Low-temperature chlorination roasting technology for the simultaneous recovery of valuable metals from spent LiCoO₂ cathode material

Abstract

With the continuous increase in the disposal volume of spent lithium-ion batteries (LIBs), properly recycling spent LIBs has become essential for the advancement of the circular economy. This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials. The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free, model-fitting, and Z(α) function (α is conversion rate). Results indicated that the reaction was dominated by the first-order (F1) model when the conversion rate was less than or equal to 0.5 and shifted to the second-order (F2) model when the conversion rate exceeded 0.5. Optimal conditions were determined by thoroughly investigating the effects of roasting temperature, roasting time, and the mass ratio of NH₄Cl to LiCoO₂. Under the optimal conditions, namely 400°C, 20 min, and NH₄Cl/LiCoO₂ mass ratio of 3:1, the leaching efficiency of Li and Co reached 99.43% and 99.05%, respectively. Analysis of the roasted products revealed that valuable metals in LiCoO₂ transformed into CoCl₂ and LiCl. Furthermore, the reaction mechanism was elucidated, providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective. This technology can guide the development of LIB recycling processes with low energy consumption, low secondary pollution, high recovery efficiency, and high added value.

Keywords

spent lithium-ion battery / thermodynamics / chlorination roasting / kinetics / circular economy