Unveiling the Oxygen Migration Retarding Effort of Carbon Coating During Disproportionation Enabling High-ICE and Long-Cycle-Life SiO Anodes

Abstract

Low initial coulombic efficiency (ICE) and poor cycling performance are the pain points that hinder the commercialization of silicon monoxide (SiO) anode materials. Unfortunately, disproportionation commonly used to enhance cycling performance significantly reduces prelithiation efficiency, making it difficult to achieve both high-ICE and long-cycle-life SiO anodes. Herein, the intrinsic contradiction between disproportionation and prelithiation is successfully reconciled through the ingenious application of the carbon coating strategy, achieving a synergistic enhancement among the three processes (carbon coating, disproportionation, and prelithiation). The prepared SiO anode exhibits excellent electrochemical performance with an ICE as high as 113.74% and a reversible capacity of 713.68 mAh g⁻¹ after 750 cycles. In-depth investigations reveal that carbon optimizes the distribution of Si and O within the disproportionated SiO, effectively thinning the SiO₂ surface layer and releasing the shielded Si, thereby enhancing reversible capacity and prelithiation efficiency. TG-FTIR analysis further elucidates the underlying mechanism, demonstrating that the carbon effectively inhibits the outward migration and escape of O during disproportionation. In summary, this study uncovers the pivotal role of carbon coating in regulating the disproportionation behavior, promoting efficient prelithiation, and enhancing the capacity recovery of SiO.