Investigating the Influence of Transition Metal Composition on High-Voltage Cathodes Performance By Using Magnetic Susceptibility

Abstract

High-voltage cathodes are indispensable to enable the high-energy-density batteries. This work demonstrates the effect of Ni/Mn composition on structure of pristine and cycled layered Li-Ni-Mn/Al-Co oxide (NMC and NCA) during high-voltage operation (4.75V vs. Li). Particle morphology and elemental composition of all material was investigated by using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) analysis. Among the various materials NMC622 had the best uniformity in particle size at ~10um while the other materials ranged from ~5-10um. X-ray diffraction (XRD) spectra of the as-obtained powders showed little variation in the structure of layered oxide with different transition metal ion compositions. Temperature dependent magnetic susceptibility results show that NMC622 (with 60% Ni) is layered with less magnetic ordering which was very similar to that of NCA811 (80% Ni) while NMC442 (40% Ni) showed strong magnetic ordering, which suggests exchange of strong magnetic interaction among transition metal ions in NMC442 material. The structural differences that were observed from magnetic susceptibility results were correlated with the electrochemical performance. The detailed pristine structure and structural evolution in layered oxides varying the Ni concentration in the light of magnetic susceptibility will be presented.