UNIST Develops 'Redox Mediator' for Lithium-Air Batteries

2025-02-28

Professor Won-jin Kwak’s team of UNIST (Ulsan National Institute of Science & Technology), in collaboration with Professor Sung-eun Seo's team at Ajou University and Professor Shuming Chen's team at Oberlin College in the United States, has developed a 'redox mediator' for lithium-air batteries. The additive developed is expected to accelerate the commercialization of lithium-air batteries, which have a capacity up to five times larger than existing lithium-ion batteries.

Lithium-air batteries are next-generation energy storage systems with a very high capacity compared to lithium-ion batteries. However, they have low energy efficiency due to high charging voltage and have poor battery reversibility due to various side reactions.

The redox mediator of a battery is an important additive that determines the energy efficiency and lifespan of a lithium-air battery. This redox mediator lowers the high voltage required to charge the lithium-air battery, allowing charging at a lower voltage, thereby increasing energy efficiency and lifespan.

The research team developed a redox mediator that does not react well with reactive oxygen species. The newly developed redox mediator, BAC (7,7'-bi-7-azabicyclo[2.2.1]heptane), maintained the battery charging voltage at the same level of 3.5V before and after exposure to singlet oxygen, and the ratio of oxygen released during charging was 82% and 79%, respectively, confirming excellent stability and reversibility.

Source: https://www.e-science.co.kr/news/articleView.html?idxno=101558