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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-Bi x) anodes are fabricated through a facile dealloying strategy based on the Sn 100-x Bi x (x = 1, 5, 10, 43, at.%) precursor alloys. Among them, the P–Bi 10 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–Bi 5 and P–Bi 10 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. [Display omitted] • P-Bi x anodes were facilely fabricated through dealloying of Sn 100-x Bi x precursors. • The P–Bi 10 shows superior Mg storage performance and compatibility with Mg(TFSI) 2. • Operando XRD unveiled a simple two-phase reaction between Bi and Mg 3 Bi 2. [ABSTRACT FROM AUTHOR]