Research And Pilot-production Of Battery Grade Co₃O₄

Co₃O₄ powder has extensive applications in the fields of catalysis, magnetic material and electro-chemistry. More and more strict specifications are needed for Co₃O₄ powder in market. According to Co₃O₄ powder production process of hydro-chemistry method, it is of great signification to develop the right method and theory to control the particle morphology, size and size distribution for preparing high quality battery grade Co₃O₄ powder.In carbamide homogeneous precipitation system, under the condition of the different reagents concentration, the precipitation particles with diverse morphologies were obtained. The main reason was that the primary particles had different chemical compositions for the effects of the different kinds of anions and stoichion-chemical compositions of the primary particles. According to the Gibbs Law, the early-formed fine particles had the ability of absorbing molecules or ions in the solution to decrease the interface energy of the precipitation system, which gave an idea of by designing a lower interface tension system to make the particles exist in the thermo-dynamic stable state and produce the mono-disperse system with special morphology and size. The surface of particles was charged by adsorption effect and so the electric barriers against the aggregation between particles were established. The adjusting of surface charging of the particles could be performed by the reference of the zeta potential of the particles in the suspension. The experimental results showed that the zeta potential could be taken as a sigh to guide the designing of this kind of stable system. According to the change of the zeta potential along with PH value in several typical systems, the experimental conditions were chosen to adjust the interface tension of the precipitation system and the mono-disperse cobalt compound could be produced by adjusting PH value and ion tension in the reaction and aging process.During the process preparing CoCO₃ using well-proportioned NH₄HCO₃ as precipitator continuously, on the basis of the theory of crystallography and catalysts preparation, the crystallization and growth processes and the other relative factors of spherical Co₃O₄ crystal prepared by chemical precipitation method were thoroughly analyzed. In this paper, the spherical CoCO₃ with high tap density and crystallinity degree, good flow ability were prepared by the "controlled chemical crystallization method". The effects of main preparation technology conditions such as reaction PH value, mix way, reaction time etc on the crystallization processes and physical properties of CoCO₃ were studied in details.Furthermore, the change law and correlative theory of powder size and morphology were studied on the process thermolysis. During the processing preparing the spinel-type battery grade CoCO₃ powder the inheritance ability of shape was appeared between calcinate products andprecursor. At low temperature powder products presented porous characteristics. And under suitable temperature(⁸50'C )and calcinate time(8h)the polyhedron-shaped battery grade COCO3 powder could be obtained.Based on laboratory research, utilizing NH4HCO3 continuous and well-proportioned precipitation system, the pilot-production system for battery grade CO3O4 was perfectly designed.and some key factors were well handled: the choice of production material, manufacture equipment and improvement of manufacture technical procedure. Such pilot-production products were used to produce cathode material LiCoCh for Li-ion battery in some national grand factory. The result of analysis and test to the cathode material stated that such pilot-production product can completely meet LiCoC>2 quality standard. It characterized by perfect electrochemical performance and this technology was the pioneer in this field countrywide.