Effect of Sn Addition on Anode Properties of SiOx in Sodium-Ion Batteries (Supporting Information)

Our group has investigated the properties of lithium-ion battery anodes fabricated using Sn/SiOx (SiOx is a mixed phase of Si clusters and amorphous SiO2 matrix). The addition of Sn improves the conductivity of the SiO2 matrix, while the formation of the Li+-conductive Li2Si2O5 phase in the SiO2 matrix improves Si utilization. The charge–discharge cycle life is also extended. In this study, Sn-doped SiOx has been used to fabricate the anode of a sodium-ion battery, and its charge–discharge properties are evaluated. The addition of 3 wt% Sn to SiOx improves the cycle property, as revealed by charge–discharge tests. X-ray diffraction analysis confirmed that the Na+-conductive Na2Si2O5 phase is formed during the charging and discharging processes. These results indicate that adding Sn improves the electronic conductivity of SiO2, and Na2Si2O5 facilitated the movement of Na in the SiO2 matrix. Thus, the utilization of Si is enhanced, and a high discharge capacity is achieved.