New horizons for the e-car: When will the solid-state battery come?

The solid-state battery is something like the "Holy Grail" of battery researchers and thus also of future electromobility.

New horizons for the e-car: When will the solid-state battery come?

The solid-state battery is something like the "Holy Grail" of battery researchers and thus also of future electromobility. If there were a breakthrough in this technology, the decisive weaknesses of the electric car could be eliminated in one fell swoop. There are even manufacturers who are already talking about an "end game".

The solid-state battery is intended to take the e-car to new heights: the vehicle manufacturers promise themselves and their customers ultra-short charging times, maximum ranges, total fire safety and lower costs from the new rechargeable battery technology. But the race for the super battery is still open: will it come at all? And if so: when and with which brand?

Most recently, Nissan had caused a stir when it came to solid or solid-state technology: the Japanese announced in April that they would start pilot production from 2024, with the first series car coming onto the market in 2028. The group sees itself far ahead in development and is demonstratively optimistic. Technology boss Kazuhiro Doi at least gave journalists an unusually open insight into plans and the state of development in mid-April. The detailed lecture was all the more unusual as other car manufacturers are also making exciting announcements, but have so far been conspicuously holding back on technical details.

What is clear, however, is that all major car manufacturers are working flat out on the super battery. VW's battery chief Frank Blume even spoke of an "endgame" in battery technology that every company wants to win. In this race, the Wolfsburg team works together with the US company Quantumscape, in which they also hold the majority of the shares. The startup is considered one of the most promising contenders for the role of solids pioneer. According to previous announcements, the technology should be available as early as 2025, and at least one pilot plant could then start test production.

Blume speaks of a range increase of 30 percent compared to current lithium-ion batteries, at the same time the charging time should be halved. Both together could finally solve the range problem of electric cars. No wonder other players like Toyota, Panasonic, BMW, Ford and LG are also taking part in the race. They give dates between 2025 and 2030 for the start.

The difference between the solid-state battery and today's rechargeable batteries is initially only small: instead of a liquid electrolyte, a solid one is used. The electrolyte is one of the central components in every battery and is responsible for transporting the ions between the anode and cathode, which in turn allows the electrons to migrate in the opposite direction, which ensures the current flow and ultimately drives the electric motor. Solid-state batteries are already in use outside of cars, not only in electronics, but also in commercial vehicle and small series construction. For example, the Mercedes Citaro bus runs on a special variant of the solid-state battery, which has to be preheated and is therefore not suitable for cars.

Simply switching from liquid to solid has potential advantages: because while liquid electrolyte burns as easily and quickly as chemically related petrol, its solid counterpart is almost impossible to set on fire. This could be a safety advantage, especially in the event of collisions between e-cars. However, this would not mean much, because current liquid-electrolyte batteries for e-cars are now considered to be very safe.

The point that makes solid technology really interesting is something else. Because the use of the solid electrolyte allows the use of alternative anode materials: Instead of making the anode from graphite, as is common today, it could then be made from lithium, for example, which has a significantly higher electrochemical potential. Its larger specific capacity enables higher energy density with the same battery volume and ultimately a longer range. The 30 percent of VW man Blume are generally considered not unlikely.

Metallic lithium as an anode material is not a new discovery. Researchers experimented with the efficient material years ago; However, in connection with the combustible liquid electrolyte, these batteries were far too unsafe for series use in vehicles. The reason is the poor controllability of the anode structure as the battery ages. It changes its shape significantly over the numerous charging cycles, which has led to fire-hazardous short circuits with liquid electrolytes as soon as the proliferating fingers reached the cathode side. This is not so easy with solid electrolytes, but there is also a risk of the cell being deformed and destroyed.

Nevertheless, an anode made of lithium is considered a suitable approach, at least in research, if the stability and safety problems can be solved. In principle, however, other material combinations are also possible. The same applies as is often the case in battery research: If you change a component or a requirement, there are numerous new possible combinations and solutions. Nissan developer Doi is also using large databases and artificial intelligence to investigate numerous variations, some of which could have potential for series production. None of the researching manufacturers is currently making a clear commitment to the lithium anode. The situation seems clearer when it comes to electrolytes: Sulfur-based ceramics should generally prevail there. It scores above all with its very high conductivity compared to polymers and phosphate ceramics.

After deciding on the electrode material and electrolyte variant, the industry still has to master the production. Nissan claims lower costs compared to the liquid battery, but there is still no practical evidence. Some other experts even expect higher prices for solid state cells.

Ultimately, it remains to be seen how the price-performance ratio of the new technology in its various possible variants will be in the future. A lot seems possible between use in mass vehicles and exclusive use in luxury cars. The sudden end for the classic liquid battery is unlikely to mean the market launch of the solid battery. After all, the current technology has a development lead of around 30 years that cannot easily be caught up: it has proven itself in the car, materials and production processes have been tested and their performance will continue to increase in the coming years.

In general, the battery range is likely to become more differentiated in the coming years. The scarcity of materials and price fluctuations alone will ensure a wide range of different battery variants. In addition to the classic NMC lithium-ion batteries, there are already inexpensive iron phosphate batteries, and even cheaper sodium batteries could soon be added. And finally the solid-state battery. Which model is offered in which vehicle will then depend above all on the specific requirements and the customers' willingness to pay.

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