锂离子电池富镍三元材料的合成放大化和改性研究

发布时间：2018-04-30 19:42

本文选题：镍钴锰酸锂材料 + 成核　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着动力电池市场的迅猛发展,电池的正极材料逐渐成为产业化研究的主要方向之一,其中富镍组分的三元镍钴锰811材料凭借高放电比容量(200 mAh g~(-1))、低成本的特点成为下一步产业化的热点。目前三元NCM镍钴锰材料最为常见和成熟的合成方法是先使用共沉淀法合成三元材料前驱体,再混锂高温固相烧结,这种方法可以得到粒度分布可控、振实密度高的球型三元正极材料。目前经过多年的实验室小规模研究,已基本探寻出控制材料振实密度和颗粒粒径的影响条件,研究出温度、pH值、氨/金属进料比等关键因素对一次颗粒、堆积致密度及振实密度的作用规律,探索出了稳定的合成工艺,合成出了高振实密度(ρ2.1 g cm~(-3))的前驱体材料,已经具备了放大化合成的条件。本论文从产业化角度出发,使用共沉淀法进行合成放大研究,分别从晶体的成核与生长角度对镍钴锰酸锂材料的前驱体——氢氧化镍钴锰材料的振实密度和颗粒粒径进行研究。研究了放大化反应釜中,底液量对初级成核与团聚的影响,重点分析了搅拌桨叶、固液比、晶体粒度和搅拌速度对氢氧化镍钴锰材料的二次成核影响;研究了搅拌速度、搅拌桨叶、固液比和反应时间对二次颗粒生长的影响。在已有的实验室小釜工艺基础上,针对工艺放大后由搅拌问题带来的不断成核、振实密度低和颗粒粒径变化等现象,设计新反应工艺,获得了高振实(ρ=2.04 g cm~(-3))、小粒径的前驱体材料,其倍率性能和循环性能都要明显优于商业材料。碱性过高是富镍三元材料产业化面临的一个重要问题,同时还影响电极材料的性能发挥,使用一种酸性的聚苯胺PANI进行洗涤处理可以有效的去除富镍三元材料表面的碱性锂残余物,提高了活性材料的电导率和锂离子扩散系数,同时不对材料的晶体结构造成明显改变,不会造成容量的损失,全面地提升了富镍三元材料的循环性能和倍率性能。此外,在此基础上包覆PANI还可以进一步提升富镍三元材料的循环性能。
[Abstract]:With the rapid development of power battery market, the cathode material of battery has gradually become one of the main research directions of industrialization. Among them, nickel rich ternary Ni-Co-Mn 811 material with high discharge specific capacity of 200 mAh / g ~ (-1) has become the focus of industrialization in the next step because of its low cost. At present, the most common and mature synthesis method for ternary NCM materials is to synthesize ternary precursors by coprecipitation, and then to mix lithium with high temperature solid state sintering. The particle size distribution can be controlled by this method. Spherical ternary cathode material with high vibrational density. At present, after many years of small-scale laboratory research, the influence conditions of controlling material vibrational density and particle size have been basically explored, and the key factors such as temperature and pH value, ammonia / metal feed ratio and other key factors to primary particles have been studied. On the basis of the effect of stacking density and vibrational density, a stable synthetic process has been explored, and a precursor material with high vibrational density (蟻 2.1 g / cm ~ (-1) has been synthesized. The conditions for amplification synthesis have been obtained. In this paper, the coprecipitation method was used to study the synthesis amplification from the perspective of industrialization. The vibrational density and particle size of nickel cobalt manganese hydroxide precursor, nickel-cobalt manganese hydroxide, were studied from the point of view of crystal nucleation and growth respectively. The effect of the amount of base liquid on primary nucleation and agglomeration in a scale-up reactor was studied. The effects of stirring blade, solid-liquid ratio, crystal size and stirring speed on the secondary nucleation of nickel-cobalt-manganese hydroxide materials were analyzed. Effects of stirring blade, solid / liquid ratio and reaction time on secondary particle growth. Based on the existing laboratory reactor process, a new reaction process was designed to solve the problems of continuous nucleation, low vibrational density and particle size change caused by agitation. The ratio and cyclic properties of the precursor materials with high vibrational strength (蟻 ~ (2. 04) g / cm ~ (-1)) and small particle size are obviously superior to those of commercial materials. Too high alkalinity is an important problem in the industrialization of nickel rich ternary materials, and it also affects the performance of electrode materials. Using an acidic Polyaniline PANI for washing can effectively remove the alkaline lithium residue on the surface of nickel rich ternary material, and improve the conductivity and the diffusion coefficient of lithium ion of the active material. At the same time, the crystal structure of the material is not obviously changed, and the loss of capacity will not be caused. The cycling performance and the rate performance of the nickel rich ternary material are improved completely. In addition, coating PANI on this basis can further improve the cycling performance of nickel rich ternary materials.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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