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28-10-2020 | Battery | News | Article

"Mass production decides on solid-state battery success"

Christiane Köllner
2 min reading time

What potential do solid-state batteries have for electric cars? Springer Professional spoke to Akira Yoshino, the inventor of the lithium-ion battery, about this. 

Springer Professional: The solid-state battery cell technology is regarded as the most promising approach to electro mobility of the future. What are the benefits of solid-state batteries compared to conventional lithium-ion batteries? 

Yoshino: I think the biggest benefit of the solid-state batteries is that they allow higher operating temperatures due to better thermal stability. Especially, if you consider automotive application, solid systems can do without the cooling system for the battery. 

Are there any downsides?

A key challenge is the Lithium ion transport through the solid electrolyte and in particular over the interfaces with the electrodes. The resistance at the electrode respectively solid electrolyte interface is too high, impeding fast charging and discharging. Volume expansion in intercalation materials is also significant barrier to solid-state batteries. If the battery expands or shrinks a little, there is a risk that the surface contact will break off so that there is no more charge transport.

Research on solid-state batteries is currently very strong. What is the reason for this? At what stage is solid-state batteries development currently at?

Due to higher electrochemical stability, there is the possibility to use new, different materials for the cathode and anode that we couldn’t use before. Very small solid state batteries are already commercialized. Regarding large-sized solid state batteries that could be used for automotive, the development is still in its early stages. Other battery candidates did not have yet achieved the breakthrough beyond the research stage.

What differences do exist in the consumption of scarce and expensive raw materials if you compare solid-state batteries to lithium-ion batteries with liquid electrolyte?

Almost the same materials are used for the cathode and anode of solid state batteries. There is a trend away from using scarce material and finding ways of using less of them. In addition, it will be especially central for the vehicle applications to recycle the metal for the battery. The technology to recycle for example the cobalt or the nickel is established. Technically, it is possible to recycle, but it is costly. 

What are the most challenging technological aspects regarding scalable production methods of solid-state batteries?  

It is important to produce solid electrolytes that can be packed tightly but remain flexible, so that the ions and electrons can flow easily while the anode has room to expand and contract. Minimizing the deformation of the electrolytes is decisive, as this influences the long-term performance degradation of the battery.  

Toyota plans to start limited production of solid-state batteries for electric cars in 2025. How realistic is a market launch by 2025?

Toyota has finished testing. So, then they say 2025, I think they are talking about a prototype or small series production for testing. For the solid-state battery to succeed, mass production will be decisive.

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