Won-Sub Yoon is a professor in the Department of Energy Science at Sungkyunkwan University (SKKU), South Korea. He earned his PhD in materials science and engineering from Yonsei University. He worked at Brookhaven National Laboratory as a principal investigator and Kookmin University as a faculty member. He has been a board member of the International Battery Association (IBA) and the International Meeting on Lithium Batteries (IMLB). He has over 25 years of experience in rechargeable batteries with more than 240 SCI papers. His research group focuses on the electrode materials and the reaction/fading mechanisms for Li rechargeable batteries, employing various advanced synchrotron X-ray techniques.