Effect of niobium doping on the electrochemical performance of nickel-based cathode materials

To find out the way to maintain the electrochemical cycle stability and the high-temperature performance of nickel-based cathode materials LiNi_0.8Co_0.1Mn_0.1O₂ is the key to its wide application to industry. This paper focuses on the improvement of the electrochemical properties of nickel-based cathode materials by doping niobium. The cathode materials of Li(Ni_0.8Co_0.1Mn_0.1)_1-xNb_xO₂（x = 0, 0.01, 0.02, 0.03) were synthesized by calcining the mixtures of LiOH·H₂O, Nb₂O₅ and the ternary material sphericalNi_0.8Co_0.1Mn_0.1(OH) ₂ precursor which was made from sulphate by co-precipitation method in N₂ atmosphere. The XRD results showed that small amount of the Nb⁵⁺ ions could dope into the cathode materials’ lattice and formed Li3NbO4with stable chemical properties on the surface of the cathode materials. When x was 0.02, the special capacity of the first discharge was 172.9 mAh/g and the capacity retention rate was 97.47% after 100 cycles at 25℃, within the voltage range of 2.75~4.2 V and with the ratio of 0.2 C. At 50℃and with the ratio of 0.5 C, the capacity retention rate changed little after 100 cycles and the average discharge specific capacity was 183.7 mAh/g. Moreover, the sample had good rate performance.