TSFZ Growth and Anisotropic Ionic Conductivity of Zr-Doped LiCoO₂ Single Crystals

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High Resolution Image Download MS PowerPoint Slide To aid the development of cathode materials for use in Li-ion batteries, for the first time, LiCo 1– x Zr x O 2 single crystals were successfully grown via the traveling solvent floating zone (TSFZ) technique. The crystals grown using 0.50 at. % Zr-doped feeds were single crystals with very small (Co, Zr)O x inclusions (approximately 6 μm in size), whereas large size inclusions segregated in the crystals grown using the feed of 1.00 at. % Zr. The Zr concentrations of the LiCoO 2 phase in both crystals were determined to be 0.26 ± 0.01 and 0.26 ± 0.05 at. %, respectively, along the growth direction, which is almost identical to each other but lower than the actual Zr concentration in feeds (0.50 and 1.00 at. % Zr). The ionic conductivities of LiCo 0.9974 Zr 0.0026 O 2 single crystals along [100] and [001] were 8.3 × 10 –6 and 4.0 × 10 –8 S·cm –1, respectively, which are approximately twice as large as those of LiCoO 2 (σ [100] = 4.0 × 10 –6, σ [001] = 2.4 × 10 –8 S·cm –1 ). The anisotropy of ionic conductivity in LiCo 0.9974 Zr 0.0026 O 2 was found to be 207. The results obtained in this study have the potential to improve the energy density and safety of Li-ion batteries.