Achieving High Energy Density, Nickel-Free Sodium-Ion Full Cells with Direct-Contact Presodiation

Much like lithium-ion batteries, sodium-ion batteries are plagued by loss of cyclable ion inventory at both the cathode and the anode which limits the realized capacity of a cell. Loss of sodium ions due to the formation of the solid electrolyte interphase at the anode occurs primarily during the initial cycles of a battery, but in high volume expansion materials, such as antimony (Sb), this can be a continuous loss mechanism. Presodiation treatments aim to compensate for future losses by introducing an excess of sodium (Na) ions into the anode prior to cycling. Among the most industrially relevant of these techniques is direct-contact presodiation. In this work, we demonstrate the ability to controllably and reproducibly presodiate Sb, a high-energy density alloying anode through control of both pressure and time of treatment to enable a sodium-ion full-cell with improved initial coulombic efficiency (ICE) and without any critical materials at the anode or the cathode. In addition, we compare the effectiveness of our treatment method against a standard electrochemical presodiation protocol and analyze the surface chemistry of the anode in both cases with X-ray photoelectron spectroscopy (XPS).