Modeling multicycle anodic degradation in hard carbon-based sodium-ion batteries

Due to abundant raw materials and ecological friendliness, sodium-ion batteries (SIBs) are considered a promising alternative to lithium-ion batteries (LIBs) for energy storage applications. This assertion is based on the recent advances in technology and the proven capabilities of SIBs. Physics-based modeling (PBM) is a cost-effective approach for understanding the electrochemical kinetics and degradation mechanisms of batteries. In this paper, the authors developed a single-particle model with electrolyte interactions (SPMe) coupled with anodic degradation in a sodium vanadium phosphate fluoride (NVPF)/Hard carbon cell. Stress generation due to intercalation, adsorption, and pore-filling is considered. Degradation due to sodium plating/stripping with dead sodium storage, solid-electrolyte interphase (SEI) growth/fracture, and loss of active material is simulated at a 1C charging rate over 300 cycles. The developed model is shown to be reliable for predicting capacity degradation and discharge profiles. The model provides insight into the suppression of SEI and dead sodium, and their effects on resistance during battery aging. The results show the role of initial SEI thickness variation (1 nm–20 nm) across different levels of dead sodium storage (1%–5%). Ultimately, the capacity degradation is assessed for the simulated cell. The proposed model can serve as a reference for the design of SIBs.