Intercalation species regulation in layered vanadium oxide scaffolds enables long cycle life Mg-metal anodes

Abstract

Magnesium-metal anode has received tremendous attention because of its rich resources, satisfied volumetric capacity and intrinsic safety. Three-dimensional scaffolds can homogenize the electrodeposition of Mg and elongate its lifespan, yet the lack of reasonable design strategies seriously hinders their practical implementation. Herein, as a proof-of-concept, a conjugated polyaniline intercalation strategy is employed to expand the interlayer of V2O5 nanosheets-assembling scaffolds, which display elongated cycle life and reduced Mg stripping/plating overpotentials. The underlying contributions of polyaniline intercalation are revealed to be the acceleration of the Mg-ions diffusion kinetics, the introduction of additional active sites by partial Mg-ions pre-insertion and the improved magnesiophilic property, all of which facilitate the subsequent uniform electrodeposition of Mg with boosted electrochemical kinetics. In contrast, V2O5 scaffolds without any intercalant or with water/polyaniline co-intercalation show inferior Mg stripping/plating reversibility and unsatisfied lifespan due to the non-uniform Mg electrodeposition or the passivation of Mg metal anodes by the escaping water molecules. Moreover, this facile conjugated polymer intercalation strategy is demonstrated to be applicable to other promising metal-anode chemistries.