Organic oxalate as leachant and precipitant for the recovery of valuable metals from spent lithium-ion batteries

Spent lithium-ion batteries containing lots of strategic resources such as cobalt and lithium are considered as an attractive secondary resource. In this work, an environmentally compatible process based on vacuum pyrolysis, oxalate leaching and precipitation is applied to recover cobalt and lithium from spent lithium-ion batteries. Oxalate is introduced as leaching reagent meanwhile as precipitant which leaches and precipitates cobalt from LiCoO2 and CoO directly as CoC2O4·2H2O with 1.0 M oxalate solution at 80 °C and solid/liquid ratio of 50 g L−1 for 120 min. The reaction efficiency of more than 98% of LiCoO2 can be achieved and cobalt and lithium can also be separated efficiently during the hydrometallurgical process. The combined process is simple and adequate for the recovery of valuable metals from spent lithium-ion batteries.

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► Vacuum pyrolysis as a pretreatment was used to separate cathode material from aluminum foils.
► Cobalt and lithium can be leached using oxalate while cobalt can be directly precipitated as cobalt oxalate.
► Cobalt and lithium can be separated efficiently from each other only in the oxalate leaching process.
► High reaction efficiency of LiCoO2 was obtained with oxalate.