leaching procedure and kinetic studies of cobalt in cathode materials from spent lithium ion batteries using organic citric acid as leachant

an approach to recycle precious metals of cathode materials from spent lithium cobalt oxide batteries by using organic citric acid and hydrogen peroxide has been studied in this paper. the effects of molar ratio, solid-liquid ratio, reaction time and temperature on leaching efficiency of cobalt were investigated respectively. meanwhile the leaching kinetics equation of cobalt was established, and the apparent activation energy of leaching reaction of cobalt was calculated out. the results show that when the molar ratio of citric acid to lithium cobalt oxides is 4:1, solid-to-liquid ratio is 15 g/l, the reaction temperature is 90 oc, the reaction time is 5 h and concentration of h2o2 is 1.0 vol. %, the leaching efficiency could be up to 99.07%. the apparent activation energy of cobalt leaching reaction is 45.724 kj/mol, and by means of conducting fitting test for the relationship between lithium cobalt oxides powder with different particle sizes and leaching efficiency, it can be concluded that the reaction of lithium cobalt oxides using citric acid and hydrogen peroxide is chemical reaction control.