Galvanic Replacement of Magnesium Nanowire Arrays to Form Templated Antimony Frameworks

The emerging criticality of key constituents of Li-ion batteries has focused attention on more earth-abundant battery chemistries. Realizing the promise of alternative chemistries such as multivalent batteries requires the effective utilization of metal anodes. Utilization of pure magnesium as a negative electrode has been stymied by challenges such as formation of passivation layers, proclivity to form 3D deposits, and electromechanical instabilities. As such, considerable recent attention has focused on the design of composites that blend magnesium with a less electrochemically active metal. Here, we report a facile electroless galvanic replacement reaction to prepare 3D scaffolds incorporating antimony through the reaction of antimony halides with large-area electrodeposited magnesium nanowire arrays. The kinetics of the galvanic replacement reaction and the morphology of the resulting products are modulated by varying the activity coefficient and concentration of dissolved antimony-ions, which in turn is controlled through choice of the halide precursor and its solution concentration. The obtained products range from speckled antimony particles deposited across magnesium nanowires to continuous antimony scaffolds encasing electroactive magnesium cores and core–shell structures. The design of antimony-scaffolded composite architectures that nevertheless permit electrochemical accessibility of a magnesium core represents a promising scalable approach to the design of anodic frameworks.