Scientists from Pennsylvania State University report that they have charged a lithium-ion battery from an electric car in ten minutes, adding a range of 321 to 482 kilometers. They have achieved this by applying a relatively high temperature for a short period of time.
, this method can be used for at least 2500 charging cycles, or the equivalent of approximately 800,000 km. This means that, according to him, 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 large capacity is necessary, and then the lithium ions tend to create a deposit on the surface of the anode on the surface of the negative electrode and the electrolyte as metallic lithium. The intercalation, or the process by which the ions are incorporated into the structure of the electrode, is disturbed by this deposition and therefore the performance decreases. Ultimately, even structures can form that lead to unsafe situations and short circuits.
If the temperature in the battery cell becomes high enough, this problem is prevented, because the lithium ions move fast enough so that no deposition occurs. However, according to Wang, a temperature of 60 degrees Celsius is ‘extreme’ and ‘forbidden in the battery arena’. In the field of battery research and chemistry, it is assumed that this temperature is too high, creating a risk for the internal materials and drastically reducing the life of the battery.
Wang and his research team came to the conclusion that this problem can be solved if the battery can be heated to 60 degrees Celsius for the duration of just ten minutes, just long enough for the charging process, and then quickly cooled to room temperature again . With such a short heating and rapid cooling, the lithium does not get the chance to cause a deposit and the heating is too short to affect the overall performance of the battery.
To quickly raise the temperature, the researchers used a kind of self-heating battery with a thin nickel foil layer, with which an internal self-heating structure was formed, as it were, which warms up through resistance heating. This also heats the inside of the battery and the battery can be recharged up to 80 percent in ten minutes, without the aforementioned problems occurring.
According to the researchers, this demonstrates that the old idea that lithium batteries should not be charged at high temperatures no longer holds true. Wang believes that the advantages of a short-term high temperature quickly outweigh the disadvantages. that he expects it to take another two to three years before it can be used in commercial cars.
However, the technical findings 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 investigation. 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 load 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 he believes is achievable with the existing fast chargers.
The research is in the scientific journal Joule, under the title Asymmetric Temperature Modulation for Extreme Fast Charging or Lithium-Ion Batteries.