Investigation of hydrohalic acids as lixiviants for the leaching of cathode metals from spent lithium-ion batteries

The exploration of alternative energy sources is inextricably linked with energy storage considerations. Current high density energy storage options on the market rely heavily on lithium (Li)-based technologies. A projected increase in energy storage technology demand has sounded the alarm on a need to develop suitable approaches for the recovery of the various constituent metals from spent Li-ion batteries (LIBs). This, coupled with urgent consideration for the environment has necessitated the investigation of various LIB metal recovery techniques. In this work, we explore the novel application of the hydrohalic acids, hydrobromic (HBr) and hydroiodic (HI) acid, as lixiviants in a series of leaching experimental investigations on LIB cathode powder. A methodology for battery disassembly and cell cathode material recovery is presented leading up to the metal leaching. Our results indicate that the lixiviants can be utilized in the absence of a reducing agent which is typically present in conventional LIB leaching systems. The highest recoveries of the constituent metals, Co, Li, Mn and Ni in the HI system were 92.9 %, 93.6 %, 93.1 % and 94.5 % respectively, at an operating temperature of 60 ℃ and with a 1.5 M HI concentration. The HBr system achieved metal recoveries of 90.6 %, 89.1 %, 83.1 % and 96.4 % for Co, Li, Mn and Ni respectively, at 60 ℃ and using 2 M HBr. Kinetic studies showed that the leaching mechanism for both acids follow a chemical reaction-controlled model.