For years there has been talk of the advent of solid-state batteries with a much greater capacity and much faster charging than normal lithium batteries. So far, however, their development and deployment have been hampered by technical complexity. However, Tavo Romann, a physiochemist at the University of Tartu, says they may reach the market to a limited extent in the coming years.
Lithium-ion batteries contain a liquid electrolyte, where the substance that conducts the lithium ions is in the form of a gel. The electrolyte guarantees electrical conductivity, i.e. the free circulation of ions between the negative and positive electrodes, anode and cathode. The name solid-state battery comes from the fact that the electrolyte is in solid form.
According to Romann, solid-state batteries have been in development for about ten years. First, large electric car manufacturers, led by Toyota, are interested in their development.
“The ordinary lithium-ion battery has already been developed to the end. Probably not to the end, but there has been no breakneck progress or development recently. Most of the battery industry’s development resources are currently directed at development of solid batteries state batteries. More lithium can be put into them and thus their energy capacity can be increased,” Romann told ERR. Additionally, solid-state batteries can be charged much faster.
One of the challenges in developing solid-state batteries is their safety. If more lithium, i.e. more energy, is loaded into the battery, short circuits cause much more damage. Therefore, they must last a long time in terms of time.
“Toyota, for example, is conducting tests to ensure that this solid-state battery will last ten years and not short-circuit. Because it contains so much energy, a short-circuit would be catastrophic; the car would simply burn down,” Romann noted.
There are also development challenges on a more technical level. While in current lithium-ion batteries the lithium penetrates between the graphite layers during charging, in solid-state batteries the graphite is completely removed from the battery, so that only solid lithium remains. To the detriment of this, according to Romann, the energy density will be even higher.
“From an anode perspective, the technical problem is that when we deposit lithium in metallic form, it is not deposited uniformly, as we would like, but instead as dendrites, or neural network-like structures, which penetrate from one electrode to ‘other, causing a short circuit,’ the researcher said.
At the same time, the dendrites do not penetrate through the solid electrolyte and therefore it is possible to use solid lithium in the electrodes. “Of course, there are still some buts. A solid electrolyte is not as good as a liquid electrolyte. However, a solid electrolyte can be made thinner, so there are ways to get around this problem,” Romann said.
According to the chemist, another problem with solid electrolyte is that it is a fragile glass-like material. “The car generates all kinds of vibrations and this is how cracks can appear in the solid electrolyte. These dendrites can grow through such cracks and short circuit the battery. This is why the test work related to increasing longevity is so important ” he stressed.
The question of price will be decisive
Presumably the price of solid-state batteries will initially be quite high. The decisive question at the beginning, according to Tavo Romanni, will be how quickly the prices of new types of batteries can be brought down.
“The technology of their production involves, for example, the use of vacuum deposition methods, which I also work on. This will certainly make them expensive initially. It may happen that a solid-state battery for an electric car is, for example example, ten times more expensive than a lithium-ion battery. In this case, they would initially only be installed in the most expensive car models,” he cited as an example.
Romann believes that the development of solid-state batteries has already reached such a point that in the coming years they will find application in fields and devices where price is not a determining factor. For example, they are mainly used in the military field or in luxury equipment.
“The development work is still ongoing, but at the moment the shortcomings are not obvious. Probably in the next few years there will be individual applications that will be very expensive. I don’t think there will be competitive competition in solid-state batteries for electric cars in the next years,” added the physiochemist.
2024-01-12 02:38:00
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