Comparative Electrical Characterization of Commercial Sodium-Ion and Lithium-Ion Cells Using Enhanced Ragone Plot Analysis

Abstract

Commercial sodium-ion battery (SIB) cells with layered oxide cathodes have recently been introduced to the market. An evaluation of their performance and comparison to existing lithium-ion battery (LIB) technologies at different temperatures and C-rates will provide valuable insights into quantifying their capabilities and identifying potential end-use applications. In this article, we present the electrical characterization of SIB cells with NMF/HC (nickel-manganese-iron/hard carbon) chemistry at different ambient temperatures and C-rates, followed by a critical comparison with existing LIB technologies with the aid of the Enhanced Ragone plot and key metrics, such as discharge capacity, maximum temperature increase, relative discharge time, and discharge efficiency. Thermodynamic characterization results reveal voltage hysteresis in the low state-of-charge region. The electrical and thermal behaviors of galvanostatic discharges across different C-rates and temperatures are also analyzed and linked to the trends in internal resistance. When compared to LIBs, the investigated SIBs show similar power delivery to LFP cells and possess interesting thermal properties: the ability to limit self-heating, and reduce the dependency of electrical behavior on ambient temperature. The tested SIBs may show potential as a promising candidate for operation at temperatures below 10 °C, or in environments with a broad range of operating temperatures without the need for extensive thermal management. Finally, the data supporting the findings of this study are publicly available.