Synthesis and Theoretical Modeling of Suitable Co-precipitation Conditions for Producing NMC111 Cathode Material for Lithium-Ion Batteries

Abstract

Lithium nickel manganese cobalt oxide (NMC111) is considered to be one of the most promising cathode materials for commercial lithium-ion battery (LIB) fabrication. Among the various synthesis procedures of NMC111, hydroxide co-precipitation followed by lithiation is the most cost-effective and scalable method. Physical and chemical properties of the co-precipitation product such as yield, particle size, morphology, and tap density, depend upon the various reaction parameters, which include pH, chelating agents, metal salt concentrations, and stirring speed. As a consequence, detailed theoretical and experimental modeling is critically required to not only understand the interdependence between the particle properties and reaction conditions but also optimize these parameters. In this study, theoretical modeling was performed to analyze the role of various NH₄OH concentrations with varying pH on the yield of the NMC(OH)₂ product. From the experimental findings, it was observed that the product obtained at a pH of 11.5 and NH₄OH concentration of 0.02 M possessed the highest tap density. Three of the hydroxide precursors with different tap density values were chosen to lithiate and were applied for coin cell fabrication. The NMC(OH)₂ precursor with the highest tap density had the highest specific capacity of 155 mAh g^–1 at 0.1 C and retained up to 78.6 mAh g^–1 at 5 C. The variation of the Li⁺ diffusion coefficient for the three selected materials was also studied using electrochemical impedance analysis.