STATE OF CHARGE AS A GOVERNING FACTOR IN VOLTAGE HYSTERESIS FOR SILICON-BASED LI-ION BATTERIES

Abstract

This work investigates voltage hysteresis in lithium half-cells using three types of silicon anodes: porous, nano, and bulk. Initial and final capacity differences observed during lithiation–delithiation cycling are corrected using a side-reaction compensation method based on Tafel kinetics. Despite this correction, a notable voltage hysteresis remains across all cell types. To uncover the origin of this hysteresis, we develop a physics-based model incorporating hydrostatic stress. Simulations reveal that stress-induced voltage contributions are minimal and insufficient to account for the observed hysteresis. We further explore how exchange current density varies with the state of charge (SOC) by proposing three SOC-dependent models: average, linear, and logarithmic. Among these, the logarithmic model most accurately replicates the experimental voltage curves, effectively minimizing hysteresis. These findings highlight the limited role of mechanical stress and the dominant influence of electrochemical kinetics on voltage behavior. This study advances the understanding of voltage hysteresis in silicon anode lithium cells and suggests modeling approaches to reduce its impact.