Abstract
Sn-based anodes for magnesium ion batteries (MIBs) arouse considerable interests, but are restrained by severe failure associated with poor electrochemical reactivity and massive volume changes during cycling. Herein, a multiphase alloying strategy is proposed to improve the electrochemical performance of Sn-based anodes through introducing an active Bi phase and an inactive Al phase to trigger the alloying reaction of Sn with Mg and accommodate large volume variations. A series of triphase Sn–Al–Bi alloys with different compositions were fabricated via a melting-solidification method. The significant performance improvement of the triphase Sn–Al–Bi electrodes stems from the interdigitated phase distribution accelerating Mg2+ ions transport and the multiphase buffering matrix alleviating the structural damage during cycling. Specially, the Sn55Al40Bi5 electrode exhibits attractive deformation capability, moderate areal specific capacity and long-term cycling stability up to 1000 cycles. Additionally, operando X-ray diffraction was performed to unveil the magnesiation/demagnesiation mechanisms of the Sn-Al-Bi electrodes. Noticeably, the Sn-Al-Bi electrodes show good compatibility with simple Mg salt electrolytes such as Mg(TFSI)2 in a full cell.
Published Version
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