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Structure Evolution and Kinetics Study of Layered LiNixMnyCozO2 (x+y+z=1) Cathode Materials during Charge Using Synchrotron X-Ray Techniques
Thursday, May 15, 2014: 18:00
Bonnet Creek Ballroom III, Lobby Level (Hilton Orlando Bonnet Creek)
Y. Zhou (Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA), S. J. Cho (Johnson Controls Inc. Milwaukee, WI 53209), S. M. Bak, X. Yu (Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA), K. W. Nam, and X. Q. Yang (Chemistry Department, Brookhaven National Laboratory)
Layer structured mixed transition metal oxides LiNi
xMn
yCo
yO
2 (x+y+z=1, NMC) have been widely studied as promising cathode materials for Li-ion batteries due to their superior properties, better thermal stability, lower cost and higher capacity comparing to LiCoO
2, which is the widely used cathode material for Li-ion cells. A typical NMC cathode with a composition of 1:1:1 (LiNi
1/3Mn
1/3Co
1/3O
2) is already being used in commercial lithium-ion battery cells. However, more systematic studies on the structure-performance relationship of the NCM materials are needed. It is critical to understand the role of each element in electrochemical performance in terms of the capacity, rate capability, cycling and calendar lifes as well as safety characteristics. In this regard, we present here a systematic study on the structural changes that occur in the NMC cathode materials with several different compositions such as NMC = 333, 433, 532, 622 and 811 during charge using combined
in-situ synchrotron based X-ray techniques.
While in situ X-ray diffraction (XRD) was used to track the average bulk crystal structural changes, in situ X-ray absorption spectroscopy (XAS) was applied to monitor the electronic structure and local structure changes around each transition metal element (Ni, Mn and Co) in the NMC cathode during charge. In addition, time-resolved XRD and Quick-EXAFS were also used for monitoring its structural changes and kinetic property of each transition metal upon charge at different C rates (C/10 to 30C). Detailed results including in situ XRD and XAS on the NMC materials with various NMC compositions during charge will be present.
Acknowledgement
The work done at Brookhaven National Lab. was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies under Contract Number DEAC02-98CH10886.
