Although LiNi0.8Co0.1Mn0.1O2 cathode material has a larger specific capacity than LiCoO2, their thermal instability has hindered their use in Li-ion cells. An AlPO4 coating on the LiNi0.8Co0.1Mn0.1O2 cathode, however, noticeably diminished the violent exothermic reaction of the cathode material with the electrolyte, without sacrificing the specific capacity of the bare LiNi0.8Co0.1Mn0.1O2 (188 mAh/g at 4.3 V charge cut off). The results were consistent with the thermal abuse tests using Li-ion cells; the AlPO4-coated LiNi0.8Co0.1Mn0.1O2 cathode did not exhibit thermal runaway with smoke and explosion, in contrast to the cell containing the bare cathode. In addition, the AlPO4-coated LiNi0.8Co0.1Mn0.1O2 cathode exhibited a superior cycle-life performance compared to the bare LiNi0.8Co0.1Mn0.1O2. (C) 2004 The Electrochemical Society.