Influence of batchelor flow on agglomeration of NMC hydroxide

In manufacturing the cathode material of lithium battery, morphology, size and size distribution of NMC oxide are directly related to the packing efficiency, which influence its energy density in battery performance. For a high packing efficiency of battery, spherical and size-uniform NMC hydroxides are thus required, which is determined by agglomeration process in reaction crystallization. [1-2] So, understanding and investigating the agglomeration process is necessary to obtain the desired agglomerates of morphology, size and size distribution. [1-4] Therefore, the present study focused on the influence of periodic fluid fields of Batchelor flow on agglomeration of NMC hydroxide. The Batchelor flow induced between two concentric disks of crystallizer (called Rotation disk (RD) crystallizer) was applied for the reaction crystallization of NMC hydroxides, as shown in Fig.1 (a). Due to effective collision of particles and shaping process in periodic Batchelor flow, the spherical and sizeuniform agglomerates of NMC hydroxides was produced in RD crystallizer, which was operated in continuous mode. Here, the mean residence time of RD crystallizer was 0.5hr, which was much shorter than in any previous studies running in mixing tank crystallizers at batch or continuous operations. A high fluid shear of Batchelor flow reduced the mean particle size and changed the irregularly shaped agglomerate particles into spherical ones, also, the agglomerate size distribution was narrower with increasing rotation speed of inner disk. (Fig.1 (b)) As a result, the agglomerates of NMC hydroxide with the tap density of about 2.1 g/cm³ were obtained at a high rotation speed of 1500 rpm in RD crystallizer. So, it could be inferred that that a RD crystallizer was highly applicable for the practical production of the agglomerate of NMC hydroxide and more effective than the conventional mixing tank crystallizer.