Measuring Oxygen Release from Delithiated LiNixMnyCo1-x-yO2 and Its Effects on the Performance of High Voltage Li-Ion Cells. Issue 13 (1st January 2017)

• Record Type: Journal Article
• Authors: Xiong, D. J.; Ellis, L. D.; Li, J.; Li, Hongyang; Hynes, T.; Allen, J. P.; Xia, J.; Hall, D. S.; Hill, I. G.; Dahn, J. R.
• Is Part Of: Journal of the Electrochemical Society. Volume 164:Issue 13(2017)
• Page Start: A3025
• Page End: A3037
• Publication Date: 2017-01-01
• Subjects: capacity retention -- high voltage -- lithium-ion batteries -- mass spectrometry -- NMC electodes -- oxygen release -- positive electrodes -- surface oxygen; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0291713jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : There can be a trade-off between the lifetime and energy density of LiNix Mny Co1-x-y O2 (NMC)-containing cells that depends on their upper cutoff voltage. This work applies thermogravimetric analysis coupled with mass spectrometry (TGA-MS) to measure the release of oxygen from delithiated NMC electrode materials at high electrode potentials, i.e., low lithium content. This release is observed at relatively mild temperatures as low as 40°C. The amount of oxygen released is greatly limited using single crystal NMC particles. Electrochemical measurements demonstrate a correlation between TGA-MS results and the cycling performance of NMC/graphite cells. X-ray photoelectron spectroscopy complements the TGA-MS results and provides evidence of the solid electrolyte interphase decomposition. The results in this work offer strong support that the release of oxygen from NMC can cause oxidative decomposition of the electrolyte and is a major reason why high voltage cells can generate gas and can have poor capacity retention.