Electron-Localized RuNi Nanosheet Assemblies Enable Low-Overpotential Mg-CO₂ Battery.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Magnesium-carbon dioxide (Mg-CO2) batteries offer a promising route for simultaneous CO2 conversion and energy storage.
• The formation of a stable, insulating MgCO3 discharge product limits the energy efficiency and practical application of Mg-CO2 batteries.
• Developing catalysts to control discharge products is crucial for enhancing battery performance.

Purpose of the Study:

• To engineer a catalyst that precisely tunes the discharge product in Mg-CO2 batteries.
• To overcome the limitations imposed by MgCO3 formation and improve energy efficiency.
• To enable the reversible formation and decomposition of a more favorable discharge product.

Main Methods:

• Development of an electron-localized Ru61Ni39 nanosheet assembly catalyst.
• Engineering the surface electronic structure of the catalyst.
• In situ electrochemical spectroscopy and theoretical studies to analyze reaction mechanisms.

Main Results:

• The Ru61Ni39 catalyst precisely tunes the discharge product from MgCO3 to MgC2O4.
• Electron transfer from Ni to Ru creates localized electrons, weakening MgC2O4 binding and suppressing MgCO3 formation.
• Achieved ultralow charge overpotential (0.07 V), record energy conversion efficiency (94.1%), and stable cycling (>580 h).

Conclusions:

• The electron-localized catalyst effectively mitigates cathode passivation by enabling reversible MgC2O4 formation and decomposition.
• Precisely engineered electronic structures are key to controlling reaction pathways in Mg-CO2 batteries.
• This work presents a significant advancement in Mg-CO2 battery technology, paving the way for highly efficient energy storage and CO2 utilization.