Stable Li₂TiO₃ Shell–Li_1.17Mn_0.50Ni_0.16Co_0.17O₂ Core Architecture Based on an In-Site Synchronous Lithiation Method as a High Rate Performance and Long Cycling Life Lithium-Ion Battery Cathode

A stable shell–core architecture Li2TiO3@Li1.17Mn0.50Ni0.16Co0.17O2 (LTO@LNCM) was successfully synthesized via in-site synchronous lithiation. This architecture is designed based on the fact that Li1.17Mn0.50Ni0.16Co0.17O2 will experience oxygen release and side reactions when interacted with the electrolyte and is strengthened by means of the diffusion interphase of Li2NixCoyTi1–x–yO3 between Li1.17Mn0.50Ni0.16Co0.17O2 and Li2TiO3. Hence, the architecture functions as follows: (1) the Li2TiO3 shell, which is chemically stable, acts as a protective shell and (2) the Li2NixCoyTi1–x–yO3 transition phase zone not only enhances the close adhesion of the core to the Li2TiO3 outer shell but also has higher Li+ ionic conductivity due to doping. LTO@LNCM showed a much higher rate capability and improved cycle performance, besides a higher initial Coulombic efficiency. In particular, LNCM with 3 mol % Li2TiO3 delivered an initial discharge capacity of 306.1 mAh·g–1 at 0.1C (Coulombic efficiency of 89.9%) and a rate capacity of 155.5 mAh·g–1 at 10C. At the same time, a reversible capacity of more than 149 mAh·g–1 after 240 cycles was achieved with only 0.11% decay per cycle at 1C rate (2.0–4.8 V). Thus, based on the collective results, we expect our LTO@LNCM with a motivating Li2NixCoyTi1–x–yO3 transition phase zone to be a promising cathode material for advanced lithium-ion batteries.