Effects Of Ultrasonic-Assisted Synthesis And Copper Doping On The Properties Of LiNi_1/3Mn_1/3Co_1/3O₂

Layered LiNi1/3Mn1/3Co1/3O2 with many advantages,which is considered to be the most promising one of lithium-ion battery cathode material.But its cycle performance and rate capability also needs further improved.This paper first summarizes the development background and the working principle of lithium-ion battery especially LiNi1/3Mn1/3Co1/3O2 and the research progress of modification.The synthetic conditions were optimized by improving synthesis method as the research objective.We systematically studied the structure,morphology and electrochemical performance of LiNi1/3Mn1/3Co1/3O2.The cycle performance and rate capability was improved through the doping modification.LiNi1/3Mn1/3Co1/3O2 with the spherical of pore type,which was synthesized successfully by ultrasonic-assisted coprecipitation-solid calcination method.The performance was characterized by XRD,SEM,EDX,electrochemical testing and AC impedance test.The results show that:LiNi1/3Mn1/3Co1/3O2 synthesised by ultrasonic-assisted coprecipitation-solid calcination method is α-NaFeO2 layered structure,which is 0.8～1μm spherical secondary particles agglomerated by nano primary particle.At 0.2,1,2,4C rates,the specific discharge capacity is 164.7,146.7,131.4,105.0 mAh g-1 and capacity retention is 94.8%,94.3%,90.0%,96.4%.Good performance is attributed to that the effect of the ultrasonic making the material has the special pore spherical morphology in favour of extraction-insertion of Li+.Cu-doped LiNi1/3Mn1/3Co1/3O2 synthesised by coprecipitation method was investigated by XRD,SEM,EDX,electrochemical testing and AC impedance test.The results shows that the doping suitable amount of Cu(2wt%)does not change the basic structure and morphology of raw materials.the electrochemical results show that the initial capacity is 162.6,135.5,106.4,85.0 mAh g-1 and capacity remain is 94.28%,92.69%,101.60%,104%after 50 times in 0.2,1,2,4C rates.Improving rate capability and cycle performance of LiNi1/3Mn1/3Co1/3O2 by dopping Cu,which is attributed to that Cu reduces polarization and charge transfer impedance and improves Li+ diffusion rate of LiNi1/3Mn1/3Co1/3O2 in the cyclic process.