge!

Oxis Energy Li-S cell.

Oxis Energy is going to start selling lithium-sulfur batteries in 2016, aiming for a cost of $250/kWh by 2020. This is inexpensive compared to most current lithium-ion batteries which cost $400-$500/kWh. However, their prices can (and surely will) decline by 2020 as well, and rumor is that Tesla’s batteries are already around $250/kWh. As incredible as the range implications I mentioned above are, the financial implications are what really matter. We’ll have to see how things shake out.

“The overall cost of the materials is less – an example of this is sulfur, key to the technology, which cost under $200 per tonne,” said Howells, adding that the “predicted costs of lithium sulfur when production is ramped up is lower than competing lithium-ion technologies.”

The battery technology is undergoing testing at the Culham Science Centre in Oxford as part of Project Helios. The test system is a solar power supply utilizing a 3.8 kW 16 panel PV array, a 48 volt, 3 kW Oxis battery pack, and an SMA Sunny Boy inverter. It is currently being used to recharge a driverless vehicle. The current battery achieves an energy density of 300 Wh/kg, but they anticipate an increase to 400 Wh/kg in 2016.

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

  • Jacob

    A couple of tables from Oxis:

    In 2017 cycle life will be 500 cycles. Only in 2019 do they hope to get 1500 cycles.

  • Hans

    Seems to be much more concrete than the biosolar story. Let’s hope they can transfer their technology from the lab to the factory.

  • vensonata

    By the way I came across info today on lithium titanate batteries that now have 30,000 cycles at 100% DOD! Unfortunately they don’t have high density and are approximately twice the cost per cycle as lifepo4. But that lifecycle is amazing. As well there are limiting factors of lifespan. Info is from David Snydacker a recent Phd in electrical engineering.

    • Jacob

      Double the cost per cycle? What does that mean?

      What is exciting about it if the density is lower and cost is higher?

  • Mike Dill

    They have another problem here: they are “aiming for a cost of $250/kWh by 2020”. The commercial Tesla battery product is already there, which will make ramping their production volume and decreasing their costs very difficult.

    • Bob_Wallace

      I’m thinking that we could improve communication if we were to indicate “cell” or “pack” when talking about EV and storage system battery prices.

      Using “battery” is not sufficient. Battery can mean either cell or an assembly of cells (pack).

      Oxis Energy is likely talking about selling cells for $250/kWh. Then someone else turning them into packs. I assume.

      The article speaks of rumors of Tesla “batteries” already around $250. Tesla battery packs are rumored to be $240. There is a report from Navigant Research last October which put the current purchase price of Panasonic cells at $180. A couple more words in this article (and many others) might improve communication.

    • Matt

      Yes saying you can do cells for $250 in 2020, packs (add 33%) would be $333, and TESLA packs are $250 today; not sounding so amazing. But devil in the detail, so my assumptions may be way off. Who know maybe they will find a market segment they can grow in.

      • Bob_Wallace

        If they can pack a lot more energy into a smaller space then some applications might pay a premium.

        I’ll bring up my idea of swappable battery packs for long distance trucks. There might be some willingness to pay extra for a 300 mile range pack over a 200 mile range pack. Stretch things out to swapping every 4-5 hours rather than every 3 hours.

    • Jacob

      The thing is that there is only 1 Tesla Gigafactory.

      It cannot supply global demand alone.

      • Bob_Wallace

        Build more.

        • Jacob

          Or research Aluminium-ion batteries further and see if they really can be cycled 7000 times.

          Research Sakti3 batteries too.

          • Wayne Williamson

            lol…nothing approaching mainstream…proof is in the actual production and cost….panasonic is right there and lg is not far behind….

      • Mike Dill

        Well, the first gigafactory is a prototype. They will build more when they have worked the bugs out.

        • jeffhre

          The first 1/4 of the gigafactory is a prototype. They will Build more when they have optimized the processes for the current state of the technology.

  • Marion Meads

    Any info on the number of recharge cycles and rate of degradation? Energy density is only one thing, but will this battery last as long or longer as the other ones in the market?

    • vensonata

      Lithium sulphur has a history of short life cycles. That has been the stumbling block. If they can fix that, get ready for a 600 mile EV!

      • Jacob

        Or grid storage.

      • Mint

        Not really. Li-S batteries may be great with gravimetric density, but they’re not so hot with volumetric density. Generally, their figures for Wh/kg and Wh/L are similar:

        400 Wh/kg would mean ~400 Wh/L, which is much less than Tesla’s current cells at 620-730 Wh/L. On top of that, higher volume requires more packaging to protect it, negating some of the weight savings.

        If a car like the Model S goes from 260 Wh/kg to 400 Wh/kg, that’s only 114kg in weight savings, or 5% of the car’s mass. From that, they’ll get maybe 3% more range with a 85kWh LiS battery at most, while reducing interior space.

        LiS is not going to be a game changer. Cost is the most important metric, along with lifetime (up to a point). Volumetric density is the second most important (true for phones, too, which is the primary driver of new battery technology). Improving gravimetric density isn’t very important for EVs.

        • DesiLurker

          true, they may be the bit enablers for drones and electric aviation though with is a large enough market to deserve attention. also they tend to be less cost sensitive. Hell if they can get the density up to 600 wh/kg we might even have flying cars!

        • Jacob

          Look at the Oxis tables:

          They will not get a super-long cycle life. And probably not a giant factory like the Tesla one in Nevada to bring costs down sufficiently.

          So their best hope is mobile phones and drones where density is desirable regardless of cost.

          • Mint

            Drones yes. They need low mass above all else.

            Phones, no. Phones need volumetric density in order to pack a large battery in today’s slim form factors. LiS will have little to no success there.

    • Omega Centauri

      For vehicle applications it will have to have a proven safety record as well. I doubt that can be quickly established. Since an auto battery has to whitstand a severe car crash without catching fire, expect at least some additional weight as part of the necessary mechanical armor.

    • Joseph Dubeau

      “OXIS Li-S cells produced in 2012 have achieved an excellent cycle life: cells can be cycled over 1000 times (80% Beginning-of-Life). We expect our current cells to reach around 2000 cycles before the capacity reduces to 80% BoL.”

      • Jacob

        1000-2000 cycles.

        They better focus on mobile phones rather than grid storage.

        Because Tesla grid storage batteries can be cycled 3000-5000 times.

        • Bob_Wallace

          If Alevo is speaking truth the grid is going to get a good shaking. $100/kWh and 40,000 cycles. I think they are now manufacturing. From their website…

          High discharge power rate and high pulse current conducive to electric grid applications

          Fully dischargeable, the only lithium battery that offers 100% Depth of Discharge (DOD)

          Highly durable – can tolerate extreme temperature swing

          No calendric aging and can be stored in a complete discharged state

          Extreme long life cycle

          Constant internal resistance over cycle life

          Constant power over cycle life

          They do lose capacity over time, at 5,000 cycles they are about 50%. But that’s 13+ years of daily cycling and they should pay for themselves by then. They can hang out in low cost real estate for another 95 years and store some power.

          • Jacob

            The batteries that come out of universities such as Tel Aviv, Stanford, MIT, are much more credible.

            Alevo is secretive and private.

          • Bob_Wallace

            But convinced enough people with money to earn them a $1 billion startup fund.

            That much money invested in a new corporation has to make one take it seriously. They’ve either got a serious product or have set the record for conning a lot of big money people.

            Very few people would invest many millions of dollars in a new product without first having their own experts do a thorough evaluation.

          • Jacob

            BloomEnergy got a lot of VC funding also.

            I saw their launch. Schwarzenegger hugged Mr K.R. Sridhar on stage and Colin Powell talked.

            After that I thought that Fuel Cells are going to produce power for 11c/kWh.

            But that never happened.

        • Joseph Dubeau

          Tesla batteries cycle at 80% not 100%.
          It remains to be seen whether Tesla can compete in this

        • jeffhre

          Except that 2000 cycles at 250 miles is 500,000 miles with 80% BoL. Some automotive OEM may want to try that at some point.

    • Jacob

      A calm post from Marion!

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