Professor Kim Hee-tak and his research team at the Korea Advanced Institute of Science and Technology (KAIST) identify the cause of performance degradation in lithium-sulfur batteries through joint research with LG Energy Solution and develop technologies to improve performance./KAIST

Following the growth of the electric vehicle market, the urban air mobility (UAM) market, which connects air traffic, is gaining attention as a new turning point for the battery industry. A joint research team from a university and corporations has developed next-generation lithium-sulfur batteries to address the limitations of lithium-ion batteries used as the main energy source for air mobility.

Professor Kim Hee-tak of the Department of Bio-Chemical Engineering at the Korea Advanced Institute of Science and Technology (KAIST) noted on the 23rd that his research team, in collaboration with LG Energy Solution's joint research team, has identified the causes of performance degradation in lithium-sulfur batteries and developed technology to improve performance based on these findings. The research was published on Nov. 30 in the international journal "Advanced Energy Materials."

Last year, China's Contemporary Amperex Technology Co., Limited (CATL) announced its preparedness for the aviation battery market by revealing its "condensed battery" technology. Among this, lithium-sulfur batteries are gaining attention as the next-generation technology that surpasses existing lithium-ion batteries. Lithium-sulfur batteries can achieve over twice the energy density per weight compared to conventional lithium-ion batteries, making them a game changer in the UAM market.

However, existing lithium-sulfur battery technology requires a large amount of electrolyte for stable battery operation, which increases the battery weight and consequently results in reduced energy density. Moreover, in the sparse electrolyte environment where the electrolyte usage is reduced, the performance degradation accelerates, but the degradation mechanisms have not been clearly established, making the development of lithium-sulfur batteries for UAM challenging.

The research team developed a lithium-sulfur battery that achieves an energy density of over 400 Wh (watt-hours, a unit of power produced over one hour) per 1 kg while reducing electrolyte usage by more than 60% compared to existing batteries. They successfully ensured that the energy density is over 60% higher than that of commercial lithium-ion batteries while securing stable lifespan characteristics.

The research team conducted tests on batteries in various electrolyte environments and discovered that the main cause of performance degradation in lithium-sulfur batteries is electrolyte depletion due to electrode corrosion. To address this, they introduced "fluorinated ether solvent" to enhance the stability and reversibility of the lithium metal anode and successfully reduced electrolyte decomposition.

Professor Kim Hee-tak remarked, "This research highlights the importance of controlling the electrode interface through electrolyte design in lithium-sulfur batteries and is a representative success case achieved through collaboration between a university and corporations. It will make significant progress in accelerating the commercialization of next-generation mobility batteries such as UAM."

Reference material

Advanced Energy Materials (2024), DOI: https://doi.org/10.1002/aenm.202403828