Selective recycling of lithium from spent lithium-ion batteries by carbothermal reduction combined with multistage leaching

The indiscriminate hydrometallurgical leaching of metallic ions from spent lithium-ion batteries derived black mass significantly hinders the targeted recovery of specific metal salts. Selective recycling of lithium from electrode materials has attracted much attention because of its high value and realizability. While carbothermal reduction combined with single stage water-leaching is an alternative pathway, impurities in the electrode materials will affect the reduction process and decrease the recycling efficiency. In this study, we proposed the concept of carbothermal reduction in combination with multi-stage leaching as a facile and earth friendly approach to recycle lithium from electrode materials. Results demonstrate that cathode material of LiNixCoyMn(1-x-y)O2 can be fully reduced to Li2CO3, LiAlO2, CoO, NiO, Co, Ni. Li2CO3 can be recycled by water-leaching while LiAlO2 can be recycled by alkali-leaching. Roasting process can make lithium ions out of the aluminum-containing precipitates to form water-soluble salts, and this part of lithium can be recycled by water-leaching again. Afterwards, the comprehensive recovery rate of lithium is 87.15% when the content of aluminum in electrode materials is up to 4.03%. Findings made from this study may inspire the next generation of greener hydrometallurgical pathways to recover lithium from electrode materials even with a high aluminum content.