The electrochemical properties of bismuth-antimony-tin alloy anodes for magnesium ion batteries

Abstract

Magnesium ion batteries (MIBs) have attracted wide attention due to their high theoretical specific capacity and abundance of Mg resources. However, the kinetics of magnesiation/demagnesiation is slow due to the formation of passive film in the interface between electrolyte and anode if pure Mg is directly employed as anode material. The development of alloy-type anodes is one of the promising strategies to address this issue. In this work, the electrochemical properties of bismuth-antimony-tin (Bi–Sb–Sn) alloy anodes for MIBs have been studied. Bi–Sb–Sn alloys with varied compositions have been synthesized using the mechanical alloying method. The Mg storage mechanism of Bi–Sb–Sn anodes has been clarified and the demagnesiation activity of Mg3Sb2 is improved by Sn substitution for Mg to form SbSn phase. Additionally, the electrochemical behavior of Bi–Sb–Sn anodes shows the formed multi-phase structure and the multi-step phase transition process are beneficial to the transport kinetics of Mg ions and the cycling stability and rate performance of anodes. Specifically, the Bi10Sb10Sn80 anode can deliver high capacity as 417 mAh g−1 at a current density of 500 mA g−1 and 517 mAh g−1 at a current density of 20 mA g−1, respectively.