Study On Preparation And Properties Of LiNi_0.5Co_0.2Mn_0.3O₂ Used As Cathode Materials For Li-ion Batteries

As the kind of new energy,Li-ion batteries has generated great public attention owing to their advantages of high working voltage,large specific capacity,long life and no memory effect,which is widely used in mobile phones,cameras and laptop computers and other electronic products.In addition,the lithium-ion batteries are also used as alternative energy storage device directly applied to electric vehicles(EV)and hybrid electric vehicles(HEV),which is expected to become one of the main power sources in the 21st century.As a composite ternary materials,Lithium-ion battery cathode material LiNixCoyMn1-x-yO2 combines the respective advantages of LiCoO2,LiNiO2 and LiMn2O4 cathode material,which has high specific capacity,long cycle life,good stability,etc.So research on the preparation and properties of the material is of great significance.Lithium-ion battery ternary cathode material LiNi0.5Co0.2Mn0.3O2 is prepared by high temperature solid phase method and liquid co-precipitation method.We choose co-precipitation as the basic research method through the analysis of structure,morphology and electrochemical property.During the preparation of spherical precursor Ni0.5Co0.2Mn0.3(OH)2,we select NaOH as precipitant,NH3·H2O as complexing agent and the appropriate metal concentration,PH value,stirring speed,reaction time to synthesis spherical precursor under the protection of nitrogen atmosphere Diameter D50 of LiNi0.5Co0.2Mn0.3O2 material made by liquid co-precipitation is 10.07 μm and compaction density is 3.09 g/cm3,within the scope of the voltage from 2.7 V to 4.3 V and 0.1 C ratio for charging and discharging test,the first discharge capacity of materials is 164.3 mAh/g.Spherical precursor Ni0.5Co0.2Mn0.3(OH)2 prepared by liquid-phase coprecipitation and Li2CO3 in different proportions are mixed thoroughly and then calcined in high temperature.The most optimal conditions are determined by the influence of lithium proportions,calcination temperature,calcination time on structure,morphology and electrochemical properties of material.The results show that LiNi0.5Co0.2Mn0.3O2 material synthesized by 1.10:1 of lithium ratio,900℃ of calcination temperature,10 h of calcination time displays the regular morphology and layered structure obviously.By the electrochemical performance testing,The first discharge capacity of material is 166.9 mAh/g and the charge-discharge efficiency is 85.85%.After 30 charge-discharge circles,the discharge capacity of material is 160.2 mAh/g and the capacity retention rate is 95.98%.LiNi0.5Co0.2Mn0.3O2 material demonstrates good electrochemical properties.