A high-voltage (5V) LiCo0.8Fe0.2MnO4 electrode with spinel-type structure has been prepared. 57 Fe Mössbauer spectra reveal high-spin Fe3+ ions in octahedral coordination in the pristine sample, which are oxidized to tetravalent iron ions. Surface treatments with zinc and magnesium have been applied. Zinc and magnesium were homogenously distributed, according to EPMA and mapping analysis, while the spinel structure is maintained. The magnesium and the zinc treatments drive to better electrochemical performance and capacity retention.