The electrochemical behavior of layer-structure LiNi1/3Mn1/3Сo1/3O2 solid solution, a positive electrode material of lithium-ion battery, with surface protective layer of amorphous lithium borate is studied. The protective coating is prepared by the eutectic incongruent melting at 750°C of a pre-synthesized compound Li3BO3, mechanically mixed with LiNi1/3Mn1/3Сo1/3O2 powder. The glassy lithium borate 3Li2O∙B2O3 is found to form island-like structures presumably localized in electrochemically active regions of the active-material particles’ surface. The optimal lithium borate content, which makes possible the LiNi1/3Mn1/3Сo1/3O2 stable cycling at 0.5 C rate with the maximum discharge capacity, is found to be equal to 1 wt %.