Study On Sintering Technology And Modification Of Lithium-ion Battery LiNi_0.5Co_0.2Mn_0.3O₂ Cathode Material

Layer rich nickel LiNi0.5Co0.2Mn0.3O2 cathode material has the advantage of low cost、higher capacity,good fast discharge performance,which has a promising prospect.But because of the high nickel contents,the cation mixing of Ni2+ and Li+ was incresing,which result to poor cycling performance.Therefore,firstly,in this paper choose optimized the sintering process of LiNi0.5Co0.2Mn0.3O2 cathode material,reduced the mixing of ions,in addition,in addition,adopted the coating way of step by step to co-coating modified process cathode material by use of C and CeO2 at different temperture,combining their advantages,improved the performance of LiNi0.5Co0.2Mn0.3O2 cathode material,combined with XRD、SEM、EDS、TEM、TGA、CV、EIS and particle size distribution analysis,the results were drawn as follows:The best sintering process conditions of precursor LiNi0.5Co0.2Mn0.3(OH)2:Li/(Ni+Mn+Co)was 1.08:1,sintering temperatura was 850℃,sintering time was 16h.Under these conditions,the cathode material showed uniform size distribution,particle size about 9.7um,has relatively good electrochemical performance,the first discharge capacity of the material was 175mAh/g in 3.0-4.3V voltage at 0.2C,after 50 times charging and discharging cycling,the capacity retention was 84.5%.The CeO2 was coated on the surface of LiNi0.5Co0.2Mn0.3O2 cathode material by sol-gel method.the structure of LiNi0.5Co0.2Mn0.3O2 was untouched by the coating of CeO2,the CeO2 was uniformly distributed on the surface of the cathode material in the form of nanoparticles,when the coating content was 1wt%,the cathode material has the best insertion and deintercalation of Li+ and electrochemical performance.After 50 times charging and discharging cycling,the capacity retention was 81.3%and 77%at 1C and 2C,much higher than 73.1%and 64.9%of no coating sample.CeO2 layer played an important role in slow interaction between electrolyte and active material.the CeO2 layer could reduced the charge transfer resistance,enhanced the stability of the electrode surface and ionic conductivity of the material,helping the insertion and deintercalation of Li+,improved the electrochemical performance.After coating lwt%CeO2,then used C coating treat can get co-coating LiNi0.5Co0.2Mn0.3O2 cathode material.the amount of 0.5wt%carbon coating content has the best electrochemical performance,the rate capability was improved obviously,when cycle five times at different rate,the discharge specific capacity of co-coating sample could up to 105 mAh/g at fifth times in 3.0-4.3V voltage at 10C,however the single and no coating sample only remained 90mAh/g and 67mAh/g,and the sample of co-coating added lOmAh/g and 11 mAh/g in terms of the first-discharge specific capacity than single coated sample at 5C and 10C.CV and EIS showed that the synergistic effect of C and CeO2 were beneficial to the lithium ion diffusion,improved the electronic conductivity,reduced the degree of polarization and charge transfer impedance greatly,the cycle performance and rate capability both improved greatly.