Probing Mg Anode Interfacial and Corrosion Properties Using an Organic/Inorganic Hybrid Electrolyte

Abstract

The high self-corrosion rate of Mg in aqueous electrolyte generates H2, which is the main impediment to restrict the utilization of Mg-air batteries. However, organic/inorganic hybrid electrolyte is prone to reduce the Mg degradation. Herein, the effect of different ethanol fractions in water with 0.6M NaCl on corrosion behavior of Mg and battery discharge performances is demonstrated. The significant corrosion inhibition in a high content of ethanol (≥20 vol. %) in electrolyte is attributed to the formation of a thinner, more corrosion protective layer enriched in magnesium oxide as demonstrated by scanning electron microscopy, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Contrarily, in water-based electrolyte a thick, porous and rough layer principally composed of magnesium hydroxide is formed. By varying the ethanol to water fraction in the electrolyte in full battery cell, it is shown that even a small ethanol content (≤ 5 vol. %), can greatly enhance the electrochemical performances of Mg anode. Within several ethanol content, 0.5 vol. % demonstrates the best performances with a limited corrosion rate and greatly improved the discharge performance and the battery lifetime.

Keywords: Magnesium-air battery, Mg corrosion, Discharge properties, Organic/inorganic hybrid electrolyte, Surface layer