A Porous Polymer Coating as a Protective Interlayer for Neutral Aqueous Magnesium−Air Batteries

High Resolution Image Download MS PowerPoint Slide Magnesium-air batteries have drawn considerable attention for their potential high energy density and the abundance of magnesium. However, their practical application is restricted by the severe self-corrosion of the Mg anode in the aqueous electrolyte, which results in low energy efficiency and limited cycle life. A polymer membrane, polyvinylidene fluoride/poly(propylene carbonate)/magnesium(II) bis(trifluoromethanesulfonyl) imide [PVDF/PPC/Mg(TFSI) 2 ], was designed and synthesized on the magnesium surface to mitigate the self-corrosion and prevent direct contact between water and the magnesium surface. Owing to its porous structure, the membrane provides multiple pathways for magnesium ion transport. The PVDF/PPC/Mg(TFSI) 2 polymer layer enhanced corrosion resistance of the pure Mg anode. When employed as a protective layer on the magnesium anode, it suppressed the corrosion and decreased the discharge working voltage from 1.48 to 1.39 V at a current density of 1 mA cm −2, compared with commercial pure magnesium. The electrochemical performance of the polymer-coated Mg anode, the microstructure of the anode after discharge, battery performance, and the underlying discharge mechanism were investigated.