Reversible Magnesium Metal Anode Enabled by Cooperative Solvation/Surface Engineering in Carbonate Electrolytes

Magnesium metal anode holds great potentials toward future high energy and safe rechargeable magnesium battery technology due to its divalent redox and dendrite-free nature. Electrolytes based on Lewis acid chemistry enable the reversible Mg plating/stripping, while they fail to match most cathode materials toward high-voltage magnesium batteries. Herein, reversible Mg plating/stripping is achieved in conventional carbonate electrolytes enabled by the cooperative solvation/surface engineering. Strongly electronegative Cl from the-MgCl2 additive of electrolyte impairs the Mg center dot center dot center dot O = C interaction to reduce the-Mg2+ desolvation barrier for accelerated redox kinetics, while the-Mg2+-conducting polymer coating on the Mg surface ensures the facile-Mg2+ migration and the effective isolation of electrolytes. As a result, reversible plating and stripping of Mg is demonstrated with a low overpotential of 0.7 V up to 2000 cycles. Moreover, benefitting from the wide electrochemical window of carbonate electrolytes, high-voltage (> 2.0 V) rechargeable magnesium batteries are achieved through assembling the electrode couple of Mg metal anode and Prussian blue-based cathodes. The present work provides a cooperative engineering strategy to promote the application of magnesium anode in carbonate electrolytes toward high energy rechargeable batteries.

Automated summary

The reversible plating and stripping of magnesium has been achieved in conventional carbonate electrolytes through cooperative solvation/surface engineering. The addition of strongly electronegative Cl from the-MgCl2 additive impairs the Mg2+ desolvation barrier to accelerate redox kinetics, while a Mg2+-conducting polymer coating on the Mg surface ensures efficient Mg2+ migration and effective electrolyte isolation.