Selective lithium recovery and integrated preparation of high-purity lithium hydroxide products from spent lithium-ion batteries

The current paper presents an innovative route for selective lithium extraction, followed by production of battery grade LiOH·H2O via reductive hydrogen roasting, water leaching and LiOH·H2O crystallization. The results suggest that during the initial hydrogen reduction stage, almost 98% of Li can be transformed into soluble LiOH·H2O with H2 reduction at 500 °C within 15 min, while Ni, Co, Mn all transform into their corresponding insoluble metals or their oxides. Consequently, almost all of Li present in the roasted material can be effectively separated from other impurities by 10 min of water leaching at 25 °C with liquid-solid (L/S) ratio of 2, such that the extraction of other metals like Ni, Co, Mn are < 0.1%. Subsequent stages allow high purity LiOH·H2O (99.92%) to be obtained directly through evaporation and crystallization. In addition, high nickel battery cathode materials (LiNi0.8Co0.1Mn0.1O2) are prepared from the recycled LiOH·H2O products and these demonstrate good electrochemical performance. Overall, this newly developed hydrogen reduction-based process may provide a more simple, efficient and environmental friendlier method for the recovery of valuable metals from spent LIBs, as well as offering great potential for straightforward industrial-scale recycling.