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Author Jalkanen, K. ♦ Lindén, J. ♦ Karppinen, M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ CATIONS ♦ COBALT IONS ♦ COBALT PHOSPHATES ♦ CONCENTRATION RATIO ♦ ELECTRODES ♦ IRON 57 ♦ IRON IONS ♦ IRON PHOSPHATES ♦ LITHIUM ION BATTERIES ♦ LITHIUM PHOSPHATES ♦ NICKEL IONS ♦ NICKELATES
Abstract We employ {sup 57}Fe Mössbauer spectroscopy as a local tool to probe electrical environments of Fe{sup 2+} and Fe{sup 3+} at different lithiation (x) and cation-substitution (y) levels in Li{sub x}Fe{sub 1−y}M{sub y}PO{sub 4}/C (M=Co, Ni) Li-ion battery electrode materials. Upon delithiation the local environment of Fe{sup 3+} remains unaffected for the parent y=0 system due to the LiFePO{sub 4}/FePO{sub 4} phase separation, whereas for y>0 changes in the electrical environment are seen for Fe{sup 3+}. When the Fe{sup 2+}/Fe{sup 3+} redox couple is partially-delithiated, a decreasing quadrupole splitting value is observed for Fe{sup 3+} with increasing y, implying a more symmetric electrical environment. The increasing concentration of the Co{sup 2+}/Ni{sup 2+} substituent introduces increasing amounts of Li atoms in the Fe{sup 3+}-containing phase, and these nearest-neighbor Li atoms are suspected to cause the changes seen in the local environment of Fe{sup 3+}. - Graphical abstract: Local environment of iron in Li{sub x}Fe{sub 1−y}(Co/Ni){sub y}PO{sub 4} is studied by {sup 57}Fe Mössbauer spectroscopy at different lithiation (x) and cation-substitution (y) levels. - Highlights: • Local Fe environment in Li{sub x}Fe{sub 1−y}(Co/Ni){sub y}PO{sub 4} is studied by {sup 57}Fe Mössbauer spectroscopy. • Co/Ni-for-Fe substitution results in a more symmetric electrical environment for Fe{sup 3+}. • Due to presence of Co{sup 2+}/Ni{sup 2+}, Li atoms are introduced into the Fe{sup 3+}-containing phase. • These nearest-neighbor Li atoms are suggested to change the local Fe{sup 3+} environment.
ISSN 00224596
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-10-15
Publisher Place United States
Journal Journal of Solid State Chemistry
Volume Number 230


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