Synthesis And Electrochemical Performances Of Cathode Materials For Lithium-ion Battery

Recently,xLi₂MnO₃·?1-x?LiMO₂?M=Ni,Co,Mn,etc.?lithium-rich solid-solution layered oxides have drawn much attention owning to their high discharge capacity(>200m Ah g^-1),low cost and good thermal stability.However,several drawbacks still exist which limit the application of these lithium-rich layered oxide materials.?1?Large irreversible capacity loss in the first cycle;?2?Voltage fade during the cycles;?3?Poor rate capability.Therefore,it is a challenge work to improve the electrochemical performances of layered rich-lithium cathode material.There are two parts of our research:?1?Synthesis and properties of xLi₂MnO₃-?1-x?Li[Ni_0.8Co_0.15Al_0.05]O₂?0.5?x?0.8?solid solution as cathode materials for li-ion secondary batteries;?2?The modify research of the0.7Li₂MnO₃-0.3Li[Ni_0.8Co_0.15Al_0.05]O₂.1.A series of layered lithium-rich oxides xLi₂MnO₃-?1-x?Li[Ni_0.8Co_0.15Al_0.05]O₂?0.5?x?0.8?have been prepared by spray drying method.The samples are divided into two parts with quench samples and without quench samples according to the different method of the cooling crystalline.The result shows that the micro-structure transfer with the increasing of the Li₂MnO₃ content in the composition.The discharge capacity of these materials shown changes which increase and then decrease gradually the increasing of the Li₂MnO₃ content.And when the x=0.6,the material exhibts the best electrochemistry properties.2.As discussion in the last part,the discharge capacity of the sample0.7Li₂MnO₃-0.3Li[Ni_0.8Co_0.15Al_0.05]O₂ increase as the test of the battery.The citric acid was tried to modify the properties of these sample.It has been found that these material modified via citric acid treatment shown significantly improved electrochemistry properties,which exhibited a reversible capacity of 244.2m Ahg^-1 compared to the bare sample.