Published on November 21, 2024 at 2:36 p.m.
More and more, rechargeable batteries are becoming part of our daily lives. Since the arrival of lithium batteries, researchers have been trying to develop batteries that are less expensive, but just as efficient. The work of the team of Eric McCalla, associate professor in the Department of Chemistry at McGill University, could lead us to replace our lithium batteries with salt-based batteries.
These batteries already exist. China produces them for use in electric vehicles. Unfortunately, their performance is already limited, because the technology developed does not allow them to be improved. We must therefore create new technology that will allow us to increase the power of these batteries. Professor McCalla’s team is working to design a new energy source that will outperform lithium batteries because they will be cheaper and more efficient.
There are three main components inside a battery. The anode, which is negatively charged, the cathode which has a positive charge and the electrolyte which facilitates exchanges between the two others. The movement of positive ions from the anode to the cathode produces electrical energy. In the case of lithium batteries, it is the positive lithium ion that produces electrical energy as it moves toward the cathode. We therefore concentrate all the positive ions in the anode. These will naturally want to join the positive cathode and thus create energy. Once all the positive ions have reached the cathode, the battery no longer works. When you recharge a battery, you put all the positive ions back into the anode and the energy creation process resumes.
In the case of salt-based batteries, it is the positively charged sodium ions that move from the anode to the cathode to generate electricity. The problem the McGill team had to deal with was the size of the ions. Those of lithium are much smaller than those of sodium. To get around this problem, the researchers developed an anode and cathode made of manganese that they oxidized to facilitate the transfer of sodium ions. The addition of two oxygen atoms to the manganese atom facilitates the absorption of ions by the anode and cathode.
Last year, a new material was released. This allows for a better exchange of sodium ions. It is the cyanide inside this new material that facilitates this exchange. However, this technology has already reached its limit. Sodium batteries of this type only give electric vehicles a range of 250 km. It is on this aspect that the team of researchers is actively working. They want to develop a more efficient battery, which offers more autonomy than the already existing sodium technology.
Professor McCalla’s team hopes to develop a battery based on materials that are abundant and less expensive than rarer metals like lithium, zinc and cobalt, which are currently used in lithium-ion batteries. They are already testing components that contain manganese, iron, salt and oxygen. However, these are unstable. Another element needs to be added to get around this problem. They therefore developed a way of doing things which allows them to test the compatibility of 64 different elements at the same time. This innovative way of doing things saves them a lot of time. Not only do they test their efficiencies, but they also do so at different temperatures to replicate the conditions electric vehicles are subjected to.
Many people think that batteries at the end of their life are not recyclable. According to the researcher, all batteries can be recycled. Rather, he sees motivation as a barrier to battery recycling. He points out that lithium-ion batteries contain metals that have high commercial value. There is therefore an interest in recovering them. This is not the case with sodium batteries. Its elements have little value and therefore the motivation to recycle them may not be there, he adds.
