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

Abstract

Expectations for high-performance secondary batteries with high capacity, long life, and low cost have increased in recent years. We have focused on a Tin (Sn) electrode as a high-capacity anode material for sodium-ion batteries, and attempted to improve battery performance using composites of Sn with various carbon materials (CMs). Electrode materials with micrometer-sized Sn and composites with Sn and 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. As a result, the Sn/C composites maintained high discharge capacities of 389–635 mAh g^-1 after 50 cycles, which were significantly higher than that for an electrode prepared with Sn alone (132 mAh g^-1). The highest capacity was obtained using acetylene black (AB) as the CM. The Sn/C composites obtained by mechanical milling have a larger specific surface area than Sn alone, and has a larger space per unit area. Therefore, it is considered that stress is easily dispersed during expansion and contraction due to the alloying-dealloying reaction and exfoliation of the active material during the charge-discharge cycles was prevented, and contributed to the improvement of battery performance.