A Review of Pretreatment Methods for Spent Lithium-Ion Batteries to Produce Black Mass – Comparison of Processes of Asia Pacific Recyclers

The aim of lithium-ion battery (LiB) recyclers is to create a closed-loop process to recover and reuse all the material as secondary sources of material to manufacture new batteries. Global LiB recycling companies apply pyrometallurgy, hydrometallurgy, or direct recycling to meet this goal. Pyrometallurgy is very energy intensive, but hydrometallurgy requires a pretreatment process and a new version of direct recycling that shows more promise for automation would also require pretreatment. Currently, recycling companies appear to favor hydrometallurgy. This review summarizes the current state of development of the pretreatment process involving battery discharging and mechanical treatment series from the literature and its application in the industry, with particular attention on Asia Pacific recyclers. The key pretreatment steps of battery discharging and mechanical treatment are the focus of this review, but pretreatment of the black mass containing cathode material prior to leaching is also included. Discharging is important to reduce the risk of fire during mechanical treatment. An interesting finding is that despite promising laboratory results, there has been no reported commercial application of battery discharging using the submersion method in an electrolyte solution. An efficient mechanical treatment of discharged batteries is essential to remove the impurities which could adversely impact the subsequent LiB processing. Research into mechanical treatment should also include a method to evaluate the liberation of material. This review has highlighted a new potential flowchart for recycling of various cathode types of LiBs.