Electrochemically-assisted leaching of active cathode materials from spent batteries with minimal pre-treatment using hydroxylated solvents

TOC description: The use of electrochemically-assisted leaching allowed an enhancement of the overall leaching efficiency of critical metals such as Li, Co and Ni from Co 3 O 4 and NMC matrices when compared to a chemical leaching. The direct use of spent NMC 622 cathodes as working electrodes provided a simple and environmentally friendly way of extracting these metals from spent batteries, as less hazardous chemicals such as N -Methyl-2-pyrrolidone are required. Spent lithium-ion batteries (LIBs) are a rapidly increasing source of waste that pose a hazardous and environmental problem. They are also a secondary source of valuable critical metals such as Li, Co, Ni and Mn. Their recycling often involves use of aggressive conditions, which challenge the sustainability character of the process. In this work, an electrochemically-assisted leaching process was carried out to dissolve valuable metals from pristine and spent LIB cathode materials under mild conditions without the need for any pre-treatment (removal of polymeric binder and current collector). Hydroxylated solvents were used as electrolytes, firstly in leaching of Co 3 O 4 , demonstrating that the applied potential played a determinant role in achieving high Co dissolution (73.1 %). Subsequently, real spent cathodes were directly used, without pre-treatment, as working electrodes under mild working conditions. Up to 82 % Li, 62 % Co, 60 % Ni and 52 % Mn were leached at potentials up to 3 V with fast kinetics in the first 30 min of the process. The structural changes caused by initial delithiation of the black mass, corrosion of the Al from the current collector, and the presence of binder, were identified as key in achieving competitive metal leaching efficiency values. This process can pave the way for new LIB recycling processes with less pre-treatment requirements, in milder conditions while still being scalable to an industrial setting.