Thermal stabilities of a series of blended LiMn2O4 (LMO)eLiNi1/3Co1/3Mn1/3O2 (NCM) cathode materials with different weight ratios were studied by in situ time-resolved X-ray diffraction (XRD) combined with mass spectroscopy in the temperature range of 25 °C-580 °C under helium atmosphere. Upon heating, the electrochemically delithiated LMO changed into Mn3O4 phase at around 250 °C. Formation of MnO with rock-salt structure started at 520 °C. This observation is in contrast to the previous report for chemically delithiated LMO in air, in which a process of λ-MnO2 transforming to β-MnO2 was observed. Oxygen peak was not observed in all cases, presumably as a result of either consumption by the carbon or detection limit. CO2 profile correlates well with the phase transition and indirectly suggests the oxygen release of the cathode. Introducing NCM into LMO has two effects: first, it makes the high temperature rock-salt phase formation more complicated with more peaks in CO2 profile due to different MO (M = Ni, Mn, Co) phases; secondly, the onset temperature of CO2 release is lowered, implying lowered oxygen release temperature. Upon heating, XRD patterns indicate the NCM part reacts first, followed by the LMO part. This confirms the better thermal stability of LMO over NCM.
|Number of pages||5|
|Journal||Journal of Power Sources|
|Publication status||Published - 2015 Mar 1|
Bibliographical noteFunding Information:
This work 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 DE-AC02-98CH10886 . Use of the NSLS was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences , under Contract No. DE-AC02-98CH10886 . MS is supported by a start-up grant from the Hong Kong University of Science and Technology . This work was also supported by the Energy Efficiency & Resources of the Korea Institute of Energy Technology Evaluation and Planning grant funded by the Korea government Ministry of Trade, Industry & Energy (Project no. 20142020103090 ). The authors appreciate the invaluable discussion with Prof. Jean-Marie Tarascon.
© 2014 Elsevier B.V. All rights reserved.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering