In Situ Alloying Reaction Constructing Rich Magnesophilic Sites Toward Highly Stable and High-Rate Rechargeable Magnesium Batteries

Abstract

Rechargeable magnesium batteries (RMBs) have emerged as a promising alternative to lithiumion batteries owing to abundant magnesium (Mg) resources and the high volumetric capacity.Nevertheless, the practical application of RMBs is constrained by the inadequate compatibility between Mg metal anodes and electrolytes, which manifests as issues such as passivation layer formation and dendrite growth. Herein, to address these challenges, a controllable vacuum thermal evaporation technology was firstly employed to construct an ultra-thin and flat bismuth (Bi) nanoparticle artificial interface on the Mg metal surface (Bi@Mg), yielding a high-performance Mg anode for a practical Mg battery pouch cell. During the charge-discharge cycling, the nano-sized Bimetal particles undergo an in situ alloying reaction to form the Mg 3 Bi 2 alloy layer, generating abundant magnesiophilic sites that accelerate Mg 2+ ion transport and induce uniform Mg deposition.Benefiting from this unique Mg 2+ ion deposition mechanism, the symmetric Bi@Mg cell exhibits remarkable cycling stability, with a lifespan exceeding 4000 h (at the current density of 0.2 mA cm - 2 ) with low polarization in the all-phenyl complex (APC) electrolyte. Furthermore, the Bi@Mg||Mo 6 S 8 full cell demonstrates a high specific capacity of 73.78 mAh g -1 with 94.86% capacity retention even after 2000 cycles at 1 C. Notably, Bi@Mg anode enables stable operation of a pouch cell (100 cycles at 1 C), further confirming its potential for practical applications. This study provides a novel strategy for constructing stable Mg metal anodes and offers valuable insights for the development of high-performance practical RMBs.