Investigation On The Electrochemical Performances Of Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ Lithium-rich Cathode Material With Suface Modification

Li-rich Li1.2Ni0.13Co0.13Mn0.54O2 cathode material is considered as a promosing cathode materials for next generation li-ion batteries due to its extraordinarily high discahrge capacity. Unfortunately, li-rich layered materials demonstrate poor rate capability and a large irreversible capacity loss in the initial cycle, which limits their commercial application. In this work, Li1.2Ni0.13Co0.13Mn0.54O2 with surface modification with ZnO, LaF3 or carbon has been synthesized and the mechanisms of enhanced performances are systematically investigated with electrochemical measurements, CV, cell test instrument and AC tests.In the case of Li1.2Ni0.13Co0.13Mn0.54O2 coated with ZnO, Li1.2Ni0.13Co0.13Mn0.54O2 coated with ZnO composites are prepared by a wet-chemical method. In comparison with the pristine Li12Ni0.13Co0.13Mn0.54O2, ZnO-coating sample exhibits better rate performances and cycle capability, especially at the elevated temperature. In addition, it is interesting that the electrochemical performances of Li1.2Ni0.13Co0.13Mn0.54O2/ZnO composites are found to be related with the electrical conductivity of ZnO layer, whose defects could be controlled by annealing in different atmosphere. The electrical conductivity higher, the electrochemical performances better.LaF3-coated Li1.2Ni0.13Co0.13Mn0.54O2 cathode material is prepared by a chemical deposition technique. The LaF3 particles are uniformly deposited on the Li1.2Ni0.13Co0.13Mn0.54O2 surface. It is interesting that LaF3-coating layer can reduce the charge transfer resistance and enhance the Li-ion diffusion in solid. In comparison with the pristine Li1.2Ni0.13Co0.13Mn0.54O2, LaF3-coating sample exhibits better rate performances and cycle capability.C-coated Li1.2Mn0.54Ni0.13Co0.13O2 cathode material is successfully prepared by a sol-gel method with PVDF as carbon source. C-coating sample exhibits better cyclic reversibility. In addition, carbon layer would enhance the electronic conductivity between active material particles, protecting effectively active materials from HF attack and consequently improving the electrochemical performance.