Researchers charge EV battery in ten minutes at short-term high temperature

Scientists at Pennsylvania State University report that they charged a lithium-ion battery in an electric car in ten minutes, giving it a range of 321 to 482 kilometers. They achieved this by applying a relatively high temperature for a short period of time.

According to professor and co-researcher Chao-Yang Wang, this method can be used for at least 2500 charging cycles, or the equivalent of about 800,000 km. This means that he believes this method has the potential to contribute to a broad adoption of electric cars.

The problem with this, however, is that fast charging with a lot of power is necessary, and then the lithium ions tend to create a deposit as metallic lithium on the surface of the anode at the interface of the negative electrode and the electrolyte. The intercalation, or the process by which the ions are incorporated into the structure of the electrode, is disturbed by this deposition and thus the performance decreases. Eventually, structures can even form that lead to unsafe situations and short circuits.

If the temperature in the battery cell gets high enough, this problem is prevented because the lithium ions move fast enough so that no deposition occurs. However, a temperature of 60 degrees Celsius is, according to Wang, ‘extreme’ and ‘forbidden in the battery arena’. In the field of battery research and chemistry, it is assumed that this temperature is too high, which creates a danger for the internal materials and drastically reduces the battery’s lifespan.

Wang and his research team concluded that this problem can be solved if the battery can be heated to 60 degrees Celsius for just ten minutes, just long enough for the charging process, and then cooled down very quickly to room temperature again. . With such a short warm-up and rapid cool-down, the lithium does not get a chance to cause a deposit and the warm-up is too short to affect the overall performance of the battery.

To rapidly increase the temperature, the researchers used a kind of self-heating battery with a thin nickel foil layer, which, as it were, forms an internal self-heating structure that is heated by resistance heating. This also heats the inside of the battery and the battery could be charged up to 80 percent in ten minutes, without the aforementioned problems.

According to the researchers, this shows that the old idea that lithium batteries should not be charged at high temperatures, in principle no longer holds. Wang believes that the advantages of a short-term high temperature quickly outweigh the disadvantages. Wang tells The Guardian he expects it will take another two to three years before it can be used in commercial cars.

However, the technical inventions must be further developed before this method can be applied in electric cars. In addition, battery cells with a relatively small capacity of approximately 10Ah were used during the study. Wang states that the technology is applicable to the batteries of electric cars and that batteries of different capacities and sizes can be charged, provided that the charging capacity increases proportionally with the size of the battery. He says that a 150Ah car battery needs a fast charging station that can deliver 900A for ten minutes and that is achievable with the existing fast chargers.

The research is published in the scientific journal Joule, under the title Asymmetric Temperature Modulation for Extreme Fast Charging of Lithium-Ion Batteries.