Al and/or Mg-substituted Li[Ni0.8Co0.1Mn0.1−x−y Al x Mg y ]O2 were prepared by a co-precipitation method and characterized by X-ray diffraction with Rietveld refinement, thermogravimetric analysis, differential scanning calorimetry (DSC), and electrochemical measurements. The Rietveld refinement results show that cation mixing of Al and/or Mg-substituted Li[Ni0.8Co0.1Mn0.1−x−y Al x Mg y ]O2 was reduced with increased doping amounts of Al and Mg. The Al and/or Mg substitution in Li[Ni0.8Co0.1Mn0.1]O2 also resulted in improved electrochemical cycling behavior, structural stability, and thermal stability compared to pristine Li[Ni0.8Co0.1Mn0.1]O2. The improvements of electrochemical and thermal properties resulted from the stabilized host structure by Al and/or Mg incorporation into Li[Ni0.8Co0.1Mn0.1]O2.