Multivariate Approaches Boosting Lithium-Mediated Ammonia Electrosynthesis in Different Electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Lithium-mediated ammonia electrosynthesis in aprotic media shows high efficiency.
• Understanding the complex lithium-mediated nitrogen reduction system is crucial for optimization.
• Classical one-factor-at-a-time experiments are time-consuming for complex systems.

Purpose of the Study:

• To introduce a multivariate approach for optimizing lithium-mediated ammonia electrosynthesis.
• To reduce the number of experiments required for system optimization.
• To tailor the solid electrolyte interphase (SEI) for improved performance.

Main Methods:

• Utilized Doehlert design and surface response methodology for electrolyte optimization.
• Validated the approach with lithium tetrafluoroborate (LiBF4) salt.
• Investigated the impact of lithium salt and ethanol concentration on Faradaic efficiency (FE) and SEI.
• Proposed and tested lithium difluoro(oxalate) borate (LiFOB) for SEI modification.

Main Results:

• The multivariate approach effectively optimized electrolyte composition.
• Correlations between FE, lithium salt/ethanol content, and SEI were established.
• A novel fluorinated salt, LiFOB, was introduced to tailor the SEI layer.
• LiFOB-tailored SEI demonstrated enhanced stability and N2 permeability, boosting FE values.

Conclusions:

• Multivariate analysis is a powerful tool for optimizing complex electrochemical systems like ammonia electrosynthesis.
• The solid electrolyte interphase (SEI) plays a strategic role in lithium-mediated ammonia electrosynthesis.
• Tailoring the SEI with novel salts like LiFOB can significantly enhance ammonia production efficiency.