Structural and Electrochemical Investigation of Li(Ni0.4Co0.2-yAlyMn0.4)O2 Cathode Material

Journal Article · Tue Feb 02 04:00:00 EST 2010 · Electrochemical Society

DOI:https://doi.org/10.1149/1.3494211· OSTI ID:984355

Rumble, C; Conry, T E; Doeff, Marca; Cairns, Elton J; Penner-Hahn, James E; Deb, Aniruddha

Li(Ni{sub 0.4}Co{sub 0.2-y}Al{sub y}Mn{sub 0.4})O{sub 2} with y=0.05 was investigated to understand the effect of replacement of the cobalt by aluminum on the structural and electrochemical properties. The effect of the substitution was studied by in-situ X-ray absorption spectroscopy (XAS), utilizing a novel in situ electrochemical cell, specifically designed for long-term X-ray experiments. The cell was cycled at a moderate rate through a typical Li-ion battery operating voltage range (1.0-4.7 V). XAS measurements were performed at different states-of-charge (SOC) during cycling, at the Ni, Co, and the Mn edges, revealing details about the response of the cathode to Li insertion and extraction processes. The extended X-ray absorption fine structure region of the spectra revealed the changes of bond distance and coordination number of Ni, Co, and Mn absorbers as a function of the SOC of the material. The oxidation states of the transition metals in the system are Ni{sup 2+}, Co{sup 3+}, and Mn{sup 4+} in the as-made material (fully discharged), while during charging the Ni{sup 2+} is oxidized to Ni{sup 4+} through an intermediate stage of Ni{sup 3+}, Co{sup 3+} is oxidized towards Co{sup 4+} and Mn was found to be electrochemically inactive and remains as Mn{sup 4+}. The EXAFS results during cycling show that the Ni-O changes the most, followed by Co-O and Mn-O varies the least. These measurements on this cathode material confirmed that the material retains its symmetry and good structural short-range order leading to the superior cycling reported earlier.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Environmental Energy Technologies Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 984355
• Report Number(s): LBNL-3582E
• Journal Information: Electrochemical Society, Journal Name: Electrochemical Society
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
ABSORPTION
ABSORPTION SPECTROSCOPY
ALUMINIUM
CATHODES
COBALT
COORDINATION NUMBER
ELECTROCHEMICAL CELLS
FINE STRUCTURE
SPECTRA
SYMMETRY
TRANSITION ELEMENTS
VALENCE