Domestic researchers have developed a new protective film technology that reduces the fire risk and extends the lifespan of lithium metal batteries, which are gaining attention as next-generation batteries. This method allows for uniform application of the protective film over a larger area without damaging the lithium, raising expectations for commercialization.
The Korea Research Institute of Chemical Technology (KRICT) announced on the 13th that a research team led by Chief Researcher Seok Jeong-don developed a technology to thinly coat the surface of lithium metal with a hybrid protective film made by combining polymers and ceramics using a "transfer printing" method. This achievement was published twice in the international journal "Energy Storage Materials" in February and July 2025.
Lithium metal batteries can store about 10 times more electricity than existing batteries, making them a focus for use in electric vehicles and energy storage devices as next-generation batteries. However, the formation of "dendrites" on the lithium surface, resembling tree branches, during the charging and discharging processes has posed fire risks and reduced battery lifespan.
Previously, a wet process using organic solvents was used to create the protective film, which damaged the lithium surface and left residues, making it difficult to coat large areas or commercialize the technology. To solve this issue, the research team applied a new method called "transfer printing."
"Transfer printing" involves first creating a very thin protective layer on another substrate and then transferring this layer onto the lithium metal by pressing it with a roller. In this process, no solvents are used, preventing damage to the lithium, and uniform application of the protective film is achieved even if the lithium surface is uneven, making it efficient.
In prior research, the team developed an "alumina-gold dual protective film" that prevented dendrites from growing on the lithium surface, allowing for stable charging and discharging of the battery.
In this follow-up study, the "ceramic-polymer composite hybrid protective film" developed is extremely thin at 5 micrometers (㎛) while being uniformly applicable over a large area, making it suitable for actual battery manufacturing. In fact, batteries applying this protective film maintained 81.5% of their capacity after 100 charge-discharge cycles with low overvoltage, providing stability. Additionally, even when discharged quickly at high power, they maintained 74.1% capacity, demonstrating excellent performance. Compared to batteries without the protective film, their lifespan has doubled.
The research team expects this technology to be widely used in various fields, such as electric vehicles and energy storage devices, and believes it will also aid in the development of next-generation batteries like all-solid-state batteries and lithium-sulfur batteries.
Chief Researcher Seok noted, "This research is an achievement that combines new protective materials with a large-area transfer printing process, overcoming both interfacial stability and the limitations of existing coating processes, which had been obstacles to the commercialization of lithium metal batteries." KRICT Director Lee Young-guk also stated, "It is one of the most practical solutions for realizing high-energy-density lithium metal batteries and will contribute to securing global competitiveness in secondary batteries."
References
Energy Storage Materials (2025), DOI: https://doi.org/10.1016/j.ensm.2025.104135
Energy Storage Materials (2025), DOI: https://doi.org/10.1016/j.ensm.2025.104428