A gel-type material has been developed that extends the lifespan of long-range electric-vehicle batteries, known as high-voltage batteries, while reducing the risk of explosion. The material completely blocks the formation of reactive oxygen species, the main cause of high-voltage battery aging, and when applied, the battery lifespan increased 2.8 times and swelling decreased to about one-sixth.
A research team led by Song Hyun-gon, a professor in the Department of Energy and Chemical Engineering at Ulsan National Institute of Science and Technology (UNIST), said on the 4th that, together with senior researcher Jeong Seo-hyeon at Korea Research Institute of Chemical Technology (KRICT) and researcher Hwang Chi-hyeon at Korea Electronics Technology Institute, they developed an anthracene-based semi-solid gel electrolyte (An-PVA-CN) that fundamentally blocks the reaction in which reactive oxygen species leak from the electrode when the battery is charged at high voltage.
High-voltage batteries are lithium-ion cells charged at voltages of 4.4V or higher, and because they can store more electricity, they can make battery packs lighter. However, as the charging voltage increases, oxygen in the high-nickel cathode becomes unstable and turns into a reactive oxygen species called singlet oxygen, which escapes; this reactive oxygen generates gas, increasing the risk of battery explosion and shortening its lifespan.
The anthracene (An) in the developed electrolyte binds with unstable oxygen on the electrode surface, blocking the reaction step in which unstable oxygen atoms bind to each other. When unstable oxygen binds together, an oxygen dimer, the "seed" of reactive oxygen species, is formed. This anthracene can also capture and remove reactive oxygen species that have already formed, providing dual protection. Another component of the electrolyte, the nitrile functional group, stabilizes the nickel metal in the cathode, preventing nickel from dissolving out or the cathode structure from deforming.
Lead author Lee Jeong-in said, "What sets this study apart is that it blocks the generation stage of reactive oxygen species itself," adding, "Previously, efforts were made to neutralize reactive oxygen species after they had formed with antioxidants, or to suppress oxygen generation by manipulating the electrode."
A battery using the new electrolyte retained 81% of its initial capacity even after 500 charge-discharge cycles under a 4.55V high-voltage charging condition, whereas a conventional battery fell below 80% of its initial capacity after only 180 cycles. Because a battery is considered to have reached end of life when its capacity falls below 80% of the initial value, the lifespan increased 2.8 times.
Gas generation, which causes battery swelling, was also greatly suppressed. Unlike the conventional battery, which swelled by 85 µm (micrometers, one-millionth of a meter), the battery with the gel electrolyte swelled only about 13 µm, reducing volumetric expansion to about one-sixth.
Song Hyun-gon said, "We showed that oxygen reactions in high-voltage batteries can be directly controlled at the electrolyte design stage," adding, "This principle could be applied to the development of lightweight lithium-ion batteries for aerospace and large-capacity energy storage systems (ESS) in the future."
The study was published online on Oct. 5 (local time) in the international journal Advanced Energy Materials in the field of energy materials.
References
Advanced Energy Materials (2025), DOI: https://doi.org/10.1002/aenm.202503180