Layered oxide cathode materials for high energy density lithium batteries 

 Xiqian Yu 

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS

Abstract: The layered oxide materials with the α-NaFeO2 structure (Li1+xTM1-xO2, TM=transition metal ions) are most attractive cathode materials for lithium-ion batteries, owing to larger capacities (>200 mAh/g) than spinels or polyanionic compounds. In particular, LiTMO2 with the substitution of the transition metals by Li, forming the Li-rich or Li-excess materials (Li1+xTM1-xO2), can deliver reversible capacities exceeding 270 mAh/g. However, these materials need to charge to high voltage, which is normally above 4.5V and beyond the electrochemical window of conventional non-aqueous organic electrolyte, to obtain full capacity. The structural stability of particle surface and its interaction with electrolyte at high charging voltage play an important role in determining the overall electrochemical performances of these cathode materials. In addition, the crystal structural stability of these materials upon deep extent of lithium extraction and insertion remains a problem. In this presentation, the results of multi-scale characterization of several layered oxide cathode materials (Li1+xTM1-xO2, TM=transition metal ions), including lithium rich and regular layered oxides, were discussed in details to provide in depth understanding of the key factors governing both the bulk and surface structural stability of these materials for high-energy density applications. The strategies to improve the electrochemical performances of layered oxide cathodes are also discussed.

Biography: Dr. Xiqian Yu is an associate professor of "Hundred talents Program of CAS" at Institute of Physics, Chinese Academy of Sciences (IoP, CAS). He received his Ph.D. in Condensed Matter Physics from IoP-CAS in 2010, and then moved to Brookhaven National Laboratory as Postdoctor and then Physics Associate (2013-2016). He joined in IoP in 2016 and was awarded the “1000 young talents plan” in 2017. His current research interest is in the field of electrochemical energy storage with the main focus on the characterization of the electrode materials for rechargeable batteries. He also works on developing new in situ synchrotron and neutron based diagnostic techniques for energy storage researches.