Influences Of Surface Active Agent On Co₃O₄ Particles Prepared By Oxalic Acid Precipitation

The oxalic acid precipitation method was used to recycle the cobalt element from the worn out lithium ion battery positive materials. The influences of preparing conditions of precursor on recycle rate were investigated. Then the recycled powder was modified by two kinds of surface active agent, polyethylene glycol and carbamide. The action mechanism of these two dispersants was discussed. The main results are as follow:The cobalt element could be recycled by the oxalic acid precipitation method from the worn out lithium ion battery positive materials. When reaction conditions were pH =8⁹,reaction temperature60℃,n(H₂C₂O₄): n(Co²⁺+Li⁺)=1.20:1～1.30:1,C(H₂C₂O₄)=1.25M ,the recycle rate of cobalt was 95.3%. The cubic Co₃O₄ with average diameter of 2μm could be obtained by calcining the precursors at 750℃, which agglomerated seriously.Influences of polyethylene glycol on prepared Co₃O₄ particles were studied. The results indicated that shapes and sizes of Co3O4 particles could be controlled and modified by it. The diameter was about 0.14μm when PEG (Mw=1540, Cw=5wt%5ml )was used as dispersants.Influences of carbamide on prepared Co3O4 particles were studied. The results indicated that shapes and sizes of Co₃O₄ particles also could be controlled and modified by it. When carbamide (0.22M) was added as dispersants, the prepared powder was dispersed well and the average particle size was about 2μm.The XRD result shows that the powders calcined at 750℃is the mono-phase crystal structure and well- crystallized in the Cubic system with space group Fd3m. The particles shapes and the average particle size of the Co3O4 powder were observed by SEM. The results show that the dispersion of the powder with PEG as dispersant is better than that with carbamide as dispersant.