Binary Mg‐1 at%Gd alloy anode for high‐performance rechargeable magnesium batteries

Rechargeable magnesium batteries (RMBs) become a highly promising candidate for the large‐scale energy storage system by right of the high volumetric capacity, intrinsic safety and abundant resources of Mg anode. However, the uneven Mg stripping and large overpotential will cause a severe pitting perforation and the followed failure of Mg anode. Herein, we proposed a high‐performance binary Mg‐1 at% Gd alloy anode prepared by the melting and hot extrusion. The introduction of 1 at% Gd element can effectively reduce the Mg2+ diffusion energy barrier (0.34 eV) on alloy surface and induces the formation of a robust and low‐resistance electrolyte/anode interphase, thus enabling a uniform and fast Mg plating/stripping. As a result, the Mg‐1 at.% Gd anode displays a largely enhanced life of 220 h and a low overpotential of 213 mV at a high current density of 5.0 mA cm−2 with 2.5 mAh cm−2. Moreover, the assembled Mg‐1 at.% Gd//Mo6S8 full cell delivers a high rate performance (73.5 mAh g−1 at 5 C) and ultralong cycling stability of 8000 cycles at 5 C. This work brings new insights to design the new‐type and practical Mg alloy anodes for commercial RMBs. The 1 at% Gd element was introduced into Mg alloys for enhancing the Mg2+ migration kinetics on alloy surface and electrolyte/anode interface, rendering the uniform and fast Mg plating/stripping behaviors. Therefore, the Mg‐1 at.% Gd//Mo6S8 full cell delivers a high rate performance (73.5 mAh g−1 at 5 C) and ultralong cycling stability of 8000 cycles.