Metal Recovery from Tartaric Acid-based Leach Liquor ofLithium-ion Batteries by Antisolvent Crystallization

Sammanfattning

Lithium-ion batteries (LIB) have a higher energy density, less memory effect, low selfdischarge,and higher cell voltage than other rechargeable batteries, making them widely usedin many applications. Due to the limited lifetime of LIB and the rapid growth of the demandfor LIB, a great number of spent LIBs have been and will be generated. The unsuitabledisposition method of the spent LIBs will cause serious environmental pollution such as soiland groundwater contamination by the leaked hazardous materials. On the other hand, thesespent lithium-ion batteries containing various critical metals such as lithium, nickel,manganese and cobalt are also secondary resources for manufacturing lithium-ion batteriesand other applications. Therefore, recycling these spent LIBs to recover precious metals isvery necessary and urgent from the viewpoints of environmental protection and resourcesavings. In this work, organic acid leaching was used to recycle active cathode material from lithiumionbatteries due to its less environmental impact compared to mineral acids. The organic acidL-tartaric acid was used as a lixiviant to leach active cathode material 𝐿𝑖𝐶𝑜!/#𝑁𝑖!/#𝑀𝑛!/#𝑂$(NMC) from lithium-ion batteries. Antisolvent crystallization was investigated for the recoveryof metals from L-tartaric acid-based leach liquor. Four parameters were investigated including1) the choice of organic solvents (ethanol, methanol, acetone and 2-propanol), 2) organic toaqueous (O/A) ratio, 3) residence time, and 4) adding speed to determine the effect on therecovery efficiency of different metals. A higher O/A ratio lead to higher metal recovery efficiency. For all the transition metals, at anO/A ratio of 2 after 3h addition of antisolvent, the metal recovery follows the order acetone >2-propanol > ethanol > methanol whereas for recovery efficiency of Li follows 2-propanol >acetone > ethanol > methanol. Specifically, using acetone as an antisolvent at an O/A ratio of2 and residence time of 3h, 99.8%, 97.9%, 99.8% and 40.0% of Co, Ni, Mn and Li arerecovered. Among the four solvents, methanol as antisolvent results in significantly different resultscompared with other antisolvents. Firstly, larger amount of methanol is needed compared tothe other studied antisolvents. Secondly, when methanol is antisolvent, Li is not recovered atall the investigated conditions. At an O/A ratio of 2 and residence time of 24h, 94.3%, 94.0%,90.3% and 0.0% of Co, Ni, Mn and Li are recovered using methanol as antisolvent, indicatinga complete separation of Li from the transition metals.