The Korea Institute of Science and Technology on Tuesday claimed to have found a new way of curbing lithium-metal battery fires using semiconductor technology.

According to its researchers led by Lee Joong-kee, lithium-metal batteries, which use metals for anodes, or the negative side, are more powerful than lithium-ion batteries that use graphite for anodes. However, there is a trade-off. Lithium-metal batteries are more susceptible to fires because of dendrite issues.

Dendrites are tiny, rigid tree-like structures that grow inside batteries. When batteries are charged and discharged, lithium ions go back and forth between the positive and negative sides. When lithium ions react with electrons near the surface of the negative side, lithium ions can deposit irregularly and expand outward. These spiky needles can create punctures that make the positive and negative sides meet, which can trigger a short-circuit and potentially cause a fire.

The KIST team used semiconductor technology and created a thin layer above the negative side that allows only lithium ions to pass through, not electrons. Simply put, when lithium ions travel to the negative side, they pass through this layer first, and then meet electrons. This induces dendrites to form beneath the surface of the negative side, not above, preventing the spiky needles from creating punctures outward.

Lee and his team exposed fullerene, a classical semiconductor material, to plasma at a certain temperature. This transformed the material into a thin polymerized carbon film that can successfully suppress dendrite issues.

“During 1,200 cycles, lithium-metal batteries applied with the polymerized film didn’t suffer any dendrites issues, whereas typical lithium-metal batteries immediately could withstand just 20 cycles under the same conditions,” a KIST official said.

The official added that KIST’s lithium-metal batteries could maintain 81 percent performance after 500 cycles, a significant improvement from the 52 percent of general lithium-metal batteries.
 
By Kim Byung-wook (kbw@heraldcorp.com)