Preparation And Electrochemical Properities Of Modified LiNiO₂

Modified LiNiO2 which has the same layered structure with LiCoO2 is regarded as the promising cathode material for lithium-ion battery.In this work, LiNiO2 is prepared by co-precipitation followed by heat-treating at two stages, and the excellent preparing conditions are confirmed at the same time. Co-doped LiNiO2 materials are synthesized and the excellent doped quantity, viz., LiNi0.8Co0.2O2 is gained. Meanwhile, the Zn (Al)-doped and MgO (Al2O3)-coated LiNi0.8Co0.2O2 materials are carried out and the relatively good products are found. According to the characteristics of doped and coated materials, Al2O3-coated materials together with Zn-doped are prepared. In the end, All the products are carried out on the electrochemical test, structure characterization and morphology observation.The results of electrochemical tests show that the first specific discharge capacity of LiNiO2 is 197.3mAh·g-1 (0.2C, 3.0-4.2V, vs. Li+/Li), and the capacity retention ratio is 67.3% in the 100 cycle. The first specific discharge capacity of LiNi0.8Co0.2O2 is 190.2mAh·g-1 (0.2C, 3.0-4.2V, vs. Li+/Li), and the capacity retention ratio is 80.4%, higher than LiNiO2. Although LiNi0.8Co0.2O2 shows a lower first specific discharge capacity than LiNiO2, it has a better cycling performance after 100 cycles.Along with the doped quantity of Zn increasing, the first specific discharge capacities and cycling performance of LiNi0.8-xZnxCo0.2O2 reduce after first enhance. In the Al-doped system, along with the quantity of Al, the first specific discharge capacities of LiNi0.8-xAlxCo0.2O2 reduce gradually, but cycling performance enhances. In the two doped systems, LiNi0.78Zn0.02Co0.2O2 shows better electrochemical properities.In the two coated systems, the first specific discharge capacities of MgO(Al2O3)-coated LiNi0.8Co0.2O2 reduce gradually, but cycling performance reduces after first enhances. 0.5% Al2O3-coated LiNi0.8Co0.2O2 has the relative good electrochemical performance, and the cycling performance is better than that of LiNi0.78Zn0.02Co0.2O2.According to the traits of doped and coated experiments, 0.5% Al2O3-coated...