Water scavenger as effective electrolyte additive and hybrid binder‐free organic/inorganic cathode for Mg battery applications

Abstract

Magnesium (Mg) metal batteries are an exciting prospect as a post lithium battery owing to the high energy density and low cost. However, the formation of a poorly ion-conductive passivation layer on Mg electrode remains a major limiting factor impeding their practical applications. Herein, we adopt a potential approach by investigating the effect of water scavengers such as hexamethyldisilazane (HMDS) and 2,2-dimethoxypropane (DMP) on the performance of MgCl2-based electrolyte dissolve in co-solvent of acetonitrile (ACN) and tetra ethylene glycol dimethyl (TEGDME). Interestingly, it is found that by introducing HMDS and DMP, the Mg ion transference number increases and the stripping/plating overpotential significantly decreases. Furthermore, organic/inorganic cathode based V2O5, graphene nanoplatelets, p-benzoquinone and 2-Ethylhexylamine is designed. This optimized electrolyte coupled with the hybrid cathode allows reversible Mg deposition/dissolution. Mg/(V2O5/p-benzoquinone) battery assembled with this electrolyte can cycle over 35 times with a specific discharge capacity over 60 mAhg−1. This study offers new approaches for designing high-performance rechargeable magnesium batteries.