Various Ni-rich layered oxide cathodes (above 0.80 Ni content), such as LiNi1−y−zCoyAlzO2 (NCA), are used in electric vehicles (EVs) due to their high capacity (∼200 mAh g−1 for NCA). However, to improve cycle performance and thermal stability and to ensure longer and safer usage, numerous studies have investigated surface modification, coating, and doping of cathode materials. In this study, we have investigated the characteristics of LiNi0.85CoxMn0.15−xO2 with various Mn to Co ratios (x = 0–0.15) synthesized by a coprecipitation method. The discharge capacities of the LiNi0.85CoxMn0.15−xO2 cathodes are similar at around 206 mAh g−1 at room temperature and 213.8 mAh g−1 at 55 °C between 2.7 and 4.3 V at a 0.2C rate, while the cyclability, thermal stability, and rate capability of all samples differ according to the Mn and Co ratio. The LiNi0.85Co0.05Mn0.10O2 cathode shows the most promising electrochemical properties under different conditions among the various cathodes evaluated; it displays a high rate capacity (approximately 163 mAh g−1 at 5C rate) at 25 °C and good thermal stability (main exothermic temperature of 233.7 °C and relatively low heat evolution of 857.3 J g−1). •Ni-rich layered cathodes, LiNi0.85CoxMn0.15−xO2 were made by a coprecipitation.•The electrochemical and thermal properties with varying Mn and Co were evaluated.•The stable Ni-rich cathode composition with high-capacity could be accomplished.