LiOH·H2O recovery from nickel-rich cathode materials using the novel vacuum heat treatment method

The general lithium hydroxide monohydrate (LiOH·H2O) recovery method from waste cathode materials has environmental problems due to the use of strong acids and economic problems associated with the process of converting to LiOH·H2O. In this study, surprisingly, LiOH·H2O was successfully recovered from the LiNi0.92Co0.07Al0.11O2 cathode materials through a novel vacuum heat-treatment method. Due to the low oxygen partial pressure (2.7 × 10–7 atm), the phase transition from a conventional layered structure to a RS (rock salt) structure occurred at 700 ℃. The results from the X-ray diffraction (XRD) analysis confirmed that the (003) peak, which indicates the amount of lithium in the cathode structure, completely disappeared at temperature of 800 °C and above. After vacuum heat treatment, the obtained aqueous solution was evaporated and concentrated to obtain a crystallized white powder. As a result of the XRD analysis of this product, LiOH·H2O was indexed. To our knowledge, this is a novel method of LiOH·H2O recovery from nickel-rich cathode materials.