Design and Preparation of a Lithium‐rich Layered Oxide Cathode with a Mg‐Concentration‐Gradient Shell for Improved Rate Capability

A spherical core–shell lithium‐rich layered oxide material Li 1.5 Mn 0.75 Ni 0.20 Mg 0.05 O 2+ δ (CSLM) with a Mg‐concentration‐gradient shell is rationally designed and synthesized through a co‐precipitation method. The physicochemical and electrochemical properties of the CSLM cathode material are systematically investigated, and compared with the conventional Li 1.5 Mn 0.75 Ni 0.25 O 2+ δ (CL) cathode material. The electrochemical tests demonstrate that the CSLM cathode material exhibits better cycle stability and rate capability. The Li/CSLM cell delivers an excellent cycling performance with a capacity retention of 96.4 % after 100 cycles at 0.5 C. Moreover, at a high rate of 10 C, the Li/CSLM cell can still exhibit a high discharge capacity of 141.1 mAh g −1 , as compared with 58.9 mAh g −1 for the Li/CL cell. Thus, lithium‐rich layered oxide material Li 1.5 Mn 0.75 Ni 0.20 Mg 0.05 O 2+ δ with a Mg‐concentration‐gradient shell is a promising cathode material for advanced lithium‐ion batteries.