Preparation of Li–Co–O film by metal organic chemical vapor deposition

Abstract

LiCoO 2 films were prepared on polycrystalline Al 2 O 3 substrates by metal organic chemical vapor deposition (MOCVD), and the effect of the Li to Co source vapor ratio (R Li/Co ) and substrate temperature (T sub ) on the phases, orientation, morphology, and deposition rates were investigated. At R Li/Co > 2.0, Li 2 CO 3 , Li x Co 1¹x O, and a LiCoO 2 CoO solid solution were co-deposited with LiCoO 2 , whereas Co 3 O 4 was co-deposited with LiCoO 2 at R Li/Co < 0.7. Single-phase LiCoO 2 films were obtained in the R Li/Co range of 0.72.0 at T sub > 873 K. Rutherford backscattering spectrometry revealed that single-phase LiCoO 2 film had uniform and stoichiometric composition. The orientation of single-phase LiCoO 2 films changed from (003) to (104) and (012) with increasing T sub at R Li/Co ³ 1.0. LiCoO 2 film co-deposited with Co 3 O 4 at R Li/Co = 0.4 showed significant (101) orientation. The (003)-oriented LiCoO 2 had a flat surface with hexagonal faceted texture, whereas the (101)-and (104)-oriented LiCoO 2 had platelet grains in which the plate faces were tilted relative to the substrate surface. The highest deposition rate of single-phase LiCoO 2 film was 1020¯m h ¹1, which was 100 times greater than that reported in the literature.

In situ studies of lithium-ion diffusion in a lithium-rich thin film cathode by scanning probe microscopy techniques

“…S1(a), ESI †). 27,28 In consideration of the thin film preparation method, the parallel alignment of (003) planes is preferred in layered structure thin film deposited by the PLD technique. 26 The presence of only (003) reflection for the Li-rich film cathode indicates that, within the sensitivity of the measurement, most grains are (003) oriented, i.e., with the c-axis aligned normal to the plane of the film.…”

“…26 In addition, the (003) oriented grains usually have a flat surface with hexagonal facet texture; whereas (101) and (104) oriented grains usually have a platelet feature. 27,28 In consideration of the thin film preparation method, the parallel alignment of (003) planes is preferred in layered structure thin film deposited by the PLD technique. 29,30 Therefore, the grains with well-defined hexagon-like geometry [Fig.…”