Study On Structre Properties Of Cobalt And Cobalt Compounds From Secondary Resources And Original Mineral

Because of its excellent physical, chemical and mechanical properties, cobalt is widely used in batteries, hard alloy, petrochemical, automobile manufacturing, machine tools, magnetic materials, and many other industries, becoming an important strategic metal resources. A lot of cobalt are used in China, but cobalt resources in China are extremely scarce. Recycled cobalt resources become an important cobalt supply. In this thesis, the properties of the secondary and the original cobalt and cobalt compounds, are mainly studied, and the structure properties of them. Are also prepared and fixed. XRD, SEM, TEM, laser particle size analyzer were used to test and analyze the structure. Cobalt oxide was used to prepare battery materials, and the electrochemical performance of battery materials is investigated, in order to obtain the recycled cobalt products as good as original products.The secondary and the original cobalt carbonate are both of monoclinic structure. Both the recycled and the original cobalt carbonate have a spherical particle morphrogy anda uniform particle size. The original paricles exist as aggregates. The FWHM (Full Wave at Half Maximum) of the XRD peaks of the recycled cobalt is twice wider than that of the original, and the continuity of lattice fringes of recycled cobalt carbonate are worse than these of the original. The crystallinity of recycled cobalt is worse than that of the original, but the original cobalt carbonate has a better structure than the recycled.Using cobalt carbonate as raw materials, cobalt oxide wasprepared in air and nitrogen atmosphere respectively, and then the structure performance of the calcined products were fixed. The calcined products in the air atmosphere are predominantly composed of CoO with face-centered cubic structure, and a small of fraction Co3O4 with routine spinel structure. The calcined products in the nitrogen atmosphere are face-centered cubic structure CoO, the crystallinity of the cobalt oxide is higher than that of those prepared in the air atmosphere. The crystallinity became batter as the holding time becomes longer; the structure fix effect in the nitrogen is batter than that in the air atmosphere.One-step and two-step methods were used to fix and prepare the metal cobalt. The products prepared by one-step are face-centered cubic cobalt metal, the structure performance of the recycled cobalt metal has been greatly improved, and the crystallinity of the original cobalt is batter than that of recycled cobalt. The products of two-step are hexagonal crystal cobalt, the recycled cobalt fixed by two-step method (air+H2) is alittle worse than that of original. The structure performance of the recycled cobalt fixed by two-step method (N2+H2) is as good as that of original cobalt. The fixing result by two-step methof is better than that of one-step method.LiCoO2 cathode materials were prepared from original and recovery Cobalt oxide. The results show that the recovery cobalt and the original mineral cobalt products are both layered structure LiCoO2 of a-NaFeO2 type, and the differences between the two kinds of LiCoO2 cathode materials reduced greatly through the former experiments controlled. The charge and discharge performance of the button batteries showed that, the initial discharge capacity of the LiCoO2 sample prepared by the recovery product is 109.4mAh/g, and the initial discharge capacity of the LiCoO2 sample prepared by the original mineral product is 110.3mAh/g. The cycle performance of the battery show that, after 50 times of cycle, the capacity maintenance proportion of the battery prepared by the recovery cobalt is about 86.6%. And the capacity maintenance proportion of original battery is about 86.3%. The recovery cobalt product can be well in the batteries after the former performance repair and shows good application performance, even better than the original mineral product.