Probing the Reversibility of Silicon Monoxide Electrodes for Lithium-Ion Batteries

Silicon monoxide is a potential high-capacity anode material for lithium-ion batteries. However, its low initial Coulombic efficiency hinders its adoption in commercial batteries. Here, we use an electrochemical approach, depth of discharge test, to study the origin of the irreversibility in SiO electrodes. We find two contributions to the irreversible capacity of SiO, depending on the reaction products during lithiation. Carbon-coating the material improves the reversible capacity as it increases its electrical conductivity. Disproportionation is an effective way to decrease irreversibility in the initial cycle with the formation of large cluster of SiO₂ which is electrochemically inactive. Though, the reversible capacity is reduced.