ABSTRACT: In commercial Li-ion batteries, well-ordered close-packed oxides, particularly, layered lithium transition metal oxides, LiTMO2 (TM = Ni, Mn, Co, Al), are widely used. Despite the high theoretical capacity of these layered oxides (> 270 mAh/g), they are typically operated to deliver a capacity of less than 200 mAh/g to attain good cycling and safety attributes. Nowadays, strategies to push the capacity limit of such materials have led to the development of Li-rich layered oxides, which can consistently deliver a reversible capacity approaching 300 mAh/g. This exceptionally high capacity is far beyond the theoretical capacity from Ni and Co redox, for example, Ni redox (Ni2+/4+) can only account for a theoretical capacity of 127 mAh/g in a Co-free compound, Li1.2Ni0.2Mn0.6O2. This has been directed to the participation of anionic lattice oxygen in the electrochemical reaction. Recently, our work has been directed toward probing the anionic oxygen activity in high capacity Ni-based layered oxide cathodes for Li-ion batteries. I will present our recent studies on anionic oxygen activity in Li-rich layered oxides from material perspective via tackling the effect of transition metal species.
Bio-sketch: Wei Tong is a Scientist/Principal Investigator in Energy Storage and Distributed Resources Division at Lawrence Berkeley National Laboratory. She obtained her Ph.D. degree in Materials Science and Engineering at Rutgers, The State University of New Jersey. Afterwards she joined Wildcat Discovery Technologies, Inc. as a Scientist. Dr. Tong has over 10 years’ experience in battery materials research and development, including 3 years’ experience in combinatorial material design and high throughput electrochemical screening. She specializes in chemical synthesis of solid state materials with emphasis on combinatorial library design and high throughput screening of battery materials. Her extensive experience and practical knowledge in battery materials research have led to over 10 inventions in the battery field. Her research interests also extend to in-depth understanding of the electrochemical reaction mechanism within the bulk electrode and at the interface through the advanced characterization techniques.