Electrochemical evaluation of Sn/C composites as high-performance anodes for sodium-ion batteries

Abstract

Recently, the demand for high-performance secondary batteries with high capacities, long lifespans, and low cost has increased. We focus on a Tin (Sn) electrode as a high-capacity anode material for sodium-ion batteries and attempt to improve battery performance using its composites with various carbon materials (CMs). Electrode materials of micrometer-sized Sn powder and composites of Sn with three types of CMs were prepared by mechanical milling for 6 h. 2032-type coin cells were assembled, and constant current charge–discharge tests were performed for up to 50 cycles. The Sn/C composite anodes maintained high discharge capacities of 389–635 mAh g⁻¹ after 50 cycles, which are significantly higher than that off an electrode prepared using only Sn (132 mAh g⁻¹). The highest capacity was obtained using acetylene black as the CM. All the Sn/C composites prepared by mechanical milling had a larger specific surface area and more gaps than only Sn. As a result, stress was easily dispersed during the expansion and contraction of the electrode in the alloying and dealloying processes, which prevented the exfoliation of the active material during cycling and remarkably improved the battery performance.