Preparation And Modification Of LiNi_1/3Co_1/3Mn_1/3O₂ Materials For Li Ion Batteries

The layered structure LiNi_1/3Co_1/3Mn_1/3O₂ cathode material has a lot of advantages,such as high working voltage,high discharge capacity,good thermal stability,low cost and so on.So it has very broad application prospects.However,LiNi_1/3Co_1/3Mn_1/3O₂ cathode material occurs attenuation easily which is caused by the corrosion of electrolyte.In order to solve the above problems,this paper mainly researches the optimization of preparation and surface modification of LiNi_1/3Co_1/3Mn_1/3O₂ cathode material.LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials were synthesized by solid-state method.And exploreing the influence of the performance which was caused by the temperature and time of the preparation process.A lot of tests were used to detect the samples,and the results showed that the sample which was synthesized at 900 oC for 12 hours had the best electrochemical properties.At the current density of 1.0 C,the initial discharge capacity was 137.1 mAh/g.Besides,the specific discharge capacity was 112.6 m Ah/g after 20 cycles charge-discharge test,and its capacity retention rate was 82.13%.The MnO₂/LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials were synthesized by precipitation reaction.X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and cyclic vohammetry?CV?measurement were used to investigate the structure and electrochemical performance of the samples.The test results tended to reinforce that all of the samples had ?-NaFeO2 layered structure.Besides,MnO₂ coated layer could inhibit the side effects between Li Ni1/3Co1/3Mn1/3O2 and electrolyte and its cycling stability was improved.The materials could deliver a capacity retention ratio up to 90.16% after 100 cycles at the current density of 200 mA/g with the amount of coating was 3 wt%.The La₂O₃/LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials were successfully prepared by homogeneous precipitation method.We could find that this surface modification did not change the crystal structure while their electrochemical performance was improved after studying the structure and electrochemical performance of this new cathode material.The initial discharge capacity of the sample could reach up to 181.3 mAh/g with 200 mA/gcurrent density.In addition,after 100 cycles the discharge capacity also maintained about174.3 mAh/g and the capacity retention ratio could attain 96.13%.