Modeling the Non-linearities of Charge-Transfers and Solid Electrolyte Interphase Resistances for a Sodium-Ion Battery with a Hard Carbon Electrode

Sodium-ion batteries are a promising technology whose performance are getting closer to those of lithium-ion batteries. The electrochemical phenomena are mostly the same for these two technologies, but the sodium-ion battery studied in this paper has a negative electrode made of hard carbon “HC” in which different phenomena occur when the state of charge “SoC” decreases. In this paper, we characterized this sodium-ion battery thanks to a physic-based model that can represent the non-linearities of the charge transfers and solid electrolyte interphase “SEI” resistances. In this initial study, we found that this model represents accurately the battery non-linearities for high SoC, making it able to characterize its charge transfers and SEI (eg. for diagnosis purpose). However, the model failed to represent the cell behavior below SoC 40–50%, suggesting that it should be improved for batteries with HC electrodes.