Aug 2, 2019 - 04:14 pm

Solid electrolyte batteries – the next big thing?!

All-solid-state batteries would be a true revolution. But one that is hardly foreseeable.

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Battery cells with a solid electrolyte promise high energy densities. Batteries in electric cars could thus become smaller and lighter – and the range could increase. But when is an open question we here try to answer.

Our contributor Christoph M. Schwarzer spoke to experts to analyse the current situation for electrive. Whether and when all-solid-state batteries reach series production is an open question that companies are racing to close. “We have entered a new age,” announced Shigeki Terashi in June. According to the high-ranking Toyota manager, progress has exceeded expectations. They want to present a battery with solid electrolyte for the 2020 Olympic Games in Tokyo. The statement led to euphoria: Japanese corporate culture prefers the understatement. If Toyota speaks of a breakthrough, then there should be something to it. And indeed, the series production of an all-solid-state battery would be a revolution in cell chemistry that so far has only developed evolutionarily. However, everyone involved is a long way from achieving this.

A look at the small print at Toyota also shows that. The announcement of several cooperations had prompted Terashi’s statement. Among other things, Toyota plans to establish a joint venture for the development of solid-state batteries “by the end of 2020” with its long-standing partner Panasonic, which manufactures the nickel-metal hydride batteries for the company’s hybrid cars. This careful formulation alone shows how far one is from series production. Nevertheless, industry and researchers agree: the opportunities are high, and the potential of All-Solid-State is outstanding.

A vital evaluation criterion for battery cells is energy density. One has to differentiate between the gravimetric unit watt-hours per kilogram (Wh/kg) and the volumetric unit watt-hours per litre (Wh/l). Typical cells are 250 Wh/kg and over 600 Wh/l. Both parameters are essential: the weight because it reflects the batteries’ worst disadvantage, namely the extreme use of materials. According to BMW, a good 60 per cent of electrical energy is recuperated during deceleration – but this also means that more than a third is lost. The ballast of an electric car is, therefore, less important than that of a conventional vehicle, but it is by no means indifferent from an energy perspective either. Volumetric energy density, on the other hand, is relevant as the trend towards more and more capacity enlarges the space required for installation. As with Volkswagen’s modular electrification kit (MEB), this space is best found between the axles but is naturally limited.

Up to 70 per cent more volumetric energy density

The introduction of solid electrolytes could increase gravimetric energy density by 40 per cent, and volumetric energy density by 70 per cent, Dr Johannes Kasnatscheew of Forschungszentrum Jülich explains in the interview with electrive. The scientist first worked on liquid electrolytes and now is a specialist for solid electrolyte batteries: “We are looking for the material that enables the best compromise.” There are inorganic electrolytes such as ceramics and glasses as well as organic electrolytes such as polymers. Both have advantages and disadvantages.

Reasonable conductivity, high mechanical robustness, but very high contact resistances during charging and discharging characterise inorganic solid electrolytes. The current flowing is still too low. Organic solid electrolytes, on the other hand, have less contact resistance, but low conductivity. At congresses, scientists continue to discuss the suitability of compounds. At present, sulfid-based inorganic ceramic solid electrolytes are the favourite in terms of conductivity.

The lithium metal anode is the key

In current batteries, the liquid electrolyte is the inactive medium in which the lithium ions migrate between the cathode and anode. However, the highlight of solid electrolytes is not the simple replacement in the sense of an exchange: “With solid electrolytes, we can realise lithium metal instead of graphite-based anodes,” explains Dr Johannes Kasnatscheew. This is the only way to make significant progress in energy density.

If this were to work, it would also drastically improve the use of energy in production and thus the CO2 balance: Today, drying is a complex and energy-intensive process. This would at least be superfluous on the anode side when using solid electrolytes because the foil is from lithium metal. This also reduces toxicity.

When asked how he classifies the prospects for implementation, Kasnatscheev replies diplomatically: “Solid electrolytes are very promising, but remain challenging.”

The success of solid electrolyte batteries is dubious

Electrive spoke with other experts in the industry. They expect to see neither the series production nor the installation into a series car before 2025. So far, there has been no sample of solid electrolyte batteries that could beat current products in terms of their properties. Besides, it first would need to be shown, how pure lithium metal anodes could be produced safely and in mass.

At the same time, it is clear that billions of lithium-ion cells with liquid electrolytes are being built without any significant difficulties. Their development does not stop either; there is a permanent evolutionary improvement. A replacement of the current lithium-ion generation, according to one expert, is not up for discussion.

Nevertheless, the research and development of all-solid-state batteries do not belong in the fairytale realm of promising miracles. The seriousness with which many people around the world are working and the transparency demanded by scientific institutes are no guarantee for success, but proof that there is a well-founded rational hope for change and the Next Big Thing.

Reporting by Christoph M. Schwarzer.

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10 Kommentare zu “Solid electrolyte batteries – the next big thing?!

  1. ROBERT LANGFORD

    Is it possible that they can be fabricated in any shape?

    • Gerrit

      Hello,
      I do not know how to interpret this article.
      On the one hand we can read:

      We have entered a new age,” announced Shigeki Terashi in June. According to the high-ranking Toyota manager, progress has exceeded expectations. They want to present a battery with solid electrolyte for the 2020 Olympic Games in Tokyo

      And on the other hand:

      A look at the small print at Toyota also shows that. The announcement of several cooperations had prompted Terashi’s statement. Among other things, Toyota plans to establish a joint venture for the development of solid-state batteries “by the end of 2020” with its long-standing partner Panasonic

      What do we have to beleave? Has toyota developed a solid state battery and will be announced in 2020 or not?

      Can somebody clarify?

      Your sincerely,

      Gerrit

    • Alex Volta

      Solis state batteries will also be deployed in personal electronics such as wearables, hearables, health monitoring and IoT . These offer massive demand opportunities

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  3. Ron Stansfield

    You published an article on January 6th stating that Prologium has developed a SSB and is in discussions with manufacturers to bring it to market. This appears to contradict the pessimistic claims about SSBs in this article. Perhaps you can clarify your position.

  4. levi

    At the end of the article, other experts say this revolution will not take place before 2025.

  5. Jani

    Ilika is way ahead in this field. I would ask you all to take a close look at this company.

  6. Rebecca

    Do keep in mind..they are going up against Tesla..who is creating one also

  7. R Selvaraj

    Stanford university and MIT are way ahead in development of sold state batteries technology.

    • Ernest Demaray, Ph.D Chemical Physics

      The solid state thin film micro battery has been in production at STMicro since 2012 or so. It utilizes a solid state electrolyte LIPON invented and developed at Oak Ridge National Labs by John Bates years ago that has a conductivity ~ 3 E-6 S/cm, much lower than more recent electrolytes but good enough. It also utilizes a Li metal anode. It’s limitation is the conductivity of the cathode material LiCoO2 which in turn limits the cathode to ~10 microns which gives the single layer ~ 1 cm2 cell a little less than 1 mAh capacity. Similar vacuum deposited micro batteries where manufactured by Infinite Power solutions, now acquired by Apple. Front Edge and others also manufactured similar micro batteries which have been tested to 60,000 cycles by Dr. Nancy Dudney at ORNL or more and have self discharge in a year that can’t be measured. It’s only a matter of time before a high capacity battery with greater than 500 – 600 Wh/kg and greater than 1200 Wh/l is available with similar cycle life and self discharge. Which brings up the issue of $/Wh-cycle. With 50 to 100 thousand cycles the cost per watt-hr cycle will be less than the cost to dispatch the same energy over the grid. With years of storage, the intermittancy of renewable energy will disappear and batteries will go from direct to indirect and become assets. When the self discharge is less than inflation, energy will become sovereign, the essential condition to eliminate energy poverty.

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Found on electrive.com
https://www.electrive.com/2019/08/02/solid-electrolyte-batteries-the-next-big-thing/
02.08.2019 16:18