Improvement of electrochemical properties of MgO-coated LiNi0.4Co0.2Mn0.4O2 cathode materials for lithium ion batteries

The surface of LiNi0.4Co0.2Mn0.4O2 cathode is coated using MgO coating materials. The electrochemical properties of the coated materials are investigated as a function of the pH value of the coating solution and the composition of coating materials. Their microscopic structural features have been investigated using scanning electron microscopy and X-ray diffraction. The electrochemical properties of the samples were monitored using coin-cell by galvanostatic charge–discharge cycling test, EDS test, EIS test, and cyclic voltammetry. The coating solution with pH = 10.5 is found to be favorable for the formation of stable coating layers, which enhances the electrochemical properties. In contrast, 2 % MgO-coated LiNi0.4Co0.2Mn0.4O2 shows better cycle performance and rate capability than the bare sample. Such enhancements are attributed to the presence of a stable MgO layer which acts as the interfacial stabilizer on the surface of LiNi0.4Co0.2Mn0.4O2.