Dealloying induced Porous Bi anodes for rechargeable magnesium-ion batteries

Alloy-type anodes have attracted extensive attention in magnesium-ion batteries (MIBs) due to their low reaction potentials and high theoretical specific capacities. However, the kinetically sluggish Mg insertion/extraction and diffusion in electrode materials, as well as the huge volume changes resulting in the capacity decay limit their further development. Herein, a series of porous-Bi (P-Bix) anodes are fabricated through a facile dealloying strategy based on the Sn100-xBix (x = 1, 5, 10, 43, at.%) precursor alloys. Among them, the P-Bi10 anode delivers a high discharge specific capacity (376.0 mAh g-1 at 500 mA g-1), greatly improved rate capability (363.3 mAh g- 1 at 1000 mA g-1) and good cycling stability even at 2000 mA g-1 (104.0 mAh g-1 after 1000 cycles). Furthermore, operando X-ray diffraction (XRD) is performed to unveil the magnesiation/demagnesiation mechanisms of the P-Bi5 and P-Bi10 anodes, indicating a simple two-phase reaction process. Additionally, the P-Bi 10 anode displays good compatibility with conventional Mg salt electrolytes such as Mg(TFSI) 2 . Our findings could provide useful information on design of high-performance alloy -type anode materials for MIBs.