Interview: progress of the SIMBA project and the worldwide challenges with Sodium-ion batteries

The SIMBA project aims to solve several persistent scientific and technical challenges of Sodium (Na)-ion batteries, trying to understand the battery chemistries (e.g., electrochemical processes and degradation mechanisms), but also challenges with the electrodes processing, solid-state electrolyte integration and cell manufacturing. Since the project started in January 2021, many changes have taken place in the development and commercialization of Sodium-ion batteries worldwide, especially in Asia.

To discuss the progress of the SIMBA project within these worldwide developments, Uniresearch interviewed the deputy coordinator of the project, Dr. Magdalena Graczyk-Zajac, and Prof. Stefano Passerini, SIMBA partner and expert on Sodium-ion batteries.

How do you see the progress in SIMBA on sodium ion batteries compared to the situation in the rest of Europe? And worldwide (e.g., compared to China)?

For Stefano Passerini (SP) the progress of the SIMBA project can be regarded as significant in Europe, as it is adding new knowledge on Na-ion batteries compared to other R&D projects in Europe. For example, the Single Ion Polymer Electrolyte (SIPE) is unique and shows much potential. However, in comparison to China, Europe is quite behind on the development and upscaled production of materials and Na-ion cells with liquid electrolyte. In China, this kind of “conventional” cells are close to or even already on the market. Magdalena Graczyk-Zajac (MG) adds that cylindrical sodium cells with liquid electrolyte of numerous suppliers can be already purchased on the market.  Moreover, home storage systems consisting of a small Lithium-ion battery combined with a Na-ion battery part with a higher capacity can be purchased on the Chinese market. Concerning the SIMBA project, MG mentions that the SIPE and an anode less cell configuration developed in SIMBA are still quite new, but that the same ideas are also under competitive investigation in China and the challenge is to keep up with the speed of research now done in China.

Do you believe Europe can make a difference in R&D on sodium batteries and if so to what aspect specifically?

SP refers to the single ion conductor (SIPE), which is promising research which may work well with Na metal anode yielding good quality sodium plating out of polymer electrolyte. This is very good EU-based research (as usual). Note that the same happened with lithium batteries, the most and best research was done in Europe, but the further industrialization of the Li-ion cells were foremost done in Japan, South Korea and China. The step from R&D to industrialization is the most difficult part in Europe currently as industry is not (yet) willingly to invest in low-to-medium TRL level technologies. MG adds that Europe now does not have the industry ready for cell production, maybe with the exception of the Northvolt. Why? An important reason is the way the innovative battery start-ups are financed. In China the higher TRL projects are financed 100% by the Chinese state, meanwhile in Europe industrial partners can receive 50-60% funding. This could and should trigger more collaboration between the European research partners and for example Japanese industrial partners. SP: This is more and more happening between Japan and Germany for example and in new proposals on Sodium-ion and other batteries this collaboration is being stimulated. Japan has still a very strong Li-ion industry, so they have the knowledge to scale up although they are not the market leader anymore. SP wants to add that he believes one important reason for slow progress in Europe is that European-based big industry corporations should have much bigger roles in the industrialization and currently seem to lack interest in doing so. MG agrees and also sees less support from the European chemical industry in development of new battery technologies and industrial upscaling.

In the last SIMBA Advisory board workshop (5 June 2023) it seemed that battery manufacturers were keener to develop further the SIMBA baseline cells (i.e., with liquid electrolyte) than the proposed SIMBA cells with solid electrolyte. How can battery manufacturers become convinced of the solid electrolyte usage?

SP: Currently the focus is still very strongly on Li-ion cells. Regarding the solid-state cells, there is some interest in Asia for this kind of batteries. In Germany the research focus is now much more on polymer, but I should add that only a few years ago I was laughed at the idea of further developing such solid-state cells. Therefore, the industrial focus in Europe is still more on liquid electrolyte than on polymer / solid-state. MG: In the USA a lot of money has been spent on the development of solid state (Li) batteries by big companies like Volkswagen, BMW etc together with US startups, but we still have to wait for industrial cells. This indicates that up-scaling remains one of the main challenges in the development of all-solid-state cells. SP: By the way, it is quite strange that European car manufacturers like Volkswagen, BMW have made this investment in the US and not as much in Europe.

Battery regulations for sodium such as shipment regulations etc. are postponed till 2025: is this a creation of a barrier for battery manufacturers to move towards large scale sodium battery (component) production line setup?

MG: Transport of Sodium-ion cells is a huge barrier now since the regulations are postponed. In general, it is pretty difficult to transport cells/modules from China to Europe but also within continental Europe this is not easy. SP adds that once Sodium batteries will be commercialized, regulations will follow, but that it is very important that cells and single components will be produced in Europe to overcome this. MG: this will happen automatically as soon as regulations are in place.

How do both see the future of Sodium-ion batteries in Europe?

SP sees a good future for Sodium-ion batteries, at least within the stationary storage sector. MG adds that also low-cost cars will use Sodium-ion batteries in the future, as these batteries perform much better in low temperatures than Li-ion batteries. She mentions LFP batteries, which were not considered as “good enough” for Electric Vehicles (EV) six years ago, but nowadays are powering EVs and are of huge interest for trucks. In the latter case MG thinks Sodium-ion batteries will also be very interesting once higher cycling stability available. And of course, for stationary storage Sodium-ion batteries will be a key solution. On the question where these Sodium-ion cells will be produced, MG sees a future for Europe but if transport becomes easier/cheaper than it will be more difficult. SP is more pessimistic and he thinks that as long as Sodium-ion batteries can be shipped fully-discharged they will be manufactured in low wage countries.