Co-Al co-doped cathode material LiNi0.8Co0.2-xAlxO2 (0≤x≤0.15) was directly synthesized without artificial grinding and washing by a eutectic molten-salt mixture (0.38LiOH-0.62LiNO3) method. According to this method, the eutectic molten-salt mixture was self-mixed with high tap density precursor Ni0.8Co0.2-xAlx(OH)2 thoroughly at low temperature and then sintered at a certain temperature. The tap-density of LiNi0.8Co0.15Al0.05O2 obtained is 2.97 g·cm-3. According to XRD and SEM, these LiNi0.8Co0.2-x AlxO2 materials have an order α-NaFeO2 layer structure and regular morphology. The charge-discharge tests show that the LiNi0.8Co0.15Al0.05O2 has an initial discharge capacity as high as 167.5 mAh·g-1 and excellent capacity retention in the range from 3.0 V to 4.3 V at a specific current of 0.2 C.