Based on an innovative green recycling route for recycling and re-synthesis of spent lithium-ion batteries, LiCoO2 was synthesized by a molten salt method with LiCl-KCl as a molten salt medium and LiOH·H2O and Co2O3 as raw materials, and then the button batteries were prepared for resource recycling. The reaction kinetics of lithium cobalt oxide synthesis and the effect of reaction conditions on the structure and morphology of LiCoO2 were investigated. The battery performance of LiCoO2 was characterized by electrochemical analysis. The results show that the activation energies of the three endothermic reaction processes in the synthesis calculated by the Kissinger model are 34.212 00, 168.539 25 kJ/mol and 221.261 81 kJ/mol, respectively. The product of LiCoO2 has a good hexagonal lattice structure when calcined at 750 ℃ for 6 h. The charge-discharge and cycle performance of the battery were tested at 0.2 C rate and 2.4-4.2 V. The experimental battery prepared by LiCoO2 calcined at 750 ℃ for 6 h has the first charge-discharge specific capacity of 150 mA?偸h/g and 147 mA?偸h/g, the Coulombic efficiency is 98%, and the discharge specific capacity after 50 cycles of charge and discharge is still 129 mA?偸h/g. The battery still has a good charge and discharge performance after rate cycle.