Layered Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 and Li[Li0.1Mn0.43Ni0.23Co0.23]O-2 cathodes belonging to the Li[Li(1-x)/3Mn(2-x)/3Nix/3Cox/3]O-2 solid solution series between Li[Li1/3Mn2/3]O-2 and LiCo1/3Ni1/3Mn1/3O2 have been synthesized and characterized by charge-discharge measurements in lithium cells before and after modifying their surface with Al2O3. The surface-modified cathodes show significantly lower irreversible capacity loss (ICL) and higher discharge capacity with excellent cyclability compared to the unmodified counterparts. For example, surface modified Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 shows a remarkably high capacity of 285 mAh/g with an ICL of 41 mAh/g and good rate capability. This capacity value is much higher than that achieved with the previously known Li[Li0.17Mn0.58Ni0.25]O-2 after similar surface modification (< 255mAh/g). (c) 2006 The Electrochemical Society.