Storing surplus electricity from solar or wind power in order to access reserves when needed is one of the keys to the energy transition. Since lithium-ion batteries lose storage capacity over time, replacements are being sought. Researchers from Vienna and Spain can now create one – an oxygen ion battery made of ceramic. They recently presented their development in the journal Advanced Energy Materials.
In addition to the loss of performance during the many charge and discharge processes, it is above all the rare, expensive and toxic material that is often mined under disastrous working conditions and is required to build lithium-ion batteries, casting the technology in an unfavorable light. For example, cobalt, nickel or manganese, found in batteries used in large numbers in electric vehicles, is often mined under questionable conditions.
It also takes a lot of energy to produce such a battery. Recycling is also difficult. An additional risk of lithium-ion batteries is that damage to the battery, overcharging, or overheating of the battery can cause the cells to crack. Fires can break out very quickly. So many scientists around the world are looking for other battery concepts.
Now a team led by Alexander Schmid and Jürgen Flieg of the Institute of Chemical Technologies and Analytics at the Vienna University of Technology (TU) in collaboration with the Catalan Institute for Energy Research (IREC) in Barcelona has now presented such a study. The technology has now been patented, according to a TU broadcast on Wednesday.
The Vienna team has been working on using ceramic materials bonded to fuel cells for some time. “This gave us the idea of checking whether these materials are also suitable for making a battery,” says Schmid. The principle is no different from that of lithium-ion batteries. Ceramic components can absorb negatively charged oxygen ions and release them again. If an electrical voltage is applied to the structure, the ions begin to migrate from one ceramic material to another. The battery is charging. Upon discharge, the charged oxygen atoms are allowed to flow back out and the stored energy in the form of electric current is tapped out.
The battery is replenished by air
While in many rechargeable batteries you run into the problem “that the charge carriers can no longer move at some point” and performance drops sharply as a result, according to Schmid, this scenario doesn’t threaten the oxygen battery to anywhere near the same. Limit. If oxygen is lost during operation, it can simply be taken from the surrounding air and the battery regenerates itself.
Fleij explained that the use of non-combustible ceramic materials makes fires impossible. There are also decisive advantages in terms of environmental friendliness: in parts it is relatively easy to replace some rare, expensive or toxic materials with others. Although the researchers are still using the rather rare lanthanum in the prototype, they are already considering replacing the element with cheaper alternatives. In any case, the concept does not require cobalt or nickel, according to the scientists.
However, this development has a benefit: You can only store about a third of the energy that a lithium-ion battery of the same size stores on average. This does not make the oxygen ion battery a promising candidate as a power supply for small devices such as smartphones. However, the researchers see a lot of potential in large-scale systems, where such large energy storage units are needed.
This is the case, for example, where excess power, which is generated at wind farms at night when there is a lot of wind, must be temporarily stored, but is not immediately used at that time. “If you build an entire building with energy storage units anyway, low energy density doesn’t play a decisive role,” Schmid says.
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