Een betere batterij ontwerpen – Weg met kobalt en binnen met…TAQ?

Researchers at the Massachusetts Institute of Technology (MIT) have recently ontwikkeld a new type of battery technology that forgoes the need for precious metals.  In their place? An organic cathode known as bis-tetraaminobenzoquinone or ‘TAQ’.

Het belang van batterijen

With the rise of EVs (Electric Vehicles) – largely thanks to American Tesla (TSLA ) and Chinese BYD and CATL – battery technology has become more important than ever as they are relevant not only for electronics, but also for mobility. And soon for the electric grid as well, in order to balance out the intermittency of renewable energies like wind and solar.

Werelwijd EV-verkopen – Source: IEA

Tot op heden is de dominante chemie voor batterijen lithium-iontechnologie. Dit komt omdat deze batterijen een van de meest energiedichte zijn wanneer gemeten in kW/kg. Deze metriek is verreweg het belangrijkst in mobilietoepassingen, aangezien elk extra kilo batterij een behoefte aan meer batterij en/of minder bereik betekent.

Dus, aangezien EV’s bewezen hebben de waarschijnlijk sleuteltechnologie van de toekomst voor auto’s te zijn (en misschien vrachtwagens en zelfs vliegtuigen), is er aanzienlijke inspanning geleverd om batterijtechnologie te verbeteren.

Lithium-ion opgeven?

While highly dense, traditional lithium-ion technology is not without flaws. There is a list of problems to be solved:

• De dichtheid is nog steeds relatief laag vergeleken met vloeibare brandstoffen zoals benzine en diesel, wat leidt tot range‑angst.
• Opladen kan redelijk traag zijn, wat een probleem is voor veel bestuurders en commerciële toepassingen.
• Batterijen zijn duur, grotendeels vanwege de noodzaak voor dure mineralen.
  • Dit zorgde ervoor dat EV’s aanvankelijk meer een luxeproduct waren dan een normaal consumentengoed.
  • De winning van deze mineralen is zelden milieuvriendelijk en gaat vaak gepaard met afschuwelijke arbeidsomstandigheden en uitbuiting van arme arbeiders of kinderen in mijnen, vooral in het geval van kobalt in Congo.

As a result, plenty of alternative chemistries have been considered. This includes and is not restricted to,

• LFP (Lithium‑ijzerfosfaat)
• natrium‑ion
• solid‑state batterijen
• lithium‑zwavel
• grafiet
• glazen batterijen

De oxidatie van aluminium has even been discussed as an alternative to batteries altogether. However, all of these alternatives have their limitations. This can include a shorter lifespan, manufacturing difficulty, etc.

(We bespraken in detail de voordelen en beperkingen van elk van deze technologieën in ons artikel “De toekomst van mobiliteit – Batterijtechnologie”).

The most promising, like solid-state batteries, are still at an experimental stage, and the ones ready for commercialization, like LFP and sodium-ion, suffer from lower energy density than lithium-ion.

There is probably a market for these lower-density batteries, as they are also much cheaper to produce. The Chinese company CATL (300750.SZ), which produces more than half of the planet’s batteries, is among the leaders in this field. We discussed the leading battery manufacturers in our article “Top 10 batterijacties om in te investeren”.

Still, ultimately, the ideal EV would have a cheap AND powerful battery. This combination will be likely required to fully replace the combustion engine, especially for commercial applications.

Het kathodeprobleem van lithium-ion

Most of the limitations of lithium-ion come from the chemical and physical properties of the cathode part of the battery. It is the cathode that typically requires cobalt, and even in cobalt-free potential alternatives, usually relies heavily on other costly metals like nickel and magnesium.

(The metals required for the transition to EVs and renewables were discussed further in our article “Top 10 Battery Metals & Renewable Energy Mining Stocks”)

These metals are required to be mined, cause pollution, and work conditions are often terrible. They are also toxic, making recycling batteries a more complicated task.

Bron: Visual Capitalist

Researchers have been looking at carbon-based alternatives, or the so-called organic cathodes. For now, this has been rather unsuccessful, as organic cathodes have either been too low in energy density or not durable enough to use in the context of frequent charge-discharge cycles of EVs.

This might have changed, thanks to the aforementioned discovery by MIT researchers.

Een nieuw type organische kathode

Prof. Mircea Dincă, werkzaam als W.M. Keck Professor of Energy aan MIT, has recently explored new organic compounds previously untested for cathode applications. Instead of the previously explored organosulfur and carbonyl compounds, he looked at a compound called TAQ (bis-tetraaminobenzoquinone). His team had previously demonstrated the potential of this chemical as a supercapacitor material.

TAQ has great potential for use in batteries, as it forms “gelaagde solid‑state structuren die potentieel kunnen concurreren met de prestaties van traditionele kobalt‑gebaseerde kathodes.”

In itself, this would not have been enough. The MIT researchers also found how to improve the adherence of TAQ to the cathode’s stainless-steel current collector, improving the stability of the new proof-of-concept cathode prototype.

By adding cellulose- and rubber-containing materials to the TAQ, they safely achieved more than 2,000 charge-discharge cycles. The energy density was also higher than with cobalt-based cathodes, and the charging took less than 6 minutes.

Wat is het volgende?

This is, for now, a laboratory prototype, and further work will be required to scale it up to the full EV battery pack size—and even further effort to see how to make a scaled-up manufacturing process for this new battery chemistry.

Still, this is among the first time that an organic cathode has out-competed cobalt-based lithium-ion designs on every important metric: energy density, cost of materials, and charging speed.

This shows that lithium-ion chemistry could stay the mainstream battery chemistry, as long as it can solve its reliance on metals that cause ethical and environmental issues.

Another thing the research by Pr Dincă proves is that organic cathodes have great potential, with potentially thousands of other organic compounds yet untested for this application. So even if TAQ ends up insufficient to displace cobalt and nickel, other chemicals similar to TAQ might achieve it.

Lithium-ion designs also benefit from a massive preexisting supply chain and manufacturing base. And it would be a lot easier just to change the cathode than rebuild battery factories from the ground up to accommodate new chemistries. So, improving lithium-ion might make a lot of sense from a business point of view.

It is also worth noting that organic cathodes have been discussed for other types of batteries as well, for example, for aluminium‑ion, natrium-/kalium‑ion, zink, or calcium‑gebaseerde dual‑ion batteries. So, it is possible that the discovery of TAQ’s properties can be applied to other battery types than lithium-ion.

In any case, organic components in batteries will make them easier to recycle, an issue (an investing opportunity) we explored in depth in our article “Addressing the Li-ion Dilemma: Disposing of Defunct Battery Cells in an Increasingly Electrified World”.

Organische kathodebedrijven

Volkswagen AG

The research of Pr. Mircea Dincă was funded by Automobili Lamborghini S.p.A., a subsidiary of Audi, owned by the Volkswagen Group. A patent application for the organic cathode technology has already been filed.

The German automaker is the second-largest car producer in the world, behind only Toyota. The company was, for a time, lagging in EV technology but has worked hard to catch up since, notably with the ID car series and multiple hybrid models as well.

Bron: Volkswagen

Tegen 2033, de Volkswagen Group plant alleen EV’s te produceren in Europa.

The collaboration with the MIT researchers is just one among many, with other partnerships about EVs including:

• Een partnerschap met Renault voor een EV van 20.000 euro.
• Een investering van $700 M in het Chinese Xpeng om EV-verkopen in China te stimuleren.
• Een partnerschap met de Chinese SAIC Motor om EV-platforms te leveren aan Volkswagen.
• Een partnerschap met Jetta Motor voor het verwerven van EV-technologie.
• Een partnerschap van $492 M met Magna om de iconische Scout SUV’s te revitaliseren als EV

With its ambitious plans regarding EVs and access to advanced EV technology from leading Chinese companies, Volkswagen is in a good position to look at MIT’s organic cathode patented technology and work on deploying it at scale in its future EVs.

Andere organische batterijbedrijven

While they are not developing new cathodes, two startups are working on using organic compounds to improve the anode performances, Store Dot and EnergyX.