Study On Preparation And Modification Of High Nickel Ternary Cathode Materials

In recent years,new energy vehicles have entered the rapid development track.The core components of the filed ion battery anode materials have become the biggest contributors to solving"mileage anxiety".Among them,the large-capacity nickel-rich anode material Li Ni_0.8Co_0.1Mn_0.1O₂（referred to as NCM811,The same below）is very popular.However,the problem of cyclic capacity attenuation and safety of NCM has been the main reason to limit its promotion.In this paper,the problem of cycle capacity attenuation of NCM811 is studied from material preparation and coating doping modification.（1）NCM811 with regular morphology and uniform particle size distribution was synthesized by sol-gel method,and the influence of sol-gel process on the structure,morphology and electrochemical performance of NCM811 was discussed.The results show that the structure and performance of NCM811 cathode materials increase first and then decrease with the increase of the reaction temperature and the concentration of the complexing agent,and decrease with the increase of the calcination temperature.（2）The second part of the work is to modify the coating on the basis of NCM811finished product.The surface coating of NCM811 was performed by wet chemical hydrolysis,and the surface modified NCM811 electrode material was obtained by heat treatment of zinc phosphate and sodium phosphate.The effect of surface modification treatment on the electrochemical performance of the material was discussed in detail.Combined with the XPS and EDS test results,the surface modification treatment of zinc phosphate not only builds a protective layer at the interface between the sample and the electrolyte.During high-temperature sintering,Zn²⁺ions penetrate into the electrode material and play a similar doped stable structure.effect.At the same time,PVP and citric acid-assisted coating method were used for surface modification treatment,and the internal mechanism and action mechanism of the coating method were further studied.（3）The third part of the work is to modify the coating and doping of the lithium ion conductor based on the NCM811 finished product.The NCM811 electrode material with lithium phosphate and lithium titanium phosphate surface modification was obtained by coating with lithium phosphate and lithium titanium phosphate,and the influence of surface modification treatment on the electrochemical performance of the material was discussed in detail.The effects of doping ions with different radii on the finished NCM811were also studied.The experimental results show that the coating and ion doping of lithium ion conductors improve the electrochemical performance of materials.