Vapor Growth and Chemical Delithiation of Stoichiometric LiCoO2 Crystals

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• 作者：Qiyin Lin ; Qing鈥檃n Li ; Kenneth E. Gray ; John F. Mitchell
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：March 7, 2012
• 年：2012
• 卷：12
• 期：3
• 页码：1232-1238
• 全文大小：379K
• 年卷期：v.12,no.3(March 7, 2012)
• ISSN：1528-7505

文摘

Single crystals of LiCoO₂ have been grown by a vapor transport method at high temperature and normal atmospheric pressure. The plate-like single crystals have large (00l) facets (up to 1 mm²) and thicknesses ranging from 5 to 50 渭m. A single-crystal X-ray diffraction study confirmed the trigonal R3̅m space group with lattice parameters a = 2.8150(3) 脜 and c = 14.0516(6) 脜 at room temperature. Electrical transport measurements indicated that as-grown crystals are highly insulating, with electrical resistivity in the order of T惟 cm at room temperature. This contrasts with the value of 5 惟 cm previously reported for a flux-grown crystal and suggests that vapor growth crystals may have fewer defects. Li-ion deintercalation of LiCoO₂ crystals was carried out by a chemical extraction process. A quasi-in situ XRD approach was utilized to monitor the structural evolution during the Li-ion extraction process, which exhibited the progression of phases widely established for this system, but also shows evidence of inhomogeneous delithiation mechanism. Transport measurements confirm metallic behavior for delithiated Li_xCoO₂ crystals (0.5 < x < 1.0) with anomalies in the temperature of 150鈥?80 K.