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High quality LiCoO 2 crystals, useful as cathode material for lithium-ion rechargeable batteries, were successfully grown at a holding temperature of 800-1000 °C using the NaCl flux cooling method. The morphology, structure, size uniformity, and crystallinity of the obtained LiCoO 2 crystals were obviously dependent on the growth conditions, such as the holding temperature and the starting composition. Well-developed, highly crystalline LiCoO 2 crystals were first grown at a holding temperature of 900 °C from a NaCl flux. The grown LiCoO 2 crystals had a hexagonal barrel-shaped structure with welldeveloped {001}, {104}, {101}, and {102} faces. On the basis of the powder X-ray diffraction data, the lattice parameters of the crystals were determined as a = 2.816 and c = 14.077 A ˚. These values agree approximately with those from the literature (a = 2.816 and c = 14.052 A ˚). The average crystal size was about 1.4 μm, which is a relatively small size when compared to previous reports. Transmission electron microscopy images indicate that the LiCoO 2 crystals were of very good crystallinity. It was confirmed that the charge and discharge capacities of the lithium-ion rechargeable batteries containing the grown LiCoO 2 crystals were 138 and 130 mAh 3 g -1 , respectively, values that correspond to the available capacity of 137.5 mAh 3 g -1 . The discharge capacity of the grown LiCoO 2 crystal is greater at 10 C than that of commercially available crystals.

Atomic-resolution STEM and EELS analysis provide insights into microscopic mechanisms behind oxygen loss and capacity fade in spinel-structured lithium-ion battery cathode material LiMn2O4.

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