Upcycling of lithium cobalt oxide to LiNi1/3Mn1/3Co1/3O2

Abstract

With the increasing demand for rechargeable lithium-ion batteries arises an interest in the recycling processes for such devices. Possible methods include a range of processing conditions yielding different precursors which need to be integrated into upstream production. Here, we demonstrate a synthesis method that is compatible with the organic precursor obtained from citric acid-based leaching of lithium cobalt oxide (LCO) followed by acetone antisolvent crystallization. A lithium cobalt citrate (LCC) precipitate is retrieved and used directly as a precursor to synthesize LiNi_1/3Mn_1/3Co_1/3O₂ (NMC111) via a sol–gel method. The organic precursor is the only source of Co and provides a portion of the Li, while complementary metal salts supply the remaining metals in stoichiometric amounts. The role of metal salts (either acetates or sulfates of Ni, Mn and Li) is evaluated based on chemical composition and material purity. Electrochemical evaluation of the material produced from metal acetates shows comparable performance to that from a control material. The work connects previously studied methods of downstream leaching and antisolvent extraction with the upstream production of a desired cathode material through sol–gel synthesis. It is shown that our concept provides a path for avoiding primary and hazardous extraction of cobalt as the citrates obtained from acetone antisolvent crystallization of LCO can be applied as precursors for NMC111 synthesis, with few steps and applying only non-toxic solvents.