An integrated project with the new salt battery could look like this.
Dusseldorf The Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) has developed a battery whose most important component is found in every kitchen: sodium chloride or, to put it more simply, common salt. Together with the Australian battery company Altech, the salt-based storage system is now to go into industrial production.
Preparations for the 100-megawatt production facility are already in full swing in Schwarze Pumpe, Saxony. “Sodium chloride is the main component of the active material. There is also nickel, which is fully recycled. Our battery is therefore based on readily available materials in Europe,” says the head of Fraunhofer IKTS, Alexander Michaelis. He helped develop the battery.
The pilot plant in Dresden is already in place. The sodium chloride battery should not only be cheaper than the lithium-ion competition – it is also non-flammable, has a longer life cycle, does not require rare earths and works regardless of the weather – regardless of whether the outside temperature is minus ten or plus 40 degrees .
Too big for the electric car
The disadvantages: it is significantly larger and much heavier than a lithium-ion battery. It is therefore not suitable for use in electric cars. “However, that doesn’t matter for stationary storage,” says Michaelis. And that’s where he sees the gap for his salt battery. The need is great.
Storage for the power grid serves to cushion peak loads at times of the day when the demand for electricity is particularly high and plays an extremely important role in the energy transition.
Because renewables only produce electricity when the wind is blowing or the sun is shining, and not necessarily when consumption is at its highest, there are always phases in which fossil power plants have to fill in the gaps. At the same time, wind and solar systems are switched off if they are currently producing more electricity than is being consumed.
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Memory can help solve the problem. “Stationary storage is one of the most underestimated areas at the moment. Calculations always assume a relatively low value for stationary storage. That’s wrong. There is huge growth right now,” explains battery expert Maximilian Fichtner, head of the Helmholtz Institute Ulm for Electrochemical Energy Storage.
In fact, the demand for large-scale storage is increasing significantly. According to Bloomberg New Energy Finance (BNEF), at the end of 2021 there were stationary batteries around the world with a total capacity of 27 gigawatts. If the market researchers previously expected a global capacity of one terawatt hour by 2030, they even had to raise their forecast by 13 percent at the end of last year.
Overall, according to BNEF, the US and China are currently the largest markets for battery storage, but Europe is catching up. The analysts have already doubled their forecast for battery growth in Germany.
As with electric cars, the market-dominating technology for large batteries is the lithium-ion battery. The proven technology is also used in the network booster project of the transmission network operators. One of the largest storage grids in the world is currently being built in Kupferzell. But there are also other promising technologies such as pumped storage power plants or redox flow batteries that store energy using large tanks of liquid. Or the sodium chloride battery.
A solid ceramic tube is an important part of the salt battery.
However, the idea is not new. The technology behind it has been around since the 1970s. It was originally developed in South Africa under the name “Zebra Battery” (zero emission battery). But not as grid storage, but as a battery for electric cars.
Among other things, the car company Mercedes had tried the technology. Due to its size and weight, however, the salt battery did not stand a chance in the electric car sector. In the case of stationary storage, this is irrelevant.
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“The design was initially very complex because it was aimed at electric cars. We simplified that and optimized the size in such a way that the result is an extremely cheap battery,” says battery specialist Michaelis. The Fraunhofer Institute has invested a double-digit million amount and ten years of research in the development of the so-called Cerenergy battery.
From the pilot plant to industrial production
The battery consists of a solid ceramic tube (Solid State Technology) that serves as the electrolyte, with a positive pole in the middle. The solid allows the transfer of sodium ions through the tube. It is filled with cathode granules made of common salt and nickel. When charged, sodium permeates through the electrolyte to form the anode. In discharge mode, the process is reversed.
To ensure contact between the solid cathode granules and the ceramic electrolyte tube, the positive electrode is flooded with molten chloroaluminate. The ceramic tube is encased in a stainless steel container that serves as the negative pole.
“The institute in Dresden already has a 10-kilowatt-hour battery from the pilot plant. Our task now is to develop efficient industrial production and build the plant,” says Uwe Ahrens, head of Altech’s German subsidiary. He estimates the cost of building the factory to be in the mid three-digit million range. The first batteries are scheduled to roll off the production line in 2025.
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