Tuesday, 30 May 2017: 14:40
Grand Salon D - Section 21 (Hilton New Orleans Riverside)
R. E. Ruther, A. S. Pandian (Oak Ridge National Laboratory), P. Yan (Pacific Northwest National Laboratory), J. N. Weker (SLAC National Accelerator Laboratory, USA), C. Wang (Pacific Northwest National Laboratory), and J. Nanda (Oak Ridge National Laboratory)
Cathode chemistries with more than one lithium per transition metal (multi-lithium cathodes) are one approach for increasing the energy density of lithium-ion cells. Examples include lithium-rich NMCs (
xLi
2MnO
3·
(1−x)LiMO
2 where M=Mn, Ni, Co), anti-fluorite type oxides, and several polyanionic compounds. Many of these cathodes have very high theoretical capacities, but none has proven practical for commercial cells. These materials generally undergo structural transformations, often accompanied by oxygen loss, which limit electrochemical reversibility. In this contribution, we present a thorough investigation of Li
2Cu
0.5Ni
0.5O
2, as a model system to understand the larger family of multi-lithium cathodes. Results from XRD, Raman spectroscopy, TEM, XANES, and gas evolution measurements follow the chemical, structural, and morphological changes that occur during electrochemical cycling. Our study broadly demonstrates the challenges associated with multi-lithium transition metal oxides, where there is close interplay between structure, transport, and oxygen loss that limits their use as high capacity cathodes for advanced lithium-ion systems.
Acknowledgement
Research has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program. The authors acknowledge the support of Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Stanford University. X-ray diffraction was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The TEM work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a DOE User Facility operated by Battelle for the DOE Office of Biological and Environmental Research. Pacific Northwest National Laboratory is operated for the DOE under Contract DE-AC06-76RLO 1830.
