Scalable synthesis and characterization of cobalt-free cathode active materials for sodium-ion batteries: Optimization of kinetic and hydrodynamic parameters

The development of the sodium-ion batteries (SIBs) presents itself as the sustainable future in the energy storage sector to replace lithium-ion batteries (LIBs), as sodium resources are abundant and SIBs are cheaper alternatives than LIBs. However, challenges such as lower energy density, cycling stability, and the scarcity of materials like cobalt in standard Nickel-Cobalt-Manganese (NCM) based materials are significant limitations to their widespread adoption. This study presents the co-precipitation technique to address such challenges, exploring the synthesis and characterization of cobalt-free magnesium-doped Nickel-Manganese cathode materials (Na-NiMnMg). The research explores several concentrations of Mg as a dopant to achieve the best properties of materials. Additionally, optimizing synthesis parameters ensures consistency in material quality. A key focus of this work is assessing the feasibility of scaling up cobalt-free cathode materials while maintaining the physical and electrochemical properties of materials which are characterized by several standard methods like Powdered X-ray diffraction spectroscopy (PXRD), Scanning electron microscopy (SEM) Particle Size Analysis (PSA), and (X-ray Photoelectron Spectroscopy) XPS for physical properties and Galvanostatic Charge-Discharge (GCD). The optimized material delivered a specific capacity exceeding 185 mAh/g with stable performance over 60 cycles and energy densities ranging from 1100 to 1270 Wh/L. The results demonstrate excellent capacity retention and rate capability, and structural stability. Process optimization strategies—covering dopant levels, impeller design and speed, and reaction temperature—significantly improved synthesis efficiency and scalability, supporting the feasibility of industrial-scale production of cobalt-free SIB cathodes.