Synthesis Of Rich Nickel Ternary Cathode Material By A Novel Hydrothermal Process

With the developmentof hybrid electric vehicle?HEV?and electric vehicles?EV?and the demand of devices to store solar,wind and other natural energy,high capacity ion batteries become a hot topic.The commercial cathode material,LiCoO₂,was not competitive because of its high cost and poor cycling stability,so the research of new lithium-ion batterycathode materials has become the hotspot.Ni_0.6Co_0.2Mn_0.2O₂ and LiNi_0.8Co_0.1Mn_0.1O₂ has become one of the ideal hybrid battery cathode materials due to its high theoretical capacity?280m Ah/g?,but the disorder of positive ion made high nickel ternary shuffle capacity and cycle stability terrible.Therefore,it is very common to increase thecapacity of LiNi_0.6Co_0.2Mn_0.2O₂and LiNi_0.8Co_0.1Mn_0.1O₂ and the cycling performance.As used herein,the hydrothermal synthesis of Ni_0.6Co_0.2Mn_0.2CO₃ and Ni_0.8Co_0.1Mn_0.1CO₃ precursors were mixed with lithium and then calcined in two stages,wegotLiNi_0.6Co_0.2Mn_0.2O₂andLiNi_0.8Co_0.1Mn_0.1O₂cathodematerial.According to the examining of the material,we studied charge-discharge performance of LiNi_0.8Co_0.1Mn_0.1O₂ and LiNi_0.6Co_0.2Mn_0.2O₂ and eventually selected the optimum sintering temperature and hydrothermal reaction temperature.Nickel acetate,cobalt acetate,manganese acetate were used as raw materials;urea were used as precipitating agent.Ni_0.6Co_0.2Mn_0.2CO₃ was prepared by hydrothermal method.Li₂CO₃ as lithium source of lithium was mixed with Ni_0.6Co_0.2Mn_0.2CO₃ precursor,we obtained LiNi_0.6Co_0.2Mn_0.2O₂ materials within the tube furnace oxygen atmosphere divided two-stage high-temperature calcination.Sintering at 550^oC for four hours and 850^oCfor 12 hours,the material could still remain the morphology of the precursor.It has a particle size of about long 5um,crystal,from sheet-like stacked.This material showed good electrochemical performance:the first discharge capacity of the sample was 181.1mAh/g with a initial coulombic efficiency of 89.5%at 0.2C rate in a lithium half-cell.And the capacity retention rate was 100 after 85.6%cycles.Nickel acetate,cobalt acetate,manganese acetate were mixed with a molar ratio of Ni:Co:Mn?8:1:1?,urea were used as precipitating agent.Ni_0.8Co_0.1Mn_0.1CO₃precursor was prepared by hydrothermal method,we used Li₂CO₃ as lithium source of lithium,and got LiNi_0.8Co_0.1Mn_0.1O₂ composite cathode materials within the tube furnace oxygen atmosphere by two-stage hightemperature calcination.Result showed that the calcination process was divided into two stages:it could maintain the morphology of precursor pupal by calcining at 550^oC for four hours and 850^oC for calcination 12 hours.But there are certain contraction change,the first discharge capacity was 191.1mAh/g at 0.2C rate,the first coulombic efficiency reached90%.After 50 cycles,the capacity retention rate was 92.8%.The material's first cycling discharge capacity is higher than LiNi_0.6Co_0.2Mn_0.2O₂cathode material,but the performance of the long cycle cycle is poor than LiNi_0.6Co_0.2Mn_0.2O₂ material.