Deciphering the Impacts of Al, Fe, Li Sulfate Impurities on the Synthesis and Performances of LiNi0.6Mn0.2Co0.2O2 Cathode Materials

The recycling of LiNi0.6Mn0.2Co0.2O2 cathode active material (CAM) from Li-ion batteries cannot avoid the presence of impurities in the recycled Ni-, Co-, or Mn sulfates. The precise understanding of the impurities influence on the resynthesis is of uttermost importance. To tackle this goal, this study simulated the resynthesis process by adding on purpose and separately Al-, Fe-, and Li-sulfate in the regular CAM synthesis. Their effects on the morphology, elemental composition, crystal structure, and electrochemical performances of Ni0.6Mn0.2Co0.2Mx(OH)2 and LiNi0.6Mn0.2Co0.2MxO2 were systematically investigated for x = 0.0005, 0.005, and 0.05. The in-house reference material synthesized via a coprecipitation reaction allowed to produce a well-characterized basis. Above xAl = 0.0005, the hydroxide secondary particles lost their spherical form and above xFe = 0.005, the crystal structure was affected. Both effects led to cell capacity decay, contrary to the discrete influence of Li. The absence of any positive effects reported by similar studies, the complexity of the various influences of these foreign ions and the limitations of the coin cells tests were pointed out. These results are a solid groundwork for future academic and industrial studies in the field of circular economy, by determining a tolerance threshold for each impurity. Impurities leftovers in resynthesis of Li-ion cathode materialsPrecise purity requirements in industrially recycled battery materialsAluminium is very detrimental for the morphologyIron disturbs the crystal structureLithium induces subtle changes