Selective Extraction of Lithium from Spent Lithium Batteries by Functional Ionic Liquid

The recovery of valuable elements such as Li, Co, and Ni from spent lithium-ion batteries is essential for environmental protection and energy conservation. However, the inadequate recovery efficiency of lithium by traditional methods hinders the development of this industry. Thus, a sustainable and efficient approach for the selective extraction of lithium from spent batteries by a carboxyl-functionalized ionic liquid (carboxymethyl trimethylammonium bis(trifluoromethyl)sulfonimide) to increase the recovery efficiency of lithium was designed and developed in this work. By appropriately adjusting and controlling the parameters including the pH value, extractant concentration, and phase ratio, the selective extraction of lithium was optimized with excellent selectivity and recovery efficiency. After optimization, the lithium extraction efficiency reached 96.8%. The slope method combined with FTIR spectroscopy was utilized to characterize the variations in the functional groups during extraction to reveal possible extraction mechanisms. The extraction of lithium ions from organic phases and the recycling of ionic liquids were subsequently investigated. This work proposes the concept of a green, recyclable extractant for selectively separating and recovering lithium from spent LIBs.