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X-ray photoelectron spectroscopy of negative electrodes from high-power lithium-ion cells showing various levels of power fade

Journal Article · · Electrochimica Acta

High-power lithium-ion cells for transportation applications are being developed and studied at Argonne National Laboratory. The current generation of cells containing LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}-based cathodes, graphite-based anodes, and LiPF6-based electrolytes show loss of capacity and power during accelerated testing at elevated temperatures. Negative electrode samples harvested from some cells that showed varying degrees of power and capacity fade were examined by X-ray photoelectron spectroscopy (XPS). The samples exhibited a surface film on the graphite, which was thicker on samples from cells that showed higher fade. Furthermore, solvent-based compounds were dominant on samples from low power fade cells, whereas LiPF{sub 6}-based products were dominant on samples from high power fade cells. The effect of sample rinsing and air exposure is discussed. Mechanisms are proposed to explain the formation of compounds suggested by the XPS data.

Research Organization:
Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
Sponsoring Organization:
US Department of Energy (US)
DOE Contract Number:
AC03-76SF00098
OSTI ID:
835444
Report Number(s):
LBNL--55908
Journal Information:
Electrochimica Acta, Journal Name: Electrochimica Acta Journal Issue: 28 Vol. 49
Country of Publication:
United States
Language:
English