Comprehensive Analysis of Commercial Sodium-Ion Batteries: Structural and Electrochemical Insights

Abstract

Considering the growing need for extensive energy storage solutions in smart grid technologies and affordable options for entry-level electric vehicles, sodium-ion batteries offer a promising alternative. They use raw materials that are cheaper, less toxic, and more abundant than those used in lithium-ion batteries, making them especially suitable for large-scale applications. This study comprehensively investigated four commercially available sodium-ion batteries to examine their structural and electrochemical characteristics. The cells were dissected, and the electrode dimensions, the areal mass loadings, and the material compositions were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and attenuated total reflection Fourier-transform infrared spectroscopy. Electrical characterization, including electrochemical impedance spectroscopy, C-rate testing up to 6 C under different ambient temperatures, along with cyclic aging studies, provided insights into the cells’ performance and degradation mechanisms. The findings highlighted variations in electrode coatings, particle sizes, and cathode materials among the cells, which were then correlated with their electrical behavior. This emphasized the challenges in maintaining sodium-ion battery performance, especially at low temperatures. This study was designed to establish a comprehensive knowledge base for both academic and industrial research in sodium-ion battery technology.