Rock Salt-Type LiTiO2@LiNi0.5Co0.2Mn0.3O2 as Cathode Materials with High Capacity Retention Rate and Stable Structure

Herein, a strategy is presented for improving the electrochemical performance of a LiNixCoyMn1–x–yO2 layered oxide involving the coating of rock salt-type LiTiO2 on the surface via a hydrothermal method followed by a calcination process. A thickness of approximately 10 nm of LiTiO2 coated on the surface of LiNi0.5Co0.2Mn0.3O2 (NCM523) has been achieved, and the optimal molar ratio (LiTiO2/NCM523) is found to be 1.0 mol %. The LiTiO2@LiNi0.5Co0.2Mn0.3O2 when used as a cathode material exhibits not only a higher capacity retention but also a more enhanced rate performance in comparison with that of pristine NCM523. The LiTiO2 layer protects the NCM523 active particles from being eroded by the electrolyte and reduces the volume change of the electrode active particles before and after lithium-ion intercalation/deintercalation during cycling. These new findings contribute toward the design of a stable structured nickel-based cathode material for lithium-ion batteries.