The kinetic stabilization of the cathode/electrolyte interface is essential to enhance cycle life and safety of lithium-ion batteries at high voltage application. The addition of only 2 wt.% Mg powder to the cathode slurry were found to significantly increase the cycle life of LiNi1/3Co1/3Mn1/3O2/Li half cells upon cycling to 4.6 V vs. Li/Li+, in terms of higher capacity retention, less parasitic reactions and less self-discharge. The presence of dissolved Mg2+ cations in the electrolyte during formation of the cell lead to an increased hydrolysis of the conducting salt LiPF6 and the formation of stable and effective LiPFxOy/Mg(PFxOy)2 species on the charged cathode surface.