Battery cells are a key technology for the energy transition. But here, of all places, Germany as an export nation has so far been dependent on imports: the cells are mainly produced in Asia.
–
This so-called energy density is an important factor, especially for electric mobility: the smaller and lighter the batteries, the more range the engineers can give a car.
Solid state batteries with higher energy density
In recent years, researchers have made great strides in the energy density of lithium-ion batteries. But the potential is largely exhausted.
That is why scientists are currently working intensively on new cell concepts that will one day replace the lithium-ion technology. Hottest candidate: the solid-state battery.
–
“Solid-state batteries promise a 50 percent higher energy density at the cell level than lithium-ion batteries,” says Arndt Remhof from the Swiss research institute Empa.
–
This is possible, among other things, because solid-state batteries in the space between the positive and negative poles do not contain a liquid like lithium-ion cells, but a thin, light solid. This saves weight and space. The solid also makes it possible to dispense with the graphite common in lithium-ion cells at the negative pole. This way, more energy can be stored.
Solid-state batteries play an important role in the roadmaps of many car manufacturers, explains battery researcher Remhof. VW, for example, says it will produce such batteries in Salzgitter from the middle of the next decade.
–
Demand for lithium explodes
However, solid-state batteries have one major disadvantage: they too require lithium. There are basically enough of these on Earth, but there could still be bottlenecks in the medium term.
Because the demand will explode – the demand for lithium-ion cells for electric mobility alone will increase by a factor of 20 to 40 by 2030, the Fraunhofer Institute for Systems and Innovation Research ISI expects. It is questionable whether the industry will be able to expand the capacities for the production of lithium so quickly.
On the Recycling used batteries betting doesn’t help, says Maximilian Fichtner, deputy director of the Helmholtz Institute Ulm for electrochemical energy storage. “Batteries have become so long-lasting that they can be used as solar power storage if the cars are scrapped,” says Fichtner.
–
Therefore, only moderate amounts will likely be available for recycling before 2040, the scientist says.
Sodium instead of lithium
Fichtner heads a working group at several German research institutes that is dedicated to the development of lithium-free battery cells. The most advanced is sodium ion technology. “Sodium can be found in table salt, in sea salt, just everywhere. This is an absolutely unproblematic and very cheap battery material,” says Fichtner. He expects the first sodium ion batteries to be on the market in a year or two.
However, the energy density of sodium-ion batteries is far from being able to compete with lithium cells. They will therefore not be suitable for electric cars in the foreseeable future.
For stationary storage – about for solar systems or large-scale storage, with which network operators can balance electricity supply and demand – on the other hand, yes. Because weight and size hardly play a role here.
This eases the raw material situation: “The more lithium-free batteries are used for such tasks, the more lithium is available for electromobility,” explains Fichtner.
Open questions regarding service life and efficiency
The researchers are also working on many other battery concepts that do not require lithium or other problematic raw materials – for example, magnesium-sulfur, aluminum, zinc-air or calcium batteries.
What they have in common is that it will take a long time before the first products are ready for practical use. The lifespan is often still an unsolved problem. The same applies to the efficiency: with some of these technologies, significantly more electricity has to be stored than can be extracted later.
–
One thing is certain, however: today’s dominance of lithium-ion batteries will not last. “Unlike the internal combustion engine – where the same technology is used in principle from lawnmowers to oil tankers – we will see a multitude of different concepts for batteries,” says Empa researcher Remhof. “In view of the wide range of applications, the whole range is justified, from the old lead-acid battery to the new post-lithium technology.”
–
