Electric Vehicle Battery Fire Solution? ... Development of Nonflammable Semi-Solid Electrolyte

A non-flammable semi-solid electrolyte that does not catch fire has been developed, promising a solution to the battery fire issues threatening underground parking lots caused by electric vehicles.

A joint research team consisting of Professor Song Hyungon from the Department of Energy Chemical Engineering at UNIST, Dr. Jung Seohyun from the Precision Chemical Research Center at the Korea Research Institute of Chemical Technology, and Dr. Kim Taehee from the Ulsan Next-Generation Battery Research and Development Center at the Korea Institute of Energy Technology developed a ‘non-flammable polymer semi-solid electrolyte’ capable of molecular bonding within the battery.

Until now, non-flammable electrolytes have used excessive amounts of flame retardant additives or solvents with very high boiling points. These approaches had several drawbacks, such as drastically reducing the ionic conductivity of the electrolyte.

The research team created a ‘semi-solid electrolyte’ by adding a small amount of polymer (2 wt.%) to the electrolyte. The resulting polymer semi-solid electrolyte exhibited 33% higher lithium-ion conductivity (4.8 mS/cm) compared to conventional liquid electrolytes.

The pouch-type battery utilizing this electrolyte formed an SEI layer that prevented unnecessary reactions of the electrolyte during operation, showing a 110% improvement in lifespan characteristics. Additionally, it possesses non-flammable properties by suppressing fuel and radical chain reactions during combustion.

Operating Principle of Non-Flammable Gel Electrolyte.

Jihong Jung, the first author and a researcher in the Department of Energy Chemical Engineering at UNIST, said, “We were able to suppress radical chain reactions by utilizing the interaction between the polymer polymerized inside the battery and the volatile solvent,” adding, “Electrochemical quantification to analyze the radical suppression level will greatly help in elucidating the mechanism of non-flammable electrolytes.”

Kim Mideum, co-first author and a master’s student at UNIST’s Department of Energy Chemical Engineering and the Korea Research Institute of Chemical Technology, explained, “We confirmed the excellent safety of the battery itself through various experiments, including applying the electrolyte to pouch-type batteries, not just evaluating the non-flammability of the electrolyte.”

Professor Song Hyungon of the Department of Energy Chemical Engineering stated, “The non-flammable semi-solid electrolyte using polymers can be directly applied to existing battery assembly processes, accelerating the commercialization of non-flammable batteries in the future.”

This research was conducted through collaboration among three institutions: UNIST’s research team in electrochemistry, the Korea Research Institute of Chemical Technology’s Precision Chemical Research Center in polymer synthesis, and the Korea Institute of Energy Technology’s Ulsan Next-Generation Battery Research and Development Center in battery safety experiments.

The research team filed five domestic and two international patents. The research results were selected as the supplementary cover paper of ACS Energy Letters, a prestigious journal in the energy field, and were published online on October 13.

The research was supported by the Ministry of Science and ICT’s National Research Foundation of Korea, the Korea Institute for Advancement of Technology, the Korea Research Institute of Chemical Technology, and Samsung SDI.

Research on non-flammable semi-solid electrolytes is featured on the cover of ACS Energy Letters.

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