Synthesis Technique Of Ni_（1-x-y）Co_xMn_y（OH）₂ By Coprecipitation

The development of energy storage technology promotes the increasing demand for lithium batteries.At the same time,the power market has higher and higher requirements for the performance of lithium batteries.The current performance of lithium batteries is still unable to achieve the expected effect.In order to synthesize the ternary precursor Ni_（1-x-y）Co_xMn_y（OH）₂ for lithium batteries,the effects of synthesis process factors on the physical properties of Ni_（1-x-y）Co_xMn_y（OH）₂ products,the capacity and cycle life of lithium batteries were systematically studied,which provided a strong theoretical basis and data support for industrial production.Ni_（1-x-y）Co_xMn_y（OH）₂ was prepared by coprecipitation method with battery grade nickel sulfate,cobalt sulfate,manganese sulfate,ammonia alkali and ammonia water as raw materials.The effects of ammonia concentration,pH value,synthesis temperature,solid content,stirring speed,impurities and aging time on the morphology,tap density（TD）and particle size（D50）of Ni_（1-x-y）Co_xMn_y（OH）₂ particles were analyzed by control variable method.The results show that:When the reaction temperature is controlled between 50℃and 70℃,the spherical shape of Ni_（1-x-y）Co_xMn_y（OH）₂ synthesized at 50℃is more compact,the sphericity of particles is more regular,and a small number of particles present irregular flat shape.When the reaction temperature gradually rises to 60℃,the sphericity of Ni_（1-x-y）Co_xMn_y（OH）₂ begins to deteriorate,the surface morphology of particles becomes rough,and the surface of particles begins to appear fine powder,spherical The range of particle size（D90-D10）increased to 7μm;When the concentration of ammonia is 0.3 mol/L and 0.6 mol/L respectively,the complexation effect of 0.6 mol/L ammonia is better than that of 0.3 mol/L ammonia.When the nickel cobalt manganese ion reacts with the precipitant Na OH,0.6 mol/L ammonia can promote the simultaneous precipitation of ions.The particle size（D50）of Ni_（1-x-y）Co_xMn_y（OH）₂ synthesized by the two ammonia concentrations has little difference,with an average of 10.5μm.When the concentration of ammonia is 0.3 mol/L,the morphology of Ni_（1-x-y）Co_xMn_y（OH）₂ is loose,the compactness is poor,and there are more fine powders on the surface;The particle size of Ni_（1-x-y）Co_xMn_y（OH）₂ was 10.8μm when the rotating speed of agitator was controlled between 80～250 r/min and 100 r/min.The particle size of Ni_（1-x-y）Co_xMn_y（OH）₂ decreased to 10.5μm when was 200 r/min.Finally,the particle size of Ni_（1-x-y）Co_xMn_y（OH）₂ reached 10.3μm when was 250 r/min.At low speed,the secondary grains continue to grow and the grains become larger.When the pH is 11～12.5,the spherical surface of Ni_（1-x-y）Co_xMn_y（OH）₂ synthesized at pH value of 11.2 is rough and the spherical homogeneity is poor.With the increase of pH to 12.2,the primary particles become finer and the spherical surface is smooth,but the spherical homogeneity deteriorates,and the diameter distance（D90-D10）/D50increases from 1.2 to 1.4.The higher the pH is,the easier it is for Ni Co Mn ions to precipitate completely,so there is little effect on the spherical size difference.The high alkalinity of lithium battery will lead to the conversion of Li⁺to Li OH,so pure water is used to wash away the alkalinity in the process of synthesizing Ni_（1-x-y）Co_xMn_y（OH）₂.During the aging process,the total amount of washing water is 20 m³.When the amount of washing water increases from 0 to 5 m³,the pH of the liquid after washing water decreases from 12 to 8.5.When the amount of washing water increases to8 m³,the pH of the liquid after washing water is 8.Ni_（1-x-y）Co_xMn_y（OH）₂ tons were prepared,and the washing water volume was about 8 m³,which could basically meet the requirements of large-scale production;The results show that the capacity of Ni_0.5Co_0.2Mn_0.3（OH）₂ is 140.1 m Ah/g,that of Ni_0.6Co_0.2Mn_0.2（OH）₂ is 176.15m Ah/g,and that of Ni_0.8Co_0.1Mn_0.1（OH）₂ is 191.93m Ah/g.With the increase of Ni content in ternary precursor,the gram capacity of ternary precursor increases gradually.With the increase of Ni content in Ni_（1-x-y）Co_xMn_y（OH）₂,the cell capacity increases gradually.At room temperature,the average cycle times of Ni_0.6Co_0.2Mn_0.2（OH）₂ battery with 80%capacity retention is 1025 weeks,which is higher than 850 weeks of Ni_0.8Co_0.1Mn_0.1（OH）₂ battery.Figure 44;Table 20;Reference 74...