A new additive has been developed that can enhance the lifespan and efficiency of lithium-air batteries. It is expected that the commercialization of lithium-air batteries, which have a driving range more than double that of existing batteries, will be accelerated.
Professor Kwak Won-jin's research team at Ulsan National Institute of Science and Technology (UNIST), along with Professor Seo Sung-eun from Ajou University and Professor Xu Mingqian from Oberlin College, announced on the 10th that they have developed a redox mediator called "BAC" for lithium-air batteries. This research was published in the international academic journal "Advanced Materials" on Jan. 3.
A lithium-air battery is a cell system that uses lithium as the anode and air-borne oxygen as the cathode active material. It has a capacity up to five times greater than lithium-ion batteries used in electric vehicles, allowing for a driving range that can exceed double that of conventional batteries. However, it has been faced with challenges, such as the need for high charging voltage and performance degradation caused by reactive oxygen species generated internally.
The material that addresses this issue is the redox mediator. By using a redox mediator, it is possible to charge the battery at lower voltages. As a result, energy efficiency improves while reducing the overload on the cell, thereby prolonging its lifespan.
The research team developed a redox mediator that does not react well with reactive oxygen species. According to the study, BAC maintained a battery charging voltage at approximately 3.5V even after exposure to one type of reactive oxygen species. Additionally, the ratio of oxygen released during the charging process was maintained at 79% from a previous 82%. This represents a significant difference when compared to existing redox mediators that experience an increase in charging voltage and a decrease in oxygen production by more than 50% when exposed to reactive oxygen species.
Professor Kwak noted, "Lithium-air batteries exhibit various side reactions due to reactive oxygen species, and controlling this is essential for technological advancement," adding that "the electrolyte additive developed in this study could enhance the performance of lithium-air batteries while also being useful in the development of various catalysts."
Reference materials
Advanced Materials (2025), DOI: https://doi.org/10.1002/adma.202415805