Dealloying induced Porous Bi anodes for rechargeable magnesium-ion batteries

Abstract

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-xBi_x (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–Bi₁₀ 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.