Effect of surface modifications on the layered solid solution cathodes (1-z) Li[Li1/3Mn2/3]O2-(z) Li[Mn0.5-yNi0.5-yCo2y]O2

Layered (1-z) Li[Li1/3Mn2/3](2)-(z) Li[Mn0.5-yNi0.5-yCo2y]O-2 (y = 1/12. 1/6, 1/3 and 0.25 <= z <= 0.75) solid solutions have been surface modified with 3 wt.% Al2O3, CeO2, ZrO2, SiO2, ZnO, and AlPO4 and 0.05 atom F- per formula unit and characterized by X-ray diffraction and charge-discharge measurements in lithium cells. The surface modified cathodes show lower irreversible capacity (IRC) loss in the first cycle and higher discharge capacity than the unmodified samples. An analysis of the first charge and discharge capacity values suggests that part of the oxide ion vacancies resulting from the irreversible loss of oxygen during the first charge is retained in the lattice. Surface modification leads to the retention of even more number of oxide ion vacancies in the lattice after the first charge. Surface modification with Al2O3 and AIPO(4) are particularly found to be effective in retaining more number of oxide ion vacancies and suppressing the IRC values. (C) 2008 Elsevier B.V. All rights reserved.