A Review on Environmental, Economic and Hydrometallurgical Processes of Recycling Spent Lithium-ion Batteries

The suitable electrochemical performance of lithium-ion batteries (LIBs) led to an increase in demand and the use of LIBs in electrical and electronic equipment. Naturally, increased demand will be accompanied by an enhancement in the supply of metals from mineral resources. On the other hand, the lithium metal supply scenario will not be able to meet market demand over the next few years. Spent LIBs include valuable metals like lithium, cobalt, nickel, manganese, etc., which can be considered as a secondary source for the recovery of valuable metals. LIBs also contain toxic and organic compounds whose lack of attention, causes irreparable damage to the public health and the environment. Therefore, two important perspectives on the recycling of spent LIBs are the recovery of valuable metals as secondary sources and compliance with environmental regulations. Among the recycling process of spent lithium-ion batteries, hydrometallurgical processes are a suitable technique for recovery of valuable metals from spent lithium-ion batteries, due to their advantages such as the high recovery of metals with high purity, low energy consumption, and very low gas emissions. In this paper, the main aspects of spent LIBs recycling (environmental and economic) and hydrometallurgical processes (pre-treatment, leaching by organic and inorganic acids with various reducing agents, precipitation, solvent extraction, electrochemical methods, ion exchange resin, and regeneration) used to recover valuable metals, have been investigated.