| Lithium ion batteries have many advantages such as high working voltage,good cycle performance,and environmental friendliness,and are widely used in various battery energy storage devices.The cathode material has an important influence on its working voltage,energy density and power density,and is the focus of battery research and development.The high-nickel ternary cathode material with ?-NaFeO2 layered crystal structure has become a research hotspot in recent years due to its advantages such as high energy density and good cycle performance.However,the shortcomings of serious lithium nickel ion mixing and poor material cycle stability have hindered its further development and application.In this paper,a ternary cathode material for high-nickel lithium-ion batteries is synthesized by hydrothermal method,focusing on the influence of different organic substances on the morphology of the ternary precursor and the process parameters when the cathode material is synthesized.Meanwhile,the new NCMNCA type cathode material was prepared by blending NCM and NCA two high nickel ternary materials.SEM,XRD,TG,constant current charge and discharge,cyclic voltammetry and other methods are used to characterize and test the materials produced to explore the properties of high nickel ternary cathode materials prepared by hydrothermal methods.First of all,the Ni0.8Co0.1Mn0.1?OH?2 precursor was synthesized by hydrothermal method.Explore the effects of different hydrothermal conditions?temperature,time?and the addition of various surfactants on the morphology of the precursor.It is concluded that the precursor material with uniform morphology and the highest crystallinity can be obtained when the temperature is 170 ? and the reaction time is 12 h.The cationic surfactant CTAB can improve the crystallinity of the crystal,but has little effect on the grain size.The anionic surfactant ascorbic acid will have a great influence on the crystallinity of the precursor,and in terms of morphology,the precursor can generate a special morphology with a large specific surface area.The addition of the non-ionic surfactant dimethyl succinate has a positive effect on improving the crystallinity of the precursor and reducing the grain size.The addition of polymer surfactant polyethylene glycol can effectively improve the crystallinity of the crystal,greatly improve the microscopic morphology of the precursor,and can produce a uniform and clean spherical morphology,add the amount of 10% to make the best precursor material.Secondly,Li Ni0.8Co0.1Mn0.1O2 was prepared by mixing and calcining Ni0.8Co0.1Mn0.1?OH?2 precursor with the best performance and Li OH·H2O.By means of phase analysis and electrochemical analysis,the influence of sintering temperature and time on the morphology,structure and electrochemical properties of ternary materials was explored.The result shows,The optimal process conditions for precursor mixed lithium sintering are divided into two steps,the first step is calcined at 500 ? for 6h,the second step is calcined at 800 ? for 8h.The Li Ni0.8Co0.1Mn0.1O2 prepared under this condition has the best morphology and the highest crystallinity.It can have a specific capacity of 198.5 m Ah·g-1,and the capacity retention rate is still 96.7% after 100 charge and discharge cycles.Finally,the NCA type high nickel ternary cathode material was prepared by hydrothermal method,and blended with the NCM type material to obtain a new type NCM-NCA type high nickel ternary material.Determine the properties of the material by phase analysis and electrochemical analysis.In the final experiment,a NCA type ternary material with a specific capacity of 160 m Ah·g-1 at 0.2C and a capacity retention rate of 84.96% after 100 charge and discharge cycles was successfully prepared.The specific capacity of NCM-NCA ternary material obtained by blending with NCM ternary material at 0.2C can reach 209.6 m Ah·g-1,and the capacity retention rate after 100 charge and discharge cycles is 90.0%. |
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