Preferential Extraction of Lithium from Spent Cathodes and the Regeneration of Layered Oxides for Li/Na-Ion Batteries.

The preferentially selective extraction of Li + from spent layered transition metal oxide (LiMO 2 , M = Ni, Co, Mn, etc.) cathodes has attracted extensive interest based on economic and recycling efficiency requirements. Presently, the efficient recycling of spent LiMO 2 is still challenging due to the element loss in multistep processes. Here, we developed a facile strategy to selectively extract Li + from LiMO 2 scraps with stoichiometric H 2 SO 4 . The proton exchange reaction could be driven using temperature, accompanied by the generation of soluble Li 2 SO 4 and MOOH precipitates. The extraction mechanism includes a two-stage evolution, including dissolution and ion exchange. As a result, the extraction rate of Li + is over 98.5% and that of M ions is less than 0.1% for S-NCM. For S-LCO, the selective extraction result is even better. Finally, Li 2 CO 3 products with a purity of 99.68% can be prepared from the Li + -rich leachate, demonstrating lithium recovery efficiencies as high as 95 and 96.3% from NCM scraps and S-LCO scraps, respectively. In the available cases, this work also represents the highest recycling efficiency of lithium, which can be attributed to the high leaching rate and selectivity of Li + , and even demonstrates the lowest reagent cost. The regenerated LiNi 0.5 Co 0.24 Mn 0.26 O 2 and Na 1.01 Li 0.001 Ni 0.38 Co 0.18 Mn 0.44 O 2 cathodes also deliver a decent electrochemical performance for Li-ion batteries (LIBs) and Na-ion batteries (NIBs), respectively. Our current work offers a facile, closed-loop, and scalable strategy for recycling spent LIB cathodes based on the preferentially selective extraction of Li + , which is superior to the other leaching technology in terms of its cost and recycling yield.