Research on Nb doping–coating composite modification of LiNiO2 cathode material for lithium-ion batteries

LiNiO2 (LNO) was synthesized by co-precipitation method and then modified by Nb2O5. Doped material N0 (doping molar ratio is 1%), doped and coated composite modified materials N1 and N2 (doping molar ratio is 1%, coating molar ratio is 0.5% and 1%, respectively) were obtained. XRD results show that Nb modified materials have good layered structure and low Li–Ni mixing. SEM image shows that the surface of the modified materials is more compact and smoother. EDS and TEM diagrams indicate that N1 and N2 samples can be successfully doped and coated with Nb compound. The electrochemical performance test results show that the Nb doping–coating composite modified materials have a significant impact on the cycle performance of LiNiO2, among which N1 has the best cycle performance. In the voltage range of 2.75–4.3 V, the initial discharge specific capacity of N1 at 0.1 C is 221.20 mAh/g, which is about 20 mAh/g higher than that of LiNiO2 material. And the capacity retention rate of N1 is 80.70% after 100 cycles at 1 C, which is also much higher than that of LiNiO2 (67.46%).