Preparing NTC Materials From Cathodic Active Substance Of Spent Lithium-ion Batteries

NTC materials were prepared from cathodic active substance of spent lithium-ion batteries. The optimum technological conditions of preparing precursor were investigated through the orthogonal experiments. In the co-precipitation process of preparation, the leading factors that affect the mol ratio of CoMn in the oxalate percipitate are sulfate solution concentration, pH of the reaction, reaction temperature, and the mol ratio of ethanedioic acid to Co 2+ and Mn 2+ . The optimal processing parameters are sulfate solution concentration of 0.6mol/L, reaction pH of 7.0, reaction temperature of 50℃and the mol ratio, which is 2.5:1, of ethanedioic acid to Co 2+ and Mn 2+ .The average particle size of powder which synthesized at 800℃was observed by SEM. The calcined powder keeps the spherical shape. The composition and crystal structure of the sample sintered at 1200℃was investigated by XRD. The ceramics sintered at 1200℃are composed of MnCo 2 O 4 phase with cubic spinel structure and ( Co,Mn )( Co,Mn ) 2O4 phase with tetragonal structure. The conditions of calcination and sintering that affect the electrical characteristic of products were studied.The relationships between structure and electrical properties were investigated by XRD, SEM etc. The electrical characteristic of the manganese cobalt oxide doped with lithium was under detailed discussion. The charge carrier conduction mechanics of semiconductor were also discussed. When Li + substituted Co 2+ , conduction of positive hole as charge carrier was formed, activation energy of positive hole diminished, and electrical conduction increased, so that specific resistivity at 25℃and B 25/85 constant decreased. Segregation on grain boundaries led to an increase in activation...