(Image: DGIST)

A research team from DGIST's (President Kunwoo Lee) Division of Energy & Environmental Technology, led by Principal Researcher Kim Jae-hyun, has developed a lithium metal battery using a “triple-layer solid polymer electrolyte” that offers greatly enhanced fire safety and an extended lifespan. This research holds promise for diverse applications, including in electric vehicles and large-scale energy storage systems.

Conventional solid polymer electrolyte batteries perform poorly due to structural limitations which hinder an optimal electrode contact. This could not eliminate the issue of “dendrites,” where lithium grows in tree-like structures during repeated charging and discharging cycles. Dendrites are a critical issue, as an irregular lithium growth can disrupt battery connections, potentially causing fires and explosions.

The research team, therefore, developed a triple-layer structure for the electrolyte to address such issues. Each layer serves a distinct function, significantly enhancing the battery’s safety and efficiency. This electrolyte incorporates “decabromodiphenyl ethane (DBDPE)” to prevent fires, “zeolite” to enhance the electrolyte's strength, and a high concentration of a lithium salt, “lithium bis (trifluoromethanesulfonyl) imide (LiTFSI),” to facilitate a rapid movement of lithium ions.

The triple-layer solid electrolyte features a robust middle layer that boosts the battery's mechanical strength, while its soft outer surface ensures an excellent electrode contact, facilitating an easy movement of lithium ions. This enables a faster movement of lithium ions, enhancing energy transfer rates and preventing dendrite formation effectively.

The experiment showed that the battery developed by the research team retained about 87.9 percent of its performance after 1,000 charging and discharging cycles, demonstrating a notable improvement in durability compared with traditional batteries, which typically maintain 70–80 percent of their performance. It can also extinguish itself in a fire, thus significantly reducing the fire risk. This battery is expected to be applicable across various sectors, ranging from small devices like smartphones and wearables to electric vehicles and large-scale energy storage systems.

Dr. Kim stated, "This research is anticipated to make a significant contribution to the commercialization of lithium metal batteries using solid polymer electrolytes, while providing enhanced stability and efficiency to energy storage devices."

This study was supported by the Future Materials Discovery Project (led by Professor Lee Jung-ho of Hanyang University) and the Mid-Career Researcher Program (led by Dr. Kim Jae-hyun) of the National Research Foundation of Korea. The findings were published as the cover article in an international academic journal, Small, published by Wiley.

Here is an exclusive Tech Briefs interview, edited for length and clarity, with Kim.

Tech Briefs: What was the biggest technical challenge you faced while developing this triple-layer battery?

Kim: The biggest technical challenge was overcoming the structural and physical limitations of existing solid polymer electrolytes (SPEs). Traditional PEO-based SPEs have low ion conductivity and poor interfacial contact with electrodes, leading to lithium dendrite growth and fire risks. Developing a triple-layer structure that enhances mechanical strength, ion conductivity, and fire safety simultaneously required significant innovation in material design and engineering.

Tech Briefs: What was the catalyst for this project?

Kim: The project was initiated to address critical safety and performance issues in lithium-metal batteries. Specifically, the research team aimed to develop a solution that could prevent fire and explosion risks, suppress lithium dendrite formation, and enhance ionic conductivity, paving the way for safer and more efficient next-generation energy storage systems.

Tech Briefs: Can you explain in simple terms how it works?

Kim: This battery uses a triple-layered SPE. The outer layers are soft and improve contact with the electrodes, while the middle layer is strong and prevents lithium dendrite growth. Additives like Decabromodiphenyl Ethane (DBDPE, a flame retardant) and zeolite enhance fire safety and mechanical strength. The electrolyte also uses a high concentration of LiTFSI salt, which reduces crystallinity and improves ion conductivity, allowing lithium ions to move more freely.

Tech Briefs: The article I read says, “It can also extinguish itself in a fire, thus significantly reducing the fire risk.” Please elaborate on that. How does it do that?

Kim: The battery includes a flame-retardant additive, DBDPE, in the electrolyte. When exposed to high temperatures, DBDPE releases bromine radicals, which interrupt the combustion process and extinguish flames. This self-extinguishing property significantly reduces the risk of fire and explosion.

Tech Briefs: Do you have plans for commercialization?

Kim: The final research goal of this research is technology transfer to companies. While the research is currently at the laboratory level, the team plans to conduct further stability tests and address any remaining challenges to transition the technology to commercialization. In basic concept, the result is ready for technology transfer. The final goal is to optimize the triple-layer electrolyte design for mass production and application in wearable devices, electric vehicles, and large-scale energy storage systems.

Tech Briefs: What are your next steps?

Kim: The next steps include conducting extensive stability and performance tests under real-world conditions, optimizing the manufacturing process, and collaborating with industry partners to scale up the technology for commercialization. Further research may also focus on enhancing the compatibility of the electrolyte with different electrode materials. In addition, the new additive will be used for the better electrolyte layer.

Tech Briefs: Do you have any updates you can share?

Kim: The team is actively working on refining the technology and exploring potential industry partnerships to bring the innovation closer to commercialization.

Tech Briefs: Is there anything else you’d like to add that I didn’t touch upon?

Kim: This research not only addresses fundamental issues with lithium-metal batteries but also proposes a new design methodology for next-generation energy storage. The triple-layer electrolyte concept is expected to inspire further advancements in battery safety and performance. Additionally, the team hopes this work will contribute to creating a safer and more sustainable energy landscape while inspiring young scientists to pursue innovative solutions.

Topics:
Batteries Design Energy Energy Storage Power

More From SAE Media Group