A novel rechargeable Magnesium–Air battery using “All in one” Mg anode with high reversibility

Rechargeable Magnesium-Air batteries (RMABs) are attracting significant attention for energy storage due to their uniqueness of high theoretical energy density, inherent safety and low cost. However, the exhibited poor energy efficiency as well as their short lifespan seriously hinder their further development. The main reason is that lacking a suitable electrolyte to balance the different needs of the cathode and anode, which can not only maintain the high reactivity of cathode but also achieving reversible stripping/plating of Mg anode and suppress its side reactions. To this end, we explored a novel “All in one” Mg anode and constructed a 1 M NaOH (aqueous)/“All in one” Mg anode electrolyte system for RMABs with high reversibility and excellent cycle stability. In particular, the unique design of “All in one” Mg anode which integrates Mg alloy layer, solid anolyte layer and ion exchange membrane layer, realizing the efficient reversible charge and discharge cycle of Mg anode in 1 M NaOH solution (catholyte). Thence, the availability of alkaline aqueous catholyte also preserve its high ORR/OER reactivity of air cathode, enabling the designed RMABs owns high energy efficiency 69.7% and long lifespan of 506 h at 1 mA cm⁻².