关键词: 三元正极材料, 前驱体, Ni_1/3Co_1/3Mn_1/3(OH)₂, 多釜串联工艺

Abstract:

Commercial LiNi_1/3Co_1/3Mn_1/3(OH)₂ ternary material is generally prepared by a combination of co-precipitation and solid state reaction method. The particle size distribution and morphology of Ni_1/3Co_1/3Mn_1/3(OH)₂ precursor have a great impact on the electrochemical performance of LiNi_1/3Co_1/3Mn_1/3O₂. In this work, the precursor Ni_1/3Co_1/3Mn_1/3(OH)₂ ternary cathode material was prepared by co-precipitation method with MnSO₄, NiSO₄, and CoSO₄ as raw materials, NaOH as a precipitating agent and NH₃•H₂O as a complexing agent through continuous stirred-tank reactor series (CSTRs). The effects of stirring speed on the morphology of the nuclear particles, flow quantities of crystal nuclei and ammonia, slurry regurgitation, agitator blade structure on the morphology, crystalline structure, particle size and particle size distribution of the precursor were explored. Physical characterization results showed that the primary particles of the crystal nucleus agglomerate formed secondary particles with the particle size of 4 ~ 5 μm, and the well distributed particles were near spherical at the stirring rate of 300 r·min^-1. When the pusher type agitator was used, the flow quantities of crystal nucleation and crystal growth metal liquids were 0.4  L•h^-1 and 1.72  L•h^-1, respectively, the product exhibited a single phase of β-Ni(OH)₂ with a layered structure. The particle size (D₅₀) of 6 ~ 7 μm, the tap density of ≥ 2.0 g•cm^-3, and the BET surface area of 6 ~ 10 m²•g^-1,were also obtained. The electrochemical test results revealed that the initial discharge capacity of LiNi_1/3Co_1/3Mn_1/3O₂ reached 149.7 mAh•g^-1 and the capacity retention was 94.09% after 100 cycles in the voltage range of 3.0 ~ 4.25 V at 0.2 C. The product could meet demands of high-end ternary cathode material manufacturers. The CSTRs method is simple, effective and applicable. Therefore, it can be potentially used for a large scale preparation of ternary material precursors.

Key words: Ternary cathode material, Precursor, Ni1/3Co1/3Mn1/3(OH)2, CSTRs