Preparation And Electrochemical Performance Of High Nickel Ternary Cathode Materials For Lithium/Sodium Ion Batteries

With the more and more serious problem of energy consumption and environmental pollution,new sustainable energy sources played an increasingly important role.A series of energy storage devices such as lithium-ion batteries and sodium-ion batteries have received increasing attention from researchers.The performance of lithium/sodium ion batteries depends mainly on the performance of the cathode material.Therefore,the key to improving the performance of lithium/sodium ion batteries is to improve the performance of the corresponding cathode materials.A series of studies have been made on the preparation and electrochemical performance of high nickel cathode materials for lithium/sodium ion batteries.1. LiNi_0.8Co_0.1Mn_0.1O₂ as a positive electrode material for lithium ion batteries has the advantages of high specific capacity and high energy density,but its cycle stability needs to be further improved.LiNi_0.8Co_0.1Mn_0.1O₂ is prepared by controlled crystallization-coprecipitation method and high temperature calcination method.The material was doped with Mg²⁺to was obtained through electrochemical tests,such as long cycle test,rate test,GITT and full-cell test.The material has low Li⁺/Ni²⁺cation mixing degree,uniform particle size distribution and good layered structure.When Li(Ni_0.8Co_0.1Mn_0.1)_0.97Mg_0.03O₂ is used as the cathode material of LIB,it shows the best electrochemical performance.The high reversible discharge specific capacity provided at 0.1 C is 226.1 m Ah g^-1,and the capacity retention rate of 81%can be reached after 350 cycles at a rate of 0.5 C.During the charging and assembled full cell can provide a specific energy density of 595.3 Wh kg^-1 at a rate of 0.5 C（based on the mass of the positive electrode）.The superiority of its electrochemical performance can be attributed to the proper amount of Mg²⁺doping expanding the intermediate layer and further enhancing the structural stability.2. Sodium ion batteries have become a research hotspot,because sodium resources are cathode materials with dense microsphere morphology were prepared by combining the controlled crystallization-coprecipitation method and high-temperature calcination process.Electrochemical tests such as cycle performance,CV,and GITT indicate that the Na Ni_0.8Co_0.15Al_0.05O₂ microsphere has a reversible capacity of 153.9 m Ah g^-1 at 0.1 C.And it has 93.2%and 86.7%capacity retention after 100 and 200 cycles at 1 C.During the charge capacity of 91.5 m Ah g^-1 even at a larger magnification of 5 C,which are attributed to the similar ionic radius and the same valence of Co³⁺and Al³⁺doping.As well as the special microsphere-shaped morphological structure,which enhances the structural stability of the material and improves the reversibility of the phase transition,it also provides a faster diffusion path for sodium ion/electron transport.The excellent electrochemical performance and large-scale industrial production methods make Na Ni_0.8Co_0.15Al_0.05O₂ microsphere materials promising to be excellent cathode materials for sodium ion batteries.