Effect of Electrolytes on Electrochemical Properties of Magnesium Electrodes

Abstract

Magnesium (Mg) deposition and dissolution behaviors of 0.2 M MgBu 2-(AlCl 2 Et) 2 , 0.5 M Mg(ClO 4) 2 , and 0.4 M (PhMgCl) 2-AlCl 3-based electrolytes with and without tris(pentafluorophenyl) borane (TPFPB) are investigated by ex situ scanning electron microscopy (SEM) and galvanostatic cycling of Mg/copper (Cu) cells. To ascertain the factors responsible for the anodic stability of the electrolytes, linear sweep voltammogrametry (LSV) experiments for various electrolytes and solvents are conducted. The effects of TPFPB as an additive on the anodic stability of 0.4 M (PhMgCl) 2-AlCl 3 /THF electrolyte are also discussed.

Tailoring Ion-Conducting Interphases on Magnesium Metals for High-Efficiency Rechargeable Magnesium Metal Batteries

“…Nevertheless, the construction of a rechargeable Mg battery (RMB) using conventional organic electrolytes is generally plagued by a significantly large impedance associated with the passivation layer on Mg electrodes, which mainly consists of magnesium oxide (MgO) or hydroxide (Mg­(OH) 2 ). , This Mg 2+ -insulating layer is thought to naturally form on the Mg surface upon exposure to most organic electrolytes used for rechargeable batteries or even upon contact with an extremely low level of contaminants. , In the early stage of research on RMBs, most efforts focused on inventing new electrolytes to mitigate the formation of insulating layers. For example, Grignard reagent-based alkyl halide electrolytes (e.g., dichloro-complex (DCC) and all-phenyl complex (APC)) have been demonstrated to enable the reversible stripping/deposition process of Mg metal in the electrochemical system to some extent. − However, these electrolytes mostly suffer from the poor oxidation stability limited to ∼3 V (vs Mg/Mg 2+ ), and their nucleophilic nature is incompatible with electrophilic cathodes. , Moreover, the highly corrosive halogen elements make the metallic battery components (e.g., current collectors) vulnerable to corrosion, leading to critical safety issues. , …”