‘Fast charging, long life’... KAIST develops battery separator

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 9th that the research team led by Professors Dong-gi Yoon and Hye-ryeong Byeon of the Department of Chemistry has developed a next-generation battery separator technology that precisely regulates the lithium ion movement path by controlling the molecular arrangement of liquid crystal polymers.

Lithium metal batteries are next-generation batteries that use lithium metal as a cathode and can store more energy than existing lithium-ion batteries.

However, during the charging process, 'dendrites', in which lithium gathers in one place and accumulates in the shape of sharp branches, are likely to occur. Lithium grown in this way can reduce battery life and damage the separator that prevents direct contact between the anode and cathode, causing internal short circuits and fires.

The research team focused on organizing the path through which lithium ions move. This is because if the movement path is winding, the ions must rotate and may be concentrated in a specific area.

If the path is designed so that ions move straight and evenly toward the electrode, the uneven accumulation of lithium can be reduced while charging quickly.

For this purpose, the research team used a liquid crystal material in which molecules are arranged in a certain direction. Liquid crystals have both a regular molecular arrangement like a solid and flowing properties like a liquid, and the direction of molecular arrangement can be changed depending on surface treatment.

The research team confirmed the rapid charging performance by applying the developed separator to a lithium metal battery and explained that it maintained 94% of its initial capacity even after repeating charging and discharging 100 times under fast charging conditions that theoretically allow charging in about 15 minutes.

Professor Dong-gi Yoon said, "This research is an example of how to efficiently design the movement path of lithium ions by controlling the molecular arrangement of the liquid crystal polymer, thereby improving the performance and stability of the battery." He added, "It will contribute to the development of high energy density next-generation battery technology where long driving range and fast charging are essential in the future."