Enhanced Li-ion diffusion improves N₂-to-NH₃ current efficiency at 100 mA cm^-2.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Electrochemical nitrogen (N2) reduction offers a sustainable route for ammonia (NH3) synthesis, potentially reducing carbon emissions.
• Current methods are limited by slow lithium-ion desolvation and diffusion at the solid electrolyte interphase (SEI), hindering NH3 productivity.
• Developing efficient SEI architectures is crucial for advancing ambient temperature and pressure NH3 production.

Purpose of the Study:

• To design and implement a novel layered SEI architecture for enhanced lithium-ion flux.
• To improve the efficiency and productivity of electrochemical nitrogen reduction to ammonia.
• To investigate the impact of the new SEI on NH3 production at high current densities.

Main Methods:

• Fabrication of a layered SEI comprising inorganic materials with low ion-binding affinity and high ion conductivity.
• Electrochemical characterization of the SEI performance in a lithium difluoro(oxalato)borate electrolyte.
• Measurement of Faradaic efficiency, energy efficiency, and long-term stability for NH3 production.

Main Results:

• The novel SEI architecture increased lithium-ion flux by two orders of magnitude.
• Achieved a 98% Faradaic efficiency and 21% energy efficiency for NH3 production at 100 mA cm-2.
• Demonstrated sustained 80% Faradaic efficiency over 40 hours of operation.

Conclusions:

• The concerted desolvation:diffusion layered SEI design significantly enhances Li-ion flux for efficient electrochemical NH3 production.
• This strategy enables high-performance NH3 synthesis at industrially relevant current densities.
• The developed SEI offers a promising pathway for sustainable and low-carbon ammonia manufacturing.