Predicting Morphological Evolution during Coprecipitation of MnCO₃ Battery Cathode Precursors Using Multiscale Simulations Aided by Targeted Synthesis

Abstract

The performance of lithium-ion batteries is intimately linked to both the structure and the morphology of the cathode material, which in turn is critically linked to the synthesis conditions. However, few studies focus on understanding synthesis, especially during the coprecipitation of metal oxide precursors, a process that largely determines the final morphology of the material. In this paper, we go beyond the typical equilibrium particle shape analysis conducted in the literature and incorporate kinetic aspects of morphology evolution. We perform these studies using controlled synthesis on a well-defined metal salt system (MnCO3) combined with multiscale simulations and high-resolution microscopy. Results show that with increasing metal concentration, the particles transition from rhombohedral to cubic to spherical shapes. Computational analysis using density functional theory (DFT) reveals that rhombohedral shaped particles evolve under equilibrium conditions. Phase field techniques indicate that at higher metal concentrations, fast growth kinetics of the precipitates result in the transition to cubic and, subsequently, spherical shapes, accompanied by a decrease in particle size. This study, while limited to the one metal salt system, provides an approach to shed light on the synthesis process of mixed transition metal salts, gradient materials, and other cathode materials of interest to the battery community.

Precursor Morphology Control and Electrochemical Properties of LiNi0.35Mn0.30Co0.35O2 as a Li-Ion Battery Positive Electrode Material

“…Among these methods, coprecipitation is the most common synthesis method because it results in good chemical composition homogeneity of nickel, cobalt, and manganese. , In the coprecipitation method, mixed transition metal salts and alkali solutions are fed into a stirred reaction tank, and the precipitated hydroxide particles are collected as precursors. , NMC is then synthesized by calcination of the precursor to create the lithiated structure . The morphology of NMC obtained after the calcination step usually resembles the precursors acquired from the coprecipitation process . Therefore, morphology control of the precursor is very important for the control of NMC electrochemical properties.…”

“…14 The morphology of NMC obtained after the calcination step usually resembles the precursors acquired from the coprecipitation process. 15 Therefore, morphology control of the precursor is very important for the control of NMC electrochemical properties. However, few studies have focused on the morphology of the precursor or analyzed the cause of morphological differences.…”

Status and outlook for lithium-ion battery cathode material synthesis and the application of mechanistic modeling

“…Density functional theory (DFT): DFT is an approach to finding solution to the Schrödinger equation governing quantum behavior of atoms and molecules. In computational chemistry, DFT is useful in first-principle based calculation of material properties such as lattice constants, surface energies, structural energies, elastic constants [130,131]. For detailed information on DFT readers are referred to introductory texts [132,133].…”

“…Few studies in the battery literature apply mechanistic models to investigate the process-product relationship during co-precipitation synthesis [131,149]. These studies focus on the precipitation process inside a reactor and employ a combination of mechanistic models.…”

Insight into the Coprecipitation-Controlled Crystallization Reaction for Preparing Lithium-Layered Oxide Cathodes

“…Their reaction processes are as follows where Me is the transition metal (Ni, Co, and Mn). Based on these theories, the majority of researchers have examined many influencing factors, such as the concentration of reactants, − pH values, − reaction times, − reaction temperature, feeding rates, agitation velocity, and impeller types, which are important in the nucleation and growth of crystals and thus for the morphology of the final precursor . However, a useful rule has not been proposed to guide the controlled synthesis of materials under different conditions, which would waste a lot of manpower and material resources to try various synthetic conditions.…”