of Li1+xCoO2 (0 < x
0.1) Superstoichiometric Oxides
V. V. Kaichev*, N. V. Kosova**, E. T. Devyatkina**, V. I. Bukhtiyarov*, and D. G. Kellerman***
* Boreskov Institute of Catalysis, Siberian Division, Russian Academy of Sciences,
pr. akademika Lavrent’eva 5, Novosibirsk, 630090 Russia
** Institute of Solid-State Chemistry and Mechanochemistry, Siberian Division, Russian Academy of Sciences,
Novosibirsk, Russia
*** Institute of Solid-State Chemistry, Ural Division, Russian Academy of Sciences,
ul. Pervomaiskaya 91, Yekaterinburg, 620219 Russia
E-mail: kosova@solid.nsc.ru
Received October 15, 2002
Abstract—Li1+xCoO2 (0 
x 0.1) samples prepared by the traditional ceramic technique were studied by X-
ray diffraction, IR spectroscopy, X-ray photoelectron spectroscopy, diffuse reflectance electron spectroscopy,
and magnetic measurements. The superstoichiometric oxides had a uniform crystal structure with statistically
distributed vacancies in cobalt layers and an enhanced covalence of Co–O bonds. Excess lithium caused the
appearance of a new oxygen state (O
) different from the oxide state (O2
) rather than the reduction of 
3+
ions to Co2+. The appearance of oxygen ions with an unusually low electron density was directly related to the
formation of oxygen positions with a decreased coordination number; the magnetic properties of Li1+xCoO2
were governed by exchange-coupled (Co3+
O
) pairs.
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