ISSN 0036-0295, Russian Metallurgy (Metally), Vol. 2013, No. 2, pp. 86–89. © Pleiades Publishing, Ltd., 2013. Original Russian Text © D.V. Modenov, V.N. Dokutovich, V.A. Khokhlov, B.D. Antonov, V.A. Kochedykov, I.D. Zakir’yanova, 2012, published in Rasplavy, 2012, No. 4, pp. 32–37. 86 INTRODUCTION Lithium–cobalt(III) oxide LiCoO 2 is among the most important functional materials used as cathodes in lithium ion batteries [1, 2]. These batteries are widely used in modern electronics and are the most popular current sources in such devices as cell phones, notebooks, digital cameras, and so on. Several methods for the synthesis of lithium cobal- tate are presently known. Among them are solid-state [3], mechanochemical [4], hydrothermal [5], emul- sion [6], and sol–gel [7] methods. However, they have substantial drawbacks that restrict their use. The main problem of the traditional solid-state synthesis is a low reaction rate caused by the small initial surface area of contact between the solid reactants and by the transi- tion of the process from a kinetic to a diffusion regime during the formation of the product layer that sepa- rates starting substances. For this reason, the synthesis is carried out for a long time (more than 10 h) at a high temperature (as a rule, above 900°C); as a result, agglomerated particles nonuniform in size and mor- phology are formed [8]. The mechanochemical and solid-phase methods are based on solid precursors. However, the mechanochemical process is carried out in ball mills; hence, its characteristic disadvantages are a long process time, uncontrolled particle aggregation, and the contamination of powders with the material of milling bodies [9]. The emulsion and sol–gel synthe- ses end in annealing the reaction products (usually at 400–900°C [6, 7]); as a result, they can be reduced to solid-state interaction. The hydrothermal method requires no similar annealing but needs autoclaving [10]. A promising method for the preparation of lithium cobaltate is molten salt synthesis [11–13]: it can form this compound at lower temperatures and in shorter times compared to those of the solid-state method. Here, Co 3 O 4 , CoO, LiOH, and various oxo salts (as a rule, Co(NO 3 ) 2 , Li 2 CO 3 , LiNO 3 ) that decompose under synthesis conditions are used. The application of thermally stable lithium and cobalt halides in the role of precursors has not been described. EXPERIMENTAL Lithium cobaltate was synthesized in dry air blown above a LiX melt (X = Cl, Br, I) by loading portions of small amounts of CoCl 2 . The reactions of oxidation of halide ions and combination of simple oxides to form lithium cobaltate, 4LiX + O 2 = 2Li 2 O + 2X 2 ↑, (1) 3CoCl 2 + 2O 2 = Co 3 O 4 + 3Cl 2 ↑, (2) 6Li 2 O + 4Co 3 O 4 + O 2 = 12LiCoO 2 ↓, (3) occurred at 700°C (for chloride and bromide media) or 470°C (for an iodide medium). In the case of a chloride melt, LiNO 3 as the donor of Li 2 O was introduced into the reaction system to accelerate the process. In different experiments, the amount of nitrate was varied up to the formation of the saturated solution of Li 2 O in an LiCl melt (the data on the solubility at 700°C were taken from [14]). The synthesis was carried out for 6–8 h. Then, a heterophase solidified melt cooled to the ambient temperature was dissolved in distilled water. The resulting precipitate was filtered off, washed, dried, and studied by Fourier transform infrared (IR) spec- troscopy and X-ray diffraction (XRD) analysis. The IR spectra of the powders uniformly distributed in thin (about 1 mm) pressed KBr pellets were recorded on a Synthesis of Lithium Cobaltate in Halide Melts D. V. Modenov*, V. N. Dokutovich, V. A. Khokhlov, B. D. Antonov, V. A. Kochedykov, and I. D. Zakir’yanova Institute of High-Temperature Electrochemistry, Ural Branch, Russian Academy of Sciences, ul. Akademicheskaya 20, Yekaterinburg, 620990 Russia *e-mail: Modenov@ihte.uran.ru Received April 6, 2012 Abstract—A new method for the synthesis of lithium cobaltate LiCoO 2 in salt melts is proposed and tested. The method is based on the oxidation of halide ions with molecular oxygen in LiX–CoCl 2 mixtures (X = Cl, Br, I). The chemical and phase compositions of the prepared powders and the crystal structure of the synthe- sized compound are studied by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The average size of LiCoO 2 crystallites is estimated from the X-ray diffraction data. DOI: 10.1134/S0036029513020092