Lithium metal batteries can store much more energy than the lithium-ion batteries currently in use, making them a "next-generation battery." But commercialization has been difficult because liquid electrolytes ignite easily and pose a high fire risk. Solid electrolytes have been proposed as an alternative, but existing materials perform poorly because lithium ions do not move well at room temperature.
A Korean research team has solved this problem. They developed a solid electrolyte that allows lithium ions to move 100 times faster even at room temperature.
Korea Advanced Institute of Science and Technology (KAIST) said on the 4th that a team led by Professor Byun Hye-ryeong in the Department of Chemistry and a team led by Professor Son Chang-yoon at Seoul National University jointly developed an "organic solid electrolyte film" that operates at room temperature.
The material the team used is a new porous material called "COF (Covalent Organic Framework)." With a structure perforated with small holes in a regular pattern, it serves as a favorable pathway for lithium ion transport. The electrolyte film produced this time is about one-fifth the thickness of a human hair (about 20 micrometers).
COF looks similar to MOF (Metal Organic Framework), the material that won the 2025 Nobel Prize in chemistry, but has the advantage of maintaining higher chemical stability in battery environments.
The researchers arranged functional groups that attract and shuttle lithium ions at regular intervals inside the COF, designing it so that lithium ions, which had moved quickly only at high temperatures, could move easily at room temperature as well. This enabled precise, molecular-level control of the pathways through which lithium ions travel.
In particular, they added "double sulfone-oxidized functional groups" inside the pores to help lithium ions dissociate easily and move quickly, creating channels that let the ions travel along the shortest straight path. Computational simulations showed that this pathway lowers the energy required for lithium ion movement, allowing fast transport with less energy.
In addition, the electrolyte is produced through a self-assembly method, giving it a uniform structure and an extremely smooth surface. As a result, it mates precisely with the lithium metal electrode, allowing ions to move more stably during transport.
Tests showed that the new electrolyte offered lithium ion transport speeds 10 to more than 100 times higher than existing organic solid electrolytes. When applied to a lithium metal–based lithium iron phosphate (LFP) battery, it retained more than 95% of its initial capacity even after more than 300 charge-discharge cycles and showed virtually no energy loss (coulombic efficiency of 99.999%).
Professor Byun said, "This is a result that actually implements an organic solid electrolyte that operates quickly at room temperature," adding, "If we combine it with inorganic materials going forward, we may also be able to solve problems that arise at the interface where the electrode and electrolyte meet."
The research results were published on Aug. 5 in the international journal "Advanced Energy Materials."
References
Advanced Energy Materials (2025), DOI: https://doi.org/10.1002/aenm.202504143