The structural mechanism of the improved electrochemical performances resulted from sintering atmosphere for LiNi0.5Co0.2Mn0.3O2 cathode material

The influence of preparing atmosphere on structure and the resultant electrochemical performances of LiNi0.5Co0.2Mn0.3O2 cathode material has been investigated in detail. The electrochemical performance measurements show that LiNi0.5Co0.2Mn0.3O2 cathode material can present significantly improved discharge capacities, good rate capability and excellent cycling stability simply by adjusting oxygen content in preparing atmosphere about 40 vol.%. Based on the results of rietveld refinements of the XRD data analyzed using Maud 2.14 software, the improved electrochemical performances could be ascribed to the well ordered layered structure and much lower degree of cation mixing in its structure. When the oxygen content increase to 40 vol.%, only 0.006 mol per formula unit of Ni are incorporated into the lithium layers (0.083 mol per formula unit for 10 vol.% oxygen content). Moreover, the highest ratio of I(0 0 3)/I(1 0 4) (1.6025) in XRD pattern also approves the reduced cation mixing and well ordered layered structure of the composition. The revealed conclusions will help effectively create design strategies for large-scale synthesizing the cathode material for advanced lithium ion batteries.

► Oxygen-rich sintering can facilitate the formation of ordered layered structure of LiNi0.5Co0.2Mn0.3O2 material.
► Oxygen-rich sintering can effectively suppress cation mixing of layered LiNi0.5Co0.2Mn0.3O2 material.
► Ni ion in lithium layer for LiNi0.5Co0.2Mn0.3O2 is significantly depressed by oxygen-rich sintering.
► Electrochemical properties of LiNi0.5Co0.2Mn0.3O2 are significantly improved by oxygen-rich sintering.