Lithium-ion batteries (LIBs) are currently one of the most important electrochemical energy storage devices, powering electronic mobile devices and electric vehicles alike. However, there is a remarkable difference between their rate of production and rate of recycling. At the end of their lifecycle, only a limited number of LIBs undergo any recycling treatment, with the majority going to landfills or being hoarded in households. Meanwhile, the metal resources available from spent LIBs far exceed those found in natural mineral reserves, making these batteries a valuable source, or city mine, for metals. All these features make the recycling of LIBs an advantage necessity. A crucial component recovered during the LIBs recycling process is the “black mass” – a complex mixture containing metals and compounds used in the cathodes and anodes of LIBs.