Abstract
Layered rock-salt LiNi(1−x)/2Co(1−x)/2TixO2 (0 ≤ x ≤ 0.1) and LiNi(1−x)/2Co(1−x)/2–0.05Fe0.05TixO2 (0 ≤ x ≤ 0.1) were prepared by the electrostatic spray deposition method, which is one of the solution processes, to investigate the correlation between these crystal structures and electrode properties of the multinary oxides with solid solution of Fe and Ti ions. Even with only 5 % solid solution of Fe, the cycle retention rate after 50 cycles decreased by 5–8 %. Regardless of Fe-substitution/non-substitution, the crystallite size of the powder calcined at 973 K under oxygen atmosphere became finer as the amount of Ti substitution increased. Although Ti ions do not contribute to redox, Ti-substituted materials are improved Li diffusion due to finer crystallite size, and show better discharge capacity and cycle performance as Ti content increased. Not only in the Li–Ni–Co system, but also in the Li–Ni–Co–Fe system, crystallite size refinement and improvement in initial discharge capacity and cycle performance were observed depending on the amount of Ti substitution, indicating that Ti ions contribute to lattice stabilization.
